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PART 10: Animal Structures and
Functions
Section A: Digestive System
1. Digestion: the breakdown of large food molecules into simpler compounds.
These molecules are then absorbed by the body to carry out cell activities.
 Intracellular digestion: digestion in basic multi-cellular organisms where
the digestion itself takes place in the vacuoles of their cells.
 Extracellular digestion: digestion in complex multi-cellular organisms
where food is digested in a series of organs along a digestive tract in a
gastrovascular cavity.
o Crop: a storage organ sometimes found in these organisms.
2. Human Digestive System: our digestive system is extracellular; its goal is to
break down starch (a carbohydrate), proteins, fats, and nucleic acids.
 Oral Cavity (Mouth): first step of the human digestive process.
o Mechanical digestion (mastication): the physical breakdown and
softening of food using the teeth and tongue.
o Chemical digestion: the chemical breakdown of food. In the mouth,
this breakdown is conducted by the enzyme salivary amylase which
is found in the saliva. Saliva is produced by salivary glands found in
the walls of the oral cavity.
o Bolus: chewed, salivated food in a ball shape that moves through the
pharynx (cavity in the back of the throat) and on to the esophagus.
o Esophagus: long tube connecting the oral cavity to the stomach. It
transports food by peristalsis (wavelike motion caused by
contraction and relaxation of muscles).
 Stomach: a thick, muscular sac in the gut that is highly acidic. It
temporarily stores the ingested food, partially digests proteins, and kills
bacteria.
o Gastric juices: a solution of digestive enzymes and hydrochloric acid
(HCl) that is secreted into the stomach.
 Pepsin: enzyme in gastric juices that breaks down proteins.
o Chyme: partially digested food in the stomach.
 Pancreas: organ that secretes enzymes.
o Trypsin: breaks down proteins.
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o Chymotrypsin: breaks down proteins.
o Pancreatic lipase: breaks
down lipids.
o Pancreatic amylase:
breaks down starch.
o (Deoxy)ribonuclease:
breaks down nucleic
acids.
o Pancreatic duct: tube
whereby these hormones
are transported from
pancreas to the small
intestine.
 Small Intestine: long tube
coiled below the stomach
(average 23 feet long); it has
three parts: duodenum,
jejunum, and ileum. It is in the
small intestine that all food is
completely digested.
o Pyloric sphincter: “door”
between the stomach
and the small intestine.
o Bile: a substance of the
small intestine that is an
emulsifier, meaning that it mechanically breaks down fats. Bile is
made in the liver and is stored in the gall bladder.
o (Micro)villi: folds in the small intestine that increase the surface area
for food absorption (food absorbed by capillaries in the villi)
 Lacteals: lymph vessels which absorb fatty acids in the small
intestine.
 Large Intestine: shorter and thicker tube that comes after the small
intestine. Here, water and salt are absorbed and harmless bacteria break
down potassium (Vitamin K).
o Feces: left over undigested food that moves to a storage chamber
called the rectum. Bowel muscles then push the feces out through
the anus to rid the body of the leftover toxins.
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Section B: The Respiratory System
1. Trachea: “windpipe”; tube(s) with C-shaped rings of cartilage found in worms
and vertebrates that intake air to retrieve oxygen.
 Spiracles: small openings in worms that allow air to pass to the trachea.
 Epiglottis: a flap of tissue that covers the trachea while swallowing so food
will pass down the esophagus without disrupting breathing.
2. Lungs: air sacs that expand and contract in order to absorb oxygen into the
bloodstream and release waste gases.
3. Gills: slits in the skin of an animal that use counter current-exchange in order
to transfer water to their blood (e.g., fish). All mammals had gills at some point of
development.
4. Nose: structure that cleans, warms, and moistens (same as the oral cavity)
incoming air so it can easily pass through the pharynx and larynx (voice box).
5. Bronchi: two branches of the trachea that leads to each lung.
 Bronchioles: smaller tubes that branch from the bronchi.
 Alveoli: tiny air sacs found at the end of every bronchiole. They are the
site of gas exchange since they have an enormous surface area of about
100 square metres.
o Capillary: oxygen and carbon dioxide diffuse across the membrane
between the alveoli and the capillary. The oxygen we breathe in
oxidizes the deoxygenated blood as waste CO2 enters the alveoli
from the blood to be exhaled.
6. Hemoglobin: a protein in red blood cells that transports 97% of inhaled
oxygen throughout the body through the bloodstream. The other 3% of oxygen is
absorbed into the plasma (fluid of the blood).
