unit 11

Question 1

outline the role of cell markers in blood groups?
And its impact in blood transfusions

Answer 1

cell makers are glycoproteins found on the surface of RBS which determine its blood type: IA, IB, IO, IAB has both. they also have other sefl antigen’s called Rhesus that determine its status, minus or negative.

It is important for the blood in trasnfusions to match both un group and in RH, as or else it will trigger an immune response, as the body does not recognize the self markers.

Question 2

outline the process of antibody production? (Primary immune response

Answer 2

1. phagocytes recognize antigen and engulf the pathogen via phagocytosis
2. removes the antigen from pathogen surface and binds it to MHS molceules on its own surface.
3. Helper T cells recognize these antigens and bind iwth them via complentary MHS complexes, this activates them.
4. the activiated T cells activated specifc B cells, which will begin to divide into plasma and memory cells.

Plasma cells begin production of antibodies and ocntain many mitchondria, ribosomes, and rough ER
Memory cells will remain in blood and only begin producing antibodies at rapid speeds and in larger quantities in secondary immune response.

Question 3

outline the different ways in which antibodies function

Answer 3

aggulation: stick together pathogens to help in phagocytosis
opsonisation: link pathigens to phagocytes directly
neutralisation: bind to toxins produced by pathogen to neutralize their effect.
complement activation: recruit complement proteins to attack pathogen
pathogen nutralisation bind to cell to prevent access to body cells.

Question 4

outline how vaccines work?

Answer 4

1. they are injections that contain weakened or dead form of pathogen
   2, triggeres primary immune response and so the produciton of plasma and memroy cells. the pathogen however is unable to make the person sick.
2. when the actual pathogens enters body, a secondary immune repsone is triigered which kills the pathogen before symptons develop.

(for questions with higher marks, explain the primary immune repsonse as well)

Question 5

outline the production of monoclonal antibodies?

Answer 5

1. host mammal is injcted with antibody which will trigger immune repsonse and produce antibodies
2. exctract plasma cells from host and fuse them with tumor cells, resulting in hybridoma cells wich divide uncontralably
3. this results in the production of monoclonal antibodies.

Question 6

outline the structure of skeletal muscles

look at a diagramm while explaining this, its complicated to visulaize or else.

Answer 6

they are striated muscles with have many nuclei (cell theory exception)

1st layer: (Imagine tubes stuck together) these are as a collective knows as muscles fibres, and they are surounded by a single plasma membrane called the sacrolemma.

2nd layer: these muscles fibres each contain myofibrils that are sournded by a single membrane called the sacroplasmic reticulum. there are many mitochondira between the myofibrils.

3rd layer: each myofibril (1 tube) consits of the smallest functional unit called sacromeres.

these sacromeres have light bands and dark bands. Dark Bands have a center called the M Line. Light Bands have a center called the Z line.

light band is composed of thin actin filaments, which is why they are light.

dark band is composed of thick myosin filaments whihc have multiple myosin heads.

Question 7

outline muscle contraction

Answer 7

Resting state Inhibition
1. on thin actin filaments tropomyosin blocks myosin heads binding sites
2. when stimualted to contract by motor neuron, the sacroplasmic reticulum releases calcium ions that bind to troponim which moves tropomyosin out of the way and exposes myosis binding sites.

Contraction
1. ADP myosin complexes bind to myosin site on actin filament and form cross bridges.
2. ADP is released triggering inward pull knows as poer stroke (the actin filament is pulled closer to the myosin filament)
3. New ATP molecule binds to myosin heaf which breaks the cross bridge
5. ATP is hrdolyzed into ADP, changing the angle of the myosin head allowing it to rebind to the actin filament.
6. the process is repeated until motor neuron stops firing, which is when the sacroplasmic reticulum reabsorbs the Ca ions, allowing tropomyosin to reblock the myosin head binding sites.

