Transcript PPT File

UNIT 3 PART 1: LIFE
FUNCTIONS
• ALL LIVING THINGS MUST MAINTAIN
HOMEOSTASIS – THE CONDITION OF A
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CONSTANT INTERNAL ENVIRONMENT
This means controlling many things like
temperature, pH, concentrations of molecules, etc.
All life processes together make up an organism’s
METABOLISM.
Failure to maintain homeostasis causes disease and
death.
Organisms use several life processes to maintain
homeostasis.
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UNIT 3 PART 1: LIFE
PROCESSES
• ALL LIVING THINGS MUST MAINTAIN
HOMEOSTASIS – THE CONDITION OF A
•
•
•
•
CONSTANT INTERNAL ENVIRONMENT
This means controlling many things like
temperature, pH, concentrations of molecules, etc.
All life processes together make up an organism’s
METABOLISM.
Failure to maintain homeostasis causes disease and
death.
Organisms use several life processes to maintain
homeostasis.
1. GROWTH is the process by which
organisms increase in size. It is
accomplished mainly by cell division
(mitosis) or an increase in cell size.
2. SYNTHESIS is the process of making or
building something. It involves putting
together small molecules to make larger
ones. For example, dehydration
synthesis.
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3. NUTRITION is taking in materials from
the external environment and changing
them into a form that can be used.
• Autotrophic nutrition
– Organisms that are
able to make
(synthesize) their
food from inorganic
compounds
– Photosynthesis
– Green plants, algae
& some bacteria
• Heterotrophic Nutrition
– Organisms that must
eat food
– Digest food to obtain
nutrients
– All animals, fungi,
some protists and
bacteria
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Heterotrophic
Nutrition
• Ingestion (eat)
• Digestion (hydrolysis)
– Starches  Sugar
– Proteins  Amino Acids
– Lipids  Fatty Acids
• Absorption (diffusion)
• Egestion (eliminate)
– Undigested (fecal) waste
– Never enters the body
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DIGESTION
• Starts with mechanical breakdown of food
into smaller pieces - chewing
• Increases the surface area of food
• Followed by chemical digestion by
digestive enzymes to make food small
enough so nutrients can be absorbed
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THE DIGESTIVE SYSTEM
• The function of the digestive system is nutrition.
– to break down food into usable parts providing
nutrients for other processes:
Pasta (starch) + digestive enzymes (hydrolysis) 
Simple sugars (glucose)
Starch is too big to be absorbed into cells but
glucose is small. It will diffuse through the cell
membrane and cells can use it to produce
energy. How? Where? What molecule is the
energy molecule?
• A Tube made up of
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HUMAN
Mouth
Pharynx
Esophagus
Stomach
Small intestine
Large intestine
Rectum
Anus
• Food moves through
by peristalsis
• Accessory glands that
secrete enzymes are
– Liver
– Pancreas
– Salivary glands
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THE SMALL INTESTINE
• Most chemical digestion
and absorption takes
place here
• Muscular like the
esophagus
• Intestinal glands
secrete
– Amylase: digest starch
– Protease: digest protein
– Lipase: digest lipids
• Villi increase surface
area & absorb digested
food molecules.
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VILLI
• Villi are millions of
small, fingerlike
projections that line the
small intestine
• Villi contain capillaries
to absorb sugars,
vitamins, minerals, and
amino acids into the
blood
• Villi contain lacteals to
absorb fats into the
lymph
• Absorption happens by
diffusion.
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4. TRANSPORT is the process by which
substances move into and out of cells or
are distributed within cells. This involves
diffusion, osmosis, and active transport.
What are some organelles involved in transport?
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More complex
organisms need a
circulatory system to
transport materials
to all body cells.
This is the link
between the cells
and their
environment.
Plasma is the liquid
portion of the blood
and transports
everything except
oxygen.
HUMAN
CIRCULATION
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Blood Cells
• Red blood cells (RBCs)
have hemoglobin to
carry oxygen, O2.
• White blood cells
(WBCs) fight disease by
attacking pathogens or
making antibodies.
• Platelets are cell
fragments that help in
blood clotting.
• All are made in the bone
marrow.
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Blood Vessels
• ARTERIES are
vessels that carry
blood Away from the
heart.
• VEINS are vessels
that carry blood back
to the heart.
• CAPILLARIES are
the smallest vessels
& carry blood from
arteries to the veins
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• All body cells are
surrounded by
intercellular fluid
(ICF).
• It helps to move
materials between
cells and capillaries.
