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Physiology Of Body Systems > Renal System > Flashcards

Renal System Flashcards

1
Q

What percentage of the ECF is plasma and interstitial fluid?

A

Interstitial: 80%
Plasma: 20%

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2
Q

What are the functions of the kidney?

A
  • maintain H2O balance in the body
  • regulate the volume of extracellular fluid and concentration of ECF ions
  • maintain plasma volume and osmolarity
  • control acid-base balance
  • excretion of waste products
  • excretion of foreign products
  • secretion of hormones
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3
Q

What are the components of a nephron?

A
  • tubular component

- vascular component

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4
Q

What does the efferent arteriole divide into?

A

Peritubular capillaries

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5
Q

Juxtamedullary nephrons

A
  • 15-20% of total
  • glomeruli in inner cortex
  • LoH descends filly into medulla
  • peritubular capillaries nera loop for, straight vessels known as vasa recta
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6
Q

Cortical nephrons

A
  • 80% of total
  • glomeruli in outer cortex
  • LoH dips only slightly into medulla
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7
Q

What sort of process is glomerular filtration?

A

Extracellular, nothing passes through cells just between them

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8
Q

What are the three layers of glomerular filtration?

A
  1. Glomerular capillary wall: pores between endothelial cells
  2. Basement membrane: mix of collagen (structural) and glycoproteins (repel plasma proteins)
  3. Podocytes: filtration slits between cellular foot processes, slits can change in size to change the rate of filtration
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9
Q

What are the forces affecting glomerular filtration?

A
  1. Glomerular capillary blood pressure (+)
  2. Plasma-colloid osmotic pressure (-)
  3. Bowmans capsule hydrostatic pressure (-)
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10
Q

Glomerular capillary blood pressure

A

Dependent on:

  • high systolic blood pressure
  • high afferent arteriole diameter (increase flow)
  • low efferent arteriole diameter (induce blood damming in glomerulus)
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11
Q

Plasma-colloid osmotic pressure

A

Retention of blood proteins in the glomerulus increases the osmolarity of the glomerular blood (compared to BC) and acts to draw H2O back to the glomerulus

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12
Q

Bowmans capsule hydrostatic pressure

A

Fluid dams in the Bowmans capsule which is a bottle neck and creates a backwards pressure

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13
Q

What is Kf?

A

12.5ml/min

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14
Q

What does NFP usually equal?

A

10mmHg

55-30-15

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15
Q

Why does filtration occur at such a high rate?

A
  • allows for rapid removal of wastes and foreign chemicals
  • allows for the entire plasma volume to be filtered and processes by the tubules many times a day - precise and rapid contro, of fluid volume and composition
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16
Q

How is water reabsorbed?

A

Movement of solutes into the interstitial fluid increases osmolarity and creates a concentration gradient

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17
Q

Where does the sodium reabsorption occur?

A

67% obligatory in proximal tubule
25% obligatory in the loop of henle
8% under hormonal control in the distal tubule

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18
Q

How does the Na+/K+ ATPase pump work?

A
  • sodium pumped out
  • K+ pumped in
  • K+ channels allow K+ ions to leave
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19
Q

What does the sodium potassium pump primarily do?

A

Creates a sodium concentration gradient across the lumina, membrane

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20
Q

How are glucose and amino acids reabsorbed?

A

Sodium co-transporters

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21
Q

How is chloride reabsorbed?

A

Accumulation of positive charges in the interstitial fluid creates an electrical gradient

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22
Q

What happens when water is reabsorbed?

A

Continuous reabsorption of water creates a water current, drives reabsorption into the peritubular capillary

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23
Q

What induces movement of water into the peritubular capillary?

A

High osmotic pressure

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24
Q

What is the main function of the LoH?

A

Sets up an extracellular vertical osmotic gradient that can be used by the collecting ducts to produce urine of varying concentrations

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25
Q

What are two important features of the LoH?

A
  • descending loop is only permeable to water

- ascending loop is only permeable for Na+ and Cl-

26
Q

What is the role of urea in the creation the concentration gradient?

A
  • distal tubule and first part of the collecting duct impermeable to urea
  • urea has a concentration gradient from the end of the collecting discutere back across to the LoH
  • movement of urea along this concentration gradient contributes to the high inner medullary concentration
27
Q

Why is urea important?

A

High protein diet allows high ability to control concentration of urine and vice-versa

28
Q

How is ADH released?

A
  • osmoreceptors in the thalamus either swell or shrink depending on the osmolarity
  • sends a message to the posterior lobe of the pituitary gland
29
Q

What is the action of ADH?