Question 8

outline what is meant by antagnostic muscle pairs + example

explain how it is done in insects jumping

Answer 8

In antagonistic muscles, one muscle always relaxes whilst the other contracts.

bicep and tricep
The b icep muscles are located a b ove the humerus and flex ( b end) the forearm.
The tricep muscles are located underneath the humerus and ex t end the forearm.

The hind legs in grasshoppers are perfectly adapted for jumping. muscles work antagonistically: has an extensor muscle and a flexor muscle.

1. flexor contracts (down) and the extensor (upper muscle) relaxes, the tibia flexes.
2. contraction of the extensor muscle and the relaxation of the flexor muscle. The result is the extension of the tibia, and the cockroach jumps.

Question 9

what are synovial joints? example

what is the main function of cartilage

Answer 9

joints that possess a synovial cavity between the two bones.
This cavity is filled with synovial fluid that reduces friction at the joint, allowing bones to move freely. Synovial joints allow a high range of specifc motions.

human elbow

The main function of cartilage is to protect the ends of the bone.

Question 10

annotate the human elbow joint

Answer 10

see notion

Question 11

outline the process of spermatogenesis

Answer 11

in testes, throughout life

1. germinal epethelium cells, in seminifebourus, divide miotically to produce germ cells
2. germ cells divide by mitosis to form primary spermatocyte
3. premiary spermatocyte undergoes first meiotic divison to form secondary spermatocyte.
4. second. sperma. undergoes second meiotic division to form spermatids (immature sperms)
5. spermatids bind to sertoli cells which allows them to mature, develop a tail
6. mature sperm (spermatozoa) leave seminifebourouls tubule

Question 12

outline the process of oogenesis

Answer 12

before birth, fetus in ovaries

1. germinal epithelium cells divide by mitosis to form germ cells
2. 4-5 mnoths: germ cells grow and start first meiotic divison to form primary occytes
3. 7 months: primary oocytes still undergoing meiosis but are now surounded by follicle cells, now called primary follicles (remain unchanged till puberty aorund 400’000)
4. puberty starts, one primary follice completes meoisis 1 to become mature follicle containning a secondary oocyte and a haploid polar cell on the inside of it.
5. when stimulated by HCG, secondary oocyte undergoes meiosis 2 but stops at prohase 2 and is released during ovulation.
6. rest of follicle becomes corpus leteum.

Question 13

compare and contrast oogenesis with spermatogenesis

Answer 13

Both involve mitosis and cell differentiation for cell growth
both involve two meiotic divisions

in spermatogensis millions of sperms are produced daily, whereas in oogenesis only one egg cell is produced every 14 days

spermatogensis carries on throughtout life whereas oogenesis stops at menopause

spermatogensis needs daily mitotic divisions to produce sperms whereas oogenesis requires miotic division only before birth

spermatogensis produced 4 gametes whereas oogensis produces 1 gamete and 3 polar bodies.

Question 14

outline the development of a fetus

Answer 14

Blastocyst development
1. 2 celled zygote undergoes mitosis zo form 4 celled mass after 48 hours of fertilisation
2. sucessive unequal miotic divisin results in formtation of a blastocyst, at 1 week with 125 cells
3. blastocyst moves via the cillia in the oviduct and at two weeks it is known as an embryo. once the embryo has used up all food storages in cytoplasm, the zona pellucida breaks down

Implantation
1. embryo sinks into endometrium to obtain nutrients
2. it secretes hCG which maintains the corpus luteum to continue producing progesterone and estrogen which will amintain the endometrium linning and prevent menstruation

Placental development
1. placenta begins to develop starting as finger like projections, villi, to allow for nutrient exchange
2. bone forms and the embryo is now cinsidred a fetus at 8/9 weeks
3. once large enough the fetus is sourounded by the amniotic sac and fluid which will protect it from damage.

