Unit 6 Human Physiology

Question 1

Annotate and label the small intestine

include mucosa, submucosa, muscular layer, serosa, epithelial cells

Answer 1

Four distinct tissue layers
Mucosa - inner lining, includes villi
Submucosa - connects tissue (between the mucosa and muscle.
Muscular layer - inner circular and outer longitudinal muscle perform peristalsis.
Serosa - protective outer layer
Epithelial cells - single outer layer of cells on each villus.
https://ib.bioninja.com.au/standard-level/topic-6-human-physiology/61-digestion-and-absorption/small-intestine.html

Question 2

Peristalsis

Answer 2

Moves food through the alimentary canal
mixes food with enzymes
Forces the products of digestion into contact with the wall of the intestine.
Food is moved very slowly to allow time to digest
Movement is like squeezing a toothpaste tube

Question 3

Purpose of pancreas

Answer 3

Synthesises three main enzymes (amylase, lipase and proteases)
Pancreatic juices containing enzymes are released into upper region of the small intestine (duodenum) via pancreatic duct.
The small intestine is where the final stages of digestion occur.

Question 4

Pancrease 3 main enzymes in digestion

Answer 4

Amylase - digests carbohydrates (Starch)
Lipases - digest lipids (Triglycerides)
Proteases - digest polypeptides

Question 5

Large food molecules are:

Answer 5

Usually insoluble
too large to diffuse into blood
larger molecules are broken down through hydrolysis to form products.
Products are:
usually soluble
small enough to absorb into the blood

Question 6

Villi in the digestive system

Answer 6

Many villi protrude into the lumen, increasing SA for absorption
Surrounded by a layer of epithelial cells
Cells have microvilli which increase SA further
Lacteals (lymph vessels) - allow for rapid absorption and transport of lipids
Capillaries close to epithelium - short path for diffusion, rich supply of blood.

Question 7

Absorption and Assimilation

Answer 7

Digestion breaks down large food molecules into smaller molecules.
Absorption is the uptake of these molecules into the blood.
Once in the blood, they are carried to the tissues where they are assimilated - taken in to be used

Question 8

Simple diffusion of Lipids in digestion

Answer 8

Lipids are non polar

Can pass freely through hydrophobic core of plasma membrane into epithelial cells (down concentration gradient)

Question 9

Facilitated diffusion in digestion

Answer 9

Nutrients are fructose and vitamins hydrophilic molecules use channel proteins to pass phospholipid bilayer and enter the epithelial cells (down concentration gradient)

Question 10

Active transport in digestion

Answer 10

Nutrients are glucose, amino acids and mineral ions

Protein pumps use ATP to move molecules against the concentration gradient into the epithelial cells

Question 11

Endocytosis (pinocytosis) in digestion

Answer 11

Plasma membrane folds inward to form vesicles to absorb larger molecules without digesting them

Question 12

Who is William Harvey?

Answer 12

English physician who made key contribution to anatomy and physiology.
First to describe completely systemic circulation

Question 13

Cardiac Cycle

Answer 13

Diastole - atria and ventricles relax. blood flows into heart from veins. AV valves open. SL valves closed (heart sound 2)
Atrial Systole - Atria contact. ventricles relax. blood pushed into atria. AV valves open. SL valves closed
Ventricular systole - atria relaxed. ventricles contract. blood pushed into arteries. AV valves closed (heart sound 1). Sl valves closed
https://library.med.utah.edu/kw/pharm/hyperheart/

Question 14

Atherosclerosis

Answer 14

Degenerative disease - artery wall become damaged
macrophages release growth factors, encouraging growth of fibrous tissue
cholesterol builds up in damaged areas.
eventually forms plaque and the artery wall loses elasticity.
http://www.hhmi.org/biointeractive/obesity/heart_attack.html

Question 15

Coronary heart disease

Answer 15

Atherosclerosis can lead to blood clots in the myocardial tissue
Heart attack occurs if coronary artery is completely blocked
muscle tissue dies as result

