Download Topic 6: Human Health and Physiology

Topic 6: Human Health and
Physiology
Digestion
Explain why digestion of large food molecules is
essential.
• The foods that we eat are not necessarily
usable in their current form by our tissues.
They have to be broken down and changed
into another form.
• Food molecules are simply too large to be
absorbed by the villi in the small intenstine,
once again they have to be broken down into
small forms.
Explain the need for enzymes in digestion.
• Without enzymes digestion would still occur,
however at a significantly slower pace.
State the sources, substrate, products and optimum pH
conditions for one amylase, one protease, and one lipase.
• Enzyme: Salivary Amylase | Pepsin | Pancreatic
lipase
• Source: Salivary glands | Wall of Stomach |
Pancreas
• Substrate: Starch | Proteins | Triglycerides (fats
or oils)
• Products: Maltose | Small polypeptides | Fatty
Acids and Glycerol
• Optimum pH: pH 7 | pH 1.5 - 2 | pH 7
Draw a diagram of the digestive
system.
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Mouth
Esophagus
Stomach
Small & large Intestines
Anus
Liver
Pancreas
Gall bladder
Interconnections
between structures
Outline the function of the stomach, small intestine
and large intestine.
• Digestion of proteins begins in the stomach,
where the process is catalyzed by the enzyme
pepsin where possible harmful bacteria are killed
by the stomach's acidic condition which is also
the optimum conditions (pH 1.5-2) for the
enzyme pepsin.
• In the small intestine, enzymes complete the
process where the end matter is absorbed by villi.
• The large intestine absorbs water and passes the
unabsorbable rest off as feces.
Distinguish between absorption and
assimilation.
• Absorption is when food molecules pass
through a layer of cells such as passing
through the villi.
• Assimilation is when food actually becomes
part of the body's tissue.
Explain how the structure of the villus is related to its
role in absorption of the end products of digestion.
• It increases the surface area of the small
intestine
• The epithelium has a surface of only a thin
layer of cells.
• Protein channels in the microvilli allow for
quick absorption of foods via facilitated
diffusion and active transport.
• Blood capillaries close to epithelium making it
only a small distance for diffusion to occur.
Topic 6: Human Health and
Physiology
The Transport System
Draw a diagram of the heart showing all four chambers,
associated blood vessels and valves, and the route of blood
through the heart.
State that the Coronary Arteries supply heart muscle
with oxygen and nutrients.
• The Coronary Arteries supply heart muscle
with oxygen and nutrients.
Describe the action of the heart in terms of collecting
blood, pumping blood and opening and closing valves.
• The right atrium relaxes for the
blood to be received from the
superior and inferior vena cava.
• Blood returns from the lungs to
the heart through the pulmonary
veins, now oxygenated.
• The atrioventricular valve opens
for blood to go to the right
ventricle by the contracting
atrium.
• The left atrium relaxes to receive
it and then contracts to pump
blood and open the
atrioventricular valve where then
the blood goes to the relaxed left
ventricle.
• The right ventricle then relaxes to
receive the blood from the
atrium. Then it contracts in order
to open up the pulmonary valves.
Deoxygenated blood goes
through to the pulmonary artery,
where it enters the lungs so that
the blood will be oxygenated.
• The left ventricle contracts to
open the semilunar valves and
then the blood goes through the
aorta to the rest of the body.
Describe the action of the heart in terms of collecting
blood, pumping blood and opening and closing valves.
Outline the control of the heartbeat in terms of myogenic
muscle contraction, role of the pacemaker, nerves, the
medulla of the brain and epinefrine (adrenalin).
• The heart muscle may have an intrinsic contractile property that is
independent of the nervous system
• The pacemaker is located in the wall of the right atrium at the
Sinoatrial node (SAN).
• Each time the pacemaker sends out a signal, the heart carries out a
contraction or a beat.
• The heart beats by itself (myogenic).
• Nerves and hormones can transmit messages to the pacemaker:
• Sympathetic nerve secretes adrenaline (also known as
"epinephrine") which carries messages from the brain to the
pacemaker telling the pacemaker to speed up the beating of the
heart.