A
  • binds to extracellular receptor
  • realeases cyclic AMP
  • increases permeability of CD to water by inserting new water channels
30
Q

What is the maximum concentration of urine?

A

1200ml

31
Q

Drinking seawater

A

2400

Have to produce 2 litres of urine to get ride of the extra solutes

32
Q

What factors affect ADH secretion?

A
  • nicotine (positive)
  • swallowing (negative, oropharyngeal reflex)
  • alcohol (negative)
  • stress (positive)
33
Q

What occurs with an increase in salt intake?

A
  • increased ECF osmolarity

- increased plasma volume and hence blood pressure

34
Q

What do granular cells react to in terms of the renin/angiotensin system?

A

Low Na+ levels, increases secretion of renin

35
Q

What does renin act on?

A

Angiotensinogen (already in circulation) from the liver

36
Q

What is the process of renin activation?

A
  • renin produced by granulosa cells
  • angiotensinogen from liver converts renin to angiotensin I
  • angiotensin converting enzyme from the lungs converts angiotensin I to angiotensin II
  • angiotensin II stimulates the secretion of aldosterone from the adrenal cortex
37
Q

What does aldosterone do?

A

Synthesises and inserts new sodium transporters and Na+/K+ ATPase pumps

38
Q

What other effects does angiotensin have?

A
  • increases ADH and thirst

- vasoconstriction to decrease decrease GFR and water loss

39
Q

What is the renin angiotensin system sensitive to?

A

Changes in blood pressure

40
Q

What happens in low salt intake occurs?

A
  • low plasma osmolarity
  • hypothalamus
  • ADH is secreted
  • decrease in water reabsorption
  • increase in water urine water loss
  • decreases blood volume pressure/volume
41
Q

What does ANP stand for?

A

Atrial natriuretic peptide

42
Q

What does ANP do?

A
  • rapidly brings down blood volume and pressure
  • opposes renin-angiotensin
  • increases urine production and excretion of Na+
  • rapid
  • needs a large increase in blood pressure
43
Q

What hormones does ANP decrease?

A
  • ADH
  • Renin
  • Aldosterone
44
Q

What is tubular secretion important for?

A

Rather excretion of waste products

45
Q

What are the most important substances involved in tubular secretion?

A
  • K+
  • H+
  • organic ions
46
Q

What can too much K+ cause?

A
  • decrease in membrane potential and over-excitability
47
Q

What does too little K+ cause?

A
  • reduced excitability if muscle and nerve leading to muscle weakness and cardiac arrhythmia and mental confusion
48
Q

What does increase plasma K+ do?

A

Increases aldosterone secretion, cells in the adrenal glands sense potassium at all times

49
Q

Where does the secretion of sodium occur?

A

Select set of cells in the distal tubule

50
Q

How does aldosterone increase K+ secretion?

A

More Na+/K+ ATPase pumps on the the basal surface and K+ channels in the apical surface

51
Q

Where is penicillin secreted?

A

Tubular secretion

52
Q

What is the normal pH range?

A

7.35-7.45

53
Q

What is one way of increasing bicarbonate reabsorption?

A
  • carbon dioxide and water react with carbonic anhydrase in the epithelial cell to produce bicarbonate ions
  • the bicarbonate ions move into the blood
  • the H+ ions move into the tubular lumen, react with HCO3- and the CO2 produced moves back into the cell to keep the reaction going
54
Q

What happens if the H+ concentration gets too high?

A

Pumps actively pump H+ into the tubular lumen

55
Q

What does the tubular lumen secrete to prevent acidic conditions from damaging the cells?

A
  • NaPO4-

- NH3

56
Q

What happens in the kidney during hypoventilation?

A
  • increases HCO3- reabsorption
57
Q

What happens in the kidneys during hyperventilation?

A

Little HCO3- reabsorption

58
Q

What are the two mechanisms responsible for auto regulation of the kidneys?

A
  1. Myogenic mechanism

2. Juxtaglomerular feedback

59
Q

Auto-regulation: myogenic mechanism

A

Smooth muscle in afferent arteriole wall:

  • automatically constricts when stretched (increased BP)
  • automatically relaxes when ‘destretched’
60
Q

Auto-regulation: juxtamedullary feedback increase in BP

A
  • increases salt delivery to macula densa cells which secrete ATP and adenosine which endure the granular cells to contract
61
Q

Auto-regulation: juxtamedullary feedback decrease in BP

A
  • decreases salt delivery decreases release of ATP and adenosine release by macula densa cells which results in the relaxation of the granular cells

Physiology Of Body Systems (7 decks)

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