homeostasis and the kidneys Flashcards
(19 cards)
what factors affect homeostasis
-body temperature
-pH
-Blood glucose concentration
-water potential
the physiological control systems used in homeostasis often rely on what
negative feedback mechanisms
what is osmoregulation
maintaining the water potential of the blood within restricted limits
what is ultrafilteration
when kidneys filter the blood
describe how the kidneys help osmoregulation
-kidneys filter the blood(ultrafilteration)
-then selectively reabsorb useful substances (glucose, amino acids and water)
-the metabolic waste (urea) and excess ions and water form urine
-this happens by the functional unit nephron which the kidney has many of
what are the adaptations that the cell lining (PCT) have for reabsorbing substances
-many microvilli for large surface area
-numerous mitrochondria for ATP for active transport
-carrier proteins in the cell surface membrane for active transport
describe filterate travels through loop of henle
-the descending limb of the LoH is permeable to water but not permeable to Na+ and Cl- ions
-the ascending limb is impermeable to water
-the ascending limb actively transports Na+ and Cl- ions from the fliterate into the surrounding tissue of medulla
-water leaves the ascending limb by osmosis into the tissue fluid of medulla then enters the surrounding blood capilliaries
-the loss of water in the descending limb causes Na+ and Cl- ions to diffuse from the ascending limb into the medulla
describe what happens after the filtrate reaches the medulla
-it passes through the distal convoluted tube (DCT) and down the collecting duct.
define homeostasis
homeostasis is the maintenance of an organisms internal environment within set limits
what regulates the internal conditions
endocrine and nervous system
why is homeostasis important
-enzyme activity: optimum conditions needed for enzymes to work best such as maintaining temperature and pH
-cell size: changes in WP of blood affects the amount of water in tissue fluid and cells. -cells could shrink, burst or dessicate
-independence from external conditions: animals with constant internal environment can maintain constant level activity despite the environment
describe the urinary system
-renal artery: carries dirty blood to the kidneys
-renal vein: carries clean blood away from kidney
-kidneys: filters blood by removing urea and other waste and excretes it as urine.
what is a nephron
small parts of the kidney involved in the filteration of blood
what is a glomerulus
a knot of capillaries
describe ultrafiltration produces glomerular filtrate
1.presence of pores in capillaries
2.allows small molecules such as water glucose AA and urea to pass through basement membrane
3.protein too large to go through
what is reabsorption
the movement of substances from the kidneys back into the blood such as glucose, AA, ions and water
describe how aquaporins and ADH help filter blood
- ADH released from pituitary gland. ADH travels in the blood
2.ADH binds to receptors on CD or DCT
3.aquaporins move to CSM - water moves through aquaporin by osmosis into tissue fluid and then into capillary
describe what happens when blood pressure/ volume is low
1.the kidney releases the enzyme renin
2.this converts angiotensinogen into angiotensin 1
3.this is then converted into angiotensin 2 by the enzyme ACE
4. angiotensin 2 is a hormone that increases blood pressure by causing vasoconstriction of arterioles
-it also increases the volume of blood by realsing aldosterone -which stimulates teh reabsorption of salt and water.
what are the three main roles of the kidney
-remove waste products in blood
-regulate the levels of ions in blood
-regulate the levels of water in the blood