7. CO2 Transport: Carbon dioxide travels out and throughout the body in many
ways:
 Capillaries: through the exchange of O2 and CO2 in the lungs, where it will
be breathed out into the atmosphere.
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 Bicarbonate ions: CO2
can enter red blood
cells where they react
with water to form this
ion.
 Dissolves – CO2 may
combine with the
amino group in
hemoglobin so it can
just dissolve into the
plasma.
8. Diaphragm: thin muscle
below the lungs that controls
breathing.
 Intercostal muscles:
muscles between the
ribs that allow them to
expand.
 Chemoreceptors:
sensors that control
your rate of
respiration; if blood pH
decreases, they send
nerve impulses to the
diaphragm and
intercostal muscles to
breathe faster.
9. Inspiration: the process of inhaling oxygen. The diaphragm relaxes, the ribs
expand and the lungs expand.
10. Expiration: the process of exhaling carbon dioxide. The diaphragm contracts,
the ribs return to resting position, and the lungs deflate to resting position.
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Section C: Circulatory System
1. Open circulatory system: a system where blood is carried by open-ended
blood vessels that spill blood into the body cavity (e.g., arthropods).
 Sinuses: large, open internal cavities that contain the blood of arthropods.
2. Closed circulatory system: a system where blood flows continuously through
a network of blood vessels. Earthworms, some mollusks, and all vertebrates have
this system.
3. Heart: large muscle with
2 or more chambers (4 in
humans) that pumps blood
through the circulatory
system. The four chambers
in humans are: right atrium,
right ventricle, left atrium,
and left ventricle.
4. Blood: liquid substance
that transports gases,
nutrients and wastes
throughout the body. It also
transports proteins and
immune responses where
needed.
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 Plasma: liquid part of blood.
 Blood Cells: there are three types of blood cells (which are made in bone
marrow at the centre of bones):
o Red Blood Cells (RBC’s): red cells that carry hemoglobin (the protein
that transports oxygen). Mature RBC’s lack a nucleus.
o White Blood Cells (WBC’s): blood cells that fight infection.
o Platelets: cell fragments that assist in blood clotting.
 Blood Clotting: when a blood vessel is damaged, platelets stick to the
collagen fibres of the vessel wall. The vessel and the platelets release
substances that start the series of reactions in clotting. Prothrombin (a
protein in the plasmas) converts to thrombin, which converts fibrinogen to
fibrin. Fibrin threads then close the clot.
 Blood Types: blood types are based on the type of antigen found on the
outside of red blood cells.
o Antigen – define; there are four forms: O (no antigens), A (A
antigens), B (B antigens), and AB (A and B antigens).
o Antibodies: immune substances of the white blood cells that attack
foreign substances. Antibodies will attack any antigens that aren’t
naturally in an individual’s body – that is why you can only
give/receive blood to/from certain individuals.
 Rh Factors: another antigen (not related to the others) that is either
present (+) or not (-) on red blood cells.
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Blood Type
A
B
AB
O
Rh+
Rh-
Can Give To
A, AB
B, AB
AB
A, B, AB, O
+
+ or -
Can Receive From
A, O
B, O
AB, O, A, B
O
+ or –
-
5. Systemic Circulation: the circulation of oxygenated blood throughout the
body before returning to the heart.
6. Aorta: large blood vessel (largest in the body) that transports oxygenated
blood out of the heart. The aorta and all of its branching carry oxygenated blood
through the body.
 Arteries: other large blood vessels.
 Aortic semi-lunar valve: valve that allows blood to flow from the left
ventricle to the aorta.
 Arterioles: small vessels that branch from arteries.
 Capillaries: the smallest blood vessels. As mentioned in Section B,
capillaries in the lungs are the sites of oxygen and carbon dioxide exchange.
Because they are so thin (red blood cells must push through them in single
file) the exchange of substances is easy here: oxygen and nutrients leave
the capillaries while carbon dioxide and wastes enter the capillaries.
7. Veins: blood vessels that carry deoxygenated blood from capillaries, arterioles
and arteries back to the heart.
 Venules: branches of veins that attach to the arterioles because they are
smaller.
 Superior and inferior vena cava: the largest veins in the body which are
attached to the right atrium of the heart. The superior brings blood from
the upper body, while the inferior brings blood from the lower body.
8. Right atrioventricular (AV) valve: after blood enters the right atrium, it enters
the right ventricle through this valve; also known as the tricuspid valve.
9. Pulmonary circulation: the process of oxygenating blood by sending it to the
lungs from the right ventricle.