• Another nerve tells it to slow it down, and Adrenalin, carried to the
pacemaker by the bloodstream tells it to speed up the beating of
the heart.
Explain the relationship between the structure
and function of arteries, capillaries, and veins.
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Arteries:
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Capillaries:
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Thick wall to withstand high blood pressure.
Thick outer layer of longitudinal collagen and elastic
fibers.
Thick layers of circular elastic and muscle fibers.
walls stretch and recoil for the blood to go from the
heart to the small intestine.
Narrow lumen to help maintain the high pressure.
Has pores to allow plasma and phagocytes to diffuse in
or out.
Connects the vein and artery
Moist and thin for diffusion and has a short diffusion
distance.
Narrow diameter and large quantity allow for a large
exchange of materials through diffusion
Veins
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Thin layers with a few circular elastic and muscle
fibers.
Thin walls to allow the muscles to squeeze the veins
Thin outer layer of longitudinal collagen and elastic
fibers.
Valves for blood to stay and not flow backwards.
Wide lumen to accommodate for the slow flowing of
blood
State that blood is composed of plasma, erythrocytes,
leukocytes, (Phagocytes and lymphocytes) and platelets.
• Blood is composed of
plasma, erythrocytes,
leukocytes and
platelets.
State that blood is composed of plasma, erythrocytes,
leukocytes, (Phagocytes and lymphocytes) and
platelets.
State that the following are transported by the blood;
nutrients, oxygen, carbon dioxide, hormones, antibodies,
urea and heat.
• The following are transported in the blood:
– Nutrients
– Oxygen
– Carbon dioxide
– Hormones
– Antibodies
– Urea
– Heat.
Topic 6: Human Health and
Physiology
Defense against infectious disease
Define pathogen
• Pathogen: an organism or a virus that causes a
disease.
Explain why antibiotics are effective against
bacteria but not viruses.
• Antibiotics are drugs which kill or slow the
growth of bacteria.
• Antibiotics block metabolic pathways of bacteria,
inhibiting cell wall formation and protein
synthesis, resulting in the death of foreign
bacteria.
• However, viruses are not alive and utilize the
organisms host cells to replicate, which are not
targeted by antibiotics.
• In order to kill a virus by antiobiotics human cell
has to be killed as well
Explain how skin and mucous membranes act
as barriers against pathogens.
• The skin and mucous membranes form a barrier
that prevents most pathogens from entering the
body.
• The other layers of the skin are tough and form a
physical barrier.
• These dry, keratinised layers of skin discourage
pathogen growth.
• The skin also produces a thin layer of acid and
oils.
• Mucus contain an enzyme called lysozyme which
kills bacteria.
Outline how phagocytic leukocytes ingest
pathogens in the blood and in body tissue.
• Phagocytes are a type of leukocytes which ingest and
destroy foreign matter through phagocytosis.
• They can easily move through the walls of blood
capillaries and the site in which there is an infection.
• A phagocyte comes in contact with pathogen cells and
does not recognize the glycoprotein structure on its cell
wall.
• The pathogen is then ingested through endocytosis.
Plasma membrane forms around pathogen.
• Pathogen vacuole then binds with lysosome containing
digestive enzymes which break down the pathogen.
• Large numbers of phagocytes form pus.
State the difference between antigens
and antibodies.
• Antigens are macromolecules that elicit an
immune response by lymphocytes.
• Antibodies are proteins secreted by plasma
cells that bind to a particular antigen and
mark it for elimination.
Explain antibody production.
• Antibodies are made by lymphocytes, which recognize an
enormous number of antigens, but each individual cell recognizes
only one type of antigen.
• Each lymphocyte puts some of the antibody that it makes into its
cell surface with the antigen-combining site projecting outwards.
• When a pathogen enters the body, its antigens bind to the
antibodies in the cell surface of one type of lymphocyte.
• The selected lymphocyte proliferates to give rise to a clone of
identical cells bearing receptors for the selecting antigen.
• Some of the cells develop into short-lived plasma cells that secrete
antibody specific for the antigen.
• Others develop into long-lived memory cells that can respond
rapidly upon subsequent exposure to the same antigen.
