Transcript The digestive system - GZ @ Science Class Online

Biology Year 10
Human Biology
Year 10 Science 2012
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The structure and functions of the human (as an animal) systems:
skeletal, digestive, circulatory, respiratory.
All vertebrates share the
same basic body plan,
with tissues and organs
functioning in a similar
manner. We focus on the
human body, studying
structure (anatomy) and
function (physiology).
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The structure and functions of the human (as an animal) systems:
skeletal, digestive, circulatory, respiratory.
Animals are made of complex systems of cells, which must be able to
perform all of life’s processes and work in a coordinated fashion to
maintain homeostasis (a stable internal environment).
During a human’s early
development, groups of
cells specialize into three
fundamental embryonic
layers. These embryonic
layers differentiate into a
number of specialized cells
and tissues. Tissues are
groups of cells similar in
structure and function .
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The structure and functions of the human (as an animal) systems:
skeletal, digestive, circulatory, respiratory.
Different tissues
functioning together for a
common purpose are
called organs (eg,
stomach, kidney, lung,
heart).
Organ systems are
composed of individual
organs working together
to accomplish a
coordinated activity. For
example, the heart, veins
and arteries all play a role
in circulation.
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The Human skeletal system.
The human skeletal system is an internal
skeleton that serves as a framework for the
body. This framework consists of many
individual bones and cartilages. This also
includes ligaments and the tendons which
hold bones to each other and to muscles
that contract and cause the bones to move.
The adult human skeleton contains more
than 200 bones.
The skeleton also provides mechanical
protection for many of the body's internal
organs, reducing risk of injury to them,
storage of minerals and production of
blood cells.
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The main bones in the Human skeletal system.
The main bones of the
human skeleton are
divided into two groups.
The axial skeleton is the
central group of bones
based around the spinal
(vertebral) column.
The appendicular
skeleton consists
of bones or groups
of bones which
“hang” off the
axial skeleton.
The Human skeletal system.
The main bones of the human
skeleton are:
The Skull
Shoulder girdle - clavicle and
scapula
Arm - humerus, radius and ulna
Hand - Carpals, Metacarpals and
Phalanges
Chest - Sternum and Ribs
Spine - vertebrae, Sacrum (5
fused or stuck together bones)
and Coccyx (the tiny bit at the
bottom of the spine).
Pelvic girdle - Ilium, Pubis and
Ischium.
Leg - Femur, Tibia and Fibula
Ankle - Talus and calcaneus
Foot - Tarsals, Metatarsals and
Phalanges
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A joint occurs where two bones meet .
Movement of the skeleton
occurs at the joints where two
or more bones meet. There are
different categories of joints.
Freely movable, or synovial,
joints allow a range of
movement determined by the
structure of the joint.
Examples of movable joints are
the ball and socket (shoulder),
hinge (elbow), pivot (between
the skull and neck) and
ellipsoidal joint (hand and
arm). Ligaments are inelastic
connective tissues which hold
bones together in a joint.
The structure of the skeleton and muscles of the human arm
The muscles are attached
to the bones by tendons.
When the muscles
contract they shorten and
move the bones at the
joints.
All of the bones in the
skeleton require muscles
in order to move them.
The muscles are attached
by the nervous system to
the brain which controls
their movement – either
voluntary or automatically
when required.
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The antagonistic muscles and bones act together to flex or extend the
arm
Muscles can contract, but are not designed to actively lengthen, so they are
arranged as opposing antagonistic pairs. As one muscle shortens, another is
stretched and vice versa. The contacting muscles move the bones they are
attached to.
The digestive system
The digestive
system converts
foods to simple
substances that can
be absorbed and
used by the cells of
the body. It is
composed of the
mouth, pharynx,
oesophagus,
stomach, small
intestine and large
intestine and is
aided by several
accessory organs
(liver, gall bladder,
and pancreas).
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Digestion breaks large molecules of food into small ones, which can then
pass through the wall of the gut into the blood.
Ingestion
How we take in food using our mouths
Digestion
Breaking food into smaller pieces
Absorption
Taking food into the blood
Egestion
Removal of food from the anus
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12
anus
Ingestion is how we take in food using our mouths.
