Transcript BL 1021 – Unit 4

BL 1021 – Unit 4
The Human Organ Systems
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Digestive
Circulatory
Respiratory
Immune
Endocrine
Reproductive
Nervous
Skeletal
Muscular
Excretory
BL 1021 – Unit 4.1 - 4.5
The Digestive System
4.1 Nutrition Types
• All animals are ingestive heterotrophs, meaning
they consume organic molecules that can then be
used to manufacture their necessary molecules or
can be used for necessary metabolic reactions.
• These organic molecules are found in the food that
animals eat. However, depending on the type of
food, animals will consume different types of
organic molecules. (Recall the organic molecules
important for life include proteins, nucleic acids,
carbohydrates and lipids).
4.1 Nutrition Types
• Herbivores are animals that consume plant material
only. Because plants contain cell walls, these
animals must have a way of breaking through the
cell walls to acquire the nutrition. They will have long
digestive tracts because the digesting and
processing of plant cells requires more work.
• Carnivores are those animals that eat meat. They
are predators and have adaptations such as sharp
pointy teeth for ripping and tearing flesh which is
high in protein.
• Omnivores are animals that consume both plant
material and other animals.
4.2 Animal Nutrition Process
• No matter the type of food consumed or the type
or lack of digestive system, all animals go through
four stages in their overall nutrition.
• Ingestion, the first stage, is the consumption of food
through a mouth. The mouth will often have
adaptations for catching food (tentacles) or
chewing (teeth, jaws) to increase surface area and
mechanically break the food apart.
4.2 Animal Nutrition Process
• Digestion. The process of digestion, the second
stage, involves the use of enzymes to chemically
break the food into their monomers.
• Proteins are broken down to amino acids,
carbohydrates to single sugars, etc.
• Digestion happens outside of the cells of the body.
Even though the digestive tract is inside an animal,
the actual digestion takes place in the cavity inside.
The cells of the digestive tract take up the fully
digested food molecules.
4.2 Animal Nutrition Process
• Absorption is the third stage in which the individual
monomers that resulted from the digestion are
absorbed through the tract and transported
wherever they are needed.
• Elimination. Any material not absorbed is
considered waste and is excreted (in solid form as
feces) in the fourth stage of elimination. Elimination
should not be confused with excretion. Excretion is
the removal of products made from the bodies
chemical reactions. Excretion involves the expelling
of urine or similar substances.
4.3 Human Digestive System
• The human digestive
tract begins at the
mouth cavity where
food is ingested. Teeth
are present to aid in
mechanical
breakdown of food.
• Mechanical digestion
physically breaks down
food.
4.3 Human Digestive System
• The salivary glands
release saliva. This
serves as a lubricant for
the food. The saliva
also contains enzymes
to begin carbohydrate
digestion, buffers to
stabilize pH, and
antibacterial agents to
help in the prevention
of tooth decay.
4.3 Human Digestive System
• Saliva begins the
process of chemical
digestion – the
breaking of chemical
bonds in food to make
it into the simpler forms
the body can use. Most
parts of the digestive
system have both
chemical and
mechanical digestion.
4.3 Human Digestive System
• The food, once
chewed, is
manipulated by the
tongue into a ball
called a bolus.
• The bolus is pushed
down into the
esophagus; a tube that
connects the mouth
cavity to the stomach.
4.3 Human Digestive System
• Smooth muscle exists in
the walls of most of the
digestive system. This
tissue causes periodic
contractions of the
tract that squeeze, mix
and push along food.
These waves of
contractions are called
peristalsis.
4.3 Human Digestive System
• The entrance into the
stomach is called the
cardiac sphincter which
opens to allow food to
enter and then closes.
• Once within the stomach,
longitudinal and circular
muscles within the
stomach 'churn' the food
and the enzymes are
released to continue
chemical digestion.
4.3 Human Digestive System
• The combination of
hydrochloric acid and
digestive enzymes will
begin to break down
proteins as well as
carbohydrates.
• The mixture, at this
point, is extremely
acidic and is a soupy
mixture known as
chyme. It remains in the
stomach digesting for
approximately six hours.
4.3 Human Digestive System
• The sphincters at the
entrance and exit of
the stomach are
important. If the
cardiac sphincter
malfunctions, chyme
will move back into the
esophagus, causing
heartburn and possibly
damaging the tissues of
the esophagus.
4.3 Human Digestive System
• After a while, the
chyme will leave the
stomach through the
pyloric sphincter and
into the small intestine.
• The duodenum is the
top portion of the small
intestine and also aids
in the chemical
digestion of proteins
and fats.
4.3 Human Digestive System
• Accessory glands, such
as the liver, gall
bladder, and pancreas
surround the
duodenum producing
enzymes and releasing
them into the
duodenum to aid
digestion.
4.3 Human Digestive System
• The remainder of the
small intestines are the
jejunum and ileum. In
these two sections, the
final stages of digestion
occur and food
molecules are now
ready to be absorbed.
• Throughout the small
intestine, food is mixed
and pushed along by
peristalsis movements.
4.3 Human Digestive System
• After the small intestine,
the food enters the large
intestine. At this point, the
majority of nutrition has
been extracted from the
food.
• Along the way, a large
amount of water has
been added to the food
(saliva, acids, etc.) and it
is now reabsorbed to
reduce the water lost in
feces.
4.3 Human Digestive System
• After the final journey
through the large
intestine, the undigested
material collects in the
colon until it is eliminated
as feces.
• Feces contains
undigested food and
leftover digestive
materials (acids, bile,
etc.) only. Feces does not
include other wastes
made from metabolic
activity.
4.3 Human Digestive System
• The overall purpose of the digestive system is to
isolate and break down complex organic
molecules into the building blocks needed to build
similar materials.
• As such, animals recycle organic materials (the
protein in it’s food will become proteins in itself).
4.4 Types of Digestive Tracts
• In very simple animals, there is a incomplete
digestive system with only a single-gated cavity
where digestion takes place. In phyla such as
cnidaria and platyhelminthes, a single mouth/anus
gates a cavity that performs all four stages of
digestion with no specialization.
• This is much less efficient than the specialized
digestive regions seen in a complete digestive
system. In incomplete systems, food and waste will
mix, while in a complete system food will flow only
one way.
