describe the possible mode of action of osmoreceptors to changes in water potential
shrink when water potential is low and stimulate secretion of ADA from the hypothalamus
Which organisms use ammonia as their nitrogenous waste product and why?
water-based organisms, highly soluble but highly toxic, low energy to produce
Describe the role of the hypothalamus in osmoregulation
detects changes in water potential of blood
what are the islets of Langerhans and where are they located?
endocrine cells of the liver made of alpha cells that produce glucagon and beta cells that produce insulin
what is a hormone?
a chemical produced and secreted by an endocrine gland and carried in the blood to target cell (tissue or organ)
What actions lower blood glucose concentration?
increased cellular respiration rate, glycogenesis in liver and muscle cells, conversation of glucose to fat in adipose tissue,
What enzyme is needed to catalyze the conversion of glycogen to glucose?
phosphorylase
describe the pathway of blood through the kidney
afferent arteriole --> glomerulus --> efferent arteriole --> pertiubular capillaries --> renal vein
describe three functions of the kidney
regulate composition of the blood by maintaining water potential (includes water, urea, mineral ions), regulate blood pressure
Which cells have receptors for insulin?
Almost all cells (except RBCs)
what are podocytes?
highly specialised celles of the renal capsule lifted off the cell surface membrane by little 'feet' that allow filtrate to pass beneath them through gapos in t
Which organisms use nitric acid as their N waste product and why?
birds/reptiles, light weight but energy intensive (7 ATP to product) not toxic in eggs
Describe the action of liver cells when they are stimulated by adrenaline and glucagon
convert glycogen to glucose
Which cells have receptors for glucagon?
only liver cells have receptors for glucagon
describe the role of the posterior pituitary in osmoregulation
Secretes ADH into the capillaries, ADH passes to kidney increases permeability of DCT and CD
What is this process called which increases blood glucose concentration? amino acids + glycerol --> glucose
gluconeogenesis
Describe the Urea cycle
1. Deamination (amine removed from aa--> ammonia) 2. respiration of the rest of aa 3. ammonia + CO2 --> urea (via orintine cycle)
Which cells (in the liver) secrete glucagon?
alpha cells
describe the role of abscisic acid in the closure of a stoma
ABA bins to receptors on membrane of guard cells, cause release of Ca2+ which stimulate K+ to leave guard cells, lower WP means water leaves by osmosis