1. Canine and incisors teeth rip, tear
and bite pieces of the food.
2. Suitable sized pieces of food
enter the mouth.
3. Pre-molars and molars grind the
food into smaller pieces.
4. Saliva is mixed with the food from
the saliva glands.
5. Enzymes in the saliva start
breaking down (digesting) the
food.
6. Lumps of chewed food are
swallowed down the esophagus.
7. Food moves into the stomach
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SJ Gaze
The internal structure of a human tooth.
The tooth has a hard
covering of enamel
which protects it and
gives it strength to bite
and chew food. When
tooth decay occurs the
enamel is eaten away
by bacteria and tooth
pain occurs because
acid and infection
reach the dentine and
tooth nerves. The
tooth is embedded into
the jaw bone by the
roots which secure it.
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How the different types of human teeth are used when eating.
There are 32 teeth in
a full set of adult
teeth.
The incisors at the front
of the mouth are used
to bite pieces of food.
The bicuspids (also
called premolars)
and the molars at
the back of the
mouth are used to
chew food.
The canines are bigger
and used to tear food.
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How the different types of Animal (carnivores) teeth are used when
eating.
Tiger carnivorous cat
Alligator carnivorous reptile
Otter carnivorous fish
eater
Sharp pointed
canines
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SJ Gaze
How the different types of Animal (Herbivores) teeth are used when
eating.
Horse grazing herbivore
Rabbit grazing rodent
Grey kangaroo Australian
grazing marsupial
Chisel-like incisors
No canines
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Grinding molars
SJ Gaze
How the different types of Animal (omnivores) teeth are used when
eating.
Badger eats
more animals
than plants.
Human
eats more
plants
than
animals
Flattened
molars to
grind plants
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Canines
much
smaller
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SJ Gaze
How the different types of Animal teeth (specialist) are used when
eating.
Baleen whales The
specialized filter-feeding
mechanism of baleen
whales enables them to
feed low on the food chain
by primarily eating
zooplankton and schooling
fishes.
Giant Anteater
sucks up ants
with long
tongue and has
no need for
teeth at all.
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SJ Gaze
The gut is a coiled tube and is the site of digestion and absorption.
The second stage in food
processing is digestion
Definition
Digestion
Breaking food into smaller
pieces
Once food is ingested it moves
down into the oesophagus and
then into the stomach
Definition Oesophagus The
tube that food travels from the
mouth to the stomach through
Definition
Stomach
Organ from the digestive
system that digests food
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SJ Gaze
The gut is a coiled tube and is the site of digestion and absorption.
The third stage in food processing
is absorption
Definition Absorption Taking
food into the blood
This absorption occurs in the
small intestine which the food
moves into from the stomach
and water absorption occurs in
the large intestine
Definition Small Intestine
Organ from the digestive system
that absorbs food into the blood
Definition Large intestine
Organ from the digestive system
that absorbs water from waste
food
Blood containing the absorbed
food then moves to the liver to be
further processed
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Definition
Liver
Organ
from the digestive system that stores
and distributes food
SJ Gaze
The main structure of the digestive system and its associated organs oesophagus.
The oesophagus is like a stretchy pipe that's about 25 centimeters long.
It moves food from the back of your throat to your stomach. When you swallow a
small ball of mushed-up food or liquids, a special flap called the epiglottis closes
over the opening of your windpipe to make sure the food enters the oesophagus
and not the windpipe.
Once food has entered the
oesophagus muscles in the
walls move in a wavy way to
slowly squeeze the food
through the oesophagus
(peristalsis) and into the
stomach.
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The main structure of the digestive system and its associated organs –
stomach.
Your stomach is attached to the end of the
oesophagus.
It has three important functions:
>to store the food you've eaten
>to break down the food into a liquid mixture
>to slowly empty that liquid mixture into the small
intestine
The stomach mixes, churns and mashes together
all the small pieces of food into smaller and
smaller pieces – called digestion.
It does this with help from the strong muscles in
the walls of the stomach and gastric juices that
also come from the stomach's walls.
