The Academic Blog: Topic 11: Human health & physiology HL

1.1 Describe the process of blood clotting.

Blood clotting functions to prevent blood loss from a wound, and to prevent entry of pathogens into exposed blood. Blood clotting starts when damaged cells and platelets release clotting factors that cause the production of thrombi. Thrombin in turn causes the conversion of soluble fibrinogen in the blood plasma to insoluble fibrin. Fibrin forms a net of fibres that effectively trap blood cells in the blood vessels, which is called a blood clot.

cells/tissue is damaged/cut/bruised; damaged cells/platelets release clotting factors;

(clotting factors cause the) production of thrombin;

blood plasma contains soluble fibrinogen; fibrinogen converted into fibrin; by thrombin;

forms a net of fibres trapping blood cells;

forming a clot / prevents blood loss / entry of bacteria/pathogens;

cascade of reactions/series of stages prevent accidental clotting/

speed up clotting;

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

Challenge and response

·        Pathogen is engulfed

Clonal selection

·        Vast numbers of clones of plasma and memory B-cells when B-cell is activated by T-cell

Memory cells

Memory cells are clones of B-cells as a result of immune response

Memory cells remain in body long after infection

Create faster immune response if same pathogen invades body

Polyclonal response

·        Typical pathogen activates many different types of B-cells

·        causing secretion of many different types of antibodies

·        Activation of many different cloning events

11.1.3 Define active and passive immunity.

Active immunity - immunity due to production of antibodies by organism itself after body’s defence mechanisms are stimulated by antigens.

Passive immunity - immunity through acquiring antibodies

from organism where active immunity has been stimulated, such as through the placenta, colostrum, or by injection of antibodies.

11.1.4 Explain antibody production.

Limit this to:

·        Macrophages present antigen which activates T-cells

·        Activation of helper T-cells leads to activation of B-cells

·        B-cells divide to form clones of antibody-secreting plasma cells and memory cells

11.1.5 Describe the production of monoclonal antibodies and their use in

diagnosis and in treatment.

Tumour and B-cells are fused together

tumour and B-cells are cultured and they subsequently proliferate to form a clone of dividing cells producing monoclonal antibodies

Monoclonal antibodies are used for HIV diagnosis and emergency treatment for rabies infections

Limit the uses to one example of diagnosis and one of treatment.

Detection of antibodies to HIV is one example in diagnosis. Others

are detection of a specific cardiac isoenzyme in suspected cases of

heart attack and detection of human chorionic gonadotrophin (HCG)

in pregnancy test kits. Examples of the use of these antibodies for

treatment include targeting of cancer cells with drugs attached to

monoclonal antibodies, emergency treatment of rabies, blood and

tissue typing for transplant compatibility, and purification of

industrially made interferon.

Aim 8: Production of monoclonal antibodies is certain to be a

growth area in biotechnology, with many potential applications

and consequent economic opportunities. Some of the applications

will be of most use in developing countries, raising the question

of how they will be paid for, whether commercial companies

should be expected to carry out pro bono research and development,

or whether national governments should provide funds for it

through aid budgets. Historically, the development of treatments

for tropical diseases and parasites has lagged far behind those for

the diseases prevalent in wealthier countries.

11.1.6 Explain the principle of vaccination.

Emphasize the role of memory cells. The primary and secondary

responses can be clearly illustrated by a graph.

Vaccination is the administration of a modified form of a disease-causing microorganism that stimulates the body to develop active immunity to the disease, without fully developing the disease.

11.1.7 Discuss the benefits and dangers of vaccination.Benefits should include total elimination of diseases, prevention of pandemics and epidemics, decreased health-care costs and prevention of harmful side-effects of diseases. The dangers should include the possible toxic effects of mercury in vaccines, possible overload of the immune system and possible links with autism. Aim 8: For parents there are ethical decisions to be made, to minimize risk for one’s own child, but also to help to prevent epidemics that could affect other children.

benefits: [6 max]

immunity results

can limit pandemics/epidemics/spread of (infectious) diseases;

diseases can be eradicated/smallpox eliminated;

reduces mortality/deaths due to disease;

can protect vulnerable groups/young/old/with other conditions;

decreases crippling effects of diseases (such as polio);

decreased health care costs;

risks: [6 max]

may produce (mild) symptoms of the disease;

human error in preparation/storage/administration of vaccine;

individual may react badly to vaccine / defective immune system /

hypersensitive/allergic reaction;

immunity may not be life-long / booster required;

possible toxic effects of mercury-based preservatives/thimerosal;

11.2.1 State the roles of bones, ligaments, muscles, tendons and nerves in human movement.

Bones - Rigid structure of skeleton on which a force is applied to create movement
Ligament - Tissue that joins/wraps the structures of an articulation.
Muscles - Tissue able to contract and apply a force to move a body structure, e.g. a bone.
Nerve - Group of axons wrapped together, bringing stimuli for muscles to contract.

11.2.2 + 11.2.3 Label a diagram of the human elbow joint, including cartilage,

synovial fluid, joint capsule, named bones and antagonistic muscles

(biceps and triceps) and outline the functions of these structures

11.2.4 Compare the movements of the hip joint and the knee joint.

Hip joint Knee joint

            Ball and socket joint                                       Hinge joint
        Movement in three planes                         Movement in only one plane

11.2.5 Describe the structure of striated muscle fibres, including the myofibrils

with light and dark bands, mitochondria, the sarcoplasmic reticulum,

nuclei and the sarcolemma.

11.2.6 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.

11.2.7 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 and reset myosin heads.

Details of the roles of troponin and tropomyosin are not expected.

