11. Animal physiology

11. Animal physiology

11.1 Antibody production and vaccination

Nature of science:

• Consider ethical implications of research - Jenner tested his vaccine for smallpox on a child.

Understandings:

• Every organism has unique molecules on the surface of its cells.

• Pathogens can be species-specific although others can cross species barriers.

• B lymphocytes are activated by T lymphocytes in mammals.

• Activated B cells multiply to form clones of plasma cells and memory cells.

• Plasma cells secrete antibodies.

• Antibodies aid the destruction of pathogens.

• White cells release histamine in response to allergens.

• Histamines cause allergic symptoms.

• Immunity depends upon the persistence of memory cells.

• Vaccines contain antigens that trigger immunity but do not cause the disease.

• Fusion of a tumour cell with an antibody-producing plasma cell creates a hybridoma cell.

• Monoclonal antibodies are produced by hybridoma cells.

Applications and skills:

• Application: Smallpox was the first infectious disease of humans to have been eradicated by vaccination.

• Application: Monoclonal antibodies to HCG are used in pregnancy test kits.

• Application: Antigens on the surface of red blood cells stimulate antibody production in a person with a different blood group.

• Skill: Analysis of epidemiological data related to vaccination programmes.

11.2 Movement

Nature of science:

• Developments in scientific research follow improvements in apparatus - fluorescent calcium ions have been used to study the cyclic interactions in muscle contraction.

Understandings:

• Bones and exoskeletons provide anchorage for muscles and act as levers.

• Synovial joints allow certain movements but not others.

• Movement of the body requires muscles to work in antagonistic pairs.

• Skeletal muscle fibres are multinucleate and contain specialized endoplasmic reticulum.

• Muscle fibres contain many myofibrils.

• Each myofibril is made up of contractile sarcomeres.

• The contraction of the skeletal muscle is achieved by the sliding of actin and myosin filaments.

• ATP hydrolysis and cross bridge formation are necessary for the filaments to slide.

• Calcium ions and the proteins tropomyosin and troponin control muscle contractions.

Applications and skills:

• Application: Antagonistic pairs of muscles in an insect leg.

• Skill: Annotation of a diagram of the human elbow.

• Skill: Drawing labelled diagrams of the structure of a sarcomere.

• Skill: Analysis of electron micrographs to find the state of contraction of muscle fibres.

11.3 The kidney and osmoregulation

Nature of science:

• Curiosity about particular phenomena - investigations were carried out to determine how desert animals prevent water loss in their wastes.

Understandings:

• Animals are either osmoregulators or osmoconformers.

• The Malpighian tubule system in insects and the kidney carry out osmoregulation and removal of nitrogenous wastes.

• The composition of blood in the renal artery is different from that in the renal vein.

• The ultrastructure of the glomerulus and Bowman’s capsule facilitate ultrafiltration.

• The proximal convoluted tubule selectively reabsorbs useful substances by active transport.

• The loop of Henle maintains hypertonic conditions in the medulla.

• ADH controls reabsorption of water in the collecting duct.

• The length of the loop of Henle is positively correlated with the need for water conservation in animals.

• The type of nitrogenous waste in animals is correlated with evolutionary history and habitat.

Applications and skills:

• Application: Consequences of dehydration and overhydration.

• Application: Treatment of kidney failure by hemodialysis or kidney transplant.

• Application: Blood cells, glucose, proteins and drugs are detected in urinary tests.

• Skill: Drawing and labelling a diagram of the human kidney.

• Skill: Annotation of diagrams of the nephron.

11.4 Sexual reproduction

Nature of science:

• Assessing risks and benefits associated with scientific research - the risks to human male fertility were not adequately assessed before steroids related to progesterone and estrogen were released into the environment as a result of the use of the female contraceptive pill.

Understandings:

• Spermatogenesis and oogenesis both involve mitosis, cell growth, two divisions of meiosis and differentiation.

• Processes in spermatogenesis and oogenesis result in different numbers of gametes with different amounts of cytoplasm.

• Fertilization in animals can be internal or external.

• Fertilization involves mechanisms that prevent polyspermy.

• Implantation of the blastocyst in the endometrium is essential for the continuation of pregnancy.

• HCG stimulates the ovary to secrete progesterone during early pregnancy.

• The placenta facilitates the exchange of materials between the mother and fetus.

• Estrogen and progesterone are secreted by the placenta once it has formed.

• Birth is mediated by positive feedback involving estrogen and oxytocin.

Applications and skills:

• Application: The average 38-week pregnancy in humans can be positioned on a graph showing the correlation between animal size and the development of the young at birth for other mammals.

• Skill: Annotation of diagrams of seminiferous tubule and ovary to show the stages of gametogenesis.

• Skill: Annotation of diagrams of mature sperm and egg to indicate functions.