Lecture 23 Flashcards
what are the 6 functions of kidneys?
regulation: BP, ECF volume, osmolarity | maintain ion balance | homeostatic regulation of pH | excrete waste | produce hormones
What hormone do kidneys produce?
erythropoietin
Can you live with 1 kidney?
yes
What is a nephron?
smallest functional unit of the kidney
What role do major blood vessels and blood pressure play in the renal system?
dictates how much filtration will go into the lumen of the nephron | increase BP = increase filtration
What are nephrons made out of?
epithelial cells
What does the lumen of the nephron collect?
filtrate = water, urine, waste
What is the capsule of a nephron?
connective tissue covering the kidney
What is the cortical medulla?
inner section of the kidney
What is a key characteristic of the cortical medulla?
contains a concentration gradient of solutes and an osmolarity difference between both sides of the medulla
What is important about nephrons being vascularized throughout the kidney cortex?
increase surface area = more things can move from the blood to the nephron lumen (vice-versa) = more things can be filtrated
What are the 2 types of nephrons?
cortical nephrons | juxtamedullary nephrons
What are cortical nephrons?
nephrons only within the cortex of the kidney
What are juxtamedullary nephrons?
nephrons within and next to the medulla of the kidney
What major role do juxtamedullary nephrons play? What do they have on their surfaces?
major role in reabsorption | has different sets of protein channels for different types of molecules, all under control by a hormone (vasopressin)
What are the 2 types of capillary beds intertwining the nephrons?
peritubular capillaries and vasa recta
What are the peritubular capillaries?
capillaries closely associated with the rest of the nephron from the glomerulus
What is the vasa recta?
peritubular capillaries of the juxtamedullary nephrons
What are the 3 nephron structures does the cortex of the kidney contain?
Bowman’s capsules | proximal tubules | distal tubules
What are 2 nephron structures does the medulla of the nephron contain?
loop of Henle | collecting ducts
What is the glomerulus?
site of filtration
What is the Bowman’s capsule?
encapsulates the glomerulus
What is the proximal tubule?
first segment of nephron after glomerulus
What is the distal tubule?
connects to the collecting duct
What is the collecting duct?
empties filtrate and secreted fluids into renal pelvis –> bladder
How many nephrons can connect to one collecting duct?
many
Percentage-wise, about how many nephrons are contained within the cortex of the kidney and in the medulla of the kidney?
80% cortical nephrons | 20% juxtamedullary nephrons
What is the portal system in the kidney?
capillary beds in series
What is the renal corpuscle?
glomerulus + Bowman’s capsule
What are the 4 sets of membranes that filtration, secretion, and excretion go through?
2 in nephrons and 2 in capillaries
What is the juxtaglomerular apparatus?
when ascending limb of the nephron comes into contact with the glomerulus
What is the important role in which the juxtaglomerular apparatus plays in?
secretion of renin
What are the macula densa cells?
sense distal tubule flow and release hormones renin = affect afferent arteriole diameter
What is renin?
an enzyme involved in salt and water balance | can change/regulate BP
What factor affects the reabsorption capacity of a nephron?
the length of the descending and ascending limbs of the LOH
Which nephron is longer?
juxtamedullary nephrons
What are the 3 hormones that control the kidney?
vasopressin | calcitonin | parathyroid hormone
What are the 3 basic processes of the nephron?
filtration | reabsorption | secretion
What is filtration?
fluid moves from blood to nephron lumen | ONLY in renal corpuscle | considered to be outside of body
What is reabsorption?
fluid moves from filtrate back into blood vessels = peritubular capillaries
What is secretion?
selective movement = use of transporters and channels | fluid moves from blood to filtrate