Action potential from motor neuron causes the sarcoplasmic reticulum to release calcium ions.

Calcium ions bind to troponin which removes tropomyosin from the myosin binding site, thereby allowing the myosin head to bind to its binding site on the actin.

calcium ions are released from the sarcoplasmic reticulum;
they expose the myosin binding sites (on actin) / cause movement of
blocking molecules/troponin;
cross-bridges form between actin and myosin molecules;
ATP provides energy;
for actin filaments to slide over the myosin filaments / for myosin to
push actin;
ATP provides energy to release myosin from binding site;
action can be repeated further along the molecule;11.1.1 Describe the process of blood clotting

Process of blood clotting beigns when a cell or tissue is damaged.
This cell as well as platelets release clotting factors that stimulate the production of thrombin.
Thrombin causes soluble fibrinogen to be converted to insoluble fibrin
Fibrin causes formation of a n

When cell/tissue is damaged
Damaged cells and platelets release clotting factors
These clotting factors result in thrombin production
Thrombin causes soluble fibrinogen in blood plasma to be converted to fibrin.
Fibrin causes formation of a net of fibres that blocks blood cells
Ths forms a blood clot, which prevents blood loss and blocks entry of pathogens.

cells/tissue is damaged/cut/bruised;
damaged cells/platelets release clotting factors;
(clotting factors cause the) production of thrombin;
blood plasma contains soluble fibrinogen;
fibrinogen converted into fibrin; by thrombin;
forms a net of fibres trapping blood cells;
forming a clot / prevents blood loss / entry of bacteria/pathogens;
cascade of reactions/series of stages prevent accidental clotting/ speed up clotting;

11.1.3 Define active and passive immunity.

Active immunity - Immunity occuring due to body's production of antibodies as a result of the body's defence mechanism being stimulated by antigens.

Passive immunity - Immunity arising from body's acquisition of antibodies from another organism in which active immunity has been stimulated, e.g. via the placenta, colostrum or by injection.

11.1.4 Explain antibody production

Macrophage presents antigen
Helper T-cells are activated, which in turn activates B-cells
B-cells divide to form clones of antibody-secreting plasma cells and memory cells

11.1.5 Describe production of monoclonal antibodies and their use in diagnosis and in treatment.

Production

Fusion of tumour and B-cells
Subsequent proliferation of B-cells (rapid production)
B-cells produce antibodies

Uses

Diagnosis - Detection of antibodies to HIV
Treatment -

The kidney

11.3.1 Define excretion.

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

11.3.2 Draw and label a diagram of the kidney.

Include the cortex, medulla, pelvis, ureter and renal blood vessels.

11.3.3 Annotate (NOT DRAW) a diagram of a glomerulus and associated nephron to show the function of each part.

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

Blood in the glomerulus is under high pressure, as a result of the difference between

blood (in the glomerulus) under high pressure caused by difference
in diameter of (afferent and efferent) arterioles;
fluid plasma and small molecules forced into kidney tubule/Bowman’s capsule/through fenestrations/basal membrane; preventing larger molecules/blood cells from passing through;

process of water balance is called osmoregulation; water passes into the kidney tubules by ultrafiltration;
water is reabsorbed in the proximal convoluted tubule; water reabsorbed into blood from the (descending limb) of the loop of Henle; process by osmosis;
transport of salts into the medulla of kidney;
changes salt concentration so water is reabsorbed;
ADH released into blood when water is required;
ADH causes concentrated urine / no/low ADH causes dilute urine;
this causes more reabsorption of water from the collecting duct;
excess water is released as urine;
urine concentration depends on the body’s need for water;
drinking a lot gives dilute urine;

11.3.5 Define osmoregulation.

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

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

important that some products of digestion not lost;

products in the blood stream;

ultrafiltration in the glomerulus;

fenestrated capillaries / podocytes;

basement membrane acts as the filter;

proteins too large to pass through;

importance of proximal convoluted tubule;

reabsorption of salts / glucose / ions / other named substance;

microvilli;

details of active transport;

osmosis is the reabsorption of water;

detail of osmoregulation;

(filtrate formed by) ultrafiltration;
glucose/amino acids/soluble components enter Bowman’s capsule;
proteins in blood plasma but not in filtrate/proteins not filtered out (of blood);
glucose not in urine (normally); (selective) reabsorption (of glucose);
in the proximal convoluted tubule; by active transport / microvilli increase the surface area;
little/no urea reabsorbed
concentration increases / urea more concentrated in urine than in blood plasma;
water reabsorbed from filtrate; by osmosis;
in descending limb of nephron / in proximal convoluted tubule;
salts actively transported into the medulla (from filtrate);
creating concentration gradient/hypertonic medulla;
collecting duct permeability altered depending on blood solute concentration;

11.3.7 Explain the roles of the loop of Henle, medulla, collecting duct and ADH
(vasopressin) in maintaining the water balance of the blood.

Role of loop of Henle

Creates high solute concentration gradient in medulla
Wall cells in ascending limb create energy for sodium ions to be pumped out of filtrate into interstitial fluid (fluid between cels in medulla).
Wall cells of asending limb are impermeable to water, so water is retained in filtrate

Role of medulla

Role of ADH

Role of collecting duct

Collecting duct has water channels permeable

Collecting duct has water channels permeable to water;

High solute concentration of medulla;

Reabsorption of water allows excretion of concentrated urine;

ADH secretion increases permeability of collecting duct to water;

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

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

Explain the role of the kidney in maintaining water balance in humans. (Ultrafiltration, osmoregulation and water balance 11.3.4 + 11.3.5 + 11.3.7)

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Topic 11: Human health & physiology HL