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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
What are two important features of the LoH?
- descending loop is only permeable to water | - ascending loop is only permeable for Na+ and Cl-
26
What is the role of urea in the creation the concentration gradient?
- 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
Why is urea important?
High protein diet allows high ability to control concentration of urine and vice-versa
28
How is ADH released?
- osmoreceptors in the thalamus either swell or shrink depending on the osmolarity - sends a message to the posterior lobe of the pituitary gland
29
What is the action of ADH?
- binds to extracellular receptor - realeases cyclic AMP - increases permeability of CD to water by inserting new water channels
30
What is the maximum concentration of urine?
1200ml
31
Drinking seawater
2400 | Have to produce 2 litres of urine to get ride of the extra solutes
32
What factors affect ADH secretion?
- nicotine (positive) - swallowing (negative, oropharyngeal reflex) - alcohol (negative) - stress (positive)
33
What occurs with an increase in salt intake?
- increased ECF osmolarity | - increased plasma volume and hence blood pressure
34
What do granular cells react to in terms of the renin/angiotensin system?
Low Na+ levels, increases secretion of renin
35
What does renin act on?
Angiotensinogen (already in circulation) from the liver
36
What is the process of renin activation?
- 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
What does aldosterone do?
Synthesises and inserts new sodium transporters and Na+/K+ ATPase pumps
38
What other effects does angiotensin have?
- increases ADH and thirst | - vasoconstriction to decrease decrease GFR and water loss
39
What is the renin angiotensin system sensitive to?
Changes in blood pressure
40
What happens in low salt intake occurs?
- low plasma osmolarity - hypothalamus - ADH is secreted - decrease in water reabsorption - increase in water urine water loss - decreases blood volume pressure/volume
41
What does ANP stand for?
Atrial natriuretic peptide
42
What does ANP do?
- 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
What hormones does ANP decrease?
- ADH - Renin - Aldosterone
44
What is tubular secretion important for?
Rather excretion of waste products
45
What are the most important substances involved in tubular secretion?
- K+ - H+ - organic ions
46
What can too much K+ cause?
- decrease in membrane potential and over-excitability
47
What does too little K+ cause?
- reduced excitability if muscle and nerve leading to muscle weakness and cardiac arrhythmia and mental confusion
48
What does increase plasma K+ do?
Increases aldosterone secretion, cells in the adrenal glands sense potassium at all times
49
Where does the secretion of sodium occur?
Select set of cells in the distal tubule
50
How does aldosterone increase K+ secretion?
More Na+/K+ ATPase pumps on the the basal surface and K+ channels in the apical surface
51
Where is penicillin secreted?
Tubular secretion
52
What is the normal pH range?
7.35-7.45
53
What is one way of increasing bicarbonate reabsorption?
- 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
What happens if the H+ concentration gets too high?
Pumps actively pump H+ into the tubular lumen
55
What does the tubular lumen secrete to prevent acidic conditions from damaging the cells?
- NaPO4- | - NH3
56
What happens in the kidney during hypoventilation?
- increases HCO3- reabsorption
57
What happens in the kidneys during hyperventilation?
Little HCO3- reabsorption
58
What are the two mechanisms responsible for auto regulation of the kidneys?
1. Myogenic mechanism | 2. Juxtaglomerular feedback
59
Auto-regulation: myogenic mechanism
Smooth muscle in afferent arteriole wall: - automatically constricts when stretched (increased BP) - automatically relaxes when ‘destretched’
60
Auto-regulation: juxtamedullary feedback increase in BP
- increases salt delivery to macula densa cells which secrete ATP and adenosine which endure the granular cells to contract
61
Auto-regulation: juxtamedullary feedback decrease in BP
- 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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