Question 16

Label Heart Diagram

Answer 16

http: //sciencelearn.org.nz/Contexts/See-through-Body/Sci-Media/Animation/Label-the-heart
file: ///C:/Users/isabe/OneDrive/Documents/School%20Classes/2021/Biology/Unit%206%20Human%20Physiology/Heart%20diagram.pdf

Question 17

Artery Structure

Answer 17

Relatively small lumen
Maintains high blood pressure
Muscle contracts to decrease size of lumen - causes increase in blood pressure
Elastic fibres stretch to increase the lumen with each pulse of blood.
After pulse of blood passes, fibres recoil decreasing lumen size. (helps maintain high blood pressure)
https://commons.wikimedia.org/wiki/File:Blausen_0055_ArteryWallStructure.png

Question 18

Purpose of Capillaries

Answer 18

Smallest blood vessels
adapted for exchange of substances to and from blood
enables tissues to gain nutrients and oxygen and remove waste material
allows substances to enter and leave the organism (gas exchange)
https://commons.wikimedia.org/wiki/File:Capillary_system_CERT.jpg

Question 19

Structure of Capillaries

Answer 19

Blood travels slowly under low pressure - more opportunity for exchange
basement membrane permeable to many substances
wall is one cell thick - allows easy diffusion, short diffusion distance
Walls contain pores to further aid diffusion
Massive surface area of many small capillaries.
https://commons.wikimedia.org/wiki/File:Capillary.svg

Question 20

Vein Structure

Answer 20

Return blood to heart for recirculation
large lumen (compared to arteries) means blood is under low pressure
less pressure means thinner walls and less elasticity.
contain less muscle
Have valves to prevent backflow.
https://www.pinterest.com/h255/chapter-20-the-circulatory-system-blood-vessels-an/

Question 21

What side of the body does oxygenated blood travel on?

Answer 21

Left

http://www.kscience.co.uk/animations/blood_system.swf

Question 22

What causes the beating of the heart?

Answer 22

Myogenic muscle contractions
Myocyte (muscle cell) itself is origin of contraction
controlled internally
Sinoatrial node controls HR
Wave of excitations sent from sinoatrial node - causes atria to contract
Excitation is conducted to atrioventricular node, where passes through nerves to muscles of ventricles, causing them to contract.
heart does not stop beating

Question 23

What controls the heart beat?

Answer 23

Controlled by autonomic nervous system - part of nervous system that responds automatically to changes in body conditions.
Myocardial contraction maintains the beating of the heart, used to speed up or slow down heart rate.
When exercising, more C02 is present in blood. - detected by chemoreceptors in brain’s medulla oblongata - results in a nerve signal being sent to SA node to speed the heart rate.
When C02 levels fall, another nerve (Vagus) reduces heart rate.
Adrenalin causes a rapid increase in heart rate in fight-or-flight responses, preparing the body for action.
Effect can be mimicked by stimulant drugs.

Question 24

HIV (Human Immunodeficiency virus)

Answer 24

gradually attacks imune system
AIDS develops when HIV is advanced - last stage of HIV - I left untreated, death
No current cure
It inserts its RNA into host cell
HIV attacks T-helper cells (CDC macrophages)
https://www.youtube.com/watch?v=GyofqO1TRjU

Question 25

Primary Defence

Answer 25

Physical Barriers

mucous, pH, lysozymes

Question 26

Clotting Factors

Answer 26

Clotting factors cause a series of reactions which end with fibrin (a protein) fibres forming a mesh across the wound site.
The fibrin fibres capture blood cells and platelets forming in a clot.
In the presence of air, the clot dries to form a scab with shields the healing tissues underneath.