4.5 Nutrition Problems
• Obesity occurs when an organism obtains too much
stored energy and thus its height to weight ratio goes
outside the norm. This causes strain on the
cardiovascular system.
• Undernutrition occurs when an organism does not get
enough food to obtain enough energy to perform all its
functions. This will cause the organism to have to break
down fat stores (and ultimately muscle) to support itself.
• Malnutrition refers to an organism that is not receiving
enough of one or more particular nutrients. The organism
may have enough calories to live but certain types of
function may be impaired (iron deficiency, low-protein
diet, etc.)
BL 1021 – Unit 4.6 – 4.8
The Circulatory System
4.6 Circulatory Systems
• As animals get larger and more complex, the need
for a system to more nutrients and wastes from
place to place develops.
• There are three elements common to all circulatory
systems:
• A liquid carrier substance (blood)
• Vessels to carry the liquid (may not carry the liquid
all the time however)
• A pump to move the liquid (heart)
4.7 Open and Closed
Circulatory Systems
• The Open Circulatory
system is the more
primitive circulatory
system in which a heart is
present and the fluid
being pumped is a
combination of blood
and body cavity fluid.
• As the fluid does not stay
in the vessels the whole
time, it mixes with fluids
throughout the body to
form hemolymph.
• This type of system is
found in Phylum
Arthropoda.
4.7 Open and Closed
Circulatory Systems
• This open system has
one major
disadvantage – the
organism must keep
moving to assure that
the hemolymph bathes
all the cells of the
body.
4.7 Open and Closed
Circulatory Systems
• A closed circulatory
system is a more recent
and more complex
development. In a
closed system, the
blood never leaves the
vessels and does not
mix directly with the
various intercellular
fluids.
4.7 Open and Closed
Circulatory Systems
• By having vessels
reaching to every
corner of the creature,
blood can reach all
cells of the body
without needing the
body to move.
• In this type of system,
blood flows in a direct
loop or circuit.
4.7 Open and Closed
Circulatory Systems
• Closed systems have
three types of vessels to
carry blood:
• Arteries deliver blood
from the heart. They
have thick and strong
wall to handle the highpressure blood that
comes directly from the
heart.
4.7 Open and Closed
Circulatory Systems
• Veins return blood to
the heart. They are
thinner than arteries as
the blood has dropped
in pressure by the time
it reaches them.
• Veins have one-way
valves to prevent
blood from flowing
backwards and
pooling up.
4.7 Open and Closed
Circulatory Systems
• Capillaries are the
middle-section of the
system. These are very
small and very thin
vessels that can reach
all the parts of the
body. Their thin walls
allows them to easily
diffuse nutrients and
wastes between the
tissues and the blood.
4.8 Human Circulatory System
• The human cardiovascular system is composed of a
powerful four chamber heart (two atria which
receive blood and two ventricles which send
blood), a multitude of veins, arteries and network of
capillaries, and blood.
• The circuit of blood is known as double circulation
because blood will make its way through the heart
twice (through the right side then the left side)
before completing its circuit through the body. In a
very simplified description, the flow of blood is as
follows
4.8 Human Circulatory System
• On this diagram, the
left of the diagram
shows the right side of
the body.
• The path of blood
through the body:
• 1) Blood enters the right
ventricle. This
compartment seals off
and compresses to
release high-pressure
blood.
4.8 Human Circulatory System
• 2) Blood leaves the
heart and travels to the
lungs via the
pulmonary artery.
• 3) In the lungs, the
blood takes up oxygen
and releases carbon
dioxide.
• 4) Blood returns to the
heart through the
pulmonary vein.
4.8 Human Circulatory System
• The path so far is known
as the pulmonary
circuit. This pathway
gets fresh oxygen that
will be delivered to the
rest of the body in the
next step, the systemic
circuit.
• That circuit will carry
nutrients to the body’s
tissues and remove
wastes.
4.8 Human Circulatory System
• 5) Once blood returns
from the pulmonary
vein, it collects in the
left atrium.
• 6) The blood then
pumps into the left
ventricle.
• 7) The ventricles
contract, pumping out
the blood at max
pressure into the aorta.
4.8 Human Circulatory System
• 8) Blood heads to the
various parts of the
body from the aorta
through a number of
smaller arteries.
• Arteries connect to
capillary beds which
exchange substances
with the body’s tissues.
4.8 Human Circulatory System
• 9) After exchanging
substances with the
body, the blood
collects in a series of
veins that ultimately
combine into the vena
cava.
• 10) The blood collects
into the right atrium.
4.8 Human Circulatory System
• From the right atrium
blood returns to the
right ventricle to
complete the cycle.
• Both atria contract at
the same time and
both ventricles
contract at once.
BL 1021 – Unit 4.9 – 4.14
The Respiratory and Defense Systems
4.9 Respiratory Systems
• One of the major duties of the circulatory system is
to move gases from place to place in the body.
Living cells need a fresh supply of oxygen and need
waste carbon dioxide removed.
• The respiratory system works to take in new oxygen
from the environment and expel carbon dioxide. By
working together, all of the cells of the body get the
oxygen they need.
4.9 Respiratory Systems
• Oxygen is picked up in
the blood during the
pulmonary circuit.
Carbon dioxide is
released into the lungs
at this same time.
• During the systemic
circuit, the oxygen is
delivered to all of the
body’s tissues and
carbon dioxide is
picked up from cells.
4.9 Respiratory Systems
• Some oxygen is carried
in the blood by being
dissolved into the liquid,
or plasma, component
of the blood.
• The majority, however,
is carried by red blood
cells called
erythrocytes. These a
specialized cells filled
with the protein
hemoglobin which is an
oxygen carrier.
4.9 Respiratory Systems
• Hemoglobin has a
special bonding
relationship with
oxygen.
• It strongly binds oxygen
in oxygen-rich areas
(lungs) but releases
oxygen in oxygen-poor
areas (body tissues).
• This allows hemoglobin
to deliver oxygen
where it is most
needed.
4.10 Types of Respiratory Surfaces
• For a gas like oxygen to be taken up, a special set
of cells called a respiratory surface must exist.
• This surface must be thin enough to allow gases to
diffuse in and out easily.
• This surface must be moist to allow gases to be able
to dissolve into the liquid to be absorbed.