Outline the effects of HIV on the
immune system.
• HIV attacks T-cells which are part of the immune
system that are important for the formation of
Beta lymphocytes.
• The virus enters the T-Cells and replicates there.
• As reproduction increases, the cell breaks up and
the virus RNA is spread to other T-cells.
• The virus keeps infecting and killing other T-cells,
paralyzing the immune system.
• This enables other organisms usually kept under
control by the immune system to be able to affect
the body.
Explain the cause, transmission, and
social implications of AIDS.
• AIDS or Acquired Immunodeficiency Syndrome is a collection of
symptoms and infections caused by infection with the human
immunodeficiency virus (HIV).
• Transmission:
– HIV is transmitted via direct contact of the mucous membrane with a
bodily fluid containing HIV such as blood, semen, or breast milk.
– The transmission could be through anal or penetrative sex, blood
transfusion, contaminated needles, or during pregnancy.
– Most researches think that the virus originated from the Sub-Sahara,
but the exact cause is unknown.
• Social Implications Fear and apprehension for those associated
with the disease, the lifestyle associated with the disease is
attacked, trouble getting a job or even getting health insurancedistanced from society
Topic 6: Human Health and
Physiology
Gas Exchange
State the difference between ventilation, gas
exchange and cell respiration.
• Ventilation: Is the process of inhaling and
exhaling, with oxygen entering the alveoli
(large surface area).
• Gas exchange: Process of exchanging one gas
for the other between alveoli and capillaries.
(Carbon dioxide for oxygen).
• Cell Respiration: The chemical process
occurring in the mitochondria where energy is
released as ATP.
Explain the necessity for a ventilation
system.
• A ventilation system is needed in order to
obtain oxygen for living organisms and to get
rid of carbon dioxide.
• Surface diffusion utilized by many smaller
organisms is not sufficient in supplying the
oxygen needs of the body.
• It is also needed to maintain a concentration
gradient in the alveoli.
List the features of the alveoli that adapt them
to gas exchange.
• Cells secrete fluid making the inner surface
moist.
• Increase in surface area.
• Single layer of cells allowing for short diffusion
distance
• Dense network of capillaries near the surface.
Draw a diagram of the ventilation system including
trachea, bronchi, bronchioles, and lungs.
Ventilation
system
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Trachea
Lungs
Bronchi
Bronchioles
Alveoli
Explain the mechanism of ventilation in human lungs, including the
action of the internal and external intercostals muscles, the
diaphragm, and the abdominal muscles.
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When we inhale, the diaphragm
moves down and becomes flat
because abdominal muscles
relax(allowing for more air).
The volume of the thorax increases,
air flows into the lungs.
External intercostal muscles contract.
When we exhale, abdominal muscles
contract and the diaphragm becomes
dome-shaped, moving up.
The volume of the thorax decreases
and intercostal muscles contract
causing pressure to increase.
Air flows out to equalize pressure
gradient.
Topic 6: Human Health and
Physiology
Nerves, Hormones, and Homeostasis
State that the nervous system consists of the central nervous system
(CNS) and peripheral nerves, and is composed of cells called neurons
that can carry rapid electrical impulses.
• The nervous system
consists of the central
nervous system (CNS)
and peripheral nerves,
and is composed of cells
called neurons that can
carry rapid electrical
impulses.
Draw and label a diagram of the
structure of a motor neuron.
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Include:
dendrites,
cell body with nucleus,
Axon
myelin sheath
nodes of Ranvier
motor end plates (axon
terminals).
State that nerve impulses are conducted from receptors to the CNS by
sensory neurons, within the CNS by relay neurons, and from the CNS to
effectors by motor neurons.
• Nerve impulses are conducted from receptors
to the CNS by sensory neurons, within the CNS
by relay neurons, and from the CNS to
effectors by motor neurons.
Define resting potential and action potential
(depolarization and repolarization).
The Resting Potential of a Neuron
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The cell membrane of a neuron
has charged particles (ions) on
either side.
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When the neuron is at rest (not
actively transmitting an impulse),
the outside of the membrane has
a net positive charge because it
has more positive ions than
negative ones.
