6.6 Hormones, homeostasis and reproduction

Nature of science:
Developments in scientific research follow improvements in apparatus—William Harvey was hampered in his observational research into reproduction by lack of equipment. The microscope was invented 17 years after his death. (1.8)

Understandings:

• Insulin and glucagon are secreted by β and α cells of the pancreas respectively to control blood glucose concentration.
• Thyroxin is secreted by the thyroid gland to regulate the metabolic rate and help control body temperature.
• Leptin is secreted by cells in adipose tissue and acts on the hypothalamus of the brain to inhibit appetite.
• Melatonin is secreted by the pineal gland to control circadian rhythms.
• A gene on the Y chromosome causes embryonic gonads to develop as testes and secrete testosterone.
• Testosterone causes pre-natal development of male genitalia and both sperm production and development of male secondary sexual characteristics during puberty.
• Estrogen and progesterone cause pre-natal development of female reproductive organs and female secondary sexual characteristics during puberty.
• The menstrual cycle is controlled by negative and positive feedback mechanisms involving ovarian and pituitary hormones.

Applications and skills:

• Application: Causes and treatment of Type I and Type II diabetes.
• Application: Testing of leptin on patients with clinical obesity and reasons for the failure to control the disease.
• Application: Causes of jet lag and use of melatonin to alleviate it.
• Application: The use in IVF of drugs to suspend the normal secretion of hormones, followed by the use of artificial doses of hormones to induce superovulation and establish a pregnancy.
• Application: William Harvey’s investigation of sexual reproduction in deer.
• Skill: Annotate diagrams of the male and female reproductive system to show names of structures and their functions.

Guidance:

• The roles of FSH, LH, estrogen and progesterone in the menstrual cycle are expected.
• William Harvey failed to solve the mystery of sexual reproduction because effective microscopes were not available when he was working, so fusion of gametes and subsequent embryo development remained undiscovered.

Utilization:

• Hormones are used in a variety of therapies such as replacement therapies.

Syllabus and cross-curricular links:
Biology
Topic 3.2 Chromosomes
Topic 3.3 Meiosis
Topic 10.1 Meiosis
Psychology
Core: Biological level of analysis

Aims:

• Aim 8: Scientists are aware that the drugs women take in fertility treatment pose potential risks to health. Should scientific knowledge override compassionate considerations in treating infertile couples?

6.3 Defence against infectious disease

Nature of science:
Risks associated with scientific research—Florey and Chain’s tests on the safety of penicillin would not be compliant with current protocol on testing. (4.8)

Understandings:

• The skin and mucous membranes form a primary defence against pathogens that cause infectious disease.
• Cuts in the skin are sealed by blood clotting.
• Clotting factors are released from platelets.
• The cascade results in the rapid conversion of fibrinogen to fibrin by thrombin.
• Ingestion of pathogens by phagocytic white blood cells gives non-specific immunity to diseases.
• Production of antibodies by lymphocytes in response to particular pathogens gives specific immunity.
• Antibiotics block processes that occur in prokaryotic cells but not in eukaryotic cells.
• Viruses lack a metabolism and cannot therefore be treated with antibiotics. Some strains of bacteria have evolved with genes that confer resistance to antibiotics and some strains of bacteria have multiple resistance.

Applications and skills:

• Application: Causes and consequences of blood clot formation in coronary arteries.
• Application: Florey and Chain’s experiments to test penicillin on bacterial infections in mice.
• Application: Effects of HIV on the immune system and methods of transmission.

Guidance:

• Diagrams of skin are not required.
• Subgroups of phagocyte and lymphocyte are not required but students should be aware that some lymphocytes act as memory cells and can quickly reproduce to form a clone of plasma cells if a pathogen carrying a specific antigen is re-encountered.
• The effects of HIV on the immune system should be limited to a reduction in the number of active lymphocytes and a loss of the ability to produce antibodies, leading to the development of AIDS.

International-mindedness:

• The spread and containment of diseases such as bird flu require international coordination and communication.

Utilization:

• An understanding of immunity has led to the development of vaccinations.

Syllabus and cross-curricular links:
Biology
Topic 5.2 Natural selection
Chemistry
Topic D2 Aspirin and penicillin

Aims:

• Aim 8: The social as well as the economic benefits of the control of bacterial diseases around the world should be stressed.
• Aim 9: Science has limited means in the fight against pathogens, as shown by the spread of new diseases and antibiotic-resistant bacteria.

11.1 Antibody production and vaccination

Nature of science:
Consider ethical implications of research—Jenner tested his vaccine for smallpox on a child. (4.5)

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.

Guidance:

• Limit the immune response to mammals.

International-mindedness:

• The World Health Organization initiated the campaign for the global eradication of smallpox in 1967. The campaign was deemed a success in 1977, only 10 years later.

Utilization:

• Human vaccines are often produced using the immune responses of other animals.

