Hl Human Health And Physiology

Front 1

Describe the process of blood clotting

Back 1

1. Blood vessels are damaged and exposed to the air.
2. Patelets clump at the damaged area.
3. Clotting factors are released which causes prothrombin in the plasma to turn into thrombin.
4. The thrombin causes soluble fibrinogen in the plasma to turn into insoluble fibrin fibres.
5. The insoluble fibres become entangled and create a mesh in which red blood cells become trapped, blocking blood flow.

Front 2

Outline the principle of challenge and response, clonal selection and memory cells as the basis of immunity

Back 2

• Challenge and response: When a pathogen invades the organism, the immune system is challenged and will produce antibodies against the invading pathogen as a response.
• Clonal selection: The B lymphocytes recognise the antigen by carrying their own antibodies on the outer surface of their membranes. These antibodies act as receptors binding to the specific antigen when it comes along. This binding activates the B lymphocyte causing it to rapidly divide into identical B-lymphocytes, all producing the relevant antibodies. This process is called clonal selection because the antigen selects the appropriate clone of B cells from among the millions in the body.
• Memory cells: After an infection has been dealt with, memory cells develop from the clone B lymphocytes. These antibody-producing cells survive for months or years and are able to tackle another infection of the same antigen.

Front 3

Define active and passive immunity

Back 3

Active immunity: immunity due to the production of antibodies by the organism itself after the body’s defence mechanisms have been stimulated by antigens.

Passive immunity: immunity due to the acquisition of antibodies from another organism in which active immunity has been stimulated, including via the placenta, colostrum, or by injection of antibodies.

Front 4

Explain antibody production

Back 4

1. Macrophage ingests pathogen.
2. Macrophage presents antigen to specific helper T-cell and releases chemicals (cytokines) to activate T-cell.
3. Helper T-cell divides to form a clone of memory cells and a clone of active cells.
4. Antigen is released by macrophage.
5. B-cell ingests same antigen bound to antibody and presents it on its surface.
6. Active helper T-cell with corresponding receptor releases chemicals (cytokines) which trigger B-cell to become active.
7. Activated B-cell divides to form a clone of plasma cells, and a clone of memory cells.
8. Plasma cells secrete huge quantity of specific antibody.

Front 5

Describe the production of monoclonal antibodies

Back 5

Producing large quantities of a single antibody:
1. Antigens that correspond to a desired antibody are injected into an animal.
2. B-cells producing the desired antibody are extracted from the animal.
3. Myeloma cells are obtained. These are cells which are a cancerous tumour of a plasma cell. The divide repeatedly, but do not produce antibody.
4. The B-cells are fused with the myeloma cells, producing hybridoma cells that divide endlessly and produce desired antibody.
5. The hybridoma cells are cultured and the antibodies that they produce are extraceed and purified.

Front 6

Describe the use of monoclonal antibodies in diagnosis and in treatment

Back 6

Diagnosis of Malaria:
Monoclonal antibodies are produced which bind to antigens in malarial parasites. A test plate is coated with the antibodies. A sample is left on the test plate long enough for the malaria antigens in the sample to bind to the antibodies. The sample is then rinsed off the plate. Any bound antigens are detected using more monoclonal antibodies with enzymes attached that cause a colour change. This is called an ELISA test. It can be used to measure the level of infection, or to distinguish between different strains of malaria.
Treatment of Anthrax:
Anthrax is a disease caused by a bacterium that produces toxins. Monoclonal antibodies are being developed which neutralize one of the toxins, and therefore sustain the patient's life until their immune system produces antibodies naturally.
Treatment of Rabies:
Monoclonal antibodies are injected along with the rabies vaccine. The antibodies quickly destroy the virus, and the vaccine produces a longer term immunity.

Front 7

Explain the principle of vaccination

Back 7

A vaccine contains a form of the pathogen or toxin that has modified such that it is unable to harm the body. However, it still triggers the immune response, leading to clones of memory cells. This immunological memory means that if the real pathogen invades the body, it is rapidly destroyed before it causes harm.
1. 'Pathogen' in vaccine leads to formation of active T-helper cells, plasma cell clones and clones of memory cells.
2. Plasma cells release antibodies to destroy the vaccine 'pathogen'.
3. Real pathogen invades and triggers memory helper T-cells.
4. Active helper T-cells trigger memory B-cells.
5. Large number of clones of plasma cells rapidly destroy pathogen.

