vet systems unit 4

what membrane is between plasma and interstitial fluid?

capillary membrane

2/3 of water is _, 1/3 is _

intracellular fluid, extracellular fluid that is split into intravascular fluid/plasma and interstitial fluid

how does the body counter water gain/loss?

by reabsorbing or secreting solutes

simple steady state model with sensor

cup has an amount of water in it, as water is put in equal water will leave and vice versa, and sensor will determine how much fluid needs to be retained

osmolarity

water wants to flow from low concentration solutions to high concentration solutions, sum molarity of all solutes

osmotic pressure

how much water wants to move into a space, proportional to number of particles in solution

tonicity

osmolarity of a fluid relative to another fluid

why does water move across membranes much faster than expected?

protein channels called aquaporins facilitate water flow, number of aquaporins determines how fast water can move

what fluids does osmolarity affect mainly?

ECF and ICF because they are separated by a plasma membrane that is semi-permeable

hydrostatic pressure

mechanical pressure/push exerted on a fluid

main body hydrostatic pressure

from heart, pressure will push intervascular fluid/plasma toward interstitial fluid

oncotic pressure

osmotic pressure caused by trapped macromolecules, tends to oppose hydrostatic pressure

what fluids does oncotic pressure mainly affect?

intravascular fluid and interstitial fluid because there is a much more permeable membrane

starling forces equation

Kf = (Pc + pi i) - (Pi - pi c), or filtration coefficient x (hydrostatic capillary pressure + oncotic interstitial pressure) - (hydrostatic interstitial pressure + oncotic capillary pressure)

what three functions do kidneys have for body fluid maintenance?

filtration of IVF from blood, secretion/reabsorption to modify composition of filtrate, and concentration/dilution by retaining or removing water

nephron and parts

basic functional unit of kidney, glomerulus → proximal convoluted tube → thin descending loop of Henle → thin ascending loop of Henle → thick ascending loop of Henle → distal convoluted tube → collecting duct

glomeruli

separate plasma from blood

pars convoluta/convoluted sections

has glomeruli, proximal tubules, distal tubes, and small sections of collecting duct

pars radiata/straight sections

have medullary rays, have thick and thin loops of Henle and collecting ducts

renal lobule

space from middle of one pars convoluta to the middle of next pars convoluta

what can the renal cortex be split into?

convoluted sections and straight sections

most of kidney is _ mOsm, but around apex of medulla it’s about _ mOsm, why?

300, 1200, to reabsorb water

cortical/superficial nephrons

high in the cortex, loop of Henle will not go far into medulla

juxtamedullary/deep nephrons

deep in the cortex, loop of Henle is long, penetrate deep into medulla, important for retaining water and producing concentrated urine

what animals will have more long-looped nephrons?

animals in desert climates

how much blood supply goes to kidneys at rest?

20-25%

what do kidneys have instead of veins?

efferent arterioles