Homeostasis: Excretory System (HY) Flashcards
what are the structures and pathway of the excretory system?
right/left kidneys –> right/left ureter –> bladder –> urethra
the renal artery, renal vein, and ureter enter and exit through what structure in the kidney?
renal hilum, a deep slit on surface
what is the cortex and medulla of a kidney?
cortex is the outermost layer of kidney and medulla sits within cortex
what is the pathway for the renal portal system consisting of two capillary beds?
renal artery passes through medulla and enters cortex as afferent arterioles –> glomerulus (first capillary bed) –> efferent arteriole –> vasa recta (second capillary bed) around loop of Henle
what is the role of the glomerulus?
filter waste products from blood
what is Bowman’s capsule?
cuplike structure that surrounds glomerulus
From Bowman’s capsule, what is the pathway leading to the renal pelvis (widest part of ureter connected to kidney)?
bowman’s capsule –> proximal convoluted tubule –> descending limb of Loop of Henle –> ascending limb of Loop of Henle –> distal convoluted tubule –> collecting duct –> renal pelvis and ureter
when bladder is full of urine, what is the process the leads to urination?
- stretch receptors convey to nervous system that bladder is full
- parasympathetic nervous system contract detrusor muscle lining the bladder
- micturition reflex: detrusor contraction leads to internal urethral sphincter relaxation (consists of smooth muscle so involuntary)
- individual chooses through somatic nervous system whether to relax external urethral sphincter (consists of skeletal muscle so voluntary)
what is primary function of the kidney?
regulate blood volume and osmolarity
what three processes does the kidney do to regulate blood volume and osmolarity?
- filtration
- secretion
- reabsorption
What are Starling forces between blood in capillaries and Bowman’s space (inside Bowman’s capsule)?
Not actually forces, but the pressure differential between hydrostatic pressure and oncotic pressure
higher hydrostatic pressure in glomerulus (blood) than in bowman’s space –> push blood into nephron
higher osmolarity in blood than bowman’s space –> oncotic pressure resisting push of blood into nephron
NET: push blood into nephron
What is the filtrate in context of kidney osmoregulation?
filtrate is the blood-like substance pushed into bowman’s space, doesn’t contain cells or proteins
what does it mean for one solution to be isotonic to another?
both solutions have same osmotic pressure
what does nephron secretion entail?
secreting acid, bases, ions and salts, and urea into the proximal/distal convoluted tubules using passive and active transport
also:
- can also secrete waste too large to pass through glomerulus pores
- can eliminate metabolites of medications from blood when in excess
How does a diet heavy in meat lead to a large amount of urea in urine?
heavy meat –> high protein –> lots of nitrogen –> ammonia as byproduct of metabolism –> liver converts ammonia to neutral urea –> urea travels to kidney where nephron secretes it
what does nephron reabsorption entail?
compounds that are filtered are secreted can be reabsorped into blood (glucose, vitamins, and amino acids)
when filtrate enters the proximal convoluted tubule, what is secreted and what is absorbed?
secreted: H+, urea, ammonia, K+
reabsorbed: glucose, amino acids, vitamins, some salts (sodium chloride), water
when molecules are reabsorbed into the interstitium, connective tissue surrounding nephron, how are they picked up by blood?
picked up by vasa recta
the descending limb of Henle is only permeable to what?
water
Why does the kidney alter the osmolarity of the intersitium, especially deeper in medulla?
inner medulla has high osmolarity when water needs to be conserved
it is isotonic with blood (low osmolarity) when trying to excrete water
what is the countercurrent multiplier system?
it is a system formed by the loop of Henle and vasa recta because flow of filtrate and blood are opposite one another. As a result, filtrate is constantly exposed to hypertonic blood, allowing maximal reabsorption of water.
if flow was in same direction, equilibrium would be reached, limiting water reabsorption.
the ascending loop of Henle is only permeable to what?
only permeable to salts
impermeable to water
as you go deeper into the medulla, what happens to the interstitial fluid?
the salt concentration of the interstitial fluid increases (osmolarity increases)
therefore, more water reabsorbed deeper into medulla, and more salt reabsorbed higher in the medulla
what is the diluting segment and where is it located?
the diluting segment is located on the ascending limb of the loop of henle at the transition between the inner and outer medulla.
cells lining the loop of Henle become larger in this segment due to more mitochondria –> more ATP production to drive sodium and chloride active transport reabsorption
