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human structure & function ii > Kidney Physiology > Flashcards

Kidney Physiology Flashcards

1
Q

What are the homeostatic kidney functions?

A

Regulation of blood ionic composition (Na+, K+, Cl-)

Regulation of blood pH
(H+, HCO3-)

Regulation of blood volume
(H2O)

Regulation of blood pressure

Maintenance of blood osmolarity

Production of hormones
(Calcitrol or Erythropoietin)

Excretion of metabolic wastes and foreign substances
(Drugs or Toxins)

Regulation of blood glucose levels

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2
Q

How much blood do the kidneys receive?

A

20 to 25% of cardiac output

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3
Q

Nerve supply of kidneys

A

Renal nerves: carry sympathetic outflow

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4
Q

What do the renal nerves do?

A

Regulate blood flow through the kidneys

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5
Q

What does the renal corpuscle consist of?

A

The glomerulus and the Bowman’s capsule

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6
Q

What is the glomerulus?

A

A mass of capillaries that is fed by the afferent arterioles and drains into the efferent arteriole.

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7
Q

What is the Bowman’s corpuscle?

A

It has a visceral layer of podocytes, which wrap around the capillaries.
(afferent article –> filtered in glomerulus –> efferent atriole)

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8
Q

What cannot pass through the fenestrations?

A

Blood cells and proteins

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9
Q

Where are the fenestrations located and what are they?

A

They are large leaky pores in the glomerular endothelial cells

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10
Q

What lies between the endothelium and the podocytes?

A

Basal lamina

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11
Q

What do podocytes form?

A

Pedicels

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12
Q

What are the two kinds of nephrons?

A

Cortical and Juxtamedullary

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13
Q

What is the function of the cortical nephrons?

A

To create urine with osmolarity similar to the blood.

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14
Q

Where do the juxtamedullary nephrons receive blood from?

A

Peritubular capillaries and vasa recta

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15
Q

What is the function of juxtamedullary nephrons?

A

To enable the kidney to secrete very concentrated urine.

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16
Q

Where do the ascending loops contact the afferent arteriole?

A

Macula densa

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17
Q

What kind of cells does the wall of the afferent arteriole contain?

A

Smooth muscle cells which are known as juxtaglomerular cells

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18
Q

What happens if the afferent dilates?

A

More blood is filtered

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19
Q

What happens if the efferent constricts?

A

Substances do not leave as quickly

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20
Q

What happens if the afferent dilates and the efferent constricts simultaneously?

A

The pressure increases and the substances are pushed out

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21
Q

Excretion of a solute equation

A

Glomerular filtration + secretion - reabsorption

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22
Q

What facilitates glomerular filtration?

A

Blood pressure (glomerular blood hypostatic pressure)

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23
Q

What is glomerular filtration opposed by?

A

Hydrostatic pressure and blood colloid osmotic pressure

24
Q

What moves out of the glomerulus?

A

Water and small molecules

25
Q

Explain NFP = GBHP - CPB - HP

A

GBHP = pressure pushing from the inside to exit

CPB = prevents substances from leaving from the inside (pulling back)

HP = pressure from the outside to stay within

26
Q

What is the glomerular filtration rate?

A

Amount of filtrate formed by both kidneys each minute

27
Q

What happens if the glomerular filtrate rate is too high?

A

Substances pass too quickly and are not reabsorbed

28
Q

What happens if the glomerular filtrate rate is too low?

A

Nearly all reabsorbed and some waste products not adequately excreted

29
Q

What controls the Glomerular Filtration Rate?

A

Renal Autoregulation,
Neural Regulation,
Hormonal Regulation

30
Q

What is renal auto-regulation?

A

It is a myogenic mechanism: smooth muscle cells in afferent arterioles contract to elevate blood pressure.

31
Q

What causes tubuloglomerular feedback?

A

Too much sodium

32
Q

What happens during tubulogloemrular feedback?

A
  • High glomerular filtrate rate diminishes reabsorption
  • Macula densa inhibits the release of nitric oxide
  • Afferent arterioles constrict (less blood flows through so lowers GFR)
33
Q

What is neural regulation?

A

Strong sympathetic regulation (exercise or hemorrhage) causes afferent arterioles to constrict and decrease urine output so that more blood can be available for the organs.

34
Q

What causes the restriction of the afferent arterioles in neural regulation?

A

a1-AR

35
Q

What happens during hormonal regulation?

A

Angiotensin II constricts both afferent and efferent arterioles, decreasing the glomerular filtrate rate

Atrial natriuretic peptide (ANP) relaxes mesangial cells, increasing capillary surface area and glomerular filtrate rate

36
Q

Why is ANP secreted during hormonal regulation?

A

It is secreted to stretch the cardiac atria and therefore push sodium out of the atria so that water can flow.

37
Q

What happens during tubular reabsorption?

A

Much of the filtrate is reabsorbed especially water, glucose, amino acids, and ions.

38
Q

How does secretion help?

A

It helps to manage pH and get rid of any toxic or foreign substances in the body.

39
Q

What are the two different kinds of reabsorption?

A

Paracellular reabsorption and Transcellular reabsorption

40
Q

What is paracellular reabsorption?

A

Passive fluid leakage between cells

41
Q

What is transcellular reabsorption?

A

Directly through the tubule cells (active)

42
Q

What are the two transport mechanisms?

A

Primary active transport and secondary active transport

43
Q

What happens in the primary active transport?

A

Use of ATP (accounts for 6% of total ATP use; at rest)

44
Q

What happens in the secondary active transport?

A

Driven by ion’s electrochemical gradient

Symporters move substances in the same direction

Antiporters move substances in different directions

45
Q

What are the two kinds of water reabsorption?

A

Obligatory and facultative

46
Q

What is obligatory water reabsorption?

A

Water follows the solutes that are reabsorbed, 90% of water is reabsorbed this way.

47
Q

What is facultative water reabsorption?

A

It is regulated by ADH, only 10% of water is reabsorbed this way.

48
Q

What is involved in reabsorption and secretion in PCT?

A

There are Na+ - glucose symporters
There are Na+ - H+ antiporters
Aquaporin I

49
Q

What is the function of Aquaporin I?

A

Aquaporin I is a membrane protein permeable to water.
It increases water volume when urine becomes concentrated.

50
Q

Where is aquaporin I abundant?

A

In PCT and descending limb

51
Q

What happens during reabsorption in the loop of henle?

A

Relatively impermeable to water, especially the ascending limb

Little obligatory water reabsorption

Na+ - K+ - 2Cl- symporters

52
Q

What happens to the potassium during reabsorption at the loop of Henle?

A

It leaks back to capsular space

53
Q

Reabsorption in early DCT

A

Na+ - Cl- symporters reabsorb ions

Parathyroid hormone stimulates reabsorption of Ca2+

54
Q

What does parathyroid hormone do during reabsorption in early DCT?

A

Inhibits phosphate reabsorption in the PCT enhancing its secretion

55
Q

What happens during late DCT and collecting duct?

A

Principal cells: Na+ -K+ pumps reabsorb Na+

Aquaporin 2 reabsorbs water: stimulated by ADH

Intercalated cells: reabsorb K+ and HCO3 - and secrete H+

56
Q

Which aquaporin is regulated by ADH?

A

Aquaporin 2

human structure & function ii (9 decks)

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