Topic 6: Human physiology (20hs)

6.1 Digestion and absorption

Use models as representations of the real world—dialysis tubing can be used to model absorption in the intestine. (1.10)


Arcade! link


• The contraction of circular and longitudinal muscle of the small intestine mixes the food with enzymes and moves it along the gut.
• The pancreas secretes enzymes into the lumen of the small intestine.
• Enzymes digest most macromolecules in food into monomers in the small intestine.
• Villi increase the surface area of epithelium over which absorption is carried out.
• Villi absorb monomers formed by digestion as well as mineral ions and vitamins.
• Different methods of membrane transport are required to absorb different nutrients.

Very simple interactive by Sheppard software

Interactive digestive system by EduMedia

Starch digestion lab video

Digestion video

Applications and Skills

• Application: Processes occurring in the small intestine that result in the digestion of starch and transport of the products of digestion to the liver.
• Application: Use of dialysis tubing to model absorption of digested food in the intestine.

• Skill: Production of an annotated diagram of the digestive system.
• Skill: Identification of tissue layers in transverse sections of the small intestine


• Some hydrolytic enzymes have economic importance, for example amylase in production of sugars from starch and in the brewing of beer.

6.2 The blood system

Theories are regarded as uncertain—William Harvey overturned theories developed by the ancient Greek philosopher Galen on movement of blood in the body. (1.9)


Stayin´alive – RCP link

The science of emotions Link

Arcade! link

Theory of knowledge

Our current understanding is that emotions are the product of activity in the brain rather than the heart. Is knowledge based on science more valid than knowledge based on intuition?

Can you die from a broken heart? link


• Arteries convey blood at high pressure from the ventricles to the tissues of the body.
• Arteries have muscle cells and elastic fibres in their walls.
• The muscle and elastic fibres assist in maintaining blood pressure between pump cycles.
• Blood flows through tissues in capillaries. Capillaries have permeable walls that allow exchange of materials between cells in the tissue and the blood in the capillary.
• Veins collect blood at low pressure from the tissues of the body and return it to the atria of the heart.
• Valves in veins and the heart ensure circulation of blood by preventing backflow.
• There is a separate circulation for the lungs.
• The heart beat is initiated by a group of specialized muscle cells in the right atrium called the sinoatrial node.
• The sinoatrial node acts as a pacemaker.
• The sinoatrial node sends out an electrical signal that stimulates contraction as it is propagated through the walls of the atria and then the walls of the ventricles.
• The heart rate can be increased or decreased by impulses brought to the heart through two nerves from the medulla of the brain.
• Epinephrine increases the heart rate to prepare for vigorous physical activity.

Simulation by EduMedia

Heart structure by WiscOnline

Simulation by Science Museum Minnesota

How the heart actually pumps blood? TedEd

Applications and Skills

• Application: William Harvey’s discovery of the circulation of the blood with the heart acting as the pump.
• Application: Pressure changes in the left atrium, left ventricle and aorta during the cardiac cycle.
• Application: Causes and consequences of occlusion of the coronary arteries.

Atherosclerosis review link

The Heart, Part 1 – Under Pressure by CrashCourse


• Skill: Identification of blood vessels as arteries, capillaries or veins from the structure of their walls.
• Skill: Recognition of the chambers and valves of the heart and the blood vessels connected to it in dissected hearts or in diagrams of heart structure.

Virtual heart dissection by Biologycorner

Dissection of the heart by PBS


Understanding of the structure of the cardiovascular system has allowed the development of heart surgery.

6.3 Defense against infectious disease

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)


Plague game. Can you infect the world? Link

HIV infection game Link

Arcade! link

International Mindedness

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


• 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.

Cells of the Immune System by Biointeractive

Immune response by McGraw Hills

Antibiotics animations by eBug


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.