In addition to breaking down food, gastric juices
also help kill bacteria that might be in the eaten
food.
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The main structure of the digestive system and its associated organs small and large intestine.
The small intestine is a long
tube around 3.5 to 5
centimeters around, which
connects from beneath your
stomach and is about 7 meters
long.
The small intestine breaks down
the food mixture even more so
your body can absorb all the
vitamins, minerals, proteins,
carbohydrates, and fats.
Food may spend as long as 4
hours in the small intestine and
will become a very thin, watery
mixture which can pass from
the intestine into the blood.
Small
intestine
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The small intestine is the site of absorption of the products of digestion.
The walls of the small intestine are covered in protruding villi which increase
the surface area and provide close contact for capillaries to absorb small food
particles through the wall.
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The main structure of the digestive system and its associated organs small and large intestine.
The large intestine is about 7 to 10 centimeters, which is wider than the small
intestine from which it joins on. It would measure about 1.5 meters long spread
out.
Most of the nutrients have already been removed from the food mixture before it
enters but there is waste and water left over.
Before it leaves the
large intestine, it
passes through the
part called the
colon where the
body is able to
absorb the water
and some minerals
into the blood.
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The main structure of the digestive system and its associated organs –
Pancreas, gall bladder and liver.
These organs send different juices to the first part of the small intestine. These
juices help to digest food and allow the body to absorb nutrients.
The pancreas makes enzymes that help the body digest fats and protein.
Enzymes from the liver called bile helps to absorb fats into the bloodstream.
The
gallbladder
serves as a
warehouse for
bile, storing it
until the body
needs it.
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The main structure of the digestive system and its associated organs –
pancreas, gall bladder and liver.
The nutrient-rich blood
comes directly to the liver
from the small intestine
for processing. The liver
filters out harmful
substances or wastes,
turning some of the waste
into more bile. The liver
sorts how many nutrients
will be distributed to the
body, and how many will
stay behind in storage.
The liver stores certain
vitamins and a type of
sugar your body uses for
energy.
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The main structure of the digestive system and its associated organs –
rectum and anus.
The final stage of food processing is egestion, where the waste food that
hasn’t been absorbed is moved through the rectum and out of the body
through the Anus.
Definition
Egestion
Removal of wastes
from the anus
Definition
Anus
part of the digestive
system through which
wastes exit the body
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The food we eat is divided into four main groups
There are four main food groups
Carbohydrates
>supply instant energy
>include sugar and starches
>are supplied by fruit (sugars) or by
cereals (starches)
Lipids
>act as energy stores
>include fats and oils
>are energy rich
>are made of fatty acids
Proteins
>are used for growth and repair
>are found in meat and eggs
>are made of amino acid chains
Minerals and Vitamins
>body needs them in small amounts
>found in many foods
>non-organic substances
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We use tests to determine which type of food is present.
Lipids – present in fats and oils
Protein – present in meat and eggs
Some of the food rubbed into filter
paper. Remove food and allow to
dry
Sodium
hydroxide
solution
Broken up
food
particles
A ‘grease spot’ is left where the
food was rubbed in if lipid was
present
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Add
benedicts
solution
Mixture turns
purple if protein
present
SJ Gaze
We use tests to determine which type of food is present.
Starch –present in cereals
Glucose – type of sugar
Add Benedict’s
solution
Place a few drops of iodine on the
food
Food will turn black if starch is
present
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Broken up
food
particles in
water
Heat
mixture
gently
Mixture
turns
orange if
glucose
present
SJ Gaze
The circulatory system
The structure of the circulatory
system consists of blood,
blood vessels and the heart.
The function of the circulatory
system is to be the body’s
transportation system, moving
oxygen, carbon dioxide,
nutrients, wastes, hormones,
vitamins, minerals and water
throughout the body. It also
aids in regulation of
temperature.
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The external and internal structure of the mammalian heart and its
function.
The mammal has a four
chambered heart with full
division between the
ventricles. This means there
is no mixing of the
oxygenated and
deoxygenated blood. It
contains valves, and heart
beat is controlled by the
nervous system pacemaker.