Front 8

Discuss the benefits and dangers of vaccination

Back 8

BENEFITS:
- Reduced deaths from virulent pathogens such as tuberculosis.
- Prevention of epidemics and pandemics.
- Reduced side effects as a result of infection by some pathogens e.g mumps which may cause stirelity in men.
- Assists in the eradication of a disease.
DANGERS:
- Immunity from a vaccine may not be as effective as that derived from a true infection.
- Some vaccines may result in harmful side effects.
- An attenuated vaccine may become virulent.
- Some vaccines contain mercury, which may have a toxic effect.
- The immune system may become 'overloaded'.

Front 9

State the roles of bones, ligaments, muscles, tendons and nerves inhuman movement

Back 9

Bones: Bones meet at a joint and act as levers, different types of joint between bones control the range of movement, provide rigid anchorage for muscles through tendons.
Ligaments: tough inelastic structures holding bones together.
Muscles: contain receptors that send information via sensory neurons to the brain about the position of the muscle, contract to bring about movement at a joint, work in antagonistic pairs on each side of a joint.
Tendons: join muscle to bone.
Nerves: carry impulses to and from the brain to co-ordinate muscular activity, motor neuron impulses stimulate muscles to contract, nerve impulses control timing and speed of muscle contraction.

Front 10

Label a diagram of the human elbow joint, including cartilage, synovialfluid, joint capsule, named bones and antagonistic muscles (biceps and triceps)

Back 10

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Front 11

Outline the functions of the structures in the human elbow joint

Back 11

Bones (humerus, ulna, radius): rigid structures providing anchors for muscles, create fulcrum at joint.
Muscles (Biceps = flexor muscle and bends joint, Triceps = extensor muscle and straightens joint): provide forces to move joint, act as antagonistic pair.
Cartilage: smooth, strong covering on articulating surfaces of joint.
Synovial fluid: lubricates articulating surfaces of cartilage, shock absorber.
Joint capsule: encloses joint to protect it.

Front 12

Compare the movements of the hip joint and the knee joint

Back 12

Hip joint:
- Ball and socket joint
- Moves in all three planes (forward and back, sideways, rotation).

Knee joint:
- Hinge joint
- Moves in one plane (forward and back)

Front 13

Describe the structure of striated muscle fibres, including the myofibrils with light and dark bands, mitochondria, the sarcoplasmic reticulum, nuclei and the sarcolemma

Back 13

A muscle fibre is a group of modified muscle cells, where many cells have joined together to form a single mass of cytoplasm with many nuclei.
Myofibrils: within each muscle fibre are cylindrical structures called myofibres. They consist of repeating units called sarcomeres, which have light and dark bands.The light and dark bands give the fibre a striated (striped appearance)
Mitochondria: There are mithochondria between the myofibrils.
Sarcoplasmic reticulum: a sarcoplasmic reticulum is around each myofibril. It is a special type of endoplasmic reticulum, made of a network of flattened membrane-lined cavities.
Sarcolemma: the plasma membrane of the muscle fibre is called the sarcolemma.
Nuclei: Pressed against the inside of the sarcolemma are the unusual, flattened nuclei.

Front 14

Draw and label a diagram to show the structure of a sarcomere, including Z lines, actin filaments, myosin filaments with heads, and the resultant light and dark bands

Back 14

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Front 15

Explain how skeletal muscle contracts, including the release of calcium ions from the sarcoplasmic reticulum, the formation of cross-bridges, the sliding of actin and myosin filaments, and the use of ATP to break cross-bridges andre-set myosin heads

Back 15

1. Nerve impulse arrives and depolarises sarcoplasmic reticulum membraine.
2. Voltage gated calcium channels open, releasing calcium ions.
3. Calcium ions bind to troporin.
4. Tropomyosin pulled off myosin binding sites.
5. Actin-myosin cross-bridge formed.
6. Cross-bridge bends, pulling actin past myosin, ADP released.
7. ATP binds to myosin.
8. Myosin hydrolisises ATP, this energy breaks the cross-bridge.
9. Actin and myosin separate, and the structure bends back to its original position.
10. The bridge reforms further along the actin, and the process repeats.