Question 15

outline the structure and role of placenta, plus an annotation and roles of different elements

Answer 15

disc shaped tissue structure made form fetal tissue and in close contact with maternal tissue
echange of waster materials and nutrients
circulatory system is required

Functions:
Umbilical Artery: transports blood towards fetus
Umbilical Vein: transport blood away from fetus
(the reverse of what you would expect)

placental villi: increase SA + increase in number as fetal demand increases

intervillous space: maternal blood flows there rather than in confined blood vessels

cappillaries: in villus where fetal blood flows

Chorion: sepreates villus surface and intervillous space, it is selectively permeable and thin

Question 16

how do fish, mamals and birds excrete their waste?

Answer 16

fish as ammonia, little energy but toxic, must be diluted in water

mammals: urea, only toxic at abnormal levels, requires energy and water for dilution

birds as uric acid, it is insoluble so can be stored in eggs + no water, needs much energy

Question 17

outline waste excretion in arthropods (insects)

Answer 17

conduct ion and water movement through malphigian tubules connected to alimentary canal via ileum

consists of continous tube divied into: foregut, midgut, ileum, hindgut, rectum

1. active transport by linning cells of malphigian tubules of ions into tubules which creates concetration gradient that draws water in via osmosis
2. tubule cells convert the absorbed ammonia into uric acid
3. the tubules empty the resulting uric acid solution into the hindgut where it is mixed with semi digested food
4. in rectum ions are reabsorbed causing water to also be reabsobed
5. creates dehydrated uric acid paste wich is later excreted with undigested food

Question 18

annotate the kidney and outline the structure of a nephron + fucntions

Answer 18

Bowman’s capsule: porous layer to absorb glomerular filtrate, ultrafiltration

proximal convultued tubule: reabsorbs Na+, Cl-, glucose, amino acids and water

Loop of Henle: reabsorbs water by carrying glomerular filtrate from the cortex into the medulla down a descending limb and back to the cortex with a ascending limb

distal convuluted tubule: reabsorbes: Na and Cl ions via active transport and has micorvilli and mitochondria.

Collecting duct: finutunes water reabsorption and carries filtrate to the renal pelvis

Question 19

how are the diff nutrients reabsorbed in the proximal convuluted tubule

Answer 19

1. sodium reabsorbed by active transport creating a charged gradient
2. helps chloride ions flow down concentration gradient
3. glucose and amino acids undergo facilitated diffusion (sodium ions reenter the tubule down the concentration gradient providing enegry for co transportation)
4. water is reabsorbed via osmosis, from ion gradients.

Question 20

how is water reabsorbed from glomerular filtrate in loop of henle

Answer 20

between the loop of henle there is the interstitial space, which contains a solute concentration
1. descending limb is permeable to water, water moves into interstitial space
2. Vasa Recta immediately absorbes water, restoring solute concentration in interstitial space
3. the golmerular filtrate has a high concentration now, it lost water, so in the ascending (impermeable to water) limb, active transport of sodium ions into interstitial space, which increases water absorption in descending limb, etc, etc.

this is known as the counter cunter multiplication system, reaching a maximum solute concentration

mammals who need more water retention have longer loop of henle.

Question 21

outline how the glomerulous and the bowmans capsule undergo ultrafiltration?

Answer 21

glomerulus is a knot of intertwined capillaries in the bowmans capsule

capillaries have small openings called fenstrations that are convered by the basement membranes and podocytes which fold around the blood capillary forming a network of filtration slits that hold back the blood cells during ultrafiltration.

fenestrations allow blood to flow out, however, the basement membrane acts like a sieve during the ultrafiltration process and stops the blood cells and large proteins. ex. white blood cells and RBC cannot pass, only small nutrients, salts and nutrients.

unusually high capillary pressure (that allows ultrafiltration to occur) is the result of the short, large diameter afferent arterioles conveying blood at high pressure directly to the glomerular capillaries.
The smaller diameter of the efferent arterioles leaving the glomerulus also helps maintain the pressure by restricting the outflow of blood.