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 Pulmonary artery: blood vessel that brings blood from the heart to the
lungs.
 Pulmonary semi-lunar valve: valve that controls the passage of blood
between the right ventricle and the pulmonary artery.
 Pulmonary veins: blood vessels that bring oxygenated blood from the
lungs back to the heart (left atrium).
10. Left atrioventricular (AV) value: after blood enters the left atrium, it enters
the left ventricle through this valve; also known as bicuspid valve or mitral valve.
Path of the
Circulatory
System
Oxygenated
Blood
Deoxygenated
Blood
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11. Thermoregulation: human homeostasis; there are two types:
 Ectotherms: “cold-blooded” animals; their body temperature is directly
affected by their environment.
 Endotherms: “warm-blooded” animals that regulate their own body
temperature; this is done through a process called counter current
exchange.
o Counter current exchange: warm blood arteries run parallel to
cooled veins to regulate the temperature of the body.
12. Heart regulation: the beat of the heart has to be regulated; in humans, the
heart contracts and relaxes automatically at 72 beats per minute.
 Sinoatrial (SA) node: “the pacemaker”; tissue in the right atrium that sends
an impulse through the heart. This pulse activates the AV node.
 Atrioventricular (AV) node: tissue that, in reaction to the SA node, pulses
the left side of the heart.
 Bundle of His and Purkinje Fibres: fibres in the walls of the ventricles that
contract and relax the heart in response to the SA and AV nodes.
 Systole: contraction part of the cycle
 Diastole: relaxation part of the cycle.
 Blood pressure: The pressure of the blood in the circulatory system, often
measured for diagnosis since it is closely related to the force and rate of the
heartbeat and the diameter and elasticity of the arterial walls.
o Diastolic pressure: the blood pressure (as measured by a
sphygmomanometer) after the contraction of the heart while the
chambers of the heart refill with blood.
o Systolic pressure: the blood pressure (as measured by a
sphygmomanometer) during the contraction of the left ventricle of
the heart.
o High blood pressure: Hypertension or high blood pressure is a
chronic medical condition in which the systemic arterial blood
pressure is elevated.
o Low blood pressure: Hypotension or low blood pressure is a chronic
medical condition in which the systemic arterial blood pressure is
lower than normal.
o Pulse: pressure wave generated by blood flow flowing through the
body. The average human pulse [heart rate] is 72 beats per minute.
o Sphygmomanometer [Blood Pressure Cuff]: instrument used with a
stethoscope to take blood pressure.
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 Place the cuff on the upper arm, with the stethoscope on the
inner elbow.
 Inflate the cuff to 160-180 mm to stop blood flow.
 Loosen the valve to release the pressure while listening for the
first pump of blood with the stethoscope. Wherever the dial is
for that first pump of blood is the systolic pressure.
 When you can no longer hear the blood pumping, note the
number on the dial – this one is the diastolic pressure.
 Normal ranges for systolic pressure are 100-140, whereas
diastolic is 60-90.
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Section D: Lymphatic System
1. Lymphatic System: a network of vessels that conduct lymph. This system has
three functions:
 Collect, filter and return fluid to
Lymph
the blood by the contraction of
Lymph
adjacent muscles
Nodes
 Fight infection using lymphocytes
(cells of the lymph nodes)
 Remove excess fluid from body
tissue.
2. Lymph: clear, watery fluid formed
from interstitial fluids.
3. Lymph node: a mass of tissue with a
high quantity of lymphocytes.
o Lymphocytes: important cells
in fighting infection that
multiply very quickly once in
contact with an antigen
(foreign substance) as
recognized by the immune
system (Section E). The lymph
nodes swell when you have an
infection to increase
lymphocyte production (and
because there are a lot of
lymph nodes in your neck,
doctors will touch your neck to
see if your lymph nodes are
swollen and fighting infection).
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Section E: Immune System
1. Phagocyte: a substance that engulfs antigens (foreign substances).
2. Complement proteins: proteins that remove antigens from cell walls and
membranes.
3. Interferons: inhibit viral replication by activating surrounding cells to fight it.
4. Inflammatory response: series of events that lead to swelling and/or irritation
in response to an antigen or physical injury.
5. MHC (major histocompatibility complex) marker: substance that leaves
markers on infected cells to identify them (they’ll be destroyed later).
6. T-lymphocytes: lymphocytes that fight infections and promote the
reproduction of B-lymphocytes (lymphocytes that play a large role in the humoral
immune response [as opposed to the cell-mediated immune response, which is
governed by T cells]). They are made in the bone marrow.