Front 16

Analyse electron micrographs to find the state of contraction of muscle fibres

Back 16

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Front 17

Define excretion

Back 17

Excretion is the removal from the body of the waste products of metabolic pathways

Front 18

Draw and label a diagram of the kidney

Back 18

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Front 19

Annotate a diagram of a glomerulus to show the function of each part

Back 19

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Front 20

Annotate a diagram of a nephron to show the function of each part

Back 20

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Front 21

Explain the process of ultrafiltration, including blood pressure, fenestrated blood capillaries and basement membrane

Back 21

The function of the glomerulus is production of a filtrate from the blood by a process called ultrafiltration.

Large molecules in the blood can enter the fenestrations between the capillary cells, but are unable to pass through the basement membrane. Thus, the basement membrane acts as the 'ultra-filter', and is the barrier between the filtrate and the blood. It allows small solute molecules such as glucose and urea through, but not large ones, such as proteins. The podocytes allow the filtrate to pass rapidly and easily into the space of the Bowmans capsule as there are gaps between the cells.

This is a passive system. It is also unselective, meaning the filtrate will contain approximately the same proportions of small soluble molecules as the blood leaving the glomerulus. The high blood pressure is also very important. This is due to the efferent arteriole being narrower than the afferent arteriole. This causes high blood pressure, which allows the filtrate to be pushed out of the blood.

Front 22

Define osmoregulation

Back 22

Osmoregulation is the control of the water balance of the blood, tissue or cytoplasm of a living organism.

Front 23

Explain the reabsorption of glucose, water and salts in the proximal convoluted tubule, including the roles of microvilli, osmosis and active transport

Back 23

- Glucose and salts are reabsorbed by active transport, and water is reabsorbed by osmosis.
- Normally all glucose is reabsorbed, and about 80% of the filtrate is absorbed.
- The proximal convoluted tubule is long to increase surface area.
- The microvili increase the absorptive area.
- Mitochondrian provide ATP for active transport.
- Intercellular and subcellular spaces increase surface area for export.

Front 24

Explain the differences in the concentration of proteins, glucose and urea between blood plasma, glomerular filtrate and urine

Back 24

Proteins: - Blood plasma - normal concentration.
- Glomerular filtrate - none, because they are too large to fit through the basement membrane in the Bowman's capsule.
- Urine - none, if present, it could indicate damage to the kidney.
Glucose: Blood plasma - normal concentration.
- Glomerular filtrate - glucose is small enough to pass through the basement membrane, so its concentration is approximately equal to in the plasma.
- Urine - none, normally, in a healthy person, all the glucose is reabsorbed in the proximal convoluted tubule.
Urea: - Blood plasma - normal concentration.
- Glomerular filtrate - urea is small enough to pass through the basement membrane, and so its concentration is approximately equal to in the plasma.
Urine - ideally all the filtered urea would be excreted, but because it is a small molecule, over half of that filtered get reabsorbed back into the blood.

Front 25

Explain the role of the loop of Henle and the medulla in maintaining the water balance of the blood

Back 25

- Some water and salt reabsorption occurs.
- The walls of the descending limb are permeable to water due to the increasing salt concentration of the medulla The osmotic gradient causes water to leave. This water is remved by the blood in an ascending capillary.
- The cells of the ascending limb actively transport salt into the interstital fluid. IN theory, water should follow, as an osmotic gradient has been created. However the walls of the ascending limb are impermeable to water.
- The walls of the descending limb are also permeable to salt, so it diffuses in (this means that salt is trapped in a cycle, leaving the ascending limb and returning in the descending limb.)

Front 26

Explain the role of the collecting duct and ADH (vasopressin) in maintaining the water balance of the blood

Back 26

- The walls have a variable permeability to water.
- The hormone ADH from the pituitary gland increases the permeability.
- As filtrate flows down the collecting duct, the surrounding interstital fluid is increasingly more concentrated. Thus there is an osmotic gradient between the filtrate the the interstital fluid.
- In the absence of ADH there are few water channels, and the duct wall is impermeable to water.
- ADH is used by the body to control the water balance. More will be secreted if there is too litte water, and less if there is too much.
- If ADH is present, water channels will be inserted in the duct. Therefore, the water leaves the filtrate and is removed by the blood. This results in hypertonic urine.
- However, the half-life of ADH is only a few minutes so this allows the water balance to be tightly controlled.

Front 27

Explain the presence of glucose in the urine of untreated diabetic patients

Back 27

Diabetes is the inability to prevent glucose levels in the plasma from becoming too high due to a failure of the insulin homeostatic mechanism.