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The inside has a net negative
charge, because it has more
negative ions than positive ones.
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A membrane potential is simply a
voltage that exists across a
membrane due to this unequal
distribution of charges.
When a neuron is at rest, the resting potential
is about -70 millivolts (mV), indicating that the
inside is negative relative to the outside.
The reason that the resting potential can exist
is because cell membranes are impermeable
and do not allow the flow of ions in and out of
the cell except through ion-specific channels.
Define resting potential and action potential
(depolarization and repolarization).
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An action potential occurs when a neuron sends
information down an axon, away from the cell body.
The action potential is an explosion of electrical
activity that is created by a depolarizing current.
A stimulus causes the resting potential to move
toward 0 mV. When the depolarization reaches
about -55 mV a neuron will fire an action potential.
This is the threshold.
If the neuron does not reach this critical threshold
level, then no action potential will fire.
Also, when the threshold level is reached, an action
potential of a fixed sized will always fire...for any
given neuron, the size of the action potential is
always the same.
There are no big or small action potentials in one
nerve cell - all action potentials are the same size.
Therefore, the neuron either does not reach the
threshold or a full action potential is fired - this is
the "ALL OR NONE" principle.
Explain how a nerve impulse passes
along a non-myelinated neuron.
• In resting neurons, there exists an imbalance of ions inside and
outside of the cell membranes.
• The important ions are K+ (potassium) and Na+ (sodium).
• K+ is more concentrated inside the cell and therefore tends to
diffuse out of the cell.
• It is this diffusion that causes the charge potential across the
plasma membrane (in resting neurons it is about -70 mV).
• Na+ is more concentrated outside of the cell and thus tends to
diffuse into the cell, but at a very slow rate due to the low
permeability of the plasma membrane to Na+.
• Sodium-potassium pumps embedded in the plasma membrane
work against both ions' diffusion gradients in order to preserve
the gradients and the membrane potential.
Explain the principles of synaptic
transmission.
• Include the release, diffusion and binding of
the neurotransmitter, initiation of an action
potential in the post-synaptic membrane, and
subsequent removal of the neurotransmitter.
Explain the principles of synaptic
transmission.
• Step 1. The neurotransmitter is manufactured by the
neuron and stored in vesicles at the axon terminal.
• Step 2. When the action potential reaches the axon
terminal, it causes the vesicles to release the
neurotransmitter molecules into the synaptic cleft.
• Step 3. The neurotransmitter diffuses across the cleft and
binds to receptors on the post-synaptic cell.
• Step 4. The activated receptors cause changes in the
activity of the post-synaptic neuron.
• Step 5. The neurotransmitter molecules are released from
the receptors and diffuse back into the synaptic cleft.
• Step 6. The Neurotransmitter is re-absorbed by the post
synaptic neuron. This process is known as Reuptake.
State that the endocrine system consists of glands that
release hormones that are transported in the blood.
• The endocrine system
consists of glands that
release hormones that
are transported in the
blood.
State that homeostasis involves maintaining the internal environment
between limits, including blood pH, carbon dioxide concentration, blood
glucose concentration, body temperature and water balance.
• Homeostasis involves
maintaining the internal
environment between
limits, including:
– blood pH
– carbon dioxide
concentration
– blood glucose
concentration
– body temperature
– water balance
Explain that homeostasis involves monitoring levels of variables
and correcting changes in levels by negative feedback
mechanisms.
• Homeostasis involves maintaining the body in
an environment between narrow limits by
negative feedback mechanisms.
• Negative feedbacks contain a detector which
measures the value of a feature to be
controlled.
• This sends information to an effector, which
then takes action.
Explain the control of body temperature, including the transfer of heat
in blood, and the roles of the hypothalamus, sweat glands, skin
arterioles and shivering
• Blood near the skin
exchanges heat with the
environment to preserve
37°C temperature.
• Vasoconstriction can
decrease blood flow to
the skin, preserving heat
in cold weather.
• Sweating can cool the
body as moisture on skin
evaporates.
• Shivering produces
muscle heat.