 Helper T-cells: cells that activate B-lymphocytes.
 Memory T-cells: cells that recognize viruses and antigens they have
encountered before.
 Cytotoxic T-cells: cells that kill infected cells.
 Cell-mediated response: the activation of T-lymphocytes.
7. Humoral Immunity: Immunity referring to elements dissolved in the blood or
body fluids, such as antibodies in the blood, rather than cells.
8. Macrophages: A large phagocytic cell found in stationary form in the tissues or
as a mobile white blood cell.
9. AIDS (acquired immune deficiency syndrome): a syndrome that compromises
the immune system as a result of HIV. There’s no cure and sufferers don’t die
from the syndrome itself, but rather from infections their bodies can no longer
fight.
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Section F: The Excretory System
1. Nitrogenous wastes: toxic waste substances that are liquid (or dissolve in
liquids) that are transported out of the body by the excretory system (system that
excretes nitrogenous wastes).
 Ammonia (NH3): by-product of the breakdown of proteins that are acidic to
the body; fish excrete ammonia, just as it is, whereas other animals combine it
with other substances to be excreted from the body.
 Uric Acid: a conversion of ammonia and other waste substances that are
excreted from birds (white, gooey).
 Urea: a conversion of ammonia and other waste substances that are excreted
from most mammals, including humans (clear yellow liquid).
2. Invertebrate excretory organs: invertebrates are very simple with basic
excretory structures:
 Nephridia: an organ with capillaries that
excretes wastes from earthworms.
 Malpighian tubules: tubed organs that
excrete wastes from arthropods.
3. Kidney: major excretory organ in most
mammals that regulates excretion.
 Renal cortex: outer portion of the kidney.
 Renal medulla: inner portion of the kidney.
 Two main hormones:
o Antidiuretic hormone: allows
water to be reabsorbed from the
collecting duct; helps your body
retain water if you’re dehydrated
o Aldosterone: regulates sodium
reabsorption.
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4. Nephron: tiny structures in kidneys; made up of the parts listed below.
Filtrate (plasma of the endocrine system) runs through the nephron.
 Bowman’s Capsule: site where blood enters the vessels surrounding a
nephron.
o Renal artery: artery that brings blood to the Bowman’s Capsule.
o Glomerulus: ball of capillaries within the Bowman’s Capsule.
 Proximal convoluted tubule: tube connecting the Bowman’s Capsule to the
Loop of Henle.
 Loop of Henle: loop of tubing surrounded by capillaries. Here, more wastes of
the blood are transferred into the nephron.
 Distal convoluted tubule: tube connecting the Loop of Henle to the collecting
duct.
 Collecting duct: here, the wastes are modified into urine.
There are three steps in the production of urine:
 Filtration: the blood is filtered in the glomerulus of the Bowman’s Capsule.
Proteins and blood cells stay in the blood while ions, water, glucose, urea,
and amino acids pass into the filtrate.
 Reabsorption: as the filtrate moves through, some materials are
reabsorbed. Small solutes are reabsorbed by capillaries; remaining material
is urine.
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 Secretion: as the filtrate moves through the tubules, some substances (e.g.,
potassium, hydrogen) are secreted from capillaries into the tubules.
5. Bladder: sac where urine is stored.
 Ureter: tube connecting kidneys to the bladder.
 Urethra: tube that leads urine out of the body.
6. Skin: excretory organ that gets rid of excess water and salts from the body;
largest body organ; 2.5 million sweat glands that secrete water and ions through
pores; main function is to regulate temperature.
 Three layers: epidermis, dermis (contains sweat glands), subcutaneous
tissue
o Stratum corneum: layer of dead skin cells in the epidermis
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Section G: Nervous System
1. Nervous System: The network of nerve cells and fibres that transmits nerve
impulses between parts of the body.
 Nerve Net: a simple nervous system found in simple organisms.
 Ganglia: a clump of nerve cells that developed in slightly more complex
organisms (like a primitive brain).
 Central and Peripheral Nervous Systems: Vocab #8 & 9.
 Neurons: nerve cells of the most complex organisms. Neurons make up the
brain. There are different types of neurons (Vocab #2-4). A neuron consists
of:
o Cell Body: contains the nucleus and all the usual organelles of the
cytoplasm.
o Dendrites: short extensions of the cell body that receives electrical
stimuli.
o Axon: long, slender extension that transmits impulses to be sent
throughout the body.
o Schwann’s Cells: cells that attach to the axon and develop an
insulating layer called the myelin sheath. These cells are spaced out
over the axon, separated by nodes of Ranvier. This allows impulses
so jump through the axon faster from node to node by conduction –
this kind of conduction is called saltatory conduction.