In the proximal convoluted tubule there are active transport proteins that pick up the glucose molecules as they flow past in the filtrate. If the number of glucose molecules in the filtrate is very high (because the plasma concentration was very high) then some will get missed, and leave the proximal convoluted tubule. After here, there are no glucose transport proteins, and so this glucose will end up in the urine.

Front 28

Annotate a light micrograph of testis tissue to show the location and function of interstitial cells (Leydig cells), germinal epithelium cells, developing spermatozoa and Sertoli cells

Back 28

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Front 29

Outline the processes involved in spermatogenesis within the testis, including mitosis, cell growth, the two divisions of meiosis and cell differentiation

Back 29

1. The outer layer of cells, called spermatogonia (2n) divides by mitosis, producing more spermatogonia (also 2n).
2. Spermatogonia grow into larger cells called primary spermatocytes (2n).
3. Primary spermatocytes (2n) carry out the first stage of meiosis, producing 2 secondary spermatocytes (n).
4. Each secondary spermatocyte carries out the second division of meiosis, producing four spermatids (n).
5. Spermatids differentiate into spermatozoa (n).

Front 30

Annotate a diagram of the ovary to show the location and function of germinal epithelium, primary follicles, mature follicle and secondary oocyte

Back 30

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Front 31

Outline the processes involved in oogenesis within the ovary, including mitosis, cell growth, the two divisions of meiosis, the unequal division of cytoplasm and the degeneration of polar body (IN THE FETUS)

Back 31

In a female fetus:
- oogonia cells (2n) divide by mitosis to form more diploid cells (2n).
- The diploid cells grow into larger cells called primary oocytes (2n).
- Primary oocytes start the first division of meiosis, but stop during prophase 1.
- The primary oocyte and a single layer of follicle cells around it form a primary follicle.
- When a baby girl is born, her ovaries contain approximately 400,000 primary follicles.

Front 32

Draw and label a diagram of a mature sperm

Back 32

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Front 33

Draw and label a diagram of a mature egg

Back 33

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Front 34

Outline the role of the epididymis, seminal vesicle and prostate gland in the production of semen

Back 34

Epididymis: storage structure in each testis where the sperm become mature and mobile.
Seminal vescicle: produces seminal fluid, thick due to mucus and protein, contains fructose as an energy source for sperm, contains prostaglandins which are hormones that stimulate contractions of the female reproductive tract to assist the movement of the sperm to the oviducts.
Prostate gland: produces prostate fluid, thin alkaline fluid, contains a clotting enzyme that converts the protein in seminal fluid into a gelatinous mass, this helps protect the sperm from the hostile environment of the vagina.

Front 35

Discuss similarities of spermatogenesis and oogenesis

Back 35

SIMILARITIES:
- Involve matosis at the start
- Involve cell growth
- Involve meiosis
-- Involve differentiation

Front 36

Describe the process of fertilization, including the acrosome reaction, penetration of the egg membrane by a sperm and the cortical reaction

Back 36

1. Sperm head contact zona pellucida, binds to specific glycoproteins, calcium pump activated causing uptake of calcium ions into sperm head, causing the acrosome to release enzymes including a carbohydrase and a protease.
2. Enzymes allow penetration by the sperm head of the zona pellucida this triggers completion of the second meiotic division of the oocyte.
3. Penetration of the plasma membrane by the sperm head triggers the release of calcium ions stored in the endoplasmic reticulum, this causes exocytosis of the enzymes in the cortical granules to the fluid-filled space, this is known as the cortical reaction, the enzymes do 2 things: remove the sperm binding glycoproteins, cause changes to the proteins in the zona pellucida creating the fertilisation membrane which prevents other sperm from entering the cytoplasm.
4. Fertilisation membrane spreads over surface of endoplasmic reticulum.
5. Fusion of the sperm nucleus with the egg nucleus is delayed by several hours until the division of the oocyte has taken place.

Front 37

Outline the role of HCG in early pregnancy

Back 37

- Produced by the developing placenta
- Production starts soon after implantation
- Mantains corpus luteum so production of progesterone continues
- High levels of progesterone and estrogen prevent the uterus lining from breaking down
- Can be detected int he urine with the use of monoclonal antibodies as a pregnancy test

Front 38

Outline early embryo development up to the implantation of the blastocyst

Back 38

The zygote produced by fertilisation in the oviduct starts to divide by mitosis to form a 2-cell embro, then a 4-cell embryo and so on. Eventually, a hollow ball of cells called a blastocyst is formed. While this is occuring, the embryo is transported down the oviduct to the uterus. When it is about 7 days old, the embryo implants itself into the uterus, where it continues to grow and develop.

