Human physiology flashcards

Human physiology covers the functioning of the major organ systems that maintain life. Students must understand digestion and nutrient absorption in the gut, the structure and function of the heart and blood vessels in circulation, gas exchange in the lungs, the roles of neurones and synapses in nerve signalling, hormonal control including insulin and glucagon in blood glucose regulation, the immune response involving B and T lymphocytes, and kidney function in osmoregulation and excretion. Key themes include how structure relates to function at the cellular and organ level, how negative feedback maintains homeostasis, and how the body responds to pathogens. Understanding the interplay between these systems, such as how the nervous and endocrine systems coordinate responses, is essential for achieving higher marks.

1. Card 1

   What is the role of villi in the small intestine?

   Villi increase the surface area of the small intestine, allowing more efficient absorption of digested nutrients into the blood and lymph.

2. Card 2

   How does the structure of an alveolus suit gas exchange?

   Alveoli have thin walls, a rich capillary network and a moist surface, minimising diffusion distance and maximising the concentration gradient for O2 and CO2 exchange.

3. Card 3

   What is the difference between systole and diastole?

   Systole is the contraction phase of the heart, pumping blood out; diastole is the relaxation phase, during which the chambers refill with blood.

4. Card 4

   How does insulin lower blood glucose concentration?

   Insulin is released by beta cells of the pancreas and stimulates body cells, especially liver and muscle, to take up glucose and convert it to glycogen for storage.

5. Card 5

   What is the function of glucagon in blood glucose regulation?

   Glucagon is released by alpha cells when blood glucose falls, stimulating the liver to break down glycogen into glucose via glycogenolysis, raising blood glucose.

6. Card 6

   Describe the role of B lymphocytes in the immune response.

   B lymphocytes differentiate into plasma cells that secrete antibodies specific to an antigen, neutralising pathogens and marking them for destruction.

7. Card 7

   What is the role of T lymphocytes in immunity?

   T lymphocytes include helper T cells, which activate other immune cells, and cytotoxic T cells, which directly destroy infected cells displaying foreign antigens.

8. Card 8

   How does the kidney produce urine through ultrafiltration?

   High pressure in the glomerulus forces small molecules from blood into the Bowman's capsule, forming the filtrate; large proteins and cells remain in the blood.

9. Card 9

   What is selective reabsorption in the kidney?

   In the proximal convoluted tubule, useful substances such as glucose, amino acids and water are actively or passively reabsorbed back into the blood from the filtrate.

10. Card 10

    How does a myelinated neurone transmit an impulse faster?

    The myelin sheath insulates the axon, forcing the action potential to jump between nodes of Ranvier in saltatory conduction, greatly increasing transmission speed.

11. Card 11

    What happens at a cholinergic synapse?

    An action potential triggers release of acetylcholine into the synaptic cleft; it binds receptors on the postsynaptic membrane, generating a new impulse, then is broken down by acetylcholinesterase.

12. Card 12

    What is negative feedback and give one example in human physiology?

    Negative feedback is a mechanism where a change from the set point triggers a response that reverses that change, e.g. rising blood glucose stimulates insulin release to lower it.

• Students often confuse the roles of alpha and beta cells in the pancreas, incorrectly stating that alpha cells produce insulin rather than glucagon.
• A common error is describing active transport as the main method of gas exchange in the alveoli, when in fact O2 and CO2 move entirely by diffusion down concentration gradients.
• Many students incorrectly state that the renal cortex is where the loop of Henle is found, when the loop of Henle extends into the renal medulla and is responsible for creating the osmotic gradient used in water reabsorption.

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