Question 27

What is phagocytosis

Answer 27

Detecting and moving towards a foreign material using chemotaxis (movement in response to chemicals)
the foreign material is ingested by endocytosis
lysosomes attach to ingested vesicle (which encloses foreign material) and release enzyme into it
Enzymes digest/breakdown foreign material
the remains of foreign material are expelled from phagocyte.
https://www.youtube.com/watch?v=7VQU28itVVw&feature=youtu.be

Question 28

Antigen, antibody and immune response

Answer 28

Antigen - a substance, often found on a cell or virus surface, that causes antibodies to form
Antibody - a globular protein that recognises a specific antigen and binds to it as part of an immune response. antibodies are specific to certain antigens
An immune response triggered by non-self cells
reason why blood donors need to be a match

Question 29

Antibiotics

Answer 29

Drugs used in the treatment and prevention of prokaryotic bacteria.
Designed to disrupt structures or metabolic pathways in bacteria and fungi
http://edge.alluremedia.com.au/m/l/2015/04/Pills.jpg
http://www.wiley.com/college/pratt/0471393878/instructor/activities/bacterial_drug_resistance/antibiotic_targets_web.gif

Question 30

Antibiotic resistance

Answer 30

Bacteria mutate and resistance to an antibiotic naturally arises
Causes of resistance:
over prescribing
patients not finishing treatment
overuse in livestock
lack of hygiene
lack of new antibiotics

Question 31

Acetylcholine

Answer 31

A neurotransmitter used in many synapses through the nervous system
One use is at the neuromuscular junction
http://faculty.pasadena.edu/dkwon/chap%208_files/images/image61.png

Question 32

Explain how a nerve impulse passes along a non-myelinated neuron.

Answer 32

Potential increases;
If it increases beyond threshold, more sodium channels open;
Axon depolarises, stimulating adjacent sections;
Potassium channels open, potassium (+) rushes out;
Potential is reduced (repolarisation);
Refractory period ensures one-way conduction of action potential;
sodium-potassium pump returns axon section to resting potential.

Question 33

Meylination

Answer 33

Myelin acts as an insulator
Myelinated axons only allow action potentials to occur at unmyelinated nodes
Forces the action potential to jump from node to node (saltatory conduction).
Results in impulse travels faster (up to 200 m/s) along myelinated axons compared to unmyelinated axons (2 m/s).
Saltatory conduction from node to node also reduces degradation of the impulse
Allows impulse to travel longer distances than impulses in unmyelinated axons.
The myelin sheath also reduces energy expenditure over the axon as quantity of sodium and potassium ions that need to be pumped to restore resting potential is less than that of a un-myelinated axon

Question 34

Resting potential

Answer 34

The electrical potential across the plasma membrane of a cell that is not an impulse
Resting potential is maintained by active transport (antiport)

Question 35

Action potential

Answer 35

Reversal (depolarisation) and restoration (repolarisation) other membrane potential as an impulse travels along it.

Question 36

Step through the process of action potential

Answer 36

Sodium/potassium pump maintains electrochemical gradient of resting potential.
In response to change in membrane potential, adjacent voltage-gated Na+ channels open. results in positive membrane potential (depolarisation)
Depolarisation of membrane potential causes voltage-gated Na+ channels to close and voltage K+ channels to open
K+ diffuses out of neuron rapidly and membrane potential becomes negative again. (repolarisation)

Distribution of Na+ (out) and K+ (in) is reset by the Na+/K+ pump, returning neuron to resting potential. 
Enforced rest (refractory period) ensures impulses travel in single direction

Question 37

Synaptic Transmission

Answer 37

Nerve impulse reaches terminal end Of pre-synaptic neuron.
Depolarisation causes voltage-gated calcium channels to open. Ca rushes in.
Ca causes synaptic vesicles to move to the membrane and fuse.
Neurotransmitters (NTs) that were stored in the synaptic vesicle now diffuse across the synaptic gap.
NTS bind with post-synaptic receptors. (NTs are secific to the receptor.
Enzymes in the synaptic gap break down NT. Products Of this break down are taken up by pre-synaptic neuron by active transport (Lotsa mitochondria)
Sodium channels open, causing Na to enter, leading to depolarisation of the post-synaptic neuron. Action potential initiated.
Nerve impulse propagated along the post-synaptic neuron.

Question 38

Label The synapse

Answer 38

https: //ibguides.com/biology/notes/nerves-and-hormones/
http: //www.mult-sclerosis.org/synapse.gif

Question 39

Outline the use of four methods of membrane transport in nerves and synapses (active transport, simple diffusion, facilitated diffusion, vesicle transport).