• Respiratory surfaces come in a variety of forms:
4.10 Types of Respiratory Surfaces
• Skin
• (Frogs, earthworms)
• Some organisms will
have a very thin skin
layer with capillaries
close enough to the
surface to allow gas
exchange.
• In these type of
animals, the skin must
be kept moist to
breathe.
4.10 Types of Respiratory Surfaces
• Gills
• (Fish and most aquatic
animals)
• Gills have a series of
capillaries close to the
surface.
• Gills do not need to worry
about drying out as they
re in the water.
• Gills typically have some
sort of protective cover to
keep out dirt and
parasites.
4.10 Types of Respiratory Surfaces
• Tracheae
• (insects)
• As insects live on land,
they need an
internalized system to
reduce the water lost
from the respiratory
surface.
• Tracheae are small
tube inlets on the body
that branch out within.
4.10 Types of Respiratory Surfaces
• The majority of the
tracheae is dry, with
only the “dead end”
regions coated in
water to allow diffusion.
• Tracheae branch out
to reach all the cells of
the body due and thus
insects are limited in
size as these simple
tubes only work on a
small scale.
4.10 Types of Respiratory Surfaces
• Lungs
• (mammals)
• Lungs are an internal
respiratory
compartment with a
highly-branched
structure.
• Lungs work with the
circulatory system to
deliver their gases.
4.10 Types of Respiratory Surfaces
• Lungs are localized to
one area and do not
need to reach all of the
body because the
closed circulatory
system is capable of
delivering all the gases
between the lungs and
the body.
4.11 Human Respiratory System
• The human respiratory
system, is found in the
body cavity, is
protected by the rib
cage, is lined on the
bottom by the
diaphragm and is
entered through the
nasal/mouth cavity.
4.11 Human Respiratory System
• The diaphragm pulls
on the lungs,
expanding them and
creating a negative
pressure that pulls air in.
• When the diaphragm
relaxes, the lungs
decrease in volume,
pushing air out.
4.11 Human Respiratory System
• The respiratory system is
made up of two lungs,
a left and right. Air
enters through the
nasal cavity or mouth.
• The nasal cavity
conditions the air to
make it safe for the
sensitive tissues of the
lungs.
• The nasal cavity acts as
a filter and humidifier of
the air.
4.11 Human Respiratory System
• From the nasal cavity
air travels through the
larynx. This is the voice
box that contains the
vocal cords.
• The vocal cords move
in order to cause
different vibrations
which create different
sounds to speak.
4.11 Human Respiratory System
• From the larynx, air
continues down the
trachea (windpipe)
and into two bronchi,
tubes which lead to
each lung.
• No gas exchange
occurs at this stage,
these are just piping to
feed air into/out of the
lungs.
4.11 Human Respiratory System
• The bronchi further
branch within the lung
into several smaller
tubes called
bronchioles. Each
bronchiole ends in a
series air sacs called
alveoli, which appear
like clusters of grapes.
4.11 Human Respiratory System
• The alveoli are thinwalled spheres with a
very thin liquid coating
on the inside.
• This is the site of gas
exchange.
• By having all these
small sacs, the surface
for gas exchange is
maximized.
4.11 Human Respiratory System
• Special chemicals exist
in the fluid of the lungs
that keep a thin
coating of liquid on all
of the lung’s inner
surface.
• Excess fluid buildup, like
in pneumonia, is
dangerous as it acts as
a barrier to gas
exchange, preventing
normal breathing.
4.11 Human Respiratory System
• Special chemicals exist
in the fluid of the lungs
that keep a thin
coating of liquid on all
of the lung’s inner
surface.
• Excess fluid buildup, like
in pneumonia, is
dangerous as it acts as
a barrier to gas
exchange, preventing
normal breathing.
4.12 The Defense Systems
• The first line of defense in the body is a general
series of barrier against multiple threats.
• These nonspecific external defense mechanisms
are in place to block all invaders. If an infectious
organism cannot get inside the body, it cannot
infect the body.
4.12 The Defense Systems
• The nonspecific external defense systems:
• The Skin acts as a physical barrier
• Oil and acids are produced on the skin to kill off
microorganisms
• Hairs in the nasal tract
• Mucus in internal membranes traps invaders
• Cilia in mucous membranes move mucus out
• Sweat, saliva and tears have anti-bacterial
materials
• Stomach acid kills swallowed bacteria
4.12 The Defense Systems
• The body also has internal nonspecific defences.
 White blood cells (leukocytes) destroy foreign particles and
dead cells.
 Interferon (proteins produced by virus-infected body cells)
help healthy cells resist viruses
 Complement proteins coat the surface of microbes making
them easier for white blood cells to identify them
 The inflammatory response (injured cells and invading
microorganisms release chemicals that trigger the release of
chemicals such as histamine which causes site to swell which
promotes healing)
 Damaged cells release prostaglandins which increase blood
flow to area
 Cells may release pyrogens which can stimulate a fever
4.13 The Lymphatic System
• The lymphatic system
carries fluid around the
body and is the major
carrier of the immune
system.
• The system also collects
lipids from the digestive
system as they are
extracted from food.
4.13 The Lymphatic System
• The lymphatic system is
an open system; it
collects fluid from the
spaces between the
tissues and then feeds it
back into the
circulatory system.
• The fluid that is carried
through is lymph.
4.13 The Lymphatic System
• Germs captured by the
lymph are filtered out in
the lymph nodes. These
are small masses of
tissue in the network of
lymph vessels.
• Antibodies are made in
the nodes. Antibodies
are used to label and
trap invaders.
4.13 The Lymphatic System
• At lymph nodes,
invading cells can also
be destroyed by white
blood cells.
• When lymph filters
through the spleen,
special white blood
cells destroy bacteria,
dead tissue and foreign
material.
4.13 The Lymphatic System
• At lymph nodes,
invading cells can also
be destroyed by white
blood cells.
• When lymph filters
through the spleen,
special white blood
cells destroy bacteria,
dead tissue and foreign
material.
4.14 The Immune System
• The immune system is a series of defenses to
specifically target invaders.
• The cells that are part of this defense system are
white blood cells, or leukocytes. They come in two
basic types which work together to seek out and
destroy the organisms or substances that cause
disease.
• Leukocytes are produced and stored in the thymus,
spleen and bone marrow but will move throughout
the body to fight infections.