Explain the control of blood glucose concentration, including the
roles of glucagon, insulin and α and β cells in the pancreatic
islets.
• Glucagons - released by Alpha cells in the
pancreatic islets when blood sugar is low, it
transforms stored glycogen into glucose that
enters the blood stream.
• Insulin - released by Beta cells in the
pancreatic islets when blood sugar is high, it
transforms glucose in blood to stored
glycogen.
Distinguish between type I and type II diabetes.
type I
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Type 1 diabetes is usually diagnosed in
children and young adults, and was
previously known as juvenile diabetes.
The body does not produce insulin.
Insulin is a hormone that is needed to
convert sugar, starches and other food
into energy needed for daily life.
Only 5-10% of people with
diabetes have this form of the disease.
With the help of insulin therapy
and other treatments, even young
children with type 1 diabetes can learn
to manage their condition and live long,
healthy, happy lives.
type II
• Type 2 diabetes is the most
common form of diabetes.
• The body does not produce
enough insulin or
• The cells ignore the insulin.
• When glucose builds up in
the blood instead of going
into cells, it can lead
to diabetes complications.
Topic 6: Human Health and
Physiology
Reproduction
Draw diagrams of the adult male and
female reproductive systems.
Draw diagrams of the adult male and
female reproductive systems.
Outline the role of hormones in the menstrual cycle, including Follicle
Stimulating Hormone (FSH), Luteinizing Hormone (LH), estrogen and
progesterone.
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Estrogen leads to the production of eggs,
which leads to the menstrual cycle.
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In the menstrual cycle, FSH secreted by
pituitary gland increases, this is responsible
for the growth of an oocyte (an immature
egg) and it's follicle.
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Two weeks after the start of menstruation,
ovulation occurs due to a sudden and sharp
increase in LH from the pituitary gland.
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It also causes the empty follicle to develop
into the yellow body (corpus luteum) which
starts releasing the hormone progesterone.
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This is responsible for maintaining and
thickening the endometrium (wall of the
uterus) in preparation for implantation.
Annotate a graph showing hormone levels in the menstrual cycle, illustrating
the relationship between changes in hormone levels and ovulation,
menstruation and thickening of the endometrium.
Hormone levels in the menstrual cycle
• hormone levels in the
menstrual cycle,
• changes in hormone
levels and:
– ovulation
– menstruation
– thickening of the
endometrium
List three roles of testosterone in
males.
• From birth to the age of ten, testosterone level is
very low,increasing sharply after that and begins
puberty in males.
• This is when sperm production takes place.
• Testosterone stays at high levels until the age of
40-50, then it gradually decreases.
• It is also responsible for:
– voice change,
– hair growth in certain parts of the body
– building of muscles.
Outline the process of in vitro
fertilization (IVF).
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Various drugs are injected one a day
for three weeks to stop the menstrual
cycle.
Large doses of FSH are injected to
stimulate ovaries to develop many
follicles.
HCG hormone is injected 36 hrs.
before cell collection, causing the
eggs to mature and loosen.
Eggs are removed from the ovaries of
a woman by suction through the
vagina and are placed in a glass dish.
The eggs are then cleaned to remove
blood and other unwanted material.
The egg is then incubated.
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A male provides sperm which is
collected by a doctor.
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The healthiest sperm are selected
and mixed with the egg, to force
fertilization.
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Two or three eggs are selected and
implanted in the uterus through the
vagina.
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After a few weeks, a pregnancy test is
administered.
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Later in the pregnancy, a scan is
conducted to find a heartbeat.
Discuss the ethical issues of IVF.
For IVF
– Childless and infertile couples are provided a means to have children.
– Suffering due to a genetic disease of infertility is reduced.
Against IVF
– There is a high probability that children conceived using IVF from
infertile parents would inherit this genetic disease, going against
natural selection.
– Spare embryos are killed or donated to stem cell research.
– Once fertilized embryos have been implanted in the uterus, the
parents have the option of choosing which eggs shall be removed,
essentially allowing humans the right to define life and death.
– Those who do not remove extra eggs from the uterus have multiple
births, increasing the risk of health problems for the fetus.