Answer 39

Active transport
• sodium-potassium pump resets resting potential in the axon following nerve impulse
• re-uptake of neurotransmitters to the pre-synaptic neuron following synaptic transmission
• removal of Ca from pre-synaptic neuron following synaptic transmission

Simple diffusion
• diffusion of NT across synaptic cleft
• diffusion of K+ ions out of axon in resting potential

Facilitated diffusion
• opening of voltage-gated Na and K + channels in action potential
• opening Of voltage-gated Ca channels at pre-synaptic terminal
• Na channels activated at post-synaptic terminal to propagate AP

Vesicle transport
• influx of Ca activates vesicles of neurotransmitters
• exocytosis Of NT from pre-synaptic neuron to synaptic cleft

Question 40

Types of diabetes

Answer 40

Type 1: early onset, hereditary
triggered by illness, etc
Destroys beta cells
insulin production stops

Type 2: Adult onset, Hereditary
Related to obesity and poor diet
fewer insulin receptors in liver
less sensitivity to insulin

Question 41

Label and annotate female reproductive system
https://ib.bioninja.com.au/standard-level/topic-6-human-physiology/66-hormones-homeostasis-and/female-reproductive-system.html

Answer 41

Uterus - Provides protection, nutrients and waste removal for fetus
Muscular walls contract to aid birthing process
Fallopian tube (oviduct) -
Connects ovary to uterus
Fertilisation of egg occurs here
Ovary - (meiosis) eggs stored, develop, mature
Produces estrogen and progesterone
Cervix - Muscular opening/entrance to uterus
Closes to protect fetus and opens to form birth canal
Endometrium (lining of the uterus) - develops each month for implantation of fertilised egg
Vagina - Accepts penis during sexual intercourse
sperm received here
With the cervix forms the birth canal
May include kidney, bladder, etc to show not part of RS
https://ib.bioninja.com.au/standard-level/topic-6-human-physiology/66-hormones-homeostasis-and/female-reproductive-system.html

Question 42

Label and annotate male reproductive system
https://ib.bioninja.com.au/standard-level/topic-6-human-physiology/66-hormones-homeostasis-and/male-reproductive-system.html

Answer 42

Vas deferens (sperm duct) -
carries sperm to penis during ejaculation
Prostate gland - Adds alkaline fluids that neutralise the vaginal acids
Urethra - Delivers semen during ejaculation and urine during excretion
Penis/erectile muscle - Muscles becomes erect to penetrate the vagina during sexual intercourse
Delivers sperm to top of vagina
Seminal vesicle - adds nutrients including fructose sugar for respiration
Adds mucus to protect sperm
Epididymis - Sperm mature here and become able to move
Sperm storage
testis - Produces (millions) of sperm (every day)
Produces testosterone
Scrotum - Protects and holds testes outside the body
maintains lower optimum temperature
https://ib.bioninja.com.au/standard-level/topic-6-human-physiology/66-hormones-homeostasis-and/male-reproductive-system.html

Question 43

Explain the control of blood glucose levels

Answer 43

Pancreatic cells monitor blood glucose
Absorption of glucose from digestion in the intestine increases sugar
fasting reduces blood sugar
Gluco regulation is an example of negative feedback
Uses hormones insulin and glucagon

If blood glucose is too high -
Beta cells of pancreas produce insulin
Insulin stimulates uptake of glucose to cells, eg. muscle
Insulin stimulates liver/fat cells to store glucose as glycogen
Leading to decrease in blood glucose

If blood glucose too low
Alpha cells of pancreas produce glucagon
Glucagon stimulates liver to break glycogen into glucose
Leads to increased blood sugar
http://medmovie.com/portfolio-item/diabetes/

Question 44

Thyroxin

Answer 44

Produced by thyroid gland
targets most body cells
Increases metabolic rate/rate of protein synthesis
increases heat production (eg. increased respiration)

Question 45

Leptin

Answer 45

produced by adipose cells (fat storage cells)
targets appetite control centre of the hypothalamus (in brain)
Effects: An increase in adipose tissue increases leptin secretions into the blood
causes appetite inhibition and food intake.

