K2 - Kidney Structures and Function Flashcards
what are the functions of the kidneys?
- water balance
- salt balance
- maintenance of plasma volume
- maintenance of plasma osmolarity
- acid-base balance
- excretion of metabolic waste products
- excretion of exogenous foreign compounds
- secretion of renin and erythropoietin
- conversion of vitamin D into active form
what organ in the body regulars volume, composition and osmolarity of body fluids by the controlled excretion of substances?
kidneys
what part of the kidney has a granulated appearance and lines the outside?
renal cortex
what is the region of the kidney that is made up of individual renal pyramids and has a stripped appearance?
renal medulla
where does the urine drain into in the kidneys before entering the ureter?
renal pelvis
what is the functional unit of the kidneys?
nephron
what makes up the wall of the nephron?
single layer of epithelial cells
describe the vascular component of the kidney?
renal artery > afferent arteriole > glomerulus > efferent arteriole > peritubular capillaries> venule > renal vein
what part of the nephron drains into the loop of Henle?
proximal tubule
where is the loop of Henle located?
starts off in the cortex and then loops down into the medulla before returning to the cortex
what drains tubular fluid into the collecting duct?
distal tubule
what is the importance of the juxtaglomerular apparatus?
contains specialised cells where fluid from the distal tubule passes between the afferent and efferent arterioles
what are the two types of nephrons?
juxtamedullary and cortica
l
what are the differences between the two types of nephrons?
- length of the loop of Henle is longer in the Juxtamedullary than in the cortical
- juxtamedullary has a single capillary structure called the vasa recta instead of peritubular capillaries
what type of nephron produces more concentrated urine?
juxtamedullary
what is the single layer of endothelial cells which contain pores. the afferent arteriole drains into and is important in filtration?
glomerulus
what is in close proximity of the glomerulus and is made up of single layer of epithelial cells where the inner layer contains specialised cells called podocytes?
bowman’s capsule
what specialsed vascular cells of the juxtaglomerular apparatus produces and secretes renin ?
granular cells
what are the salt sensitive cells that sense the amount of salt in the tubular fluid?
macula densa
what is urine?
modified filtrate of the blood
what importance do the kidneys have in the production of urine (3)?
- filtration system
- rich blood supply
- mechanisms for urine modification
what is glomerular filtration?
- 20% of the plasma that enters the glomerulus is filtered
- 80% of the plasma that enters the glomerulus is not filtered and returned back to the blood
what is tubular reabsorption?
tubular fluid is reabsorbed back into the blood stream via the peritubular capillaries
what is tubular secretion?
fluid from the blood stream is secreted into the tubular fluid
how do you calculate rate of filtration of a substance?
mass of X filtered into the Bowman’s capsule per unit time.
Rate of filtration of X = [X]plasma GFR
what is the constant value for GFR - glomerular filtration rate?
125ml/min
how do you calculate the Rate of excretion of a substance?
Rate of excretion of X = mass of X excreted per unit time.
Rate of excretion of X = [X]urine Vu
how do you calculate rate of reabsorption of a substance?
If rate of filtration > rate of excretion, net reabsorption of that substance has occured.
Rate of reabsorption of X = rate of filtration of X – rate of excretion of X
how do you calculate the rate of secretion of a substance?
If rate of filtration < rate of excretion, net secretion of that substance has occured.
Rate of secretion of X = rate of excretion of X – rate of filtration of X
describe the filtration component of the kidney?
glomerulus > bowman’s capsule > proximal tubule > loop of henle > distal tubule > collecting duct > renal pelvis > ureter > urinary bladder > uretha