4.14 The Immune System
• The immune system is a series of defenses to specifically
target invaders.
• The cells that are part of this defense system are white
blood cells, or leukocytes. They come in two basic types
which work together to seek out and destroy the
organisms or substances that cause disease.
• Leukocytes are produced and stored in the thymus,
spleen and bone marrow but will move throughout the
body through the lymphatic vessels to fight infections.
4.14 The Immune System
• Two major types of leukocytes:
• Phagocytes engulf and destroy invaders
• Lymphocytes allow the body to label, remember,
and recognize invaders, allowing the body to better
fight off invaders in repeated infections. There are
two major types: one labels invaders while the other
works more to destroy them.
4.14 The Immune System
• Two major types of lymphocytes:
• All lymphocytes begin life in the bone marrow.
Some cells will remain there and mature into B
Lymphocytes.
• These cells detect antigens (any invading
substance) and create antibodies that latch onto
them, labeling them for destruction.
4.14 The Immune System
• Antibodies stay in the body and thus the body is
able to easily fight off an infection much easier
during repeated infections.
• Vaccinations work by giving the body a weakened
or dead version of an antigen to learn from and
create antibodies from. This allows the body to be
ready for certain infections and when the body
encounters them again. This is not always 100%
effective as bacteria can evolve and change so
that they are not recognized by antibodies.
4.14 The Immune System
• Other lymphocytes will move from the bone marrow
to the thymus gland and mature into T
lymphocytes.
• T cells work to destroy cells that it recognizes as
invaders. This may be done directly or by detecting
cells labeled by antibodies. Thus, B cells and T cells
work together in many cases to destroy invaders. Tcells can also call in other white blood cells to help
destroy the invaders in some cases.
4.14 The Immune System
• There are two general
pathways for immune
defense:
• Humoral or AntigenMediated immunity
involves B cells creating
new antibodies by
“sizing-up” the invaders
and then circulating
those antibodies
around the body to
label all of the invaders.
4.14 The Immune System
• Humoral immunity
works well on bacteria,
microorganisms, and
fungi as it can easily
label them for
destruction.
4.14 The Immune System
• The other major type of
immunity is Cellmediated immunity.
• This system targets
infected cells for
destruction directly
using T-cells.
4.14 The Immune System
• Cell-mediated
immunity is best at
destroying viruses and
other invaders that get
inside of the body’s
cells as it will destroy
the host cell as well.
4.14 The Immune System
• With both types of immunity, cells can be mistakenly
labeled as harmful.
• In auto-immune diseases, immune cells label a
certain type of cell in the body as harmful and
destroy them. This causes damage to healthy tissues
and loss of function. Type I diabetes is caused b the
body destroying the cells of the pancreas that
produce insulin. Without these cells, the body
cannot regulate its blood sugar levels properly.
4.14 The Immune System
• Blood transfusions can cause problems too. If a
person receives blood that is a different type than
theirs, the body may label the new blood cells as
invaders and destroy them – causing clots of dead
cells to form in the blood vessels.
• Similarly, when a person receives a new organ from
a donor, the body may label the new cells as
invaders and destroy the organ in a process known
as rejection. The organ recipient may have to take
drugs to supress the immune system for the rest of
their lives. This may make them more vulnerable to
other infections.
BL 1021 – Unit 4.15 – 4.18
The Endocrine and Reproductive Systems
4.15 The Endocrine System
• The endocrine system is a series of glands that
secrete hormones that control the organs of the
body.
• Glands are a collection of epithelial cells that
secrete special chemical messengers called
hormones.
• Hormones are a variety of types of chemicals that
move through the body and trigger different kids of
responses in various organs.
4.15 The Endocrine System
• Hormones leave their
gland and travel to all
the parts of the body
through the
bloodstream.
• Hormones can only act
on a cell if it has a
receptor on its surface.
Therefore, any given
hormone will only
affect some cells of the
body.
4.15 The Endocrine System
• Different cells may also
have different types of
receptors which means
that one hormone can
cause very different
effects in different cells.
• In fact, many hormones
will cause very
opposite effects in
different cells.
4.15 The Endocrine System
• Most hormones work though negative feedback
loops.
• This works by a hormone getting produced to fix a
problem in the body. The hormone then causes an
effect to counteract the imbalance. Once
everything is back to normal, the body instructs the
gland to stop producing the hormone.
• This process lets the body use only as much
hormone as needed and prevents the body from
over-compensating for a problem.
4.15 The Endocrine System
• The hypothalamus is a
part of the brain that
can send commands
to the endocrine
glands.
• It works directly with the
pituitary gland. The
commands from the
hypothalamus instruct
the pituitary to release
different hormones.
4.15 The Endocrine System
• The pituitary hormones
control the body’s
systems in various ways.
• Many of the hormones
affect other glands of
the body, so the
pituitary is considered
the controller of the
endocrine system.
4.15 The Endocrine System
• The thyroid is a gland
that releases hormones
that stimulate growth
and metabolism.
• It is controlled by the
pituitary gland and the
hypothalamus.
4.15 The Endocrine System
• Normally, the thyroid is
controlled by negative
feedback – when the
body’s metabolism is
low, it makes more
hormones to boost the
metabolism. When the
body’s metabolism is
too high, the thyroid
stops producing
hormones.
4.15 The Endocrine System
• If the thyroid isn’t
producing enough
hormones,
hypothyroidism occurs,
causing a person to be
tired, weak and gain
weight.
• If the gland is overactive, hyperthyroidism
occurs where a person
will be very hyper,
twitchy and may lose
weight.
4.15 The Endocrine System
• The adrenal glands are
two small triangular
glands attached to
each kidney.
• Many of the adrenal
hormones work with the
kidneys to control
water and salt
balance.
4.15 The Endocrine System
• Two major adrenal
hormones are
adrenaline and
noradrenaline.
• These two work in
complement to
activate certain
systems of the body
and to deactivate
others.
4.15 The Endocrine System
• Adrenaline excites the
muscles and senses. It
causes a person to be
very alert and ready to
either fight or flee from
danger.
• Adrenaline also slows
down secondary
systems like digestion,
allowing the body to
put all its energy into
survival.
4.15 The Endocrine System
• Noradrenaline works in
the opposite way –
calming the body,
relaxing the muscles
and nerves while
promoting digestion
and healing.
