session 1 Flashcards
what is the functional unit of the kidney? describe it
nephron
pale>>corticol region
dark>>medullary region
kidneys cant regenerate new nephrons, and the # decline wiht age!
functions of kidney
Function of the Kidney
– Regulation: control the concentrations of key substances in extracellular fluid
– Excretion: excretes waste products
– Endocrine: synthesis of renin, erythropoietin, prostaglandins
– Metabolism: active form of Vitamin D, catabolism of insulin, PTH calcitonin
describe fluid compartments of the body
plasma contains cells and large organic molecules but interstitial fluid normally doesn’t
what is the predominent cation and anion in the ECF?
ECF:
Cation>> Sodium Na+
Anion>> Chloride Cl-
kidenys function by making large amount of an ultra-filtrate of plasma
means plasma w/out cells and large organic molecules
efferent and afferent arterioles bring blood to and from kidney, creating a high constant filtration pressure.
why is this improtsnt?
the pressure is important in in driving small molecules and water out of the plasma at a rate of 125ml/min or (180L per day)
this is the GFR!
(GFR) describes the flow rate of filtered fluid through the kidney
why does the kidney consume so much oxygen?
bc when the ultrafiltrate enter kidneys tubules 99% of it is reabsorbed! and this process is metabolically very demanding!
how much blood flow does the kindey need?
why is it necessaryit gets this much?
it needs (4ml/min/g) to deliver the oxygen and glucose needed to maintain their activity
location of kidney
(ureter travels at tips of transverse processes)
lower border>> L2/3
layers of kidney
Structure of Kidney
kidneys can be divided into2 steps each of which their anatomical correlate:
1) filtration= glomeruli
2) resoptio and excretion= tubular system
water and osmoalarity
water likes people! ( what keep the partay going)
kidenys effect ECF directly!
indirect effect on ICF
what happens if u fail to control the ECF volume?
changes in BP, tissue fluid and cell function!
The pH of extra cellular fluid is critical
what does it depend on?
- Depends in part on the concentration of bicarbonate in plasma
- Failure to control bicarbonate concentration will have serious consequences
______L is filitered, but then is reabsorbed, leaving____L left for excretion
180L is filitered, but then is reabsorbed, leaving 1L left for excretion
where is EPO released?
ibrocytes in the cortex release the hormone erythropoietin, which stimulates the formation of red blood cells in the bone marrow. Modified fibrocytes of the medulla secrete prostaglandins which are able to decrease blood pressure
where is the major site of reabsorption taken place? what sort of things r reabsorbes there?
how do these reabsorbed material leave? via what?
PCT
– ~60-70% of Na and water
– ~80-90% of K+
– ~90% of HCO3-
– Normally, 100% of glucose and a.a
– Water follows osmotic gradients, so filtrate remains isotonic with plasma
– Reabsorbed materials leave by peritubular capillaries
what r the 2 memebranes of the epithelial cells lining th tubules?
apical (lumnal) and basolateral side
describe the free ion distribution across cell membranes
how can particles transport across cell membranes?
transcellulary and paracellulary
what r the different types of transport?
Active transport: moves solutes from a region of their lower to a higher concentration (needs energy)
- -Primary: transport coupled DIRECTLY to an energy source (ex: Na-K atpase pump, H+ atpase, Ca+ atpase)
- -Secondary: (coupled transport or co-transport) 3aks primary, 2 or more substances interact w/ a specific membrane protein (Carrier) & r trasnported together across membrane
Osmosis: transport of water from areas of high to low concentration