Front 39

Explain how the structure and functions of the placenta, including its hormonal role in secretion of estrogen and progesterone, maintain pregnancy

Back 39

- Barrier between maternal blood and fetal blood
- Exchange site for molecules between maternal blood and fetal blood
- Is an endocrine organ – HGC, Estrogen, Progesterone and Human placental lactogen.
- Has complete hormonal control of pregnancy by week 12
- Oxygen, nutrients, antibodies and hormones are passed in to the fetal blood and carbon dioxide, urea and hormones are passed.
- Oxygenated blood is carried in the umbilical vein from the placenta to the fetus, deoxygenated blood is carried out in the umbilical arteries.
- The chorion forms the actual barrier between the maternal and fetal blood, it contains mitochondria for active transport of substances
- The placental villus has capillaries where exchange takes place
- The uterus wall has a muscular layer used during birth

Front 40

State that the fetus is supported and protected by the amniotic sac and amniotic fluid

Back 40

The fetus is supported and protected by the amniotic sac and amniotic fluid.

Front 41

State that materials are exchanged between the maternal and fetal blood in the placenta

Back 41

Materials are exchanged between the maternal and fetal blood in the placenta.

Front 42

Outline the process of birth and its hormonal control, including the changes in progesterone and oxytocin levels and positive feedback

Back 42

- Progesterone inhibits uterine contractions
- During pregnancy, the level of progesterone is high and the level of estrogen is low
- At the start of the brithprocess the level of progesterone falls and the level of estrogen rises
- Estrogen makes the uterus wall more sensitive to oxytocin
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Front 43

State the role of LH, testosterone and FSH in spermatogenesis

Back 43

Hormone: sute of production: function
Testosterone: interstitial cells of the testes: brings about puperty and maintains secondary sexual characteristics, stimulates final stages of spermatogenesis.

Follicle stimulating hormone (FSH): Anterior pituitary: stimulates the initial stages of speratogenesis

Luteinising Hormone (LH): Anterior pituitary: Stimulates secretion of testosterone by interstitial cells

Front 44

State that nutrients and waste materials are exchanged between fetal blood and maternal blood through the placenta

Back 44

Nutrients and waste materials are exchanged between fetal blood and maternal blood through the placenta.

Front 45

State that prolactin, a hormone from the anterior pituitary gland increases after birth and stimulates milk production

Back 45

State that prolactin, a hormone from the anterior pituitary gland increases after birth and stimulates milk production.

Front 46

Discuss differences of oogenesis and spermatogenesis

Back 46

- Polar bodies are only formed during oogenesis (polar bodies are structures that remove excess genetic material and do not develop into gametes)
- Each gamete forming cell in a male produces 4 gametes, wheras that in a female produces 1 gamete and 2-3 polar bodies
- Only one oocyte is released, however large numbers of sperm are released
- Sperm production is continuous, however oocyte production follows a monthly, cyclical pattern
- Both testes produce sperm, however, ovulation tends to occur from alternate ovaries each month
- Spermatogenisis commences at puberty, wheras the start of oogenesis is prenatal
- Spermatogenesis involves sertoli or nurse cells, wheras oogenesis does not

Front 47

Outline the processes involved in oogenesis within the ovary, including mitosis, cell growth, the two divisions of meiosis, the unequal division of cytoplasm and the degeneration of polar body (PUBERTY TO MENOPAUSE)

Back 47

From puberty to menopause:
- Every menstrual cycle, a few primary follicles start to develop.
- The primary oocyte completes the first division of meiosis, forming two haploid nuclei. However, the cytoplasm of the primary oocyte is divided unequally, forming a secondary oosyte (n) and a small polar body (n).
- The secondary oocyte starts the second division of meiosis, but stops in prophase 2. The follicle cells are proliferating and follicular fluid is forming.
- When the mature follicle bursts at the time of ovulation, the secondary oocyte (egg) is released.
- After fertilzation, the secondary oocyte completes the second division of meiosis to form an ovum (with a sperm already inside), and a second polar body.
- The 2 or 3 polar bodies do not develop, and eventually degenerate.