Fleming, Florey and Chain and the discovery of penicillin. Video

Blood clots British Heart Fundation

Why is it so hard to cure AIDS? TedEd


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

How do vaccines work? TedEd

Disease and vaccination simulator by Learner

VAX! A game about epidemic prevention by VaxHero 

6.4 Gas exchange

Obtain evidence for theories—epidemiological studies have contributed to our understanding of the causes of lung cancer. (1.8)


Arcade! Link

Know the Risks: A Youth Guide to E-cigarettes by CDC


• Ventilation maintains concentration gradients of oxygen and carbon dioxide between air in alveoli and blood flowing in adjacent capillaries.
• Type I pneumocytes are extremely thin alveolar cells that are adapted to carry out gas exchange.
• Type II pneumocytes secrete a solution containing surfactant that creates a moist surface inside the alveoli to prevent the sides of the alveolus adhering to each other by reducing surface tension.
• Air is carried to the lungs in the trachea and bronchi and then to the alveoli in bronchioles.
• Muscle contractions cause the pressure changes inside the thorax that force air in and out of the lungs to ventilate them.
• Different muscles are required for inspiration and expiration because muscles only do work when they contract.

Animation by JohnWiley

Gas exchange animation by McGraw Hill

Gas exchange animation by Footprints

Inspiration and Expiration animation by McGraw Hill

Online study guide by GetBodySmart

How mucus keeps us healthy by TedEd

Applications and Skills

• Application: Causes and consequences of lung cancer.
• Application: Causes and consequences of emphysema.
• Application: External and internal intercostal muscles, and diaphragm and abdominal muscles as examples of antagonistic muscle action.

Understanding lung cancer by Nucleus

How do cigarettes affect the body by TedEd

What Are the Risk Factors for Lung Cancer? by CDC

• Skill: Monitoring of ventilation in humans at rest and after mild and vigorous exercise. (Practical 6)

6.5 Neurons and synapses

Cooperation and collaboration between groups of scientists—biologists are contributing to research into memory and learning. (4.3)


Insensitive vs senseless Dr House episode link

Arcade! link

How memories form and how we lose them  by TedEd

Brain games link


• Neurons transmit electrical impulses.
• The myelination of nerve fibres allows for saltatory conduction.
• Neurons pump sodium and potassium ions across their membranes to generate a resting potential.
• An action potential consists of depolarization and repolarization of the neuron.
• Nerve impulses are action potentials propagated along the axons of neurons.
• Propagation of nerve impulses is the result of local currents that cause each successive part of the axon to reach the threshold potential.
• Synapses are junctions between neurons and between neurons and receptor or effector cells.
• When presynaptic neurons are depolarized they release a neurotransmitter into the synapse.
• A nerve impulse is only initiated if the threshold potential is reached.

Online study guide by GetBodySmart

Neurotic neurones- interactive by N Case

Build your own neuron by The Franklin Institute

Build a Neuron by BrainFacts

Virtual Neurons by BrainU

Application and skills

• Application: Secretion and reabsorption of acetylcholine by neurons at synapses.
• Application: Blocking of synaptic transmission at cholinergic synapses in insects by binding of neonicotinoid pesticides to acetylcholine receptors.

• Skill: Analysis of oscilloscope traces showing resting potentials and action potentials.


• An understanding of the workings of neurotransmitters and synapses has led to the development of numerous pharmaceuticals for the treatment of mental disorders.

6.6 Hormones, Homeostasis and Reproduction

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)


What causes insomnia? TedEd


• Insulin and glucagon are secreted by β and α cells of the pancreas respectively to control blood glucose concentration.

Regulating blood glucose by abpi

What does the pancreas do? TedEd

• Thyroxin is secreted by the thyroid gland to regulate the metabolic rate and help control body temperature.

How does the thyroid manage your metabolism? TedEd

• Leptin is secreted by cells in adipose tissue and acts on the hypothalamus of the brain to inhibit appetite.

Leptin feedback control by BioInteractive

• Melatonin is secreted by the pineal gland to control circadian rhythms.

2min Melatonin link

• 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.

Reproductive systemby CrashCourse

Application 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.

How in vitro fertilization (IVF) works TedEd

Evolution and Obesity by LearnGenetics

Inside Diabetes by LearnGenetics

• Skill: Annotate diagrams of the male and female reproductive system to show names of structures and their functions.


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

Mayo Clinic

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