Noradrenaline is
important for recovery
after an excited state.
4.15 The Endocrine System
• The Pancreas has a
portion of its mass
dedicated to helping
digestion. However, the
pancreas also plays a
major role as a
hormone-releasing
organ.
4.15 The Endocrine System
• Glucagon is one of the
major hormones
produced in the
pancreas. Glucagon
causes the body’s
stores to release more
sugars into the blood.
• This is needed in times
of fasting to keep an
energy supply to the
body’s cells.
4.15 The Endocrine System
• Insulin complements
glucagon as it works to
lower blood sugar
levels. This is important
during meal times to
prevent sugar levels
from going too high.
• Diabetes is a condition
where insulin is not
working properly.
4.15 The Endocrine System
• Type I Diabetes is
caused by the body’s
insulin-producing cells
not working properly.
This is often caused by
an autoimmune
condition where the
body destroys part of
the pancreas.
4.15 The Endocrine System
• Type II Diabetes is a
result of the body’s
receptors for insulin not
working properly any
more. Poor diet and
exercise (as well as
genetic factors) can
cause insulin to not be
as effective and thus
the body has difficulty
lowering blood sugar
levels.
4.15 The Endocrine System
• The reproductive
organs, specifically the
testes and ovaries, play
a role in secreting
important hormones.
• Many of these
hormones target the
reproductive system
directly (such as timing
the menstrual cycle or
pregnancy).
4.15 The Endocrine System
• Other hormones from
the reproductive
organs cause effects in
the whole body.
• Many of these
hormones cause the
changes associated
with aging, particularly
puberty and
menopause.
4.16 Types of Animal Reproduction
• Animals can reproduce in many ways. Some
animals have more than one possible method of
reproduction while others (like humans) only have
one.
• Asexual reproduction occurs when one organism
creates new offspring that are identical to it
(clones).
4.16 Types of Animal Reproduction
• Types of animal asexual reproduction:
• Budding – a new organism is grown off of the
original before detaching as a independent
creature. Only possible in more basic animals like
jellyfish and echinoderms.
• Fragmentation/Regeneration – an organism is
broken into segments that can each regrow into a
full organism. Found in tiny worms and echinoderms.
4.16 Types of Animal Reproduction
• Types of animal asexual reproduction:
• Parthenogenesis – females produce an egg that
develops into a full organism without being
fertilized. Found in fish, insects and some frogs and
lizards.
4.16 Types of Animal Reproduction
• Sexual reproduction requires the union of two
gametes to create a genetically unique new
offspring. Can occur two ways:
• External Fertilization – both parents release gametes
into the environment (almost always underwater)
and fertilization occurs outside of the mother. This
has the advantage of creating many offspring, but
they are unprotected and many will be eaten by
predators.
4.16 Types of Animal Reproduction
• Internal Fertilization – the process of fertilization
occurs within the mother organism. The young are
then developed further within the womb and either
released as eggs or kept longer and born fully
developed. Many species will also nurse and care
for their young after birth as well.
• External fertilization uses strength in numbers to
produce so many offspring that statistically some
will survive, internal fertilization places more
investment in each offspring to give them a higher
chance of survival.
4.16 Types of Animal Reproduction
• Internal Fertilization – the process of fertilization
occurs within the mother organism. The young are
then developed further within the womb and either
released as eggs or kept longer and born fully
developed. Many species will also nurse and care
for their young after birth as well.
• External fertilization uses strength in numbers to
produce so many offspring that statistically some
will survive, internal fertilization places more
investment in each offspring to give them a higher
chance of survival.
4.17 Human Reproductive System
• Humans, like all mammals, reproduce sexually.
Males produce many sperm gametes that are
delivered to the female during sexual intercourse to
attempt and fertilize a single ovum gamete. If
fertilized, the gamete will develop within the female
for nine months until it is born. Humans are fully
functional biologically when born, but cannot
survive without assistance. Humans are both
psychologically and hormonally wired to care for
young babies and help them survive.
4.17 Human Reproductive System
• The female
reproductive organs
are internalized.
• Gametes
(eggs/ovum)are
produced at the
ovaries within structures
called follicles. Follicles
are also the site of the
creation of many of the
important hormones
needed to regulate the
system.
4.17 Human Reproductive System
• Ovum are released
periodically during a
woman’s life. Rising
and falling levels of
several hormones
control the timing of
this process.
4.17 Human Reproductive System
• During fetal
development, the
follicles are developed.
• At the start of puberty,
the ova are developed
and the menstrual
cycle begins.
• At menopause, this
cycle ends.
4.17 Human Reproductive System
• After being developed,
the ova leaves the
ovary and travels
through the oviduct or
fallopian tubes.
• It is at this stage that a
sperm may be able to
reach an ova and
fertilize it.
4.17 Human Reproductive System
• After the oviduct, the
ova ( fertilized or not)
will enter the womb or
uterus.
• This is a thick, muscular
organ that is where a
fertilized ova will take
hold and develop. The
fetus will remain here
until birth.
4.17 Human Reproductive System
• Connecting the womb
to the exterior is the
vagina. Unfertilized ova
will be removed here,
and sperm is received
here.
• Separating the womb
and vagina is the
cervix, which has a
small opening allowing
passage between the
two.
4.17 Human Reproductive System
• The male reproductive
organs are largely
external.
• Male gametes (sperm)
and male sex hormones
are made in the testes.
The testes are kept
outside of the body in the
scrotum to keep them
cooler as sperm
production works better
at temperatures lower
than the body’s.
4.17 Human Reproductive System
• Sperm production in
males is relatively
continuous after
puberty.
• Sperm are collected
from the testes in the
epididymis and when
signalled, are sent
through the vas
deferens tubes.
4.17 Human Reproductive System
• The prostate gland
receives the sperm
from the vas deferens
and adds additional
fluids to aid and
protect the sperm from
the conditions of the
female reproductive
tract.
4.17 Human Reproductive System
• From the prostate
gland, the sperm will
enter the urethra, the
same tube used to
expel urine.
• The sperm will travel
through the urethra
down the penis and
are released to the
external environment.
4.17 Human Reproductive System
• Unlike the female
system, the male
reproductive system
does not work on a
timed cycle and
instead works ondemand when a man
reaches orgasm during
sexual intercourse.