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2. Sensory Neurons: receive impulses from the environment (ex. a touch on skin)
and sends messages back through the body. They are stimulated by the sense of
touch.
3. Motor (Effector) Neurons: receive impulses from sensory neurons and
produce a response in a muscle or a gland (ex. feel a bee sting in sensory neuron,
motor neuron makes your muscles contract to pull away).
4. Interneurons: neurons that link motor neurons to sensory neurons.
5. Resting Potential: when the inside of the plasma membrane of the axon has a
negative charge, while there is a positive charge outside. This is caused by a
sodium-potassium pump which is working backwards from most other sodiumpotassium pumps. They are transporting sodium ions out, and potassium ions in.
Many potassium ions can leave through open channels, while sodium cannot.
Channels that would allow the movement of sodium are closed during resting,
and opened during action potential. This is why neurons can carry electrical
impulses as those impulses are attracted to their negative charge.
6. Action Potential: the build up of a charge in the cell body of a neuron that
sends an impulse down an axon. Channels that allow the flow of ions over the
membrane (other than potassium) open up, allowing sodium to pass inside the
cell, making the inside more positive and the outside more negative
(depolarization). This moment only lasts a split second and causes movement of
cells. After this moment, the sodium channel closes, the potassium reopens and
the original state of resting potential returns (re-polarization); this time period is
called the refractory period. Because the action of one sodium channel reacts the
next, which reacts the next, etc., an impulse wave is formed that carries impulses
through axons on the other neurons.
Impulse Wave moving to the right.
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7. Synapse: a junction between the axon bulb (end of an axon that contains many
vesicles with neurotransmitters) and the dendrite of another neuron. The narrow
gap between these two is called the synaptic cleft.
 When the action potential reaches the axon bulb, channels open that allow
the passage of calcium ions into the axon.
 The calcium ions bind to vesicles containing neurotransmitters (chemicals
that carry information across the synaptic cleft), causing them to fuse with
the axons plasma membrane, releasing the neurotransmitters across the
synaptic cleft.
 These transmitters bind to receptor proteins to open channels that allow
the passage of ions into the receiving cell. This changes the charge of the
receiving cell, causing an action potential that will then travel down its
axon.
 The type of neurotransmitter used in this reaction is called acetylcholine.
They are broken down by the enzyme acetylcholinesterase after the
reaction.
 Multiple Synapses: when a neuron receives an excitatory action potential
(impulses to create movement and more action potentials) and an
inhibitory action potential (impulse to cease movement and stop action
potentials) at the same time, they cancel each other out and nothing
happens.
 GABA & Norepinephrine: other types of neurotransmitters that work in the
central areas of the human body.
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8. Central Nervous System: neurons of the brain and spinal chord.
 Spinal Chord: The cylindrical bundle of nerve fibres and associated tissue
that is enclosed in the spine and connects nearly all parts of the body to the
brain, with which it forms the central nervous system.
 Brain: An organ of soft nervous tissue contained in the skull of vertebrates,
functioning as the coordinating center of sensation and intellectual and
nervous activity. The brain has the following major divisions:
o Cerebrum: largest part of the human brain that controls thoughts,
coordination and voluntary activities. The cerebrum is made up of 4
lobes:
 Frontal Lobe: the front of the brain
 Temporal Lobe: below the frontal lobe.
 Occipital Lobe: lower back of the brain.
 Parietal Lobe: upper back of the brain.
o Cerebellum: coordinates muscle activity, balance and refinement of
movement.
o Brain Stem: the part of the brain continuous with the spinal cord.
Consists of the medulla oblongata, pons, midbrain and parts of the
hypothalamus.
 Hypothalamus: regulates homeostasis and hormones
(pituitary gland, growth, sexual, etc).
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 Medulla (oblongata): controls involuntary actions needed for
survival (breathing, heart, etc.).
 Pons: Controls part of the respiratory system and attaches
parts of the brain together.
 Midbrain: controls visual and auditory reflexes (blinking,
jumping at loud noises, etc.).
 Thalamus: controls sensory relay that connects impulses
between the spinal chord and cerebrum.
9. Peripheral Nervous System: The nervous system outside the brain and spinal
cord. This system can be broken down into the following:
 Somatic Nervous System: the part that controls voluntary activities, such as
the movement of your eyes to read this sentence.