Syllabus and cross-curricular links:
Biology
Topic 6.3 Defence against infectious disease
Topic 11.4 Sexual reproduction
Geography
Part 2F: The geography of food and health

Aims:

• Aim 7: Use of databases to analyse epidemiological data.

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. (1.8)

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.

Guidance:

• Elbow diagram should include cartilage, synovial fluid, joint capsule, named bones and named antagonistic muscles.
• Drawing labelled diagrams of the structure of a sarcomere should include Z lines, actin filaments, myosin filaments with heads, and the resultant light and dark bands.
• Measurement of the length of sarcomeres will require calibration of the eyepiece scale of the microscope.

Aims:

• Aim 7: Use of grip strength data loggers to assess muscle fatigue.
• Aim 7: Use of animations to visualize contraction.

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. (1.5)

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.

Guidance:

• ADH will be used in preference to vasopressin.
• The diagram of the nephron should include glomerulus, Bowman’s capsule, proximal convoluted tubule, loop of Henle, distal convoluted tubule; the relationship between the nephron and the collecting duct should be included.

Utilization:

• The removal of kidney stones by ultra sound treatment.

Syllabus and cross-curricular links:
Biology
Topic 1.3 Membrane structure
Topic 1.4 Membrane transport

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. (4.8)

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.

Guidance:

• Fertilization involves the acrosome reaction, fusion of the plasma membrane of the egg and sperm and the cortical reaction.

Utilization:
Syllabus and cross-curricular links:
Biology
Topic 3.3 Meiosis
Topic 6.6 Hormones, homeostasis and reproduction

Aims:

• Aim 8: Disputes over the responsibility for frozen human

D.5 Hormones and metabolism

Nature of science:
Cooperation and collaboration between groups of scientists—the International Council for the Control of Iodine Deficiency Disorders includes a number of scientists who work to eliminate the harm done by iodine deficiency. (4.3)

Understandings:

• Endocrine glands secrete hormones directly into the bloodstream.
• Steroid hormones bind to receptor proteins in the cytoplasm of the target cell to form a receptor–hormone complex.
• The receptor–hormone complex promotes the transcription of specific genes.
• Peptide hormones bind to receptors in the plasma membrane of the target cell.
• Binding of hormones to membrane receptors activates a cascade mediated by a second messenger inside the cell.
• The hypothalamus controls hormone secretion by the anterior and posterior lobes of the pituitary gland.
• Hormones secreted by the pituitary control growth, developmental changes, reproduction and homeostasis.

Applications and skills:

• Application: Some athletes take growth hormones to build muscles.
• Application: Control of milk secretion by oxytocin and prolactin.

Aims:

• Aim 8: There are numerous drugs that can enhance performance. Is the use of these drugs acceptable in terms of conducting a fair test as long as all athletes have equal access to them?

Thursday, January 5, 2017

Assignment: get syllabus signed

Friday, January 6, 2017

Assignment: Group 4 meeting to join groups

Monday January 9, 2017

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Tuesday, January 10, 2017

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Wednesday January 11, 2017

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Thursday, January 12, 2017

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Friday, January 13, 2017

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Monday, January 16, 2017

MLK Holiday-School Closed

Tuesday, January 17, 2017

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Wednesday, January 18, 2017

Assignment:group 4 work

Thursday, January 19, 2017

Assignment: Quiz over 6.1

Friday, January 20, 2017

Assignment: Group 4 Presentations

Monday, January 23 , 2017

Assignment: Group 4 presentations

Tuesday, January 24, 2017

Assignment: Last group 4 presentation

Wednesday, January 25, 2017

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Thursday, January 26, 2017

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Friday, January 27, 2017

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Monday, January 30, 2017

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Tuesday, January 31, 2017

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Wednesday, February 1, 2017

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Thursday, February 2 , 2017

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Monday, February 6, 2017

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Tuesday, February 7, 2017

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Thursday, February 9, 2017

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Friday, February 10, 2017

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Monday, February 13, 2017

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Tuesday, February 14, 2017

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Wednesday, February 15, 2017

4.5 Weeks Progress Reports

Thursday, February 16, 2017

Parent-Teacher Conferences

Friday, February 17, 2017

February Holiday-School Closed

Monday February 20, 2017

Presidents Day – School Closed

Tuesday, February 21, 2017

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Wednesday, February 22, 2017

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Thursday, February 23, 2017

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Friday, February 24, 2017

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Monday, February 27, 2017

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Tuesday, February 28, 2017

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Wednesday, March 1, 2017

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Thursday, March 2, 2017

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Friday, March 3, 2017

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Monday, March 6, 2017

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Tuesday, March 7, 2017

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Wednesday, March 8, 2017

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Thursday, March 19, 2017

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Friday, March 10, 2017

Teacher Workday – No School

Monday, March 13, 2017

Assignment:

HW: finish final draft of IA