4.18 Human Development
• Embryonic development begins with fertilization, or
conception, the union of a sperm and egg to form
a zygote.
• Only one sperm can enter and fertilize the egg in
the oviduct. (fallopian tube). The egg and sperm
nuclei join to form the diploid nucleus of the zygote.
4.18 Human Development
• Development of the zygote begins with cleavage,
a series of rapid cell divisions that result in a
multicellular ball. When a zygote divides for the first
time, it begins to be called an embryo.
• Cleavage continues as the embryo moves down
the oviduct toward the uterus. About 6-7 days after
fertilization, the embryo has reached the uterus as a
fluid-filled hollow ball of about 100 cells called a
blastula.
4.18 Human Development
• After the blastula is formed, further division and
specializations of cells produce the three-layered
gastrula. The three layers produced in gastrulation
are embryonic tissues called ectoderm, endoderm,
and mesoderm.
• The ectoderm eventually develops into the nervous
system and outer layer of skin (epidermis). The
endoderm eventually becomes the innermost lining
of the digestive system and organs such as the liver,
pancreas, and thyroid. The mesoderm gives rise to
most other organs and issues, such as the heart,
kidneys, and muscles.
4.18 Human Development
• Pregnancy, or gestation, is the carrying of developing
young within the female reproductive tract. It begins at
fertilization and continues until the birth of the baby. In
humans, gestation lasts about 38 weeks.
• A placenta develops. This is the organ that provides
nourishment and oxygen to the embryo and helps
dispose of its metabolic wastes. A fluid-filled sac called
the amnion encloses and protects the embryo. The
umbilical cord forms and acts as the lifeline between the
embryo and the placenta.
• The mother’s blood and the embryo’s blood are not in
direct contact. But, nutrients, oxygen, and wastes can
be passed between them.
4.18 Human Development
• The First Trimester is the first third (3 months) of pregnancy and
covers the development of a embryo to a fetus.
• Month 1
•
Tiny limb buds, which will grow into arms and legs, appear.
•
The embryo looks like a tadpole.
•
•
•
The heart and lungs begin to form. By the 25th day, the heart
starts to beat.
The neural tube, which becomes the brain and spinal cord,
begins to form.
At the end of the first month, the embryo is about 1/2 inch
long and weighs less than 1 ounce.
4.18 Human Development
• Month 2
•
•
•
•
•
All major body organs and systems are formed but not
completely developed.
The early stages of the placenta, which exchanges nutrients
from your body for waste products produced by the baby, are
visible and working.
The ears, ankles, and wrists form. The eyelids form and grow
but are sealed shut.
Fingers and toes develop.
By the end of the second month, the fetus looks more like a
person than like a tadpole, is about 1 inch long and still weighs
less than 1 ounce.
4.18 Human Development
• Month 3
•
After 8 weeks as an embryo, the baby now is called a
"fetus."
•
The fingers and toes have soft nails.
•
The mouth has 20 buds that will become "baby teeth."
•
•
•
You can hear your baby's heartbeat for the first time (10
to 12 weeks)
For the rest of pregnancy, the body organs will mature,
and the fetus will gain weight.
By the end of this month, the fetus is 2 1/2 inches long
and weighs a little over 1 ounce.
4.18 Human Development
• In the Second Trimester, the fetus is now able to kick and
becomes much more active.
• Month 4
•
The fetus moves, kicks, and swallows.
•
The skin is pink and transparent.
•
•
•
The umbilical cord continues to grow and thicken to
carry enough nourishment from mother to fetus.
The placenta is fully formed.
By the end of the fourth month, the fetus is 6 to 7 inches
long and weighs about 5 ounces.
4.18 Human Development
• Month 5
•
The fetus becomes more active, turning from side to side
and sometimes head over heels.
•
The fingernails have grown to the tips of the fingers.
•
The fetus sleeps and wakes at regular intervals.
•
•
The fetus has a month of rapid growth. At the end of the
fifth month, the fetus is 8 to 12 inches long and weighs
1/2 to 1 pound.
By the end of the fifth month (20 to 21 weeks), fetal
activity can be felt by the mother.
4.18 Human Development
• Month 6
•
The skin is red and wrinkled and covered with fine, soft
hair.
•
The eyelids begin to part and the eyes open.
•
The finger and toe prints can be seen.
•
•
The fetus continues its rapid growth. At the end of the
sixth month, the fetus is 11 to 14 inches long and weighs
1 to 1 1/2 pounds.
If born at 24 weeks or more, the fetus might survive with
intensive care.
4.18 Human Development
• The final Third Trimester features a fetus that is very active that
the mother can sense and most fetuses born during this phase
can survive.
• Month 7
•
The fetus can open and close its eyes and suck its thumb.
•
The fetus exercises by kicking and stretching.
•
The fetus responds to light and sound.
•
If born now, the fetus has a good chance for survival.
•
The fetus is now about 15 inches long and weighs about 3
pounds.
4.18 Human Development
• Month 8
•
•
•
•
•
•
Rapid brain growth continues.
The fetus is too big to move around much but can kick
strongly and roll around.
You may notice the shape of an elbow or heel against the
belly.
The bones of the head are soft and flexible to make it easier
for the baby to fit through the birth canal.
The lungs may still be immature. If born now, before 37 weeks,
the fetus is premature but has an excellent chance for survival.
The fetus is now about 18 inches long and weighs about 5
pounds.
4.18 Human Development
• Month 9
•
•
•
•
•
At 37 to 40 weeks, the baby is full-term.
The baby's lungs are mature and ready to work on their
own.
During this month the baby gains about 1/4 to 1/2
pound a week.
The baby moves into position to be born, usually
dropping into a head-down position and resting lower in
the mother's pelvis.
By the end of the ninth month, the baby weighs 6 to 9
pounds and is 19 to 21 inches long.
BL 1021 – Unit 4.19 - 4.22
The Nervous, Skeletal, and Muscular Systems
4.19 The Nervous System
• In large, complex animals, a system is needed to
control and co-ordinate activities in the creature.
• The endocrine system plays a role in regulation but
it is often too slow to adapt. The time it takes for
hormones to be produces, released, travel to their
target, and lock onto a receptor is too long
compared to how fast an animal needs to plan,
move and react to its environment.