• It is formed from parts
of blood that diffuse
out of capillaries –
water, salts, proteins,
and nutrients.
ICF
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5. RESPIRATION is the process of releasing
chemical energy.
• Most organisms need to get O2 for aerobic
respiration and remove CO2. This is gas
exchange or breathing.
• Gas exchange between an organism and
its environment takes place at the
respiratory surface.
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• Gas exchange (G.E.) happens by diffusion,
so it depends on the concentration of gases
on each side of the respiratory surface.
• A larger respiratory surface area means
more diffusion.
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HUMAN RESPIRATORY SYSTEM
• Lungs and air tubes
• Lungs fill most of
chest cavity
• Separated from
abdominal cavity by
diaphragm – muscle
that allows breathing
• Breathing rate is
controlled by the
concentration of CO2
in the blood.
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ALVEOLI
• Alveoli are tiny air
sacs that are in
clusters at the ends of
the bronchioles in the
lungs.
• They are surrounded
by capillaries.
• The walls of the
alveoli are the
respiratory surface
where G.E. takes
place by Diffusion.
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6. EXCRETION is the process by which wastes,
and excess heat, are removed.
ELIMINATION (defecation) is the removal of
unabsorbed and undigested food (feces) from
the digestive tract. This is different from
excretion.
The human body needs to remove these wastes:
– CO2 – from cellular respiration
– H2O – from cell. resp. & dehydration synthesis
– Salts – build up during metabolism
– Urea – from the breakdown of proteins
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HUMAN
• Excretory wastes pass
from the body cells to
the ICF to the blood by
diffusion where they
are removed by the
excretory organs.
• The excretory organs
include the:
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Lungs
Liver
Kidneys
Skin
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• The lungs function in the excretion of
CO2 and water vapor, the wastes of
cellular respiration. Some heat is also
lost.
• The sweat glands excrete salt, water,
and urea through pores in the skin.
• Evaporation of water helps to cool the
body. The skin’s major
role in excretion is
the removal of excess
heat.
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THE LIVER HAS THREE
FUNCTIONS
1. Detoxification – removes harmful
substances like bacteria, drugs, and
hormones from the blood, inactivates them,
and returns them to the blood for excretion.
2. Makes bile – used by the small intestine to
emulsify fats. It is stored in the gall bladder.
It is made from old red blood cells.
3. Forms urea from the breakdown of proteins.
Urea contains nitrogen (N) and is returned to
the blood for excretion at the kidneys.
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URINARY SYSTEM
• Works to remove
wastes from the
blood and produce
urine.
• The human urinary
system consists of
the:
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Kidneys
Ureters
Urinary bladder
Urethra
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KIDNEYS
• Kidneys remove urea
from the blood and
maintain body fluid
concentrations.
• Blood enters the
kidney through the
renal artery.
• Plasma filters into the
kidney by diffusion.
• Sugar, amino acids,
some salts, and most of
the water are then
reabsorbed back into the
blood.
• What is left behind in the
tubule is called urine,
and is drained from the
kidneys to the bladder.
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7. REGULATION is coordination and control
of all other life functions.
When there are changes in the internal or
external environment, organisms must
respond. The human body has two
systems of regulation that work together.
NERVOUS REGULATION
• A nervous system is a network of
specialized cells called neurons, that
carry electrical signals (impulses)
throughout the organism.
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• A stimulus is anything that causes a
receptor to start impulses.
• Receptors are specialized structures
sensitive to certain changes, forces, or
chemicals both in and out of the organism.
They are proteins on the surface of cell
membranes.
• Stimulation of a receptor sends an impulse
to an effector, which is a specialized
structure that responds to commands of
the nervous system. These can be
muscles, glands, other neurons. This is
where the action is.
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THE NEURON
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The basic structure in the nervous system.
It has three parts:
1. Body - contains the nucleus and organelles
2. Dendrites - short extensions from the body and receive
impulses and carry them toward the cell body
3. Axon – long thin fiber that extends away from the body
and carries impulses Away from the cell to another
neuron or effector
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• The axon is surrounded by Schwann cells
which are surrounded by a myelin sheath
with nodes between the cells. Impulses
travel in jumps from node to node.
• The terminal branches at the end of the
axon almost, but do not touch other cells
or effectors. The gap is called a synapse,
and one axon can
have thousands of
synapses.
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Label the neuron below using these terms:
axon
dendrite
axon terminals
node
nucleus
Schwann cell
cell body
myelin sheath
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The Synapse
• A synapse is a small gap
between nerve cells or
effectors.
• The axon secretes a
neurotransmitter to cross
the synapse and start an
impulse in the next cell.
