Biology · Continuity and change

D3.3 — Homeostasis

Biology · SL / HL · syllabus-mapped notes

1. D3.3.1

   Homeostasis as maintenance of the internal environment of an organism

   Explain homeostasis, and give examples of variables kept constant.

2. D3.3.2

   Negative feedback loops in homeostasis

   Contrast positive and negative feedback, and state the parts of a negative feedback loop.

3. D3.3.3

   Regulation of blood glucose as an example of the role of hormones in homeostasis

   Explain how insulin and glucagon regulate blood glucose.

4. D3.3.4

   Physiological changes that form the basis of type 1 and type 2 diabetes

   Contrast type 1 and type 2 diabetes, and explain how each is managed.

5. D3.3.5

   Thermoregulation as an example of negative feedback control

   Explain thermoregulation as negative feedback, and the role of thermoreceptors.

6. D3.3.6

   Thermoregulation mechanisms in humans

   Explain vasoconstriction, vasodilation, shivering and sweating in humans.

7. D3.3.7

   Role of the kidney in osmoregulation and excretion

   Explain the kidney's twin roles of osmoregulation and excretion, and name the parts of a nephron.

8. D3.3.8

   Role of the glomerulus, Bowman’s capsule and proximal convoluted tubule in excretion

   Explain ultrafiltration and selective reabsorption in the proximal convoluted tubule.

9. D3.3.9

   Role of the loop of Henle

   Explain how the loop of Henle establishes the osmotic gradient in the medulla.

10. D3.3.10

    Osmoregulation by water reabsorption in the collecting ducts

    Explain how ADH and aquaporins vary water reabsorption in the collecting duct.

11. D3.3.11

    Changes in blood supply to organs in response to changes in activity

    Explain how blood is redistributed between organs as activity changes.