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The external and internal structure of the mammalian heart and its
function.
The function of the Circulatory
system must:
>ensure delivery of blood to all
tissues
>adapt so that blood flow can be
controlled and changed to
individual tissues or the body as a
whole
>convert a pulsating blood flow in
the arteries into a steady flow in the
capillaries to allow optimum
diffusion to and from the cells
>return blood to the heart
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Arteries carry blood away from the heart, veins carry blood towards the
heart.
The vascular system is composed of
arteries, arterioles, capillaries,
venules and veins. The structure of
the vessels in the different parts of
the vascular system varies and the
differences relate directly to the
function of each type of vessel.
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Arteries carry blood away from the heart, veins carry blood towards the
heart.
There are three main types of blood vessels:
>arteries, which carry blood away from the heart at relatively high pressure.
>veins, which carry blood back to the heart at relatively low pressure.
>capillaries which provide the link between the arterial and venous blood
vessels
Arteries have thick
muscular and elastic walls
to accommodate the high
blood pressure of the blood
leaving the heart.
Veins have thinner, nonmuscular walls to
accommodate the lower
blood pressure of the blood
returning to the heart.
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Capillaries are
only one cell
thick.
Arteries carry blood away from the heart, veins carry blood towards the
heart.
The Arteries and veins have different structures because they have
different functions
Artery
Vein
Direction of
flow in relation
to heart
Blood Flows from the heart
Blood flows into the heart
Pressure in the
vessels
High pressure
Low pressure
Structure of
walls
Thick and muscular to handle
the high blood pressure.
Thin and can stretch with
changing volumes of blood
Other
structures
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Contains valves to prevent back
flow of blood
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Arteries carry blood away from the heart, veins carry blood towards the heart.
Circulatory system
A Deoxygenated blood enters the right atrium
of the heart via the vena cava.
B Deoxygenated blood is pumped from the
right ventricle, via the pulmonary artery, to the
lungs.
C In the lungs, blood picks up oxygen and gets
rid of carbon dioxide.
D Oxygenated blood travels back to the heart in
the pulmonary vein.
E Oxygenated blood is pumped to vital organs
and the whole body from the left ventricle, via
the aorta.
F Digested food is absorbed by blood through
the walls of the small intestine.
G Digested food is processed and stored in the
liver.
H Waste products (urea, water, salts etc.) are
removed from the blood in the kidneys.
I Blood supplies the rest of the body with food
and oxygen. It carries away waste products.
Capillaries link arteries with veins and are the sites of exchange with the
tissues.
Arteries divide into smaller arterioles around targeted tissues. The arterioles divide
once more into smaller capillaries which are only one cell thick. Nutrients and O2
diffuse across the membranes of the capillaries from the blood to the cell supplied –
from high to low concentration. Waste products, such as CO2, will diffuse from the
cell into the capillary near the venule end. The venules rejoin into veins and waste
product contained within the blood will be pumped back to the heart.
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Blood consists of fluid (serum) containing cells – white blood cells, red
blood cells and platelets.
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White blood cells (leucocytes) –
some produce antibodies to tag
foreign and harmful objects,
others surround and eat tagged
objects. White blood cells prevent
infection becoming established.
Make up the immunity system.
Cells contain nucleus.
Red Blood cells (erythrocytes) –
contain haemoglobin, a pigment
which binds to oxygen molecules
and carries it through the
circulatory system. They contain no
nucleus.
Platelets – they collect where
there is a hole in the blood vessels
and stop the unwanted flow of
blood by clotting.
Red blood cells carry oxygen, attached to haemoglobin, around the body
of a mammal.
Mammalian red blood cells (erythrocytes)
dispose their nuclei and cell organelles
when they are mature in order to provide
more space for haemoglobin (oxygen
carrying pigment).
Because the cells have no nucleus or
organelles, they cannot produce any RNA,
and therefore they cannot divide or repair
themselves. They are constantly replaced
by new red blood cells.
Red blood cells are biconcave disks and this
shape optimises the cell for the exchange
of oxygen in the lungs. The red blood cells
are flexible so they can fit through tiny
capillaries, where they release their oxygen
to cells.