 Autonomic Nervous System: the part that controls involuntary activities,
just as your heart beating right now. In some cases, this can overlap with
the somatic nervous system. For example, you can control your breathing if
you think about it (somatic) even though you will breath involuntary when
you do not think about it (autonomic). The autonomic system can be
broken down even further into the following:
o Sympathetic Nervous System: system with the purpose to mobilize
the body's resources under stress; to induce the fight-or-flight
response.
o Enteric Nervous System: a subdivision of the peripheral nervous
system (PNS), that directly controls the gastrointestinal system.
o Parasympathetic Nervous System: opposes physiological effects of
the sympathetic nervous system. It returns the body to homeostasis
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(stimulates digestive secretions; slows the heart; constricts the
pupils; dilates blood vessels).
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Section H: Musculoskeletal System
1. Exoskeleton: a hard covering a shell of an organism with the purpose of
physically supporting the organism’s systems.
2. Endoskeleton: an internal support mechanisms found in all vertebrates
(organisms with backbones).
 Human Skeletal System: an endoskeletal system found in humans, made
up of cartilage and bone.
o Cartilage: a supportive tissue that is stiff but not solid that lacks
nerves and blood vessels. All vertebrates have cartilage during
embryonic development – some retain the cartilage skeleton (ex.
Sharks), whereas others develop bones to replace some, but not all
of the cartilage. In humans, we retain some cartilage between our
bones, and our ears and noses are made of cartilage for our entire
lives.
o Bone: a solid connective tissue that has nerves and blood vessels.
 Collagen: a fibrous protein in bone and cartilage and tendon
and other connective tissue; yields gelatin on boiling.
 Calcium Salts: a substance that makes up bones.
 Osteoblasts: bone-building cells.
 Osteoclasts: bone-breaking cells.
 Joints: where one bone connects to another. Joints are the
sites of movement between the bones.
 Ligaments: soft connective tissues that hold joints
together.
 Tendons: soft connective tissues that hold muscles to bones.
3. Human Muscular System: the anatomical system of a species that allows it to
move. The muscular system in vertebrates is controlled through the nervous
system, although some muscles (such as the cardiac muscle) can be completely
autonomous.
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 Muscles: A band or bundle of fibrous tissue in a human or animal body that
has the ability to contract, producing movement in or maintaining the
position of parts of the body. It’s cells have multiple nuclei.
o Smooth Muscle: Muscle tissue in which the contractile fibrils are not
highly ordered, occurring in the gut and other internal organs and
not under voluntary control.
o Cardiac Muscle: the muscle tissue of the heart; adapted to continued
rhythmic contraction.
 Intercalated Discs: an undulating double membrane
separating adjacent cells in cardiac muscle fibers. Intercalated
discs support synchronized contraction of cardiac tissue. They
can easily be visualized by a longitudinal section of the tissue.
o Skeletal Muscle: A muscle that is connected to the skeleton to form
part of the mechanical system that moves the limbs and other parts
of the body.
 Striations: long parallel lineages. Skeletal
muscles are characterized by striations.
 Muscle Bundles: bundles of muscle tissue that
create the visible striations. They contain the
muscle fascicles.
 Muscle Fascicles: Thin, protective layer of
muscle that encloses the muscle fibre cells.
 Muscle fibre cells: contractile cells made of
fibres called myofibrils.
 Myofibrils: contractile fibres that are subdivided
into individual contractile units called sarcomeres.
Myofibrils are surrounded motor neurons. An
action potential from the motor neuron travels to
the muscle cell and causes the myofibrils to
contract.
 Sarcoplasmic Reticulum: a storage of calcium
ions that surrounds myofibrils.
 Sarcomere: the functional unit of a muscle cell.
Two proteins, actin and myosin, work together to
contract and relax the muscles. Myosin filaments
pulls actin filaments closer together, shortening
the sarcomere. They do this when calcium is
present (as released by the axon bulb of the
neuron) – the calcium binds to proteins on the
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actin, revealing their binding sites.
The myosin head (which currently
has ADP and a Phosphate attached
to it) binds to the actin, releasing
ATP. This release of ATP causes the
myosin head to bend, pulling the
actin. ATP then re attaches to the
myosin head, breaking down to ADP
and Phosphate, causing it to return
to its original position. When calcium
is present from the neuron, this
process repeats to contract the
muscle. When the calcium is no longer released, the proteins on the actin
return to position so the myosin head can no longer bind, and the muscle
relaxes.