Question 46

Melatonin

Answer 46

Produced by pineal gland in darkness
targets pituitary and other glands
Synchronisation of the circadian rhythms including sleep timing and blood regulation

Jet lag is a condition caused by travelling between time zones

Question 47

Testis Determining factor

Answer 47

Presence and expression of SRY gene on y chromosome leads to male development
SRY codes for testis determining factor (TDF).
TDF is a DNA binding protein that acts as a transcription factor promoting the expression of other genes.

In the presence of TDF the gonads become testis.
In absence of TDF the gonads become ovaries and developing fetus becomes female.

Question 48

Menstrual Cycle day 1-28

Answer 48

Day 1-4 (follicular phase)
Menstruation. Endometrium shed.
FSH increases, stimulating follicle development.

Day 5-14 (ovulatory phase)
FSH and follicle stimulate estrogen release
Estrogen stimulates endometrium development
Estrogen stimulates LH
Peak in LH causes ovulation (day 14)

Day 14-28 (luteal phase)
Fall in LH. Corpus luteum forms from now empty follicle
Corpus luteum releases progesterone
Progesterone maintains endometrium and inhibits FSH and LH
If no fertilisation occurs, progesterone and estrogen fall, triggering mensturation and SHF release

Question 49

Explain the role of hormones in the regulation of the menstrual cycle

Answer 49

FSH and LH are produced by the pituitary gland;
estrogen and progesten are produced by the ovary;
FSH stimulates the ovary to promote development of a follicle;
The developing follicles secrete estrogen, which inhibits FSH (negative feedback);
Estrogen stimulates growth of endometrium;
Estrogen stimulates LH secretion (positive feedback);
LH stimulates follicle growth and triggers ovulation;
(the secondary oocyte leaves the ovary and) follicle becomes corpus luteum;
The corpus luteum secretes estrogen and progesterone;
Estrogen and progesterone maintain the endometrium;
Estrogen and progesterone inhibit LH and FSH (negative feedback);
After (two weeks) the corpus luteum degenerates progesterone and estrogen levels fall;
This triggers menstrual bleeding, the loss of endometrium;
The pituitary gland secreted FSH and LH, as they are no longer inhibited (and the menstrual cycle continues);

May credit marks that are clearly drawn and correctly labelled on diagrams or flow charts

Question 50

Key hormones in homeostasis and reproduction (Insulin, Glucagon, Leptin, Thryroxin, Melatonin, Testosterone, FSH, LH, Estrogen, Progesterone)

Answer 50

Insulin - Lowers blood glucose concentration - converts glucose to glycogen for strogae in liver
Glucagon - raises blood glucose concentration - onverts glycogen to glucose
Leptin - inhibits appetite
Thryroxin - regulates metabolic rate and helps to control body temperature
Melatonin - controls circadian rhythms
Testosterone - pre-natal development of genitalia, sperm production, development of male secondary sexual characteristics during puberty
FSH - stimulates growth and development of ovarian follicles (eggs)
LH - Triggers ovulation, release of oocyte from ovary
Estrogen - pre-natal development of female secondary sexual characteristics during puberty. causes uterine lining to thicken.
Progesterone - pre-natal development of female secondary sexual characteristics during puberty. maintains lining of uterus

Question 51

Presence of estrogen and progesterone in embryonic development

Answer 51

At first, secreted by mothers ovaries and later by her placenta
In absence of fetal testosterone and the presence of maternal estrogen and progesterone, ovaries developed from gonads

At puberty, secretion of estrogen and progesterone increase causing:
Primary sexual characteristic of egg release
Secondary sexual characteristics such as enlargement of breasts and growth of pubic hair

Question 52

Presence of testosterone in embryonic developement

Answer 52

Testes develop from embryonic gonads when embryo is becoming a fetus.
Testes secrete testosterone - male genitalia develop.
At puberty, secretion of testosterone increases causing:
Primary sexual characteristic of sperm production in testes
Secondary sexual characteristics such as enlargement of penis, growth of pubic hair and deepening of the voice.