• This is why the body has a second control system
that uses extremely fast electrical signals to send
messages and commands – the nervous system.
4.19 The Nervous System
• The basic cell making
up the nervous system
is the neuron.
• Neurons receive
information from
sensors and other
neurons at short
branches called
dendrites.
dendrite
cell body
axon
4.19 The Nervous System
• The core of a neuron is
the cell body. This is
where the majority of
the organelles are
located.
• Information is sent out
at the end of an axon.
Some axons are more
than a foot long, while
others are short.
dendrite
cell body
axon
4.19 The Nervous System
• Neurons “talk” to one
another by releasing
chemicals called
neurotransmitters from
their axons to the
dendrites of other
neurons.
• This gap between axons
and dendrites are called
synapses.
• These work like hormones,
a neurotransmitter may
excite, calm, or have no
effect on the neuron it
targets.
dendrite
cell body
axon
4.19 The Nervous System
• Neurons work fast because they send their signals
along their long axons using electricity.
• The electrical signals are made by disrupting the
balance of charged chemicals on the inside and
outside of the cell. Once this imbalance hits a
critical point, it causes an electro-chemical chain
reaction that travels down the axon nearly instantly.
• With neurons working so fast, it becomes possible to
make very quick decisions and react almost
instantly to changes.
4.19 The Nervous System
• The nervous system
connects to all parts of
the body – all parts
need to either send the
brain information or be
told to do something
by the brain, or both.
• The brain is the
integrator – it takes in
data and creates
commands from it.
4.19 The Nervous System
• From the brain, the
cranial nerves are a
series of connections
from the brain directly
to parts of the head
and internal organs.
• Also from the brain,
comes the spinal cord,
a series of nerves that
allow the brain to
connect with the body.
4.19 The Nervous System
• The brain and spinal
cord together are the
central nervous system
(CNS). This contains the
neurons that will mostly
just take in, compute,
and issue commands.
• The remaining nerves
make up the peripheral
nervous system (PNS)
which connect the
CNS to the rest of the
body.
4.19 The Nervous System
• The PNS contains many
of the body’s voluntary
sections (parts that we
can choose to move).
• However, there are
also the autonomic
nerves, which control
involuntary functions
like breathing,
heartbeat and
digestion.
4.19 The Nervous System
• Some parts of the body
are involuntary but we
can still have some
control over them.
Breathing blinking,
urination, etc… can be
controlled somewhat,
but the autonomic
nerves will take over
eventually.
4.19 The Nervous System
• There are four basic types of cells in the nervous system:
• Sensory neurons take up information such as taste, touch,
etc… and forward it along.
• Integrating neurons or Interneurons take information and work
with it – forming meaning, making ideas and plans, etc…
• Motor neurons cause an effect to happen such as muscles to
move, organs to perform a certain task, etc…
• The nervous system also contains other helper cells that work
with neurons to keep them healthy and working at their best.
4.19 The Nervous System
• The most basic of animals can only roughly react to
a stimulus.
• As animals get more complex they start to have
cephalization – they centralize their nervous tissue
into a CNS (usually towards the head), with brain
and/or spinal cord-like structures at its core.
• This gives animals more nervous tissue to “think” –
more neurons focused on integration rather than
just instinct and reflex.
4.19 The Nervous System
•
The brain can be divided into three regions:
•
The hindbrain contains the most basic primal functions such as
breathing, blood flow, digestion. It also contains the Cerebellum,
a very important part of the brain that helps smooth and coordinate movements. Damage to this area is nearly always fatal.
•
The midbrain also provides many basic functions such as the
sleep cycle, but also serves as a bridge between the basic and
more complex functions.
•
The forebrain allows higher-level thought. It allows memory,
planning, emotions, language, and ideas to exist. This also
includes the hypothalamus – the part of the brain that coordinates the endocrine system. Damage to this area may impair
functioning, but not necessarily be fatal.
4.19 The Nervous System
• The proportions of the
brain vary greatly
between animals. The
most animals have only
the most basic sections
needed – areas for
thirst, hunger, pain,
breathing, etc.
• More advanced
animals have larger
areas for the senses,
thinking, planning, and
social relationships.
4.20 The Sensors
•
The body has five major types of sensors. Each provides the brain with different
types of information.
•
Pain Receptors: Found in all parts of the body except for the brain, these receptors
make us aware of a dangerous situation, injury or disease. Their purpose is to alert
the body to injury or dangerous activity.
•
Thermoreceptors: Thermoreceptors sense the external temperature as well as the
internal body and blood temperature. They help warm-blooded animals
(endoderms) maintain a constant body temperature within a range.
•
Mechanoreceptors: These are receptors that are stimulated by various mechanical
energy such as touch, pressure, motion and sound. Again, these help the animal
interpret its external environment for protection and survival.
|
Chemoreceptors: Chemoreceptors detect chemical signals in the external
environment (eg., smell of smoke) and internal chemical balance such as a blood
pH change.
•
•
Electromagnetic receptors: These detect energy that has various wavelengths such
as electricity and light. The eyes contain electromagnetic receptors that respond
to various intensities of light.
4.21 The Skeletal System
• There are two main purposes of a skeletal system:
support and protection.
• The skeletal system provides a rigid framework in
which muscles can attach to allow for movement.
Without the framework, all the body tissues would
simply sag.
• The skeletal system may also be designed to
protect certain organs that have vital functions. The
skull encases the brain. All other important organs
are encased within the ribcage (heart, lungs).
4.21 The Skeletal System
• Skeletal systems come in several forms.
• Some aquatic animals use a hydrostatic skeleton
which uses pressurized water-filled pockets to
provide a semi-rigid framework.
• Arthropods use a hard exoskeleton as both an
outer coating and the framework to move.
• Sharks use a cartilage-based skeleton to reduce
weight and allow faster hunting.
• Humans and many other animals have a hardened
mineral-based internal skeleton made of bone.
4.21 The Skeletal System
• Skeletal systems come in several forms.
• Some aquatic animals use a hydrostatic skeleton
which uses pressurized water-filled pockets to
provide a semi-rigid framework.
• Arthropods use a hard exoskeleton as both an
outer coating and the framework to move.
• Sharks use a cartilage-based skeleton to reduce
weight and allow faster hunting.