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Section I: Endocrine System
1. Hormones: chemical messengers that can be produced in one region of the
body to act on target cells in another part of the body.
 Steroid Hormone: hormones made of steroids can easily pass into targeted
cells to access the DNA and perform the task.
 Protein/Peptide/Amine Hormones: hormones that are not steroids. They
must bind to the plasma membranes of target cells to signal for tasks to be
completed.
 Ecdysone: hormone that promotes moulting and mating in butterflies.
 Brain Hormone: hormone in insects that promotes the production of other
hormones.
 Juvenile hormone: a hormone that causes larvae to retain certain
characteristics into adulthood.
 Endocrine Glands: specialized organs that make hormones.
o Hypothalamus: gland that regulates the anterior pituitary gland by
secreting neurohormones.
o Pituitary Gland: the master gland that releases many hormones,
many of which stimulate other glands to make other hormones. It
has two parts:
I. Anterior Pituitary: the anterior pituitary produces six
hormones:
 Growth hormone (GH) – stimulates growth
 Adrenocorticotrophic Hormone (ACTH) – stimulates
adrenal cortex
 Thyroid-stimulating Hormone (TSH) – stimulates thyroid
gland
 Follicle-stimulating Hormone (FSH) – stimulates follicle
growth (females) and sperm development (males)
 Luteinizing Hormone (LH) – stimulates menstrual cycle
(females) and testosterone production (males)
 Prolactin (P) – stimulates mammary gland to produce
milk
II. Posterior Pituitary: the posterior pituitary produces two
hormones:
 Antidiuretic hormone – regulate nephrons
 Oxytocin – stimulates uteral and mammary contraction
in females.
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o Thyroid: located in the neck, it is the gland targeted the Thyroidstimulating Hormone (TSH) of the pituitary gland. The thyroid
secretes two hormones:
I. Thyroxin: hormone that regulates metabolic rate.
 Hyperthyroidism: individuals with an over production of
thyroxin. These people are generally thin and have
trouble putting on weight.
 Hypothyroidism: individuals with an under production
of thyroxin. These people are generally overweight and
have trouble losing that weight.
II. Calcitonin: hormone that lowers calcium levels in the blood.
o Parathyroids: four small organs that rest on the thyroid. They secrete
parathyroid hormone (PTH), which increases blood calcium levels. It
controls the breaking down and building of bones, which is called
bone remodelling.
o Pancreas: as well as producing enzymes for the digestive systems,
the pancreas also secrete insulin and glucagon.
 Islets of Langerhans: cluster of cells where the pancreas
produces hormones.
 Glucagon: increases the levels of glucose in the blood.
 Insulin: decreases the levels of glucose in the blood.
Diabetics have extremely low insulin levels and must
take it in order to survive.
o Adrenal: there are two adrenal glands, both found behind the
kidneys – the cortex and medulla.
I. Adrenal Cortex: releases two hormones:
 Glucocorticoids: promote the release of glucose in the
liver.
 Mineralocorticoids: promote the retention of water in
the kidneys.
II. Adrenal Medulla: releases two hormones:
 Epinephrine & Norepinephrine: hormone that increases
heart rate, breathing rate, blood pressure, etc. in
response to high stress.
o Testes: glands in the male reproductive system that produce the
male hormone of testosterone, a hormone that promotes sperm
production. It also controls secondary male characteristics (ex. broad
shoulders, facial hair, Adam’s Apple, etc.).
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o Ovaries: glands in the female reproductive system that produce
estrogen and progesterone, hormones that regulate the menstrual
cycle. They also control secondary female characteristics (ex. breasts,
wide hips, smaller limbs, etc.).
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Section J: Reproductive System & Embryonic Development
1. Female Reproductive System: system in females that allows fertilization and
embryonic development.
 Uterus: structure which hosts the developing fetus, produces vaginal and
uterine secretions, and passes the male's sperm through to the fallopian
tubes. It is here that a fetus develops.
o Fetus: An unborn or unhatched
offspring of a mammal, in
particular an unborn human baby
more than eight weeks after
conception.
o Endometrium: the inner lining of
the uterus.
 Fallopian Tubes (Oviduct): a pair of tubes
along which eggs travel from the ovaries
to the uterus for fertilization.
 Cervix: The narrow neck-like passage forming the lower end of the uterus.
A baby must pass through the cervix in order to be born.
 Vagina: The muscular tube leading from the external genitals to the cervix
of the uterus in women and most female mammals.
