Microstructure of the nephron Flashcards
1
Q
Renal Corpuscle
3
A
- found in renal cortex
- Bowman’s capsule (cup-shaped structure)
- Glomerulus (cluster of capillaries)
2
Q
Renal Tubule
4
A
- found in cortex and medulla
- Proximal Convoluted Tubule (closest coiled)
- Loop of Henle (in medulla)
- Distal Convoluted Tubule (distant coiled)
3
Q
Glomerular Filtration
3
A
- the fluid part of the blood is filtered through the glomerulus into Bowman’s Capsule
- blood enters through the Wider Afferent Arteriole and leave through the Narrower Efferent Arteriole creating pressure forcing filtration through the Glomerular Membrane
- 120ml blood plasma per minute is filtered (ultrafiltration - because of the pressure)
4
Q
Tubular Reabsorption
5
A
- as the fluid flows along the renal tubule, useful substances are reabsorbed into the bloodstream
- reabsorbed in the capillaries surrounding the renal tubules
- active reabsorption (Molecules bind with carrier molecules working against the concentration gradient - needs ATPs)
- absorbs all organic nutrients, fat soluble vitamins back into the blood
- Passive reabsorption (65% of water is reabsorbed through osmosis into the blood from the filtrate)
- outcome (water is actively conserved and is not lost with the urine, therefore less urine is formed and is more concentrated)
5
Q
Tubular Excretion
6
A
- unwanted substances in the blood are excreted into the tubules
- takes place in the proximal and distal tubules
- cells of the tubules remove certain molecules and ions from the blood and deposits them into the filtrate
- hydrogen and potassium (+) ions move into the filtrate and sodium ions back into the blood (water follows through osmosis)
- more creatinine and uric acids moves into the filtrate
- unwanted substances are also actively excreted
6
Q
Formation of Urine
4
A
- contains all unwanted substances of the body
- approximately 1-1.5 litres is produced daily
- composition of water is (96% water, 1.5% salts, 2% urea, small amounts of uric acid, creatinine and ammonium occur
- small quantities of drugs, colourants and preservatives
7
Q
Bowman’s Capsule
4
A
- top of the nephron
- allows for ultrafiltration to occur
- creates urinary space for filtrate to enter the nephron and pass through the proximal convoluted tubule
- Podocyte layer the inner layer
8
Q
Glomerulus
2
A
- responsible for blood filtration
- membrane contains epithelial cells that are too small for blood cells to pass through
9
Q
Afferent and Efferent Arterioles
2
A
- afferent (wider) brings blood to the glomerulus
- efferent (narrower) takes blood back around the body
10
Q
Proximal convoluted tubule
8
A
- regulates the PH of the filtrate
- secretes organic acids such as creatinine
- found in in the cortex (closest)
- very long and coiled
- surrounded by a dense capillary network
- walls are made of specialised cuboidal epithelial cells
- brush boarder of microvilli on the inner surface
- folded outer surface
- many mitochondria to produce ATP for active transport
11
Q
Loop of Henle
5
A
- in the medulla
- keeps a high concentration of salt in the medulla area
- sodium ions are actively transported out of the ascending limb (sodium pump)
- descending limb is permeable to water
- ascending limb is impermeable
12
Q
Distal Convoluted Tubule
2
A
- regulates the PH of the filtrate by secreting (K+) ions
- mediated by the hormone Aldosterone
- reabsorbs remaining Na+, H2O and HCO3-
13
Q
Cortical Collecting Tubule
4
A
- does the fine adjustments to the concentration
- principle cells secrete K+ ions
- intercalated cells secrete H+ into lumen
- synthesise HCO3- for blood
14
Q
Medullary Collecting Duct
1
A
- draws H2O and urea out because it is hypertonic interstitium
15
Q
Epithelium and Podocytes
4
A
- important role in glomerular function
- cells of the glomerular capillary loop and basement membrane from a filtration barrier
- cooperate with the mesangial cells to form structure and function for the glomerulus
- porous are the epithelial cells