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Plasma transports glucose, carbon dioxide, urea and hormones.
Plasma carries dissolved
molecules required by the body
to each cell and waste products
like carbon dioxide and urea out
of the body.
Plasma also carries a large
number of important proteins.
Albumin, the main protein in
blood, helps control the water
content of tissues and blood.
Plasma is usually yellow in colour
due but can become milky when
it transports fat absorbed from
the intestines to other organs of
the body.
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The respiratory system
The respiratory system
consists of organs that deliver
oxygen to the circulatory
system for transport to all
body cells. The respiratory
system also assists in
removing the waste product
of carbon dioxide from the
body.
Oxygen is a vital element for
metabolism. The exchange of
oxygen and carbon dioxide
between body cells, blood
and the air in the lungs is
called respiration.
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The structure of the mammalian breathing system
The human respiratory
system consists of the
nose, pharynx, larynx,
trachea, bronchi, and
lungs (composed of
bronchioles and
alveoli). The lungs are
housed in an airtight
pleural cavity framed
by the rib cage and
diaphragm.
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The structure of the mammalian breathing system
Air (comprised of
about 21% oxygen)
enters the nose,
where tiny hairs filter
out dust and
particles. Tissues
moisten and warm
the air, making it
more suitable for gas
exchange in the
lungs. Air passes
from the pharynx to
the larynx
(containing vocal
cords) and into the
trachea.
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The structure of the mammalian breathing system
The trachea divides
into the left and
right bronchi which
subdivide into
smaller and smaller
tubes called
bronchioles. These
airways are lined by
mucous membranes
and many cilia hairs
which trap and
remove particles
from the lungs.
Bronchioles open
into the alveoli
which are clustered
like
grapes.
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The structure of the alveoli and blood capillaries enable gaseous
exchange to occur.
Only one cell thick,
alveoli have direct
contact with
capillaries for gas
exchange. The
grapelike
arrangement of
alveoli creates an
enormous surface
area sufficient for
exchanging enough
oxygen and carbon
dioxide for the entire
body.
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The importance of diffusion in gaseous exchange across the alveoli.
Oxygen is transported to
the cells of the body mainly
by binding to haemoglobin
which is found within red
blood cells. Carbon dioxide
is transported by diffusion
into the plasma.
Diffusion occurs because
the oxygen is in higher
concentration in the alveoli
and moves to the lower
concentration in the blood
of the capillary.
The CO2 in the blood
diffuses into the alveoli and
out of the body because it
also moves from high to
low concentration.
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Oxygen enters into alveoli
from bronchioles
The oxygen molecules must diffuse through
both the lining of the alveolus and the lining of
the blood capillary and is eventually picked up by
red blood cells
Air breathed out contains more carbon dioxide and less oxygen than air
breathed in.
Breathing (the movement of air in and out of the lungs) is produced by
pressure differences created by changing the size of the pleural cavity. The
diaphragm contracts and the rib cage is raised. The volume of the pleural
cavity is increased, creating a partial vacuum between the lung cavity and the
atmosphere, and air enters the lung.
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Aerobic respiration involves transferring energy from glucose to a cell;
oxygen is needed and carbon dioxide is produced.
Cellular respiration is a process whereby energy is released from the
breakdown of molecules in food at the cellular level.
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Glucose enters the cell and oxygen
diffuses in – which has previously
entered the body via the respiratory
system and transported to each cell
through the circulatory system.
Glucose is broken apart in a series
of steps to release energy required
for the body. Each reaction is
assisted by enzymes.
The products of these reactions are
water and carbon dioxide – which
diffuses back out of the cell and
eventually out of the body via the
circulation and respiratory systems.
Anaerobic respiration can occur in human muscles and that lactic acid is
produced.
Sometimes our muscles
require more oxygen than
we can supply by normal
breathing.
Without oxygen present,
anaerobic respiration
takes place. The glucose
is broken down and
releases some energy.
Carbon dioxide is
produced along with
lactic acid. The lactic acid
is a waste product and
must be removed from
the body.
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