 Ovaries: structure that produces female hormones and female egg cells.
2. The Menstrual Cycle: a recurring cycle (beginning at menarche and ending at
menopause) in which the endometrial lining of the uterus prepares for pregnancy;
if pregnancy does not occur the lining is shed at menstruation; the average
menstrual cycle is 28 days. There are three phases in the menstrual cycle:
I. The Follicular Phase: LH and FSH hormones from the pituitary gland are
secreted, stimulating the growth of follicles in the ovaries. Estrogen now
thickens the endometrium to prepare to carry a baby. LH is suddenly
produced in mass amounts (Luteal surge) which triggers ovulation (the
release of an egg from a follicle which is left behind in the ovary). The egg
travels down the fallopian tube to the uterus.
II. The Luteal Phase: the follicle left in the ovary turns into a corpus luteum,
a structure that continues to secrete estrogen and progesterone. The
progesterone continues to ready the body for pregnancy by promoting
the growth of glands and blood vessels of the endometrium so that a
fertilized egg could latch on the tissue to develop. If the egg is no
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III.
fertilized in 13-15 days, phase three begins. If it is fertilized, then
embryonic development begins and HCG (human chorionic
gonadotropin) hormones are released to maintain the uterus lining for
development.
The Menstruation (Flow) Phase: because fertilization did not occur, the
uterus sheds some of its endometrium, causing bleeding. These monthly
bleeding coming from the vagina is called menstruation. After
menstruation, the cycle begins again to prepare for the possibility of
fertilization and producing offspring.
3. Male Reproductive System: system in males with a purpose of fertilizing eggs
in females to produce offspring.
 Semen: male reproductive fluid that
transports sperm in the uterus and
fallopian tubes.
o Sperm Cells: gamete (haploid)
cells that fertilize female eggs
in order to produce offspring.
 Prostate Gland: gland in males at
the neck of the urethra; produces a
viscid secretion that is the fluid part
of semen.
 Testes (Testicles): organ that produces sperm and hormones.
 Epididymis: tube by which the testes are connected to the sperm ducts.
 Sperm Duct (Vas Deferens): tube that transports sperm from the testes to
the prostate gland.
 Bladder: sac that contains urine. It is connected to the reproductive system
of males because both urine and semen are excrete from the body through
the urethra.
 Urethra: The duct by which urine is conveyed out of the body from the
bladder, and which in male vertebrates also conveys semen.
 Penis: The male genital organ of higher vertebrates, carrying the duct for
the transfer of sperm during copulation. In humans and most other
mammals, it consists largely of erectile tissue and serves also for the
elimination of urine.
 Seminal Vesicles: Each of a pair of glands that open into the vas deferens
near its junction with the urethra and secrete many of the components of
semen.
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4. Puberty: the development of sexual characteristics in a human, usually in the
early teens. Characteristics are primary (ex. sexual organs and hormones) and
secondary (ex. facial hair in men, widening of hips in women).
5. Embryonic Development: the development of a fertilized egg in a female
uterus.
 Morphogenesis: the biological process that causes an organism to develop
its shape.
 Zygote: a fertilized egg. A sperm + an ovum (egg) = a zygote.
 Morula: a small ball of cells produced by mitosis of a fertilized egg.
 Blastula: the cells reproduce in such a way that a fluid cavity called a
blastocoel is created.
 Grastrula: the shape of the zygote begins to change as the three skin layers
begin to appear as single cell layers. The ectoderm will become skin, eyes
and the nervous system. The mesoderm will become bones, muscles,
excretory, reproductive and excretory systems. The endoderm will become
the linings of the digestive and respiratory tracts, as well as other small
organs.
 Organogenesis (Neurula): the formation of the notochord and the neural
tubes (neural plates form on cells and fold in on themselves). This leads to
the production of all other organs of an embryo.
6. Embryo (Fetus): An unborn human baby, esp. in the first eight weeks from
conception, after implantation but before all the organs are developed.
 Extraembryonic Membranes: in other animals (ex. chickens) the following
membranes are present for fetal development.
o Yolk Sac: provides food for the embryo.
o Amnion: fluid filled sac that protects the embryo.
o Allantois: Membrane that controls gas exchange for the embryo.
o Charion: Membrane that encloses all other membranes.
 Fetal Embryo: in humans, the following membranes are present for fetal
development:
o Placenta: organ that provides the fetus with nutrients and oxygen,
and removes the fetus’ wastes.
 Umbilical Cord: the organ that connects the fetus to the
placenta.
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