• The neurotransmitter is
then removed by enzymes
so new signals can be
sent.
• Synapses are important
because:
– They ensure one-way
movement of impulses
– They act as an on/off
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switch
THE HUMAN NERVOUS SYSTEM
Two subsystems:
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The central nervous system
(CNS) is the brain and the
spinal cord. This system
controls most activities. It is
protected by the skull and
vertebrae, meninges, and
cerebrospinal fluid.
The peripheral nervous
system (PNS) is the network of
nerves that take impulses
between the CNS and
receptors and effectors. 32
• A reflex is an
involuntary, automatic
response to a stimulus –
blinking, sneezing,
coughing, breathing,
heartbeat, peristalsis,
pupil response
• The reflex arc is the
pathway over which the
nerve impulses travel –
most have 3 neurons: a
sensory neuron, an
interneuron, and a motor
neuron. The brain is
NOT involved.
REFLEXES
(effector)
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LABEL THE PARTS OF THE REFLEX ARC USING THESE WORDS:
SPINAL CORD
MOTOR NEURON
INTERNEURON
EFFECTOR
SENSORY NEURON
RECEPTOR
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CHEMICAL REGULATION
• Animals must make constant adjustments
to maintain homeostasis. The nervous
system acts quickly and sends its
message to specific parts of the body.
• The endocrine system helps to maintain
homeostasis by releasing chemicals into
the blood. When the chemicals reach the
target organ, a reaction occurs. This is
slower than the nervous system, but the
effects usually last longer.
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These systems can also
work together. When you
sense danger, nerves
control muscles so you
can run away and other
nerves stimulate part of
your endocrine system
which then stimulates
your heart rate and
respiratory system to
provide increased energy.
ADRENALINE/EPINEPHRINE36
GLANDS are organs made up of cells that specialize in the
secretion of substances needed by the organism.
• Exocrine glands use
ducts that carry their
secretions to where
they are used.
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Pancreas
Sweat
Mammary
Salivary
Sebaceous (oil)
• Endocrine glands
release their
secretions into the
blood stream and
affect some other part
of the body.
• These secretions are
called hormones, or
chemical
messengers.
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HORMONES
• Help to regulate metabolism, homeostasis,
growth, reproduction, and other processes.
• Each hormone acts only on specific types
of cells called target cells. How does a
hormone recognize its target cell?
• A hormone can stimulate (start or increase)
or inhibit (stop or decrease) cell activity.
• Many endocrine glands are regulated by
other hormones.
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FEEDBACK
Stimulus
Receptor
Control Center
Effector
Response
• The chemical
regulation of hormone
secretions is
accomplished by
feedback.
Feedback
• A feedback system
operates as a cycle in
which the last step
affects the first.
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Negative Feedback
• Changes in step A
produce a change in
B.
Feedback
Control
Signal
• The change in B then
feeds back to stop A.
• Ex.: Heat from a
furnace feeds back to
turn off the thermostat
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NEGATIVE FEEDBACK IN YOUR BODY:
REGULATION OF THYROXIN LEVEL IN THE
BLOOD
• Negative feedback is used to keep some
variable (thyroxin level) at a set point.
Low thyroxin level in blood
(change)
Pituitary secretes
TSH
Thyroid stops
producing thyroxin
Thyroid to produce
thyroxin
Pituitary stops
secreting TSH
Normal thyroxin level
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POSITIVE FEEDBACK
• A change starts a response that intensifies
the change.
In your body:
Contractions during
childbirth
Pushes
baby’s head
against the
uterus wall
Increases contractions
of the uterus
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PITUITARY: THE MASTER
GLAND
• Located at the base of
the brain
• Controls many of the
other endocrine glands
• Secretes:
– Oxytocin, FSH, LH,
Prolactin: Repro
– Vassopressin: Kidneys
– TSH: Thyroid
– ACTH: Adrenals
– GH: Growth hormone
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PANCREAS – Islets of Langerhans
• Small clusters of cells
located throughout the
pancreas
• Secretes insulin to
lower blood glucose
levels and glucagon to
raise levels
• Because these
hormones do opposite
jobs they are said to be
antagonistic.
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• Insulin secretion is controlled by negative
feedback.
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Ovary & Testes
• Ovaries are located on both
sides of the uterus.
• They produce estrogen and
progesterone for promotion
of the secondary sex
characteristics and
regulation of the menstrual
cycle.
• Testes are located in the
scrotum, outside the body.
• The testes produce
testosterone for promotion
of the secondary sex
characteristics.
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