section 3 (7) explain how the processes of filtration and reabsorption in the mammalian nephron regulate body fluid composition Flashcards

You may prefer our related Brainscape-certified flashcards:
1
Q

What is a nephron?

A
  • the fundamental unit of a kidney
  • a microscopic tubule
  • each kidney contains millions of nephrons
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the 4 functional parts of a nephron?

A

1) bowman’s capsule
2) proximal convoluted tubule
3) loop of Henle
4) distal convoluted tubule→ leads to → collecting duct

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the glomerulus?

A
  • a spherical network of capillaries

- Serves as the first stage in the filtering process of the blood carried out by the nephron in its formation of urine.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is the Bowmans capsule?

A
  • the enlarged part of the nephron tubule; double-walled sac
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What happens in the proximal convoluted tubule?

A
  • reabsorption of all organic nutrients (amino acids, glucose) and some ions
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What happens in the descending loop of Henle?

A
  • walls are permeable to water, not salts

- water exits as a result of the salty environment→ concentration of filtrate increases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What happens in the ascending loop of Henle?

A
  • walls are permeable to salts, not water

- sodium ions are pumped out and into the medulla, so that water can leave passively in the descending loop

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What happens in the distal convoluted tubule?

A
  • reabsorption of salts and bicarbonate
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What happens in the collecting ducts?

A
  • walls permeable to water but not salts

- the concentration of urine increases as water leaves passively into the salty medulla

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Where does filtration happen?

A
  • between the glomerulus and the Bowmans capsule
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What causes part of the blood to be forced into the Bowmans capsule?

A
  • high blood pressure in the glomerulus

- high permeability of capillary walls

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the fluid that enters the Bowman’s capsule?

A
  • Glomerular filtrate
  • contains water containing dissolved substances e.g. glucose, amino acids, salts, nitrogenous wastes
  • blood cells and large proteins do not pass through into the filtrate (retained in the blood on account of their large size)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is the progression of Glomerular filtrate?

A

Fills the hollow part of the Bowmans capsule → travels the length of nephron → reaches collecting duct as urine because of a change in chemical composition on account of addition/ removal of various substances

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Give a basic overview of reabsorption

A
  • occurs from the glomerular filtrate in the nephron tubule to the blood from the capillaries
  • at the proximal and distal tubules in the loop of Henle, materials from the Glomerular filtrate that can be reused are selectively reabsorbed into the large capillary network and interstitial fluid
  • surrounding capillaries lead to larger vessels and then eventually to the renal vein which leads filtered blood back into the bloodstream
  • substances reabsorbed include water and solutes (e.g glucose, amino acids, ions)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

outline solute reabsorption

A
  • all amino acids and glucose are reabsorbed in the proximal tubule
  • some ions and some minerals are reabsorbed in the proximal and distal tubules
  • occurs by facilitated diffusion and active transport
  • urea is no reabsorbed
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

outline water reabsorption

A
  • as solutes are reabsorbed, so is water through osmosis
  • 99% of the glomerular filtrate (only 1% is excreted in urine)
  • occurs mainly in the collecting duct
17
Q

What is secretion?

A
  • involves the removal of toxic substances from the blood capillaries to the filtrate by active transport
  • secreted substances include: urea, uric acid, ammonia, ions and drugs (penicillin etc)