Lecture 6 Flashcards
(17 cards)
What do the kidneys do?
Control body fluid composition by controlling the composition of the fluid (and indirectly controlling the interstitial fluid and intracellular fluid)
Excretion of metabolites and ingested substances
How many nephrons does a kidney have?
> 1 million
What is the renal corpuscle?
The initial filtering component
Contains glomerulus and Bowman’s capsule
How does blood go to and leave the glomerulus?
Enters through the afferent arteriole and leaves through the efferent arteriole
What are the epithelial cells found in the Bowman’s space called?
Podocytes
Tubular epithelium
What is the pathway for filtrate to take in the renal tubule?
Proximal convoluted tube
Proximal straight tube
Descending thin loop of Henle
Ascending thin loop of Henle
Thick ascending loop of Henle
Distal convoluted tube
Cortical collecting duct
Medullary collecting duct
After leaving the collecting duct, where will urine go?
Renal pelvis, then ureters to the bladder
What happens in glomerular filtration?
Plasma is filtrated into the Bowman’s Capsule from the glomerulus
Filtrate is called the ultrafiltrate
20% is filtered due to the hydrostatic and colloid osmotic gradient
What happens in tubular secretion?
Movement of substances from the peritubular capillaries to the tubules
Or the movement of a substance from the tubular epithelial cell interior to the tubular lumen
What happens in tubular reabsorption?
Occurs throughout the nephron but is greatest in the proximal tubule
What does glomerular filtration depend on?
Filtration mainly depends on charge and weight (and sometimes shape) of a substance
Why are anions less freely filtered?
Proteins of the filtration slits and predominantly negatively charged so anions are repelled
What is Glomerular filtration rate (GFR)?
The volume of fluid filtered from the glomeruli per minute
What does GFR depend on?
Net filtration pressure
Permeability characteristics
Surface area
How is the glomerulus surface area changed?
During SNS activation, actin inside mesangial cells contracts and makes mesangial cells smaller and so the SA in the glomerulus decreases
How is filtered glucose reabsorbed?
From the tubule lumen into the tubule epithelial cells
Na+ dependent glucose transporter (SGLT), sodium ions move down into cell down a conc gradient which provides energy for glucose to move against the conc gradient into the cell
Then glucose moves out of the cell via GLUT inside the cell to the interstitial fluid
Glucose then moves into the tubular capillaries by diffusion
Why can glucose appear in the urine?
In diabetes, the SGLT transporter is saturated with glucose as the transfer maximum is reached so glucose starts appearing in the urine
