BiologyCode 9700
Homeostasis in mammals
What this topic asks you to be able to do
- explain the meaning of homeostasis and why it matters in mammals
- explain the principles of homeostasis using these ideas: negative feedback; internal and external stimuli; receptors; effectors (glands and muscles); and coordination systems (the endocrine system and the nervous system)
- state that the liver makes urea by deaminating surplus amino acids
- describe how the human kidney is built, limited to: the cortex and medulla, the fibrous capsule, the renal pelvis and ureter, and the branches of the renal vein and renal artery
- Identify the parts of a nephron along with its associated blood vessels and structures as shown in diagrams, photomicrographs and electron micrographs, limited to: glomerulus, Bowman’s capsule, proximal convoluted tubule, loop of Henle, distal convoluted tubule, collecting duct
- describe and account for how urine is produced in the nephron, limited to: glomerular filtrate arising through ultrafiltration within the Bowman’s capsule, and selective reabsorption occurring in the proximal convoluted tubule
- relate the functions of the Bowman’s capsule and of the proximal convoluted tubule in urine formation to their detailed structure
- describe the roles in osmoregulation of the collecting ducts, aquaporins, antidiuretic hormone (ADH), the posterior pituitary gland and the hypothalamus
- describe the principles of cell signalling, using as the example how glucagon controls blood glucose concentration, limited to: the hormone binding to a cell surface receptor, which causes a conformational change; activation of a G-protein, which stimulates adenylyl cyclase; formation of cyclic AMP (cAMP), the second messenger; cAMP activating protein kinase A, which starts an enzyme cascade; the signal being amplified along the cascade as more and more enzymes are activated by phosphorylation; and a cellular response in which the last enzyme of the pathway is activated and catalyses the breakdown of glycogen
- explain how blood glucose concentration is regulated by negative feedback control mechanisms, referring to how insulin affects liver cells and muscle cells and how glucagon affects liver cells
- account for how test strips and biosensors work when measuring glucose concentration in blood and urine, referring to the enzymes glucose oxidase and peroxidase