• Humans and many other animals have a hardened
mineral-based internal skeleton made of bone.
4.21 The Skeletal System
• Human bone is made of living cells and an strong
network of hardened minerals (calcium, phosphate,
etc).
• Inside lies bone marrow tissue that nourishes the
bones and is the site of blood cell production.
• Bones are continuously breaking down, growing
and repairing, even in an adult where the bones
stay relatively the same size. This is known as bone
remodelling. In childhood the growth outweighed
the decay while the reverse is true in later life.
4.21 The Skeletal System
• Joints are an important
structure that allows
bones to move within
certain limits.
• Most joints will fall into
one of five types.
4.21 The Skeletal System
• Ball and Socket
• Free three-dimensional
motion with some limits.
• (hip, shoulder)
• Hinge
• Allows one-direction
movement.
• (forearm)
4.21 The Skeletal System
• Ellipsoidal
• two- directions of
movement
• (Wrist, ankle)
• Pivot
• Rotational movement
• (neck)
4.21 The Skeletal System
• Fixed Joints
• Hold bones together
but allow little to no
actual movement.
• Can be used as a
pressure-release point
to avoid a fracture.
• (hips, skull)
4.22 The Muscles
• Muscles are long collections of cells that specialize
in shortening. By each cell shortening, the whole
muscle contracts, allowing for movement.
• Muscles can only contract in one direction and
then relax to return to the previous position.
• Therefore, many muscles are paired with a partner
antagonist to pull in the opposite direction. (For
example, one set of muscles to extend a finger,
another set to retract them).
4.22 The Muscles
• Many muscles attach
to bones with tendons.
These are very tough
pieces of connective
tissue that can handle
the strain of the work
done by the body.
• If a tendon is torn/cut,
neither precise nor
strong work can be
done as the muscle is
not properly anchored.
4.22 The Muscles
• Muscle cells bundle
together to form
muscle fibers. In most
skeletal muscle, these
fibers all run in one
direction. (In the heart,
they are more crisscross).
• The axons of motor
neurons direct muscles
to contract or relax.
4.22 The Muscles
• Muscle fibers do not have
multiple levels of
contraction, they tend to
either be completely
contracted or relaxed.
• The body is able to
control how powerfully it
moves by activating
different numbers of
muscle fibers. (few fibers –
weak movements, many
fibers – stronger
movements).
BL 1021 – Unit 4.23 – 4.24
The Excretory System
4.23 Osmoregulation
• All organisms must carefully control the amount of
water and dissolved substances in their cells. If this
varies too greatly from the environment, the cells
may shrink or burst from the force of water moving
in or out of the cell (osmosis).
• The process of controlling the flow of water and
substances in and out of an organism is
osmoregulation. This is a vital part of homeostasis,
particularly for animals that live in the water.
4.23 Osmoregulation
• Many organisms, particularly those that live in salt
water, do not maintain their internal solute
concentrations and will adapt to whatever the
environment is. They are isotonic (equal in
concentration) with their environment. These are
osmoconformers.
• Animals that live in other environments such as fresh
water or on land must maintain constant internal
solute levels to resist the forces of their environment.
These contain higher concentrations than their
environments. These are osmoregulators. This
process requires the body to spend energy to
maintain its internal environment.
4.24 Human Excretory System
• The human excretory system serves three major
roles:
• Controlling the water levels in the body
(osmoregulation).
• Controlling the amounts of solutes (salt, minerals,
protein, etc…) in the body.
• Eliminating unwanted substances from the body.
4.24 Human Excretory System
• The major organ of the
excretory system is the
kidney. The kidney
takes in blood and
filters out unwanted
and excess materials.
• The kidney can control
how much water and
solutes get returned to
the blood or get
excreted based on the
needs of the body.
4.24 Human Excretory System
• Blood enters the kidney
from the renal artery.
This is a very high-flow
vessel, and a large
amount of blood flows
through the kidneys per
minute.
• The artery branches off
into a large number of
smaller vessels that
interact with nephrons
– where filtration takes
place.
4.24 Human Excretory System
• The nephron is a
complicated system of
tubules.
• A large amount of
water and solutes are
removed from the
blood at the start.
• As the urine
concentrates, much of
the water and minerals
may be returned to the
blood.
4.24 Human Excretory System
• As the fluid moves
through the nephron,
the body can choose
to expel to reabsorb
each type of material.
• For example, if the
body has excess
sodium, then sodium
will not be reabsorbed
and will be expelled in
the urine.
4.24 Human Excretory System
• A large majority of the
water that is removed
from the blood is
returned afterwards.
• If all the water that was
lost into the nephron
was excreted, animals
would need to be
nearly constantly
drinking water.
4.24 Human Excretory System
• Water is also returned
to the blood because
the urine needs to be
concentrated.
• Animals would waste a
large amount of water
if they did not
concentrate their urine.
Concentrating means
that each gram of
waste needs less water
to be removed.
4.24 Human Excretory System
• Different animal
concentrate their urine to
different degrees.
• Fish have an abundance
of water and thus can
release very
unconcentrated urine.
• Some animals in very dry
climates will concentrate
their wastes to a large
degree into a thick paste.
• Humans fall in the middle
with a concentrated
liquid.
4.24 Human Excretory System
• After reabsorbing
water and useful
solutes, the blood
vessels recombine into
veins and leave the
kidney.
• The filtered material
finishes concentrating
and leaves the kidney
into the ureter.
4.24 Human Excretory System
• The unwanted
materials filtered out by
the kidney are carried
to the urinary bladder
by the ureter for
storage.
• No major processes
occur in the bladder, it
is just a storage
location.
4.24 Human Excretory System
• The bladder contains a
number of special
nerve cells that stretch
along with it as it fills.
• These cells allow the
body to know when
the bladder is full.
4.24 Human Excretory System
• When the bladder is
full, the urge to urinate
arises. The body has
the ability to resist
urination for a limited
period, but eventually
the autonomic nerves
win out.
• This is similar to the
ability to partially
control blinking or
breathing.
4.24 Human Excretory System
• Urine finally leaves the
body through the
urethra.
• In women, the urethra
opens directly to the
exterior near the
vaginal opening.
• In men, the urethra
connects with the vas
deferens. Thus, the final
section of the urethra
can carry urine or
semen.