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MEDSCI 142 > Section 6: Renal System > Flashcards

Section 6: Renal System Flashcards

1
Q

External anatomy of kidneys

A 
Renal capsule (innermost layer)
Adipose capsule
Renal fascia (outermost layer)

All made of CT - provides padding, protection and packaging

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2
Q

Kidneys: Renal capsule

A

Physical barrier; protection against trauma

Maintains shape of kidneys

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3
Q

Kidneys: Adipose capsule

A

Padding; physical protection

Maintains position of kidneys

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4
Q

Kidneys: Renal fascia

A

Anchors kidneys to surrounding structures

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5
Q

Parenchyma of kidney

A

Functional portion
Contains ~1 million nephrons (functional units)
Focusing on juxtamedullary nephrons

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6
Q

Kidneys: Renal corpuscle - components

A

Glomerulus (blood) - endothelium
- input: afferent arterioles
- output: efferent arterioles
Glomerular (Bowman’s) capsule - epithelium
- visceral: podocytes (modified epithelium)
- parietal: from outer wall of capsule (simple squamous)

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7
Q

Kidneys: Filtration membrane - parts

A

Fenestration (pore) of glomerular endothelial cell
Basal lamina of glomerulus
Slit membrane between pedicles

Differential filtering

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8
Q

Kidneys: Filtration membrane - fenestration

A

Prevents filtration of blood cells, but allows all components of blood plasma to pass

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9
Q

Kidneys: Filtration membrane - basal lamina

A

Prevents filtration of larger proteins

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10
Q

Kidneys: Filtration membrane - slit membrane

A

Prevents filtration of medium-sized proteins

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11
Q

Filtration unit and substrate

A

Filtration unit = nephrons

Substrate = blood supply

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12
Q

Kidney mass

A

~150g

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13
Q

Kidneys: Renal columns

A

Extension of cortex into medulla

Lots of blood vessels and tissue embedded here

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14
Q

Kidneys: Interlobar

A

Between 2 lobes

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15
Q

Kidneys: Nephrons - arrangement

A

Not randomly arranged

Very tightly packed in organised ways and all collect into a bunch (bouquet)

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16
Q

Kidneys: Calyces

A

Cup-like structures that collect urine from papillary

Start with smaller cups which merge to form bigger cups

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17
Q

Kidneys: Interlobar artery

A

Red blood vessel found between 2 lobes

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18
Q

Kidneys: Nephrons - classes

A

Some located higher up near cortical area

Others located lower down near medulla

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19
Q

Kidneys: Juxtamedullary nephrons

A

Nephrons close to cortical-medullary junction

Responsible for helping us make concentrated urine

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20
Q

Kidneys: Arcuate artery

A

Where renal artery arches as it comes up to the cortex at cortical-medullary junction
Gives rise to interlobular arteries

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21
Q

Kidneys: Interlobular arteries

A

Feed the lobules

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22
Q

Kidneys: Glomerulus / glomerular capillaries - form an important part of…

A

The filtration barrier

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23
Q

Afferent arteriole is ____ of the filtration apparatus

A

Upstream

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24
Q

Efferent arteriole - pathways

A

Can stay in cortex and feed cells that make up tubular parts of nephron
Or can delve deep into medulla and feed cells of tubular parts of nephron located here

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25
Q

Ascending vs descending vasa recta

A

Ascending: venous blood; relatively O2-poor blood
Descending: arterial blood; relatively O2-rich blood

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26
Q

Peritubular capillaries of medulla

A

Where gas exchange happens

O2 is absorbed by cells of nephron and CO2 is transported back into blood in peritubular capillaries

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27
Q

Kidneys: Where does blood transition from arterial to venous

A

In the peritubular capillaries

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28
Q

Peritubular capillaries: Venous blood - pathway

A

Travels into interlobular veins –> arcuate vein –> interlobar vein –> converge and exit kidney by renal vein –> IVC –> heart

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29
Q

Where does filtration begin

A

Renal corpuscles

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30
Q

Corpuscles

A

Capsulated structures

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31
Q

Interaction between what enables filtration to take place

A

Podocytes and underlying glomerular capillaries

Tgt they form the filtration barrier

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32
Q

Kidneys: Capsular / urinary space

A

Space between visceral and parietal epithelium

Where filtrate accumulates and eventually flows out the renal corpuscle into the tubular portion

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33
Q

Kidneys: What is the basal lamina made up of

A

BM secreted by podocyte

BM secreted by endothelial cells

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34
Q

Kidneys: Glomerular capillaries - texture

A

Not a smooth surface because has pores

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35
Q

Kidneys: Differential filtering - what happens to the proteins that get trapped

A

Either bounce back into blood circulation or are phagocytosed and recycled

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36
Q

Kidneys: Proximal convoluted tubule - cells

A

Have microvilli on apical membrane

Involved in transport

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37
Q

Kidneys: Distal convoluted tubule of many nephrons…

A

Combine and feed into a single collecting duct

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38
Q

Kidneys: Distal convoluted tubule - function

A

Monitors how things are going and provide feedback to influence the beginning of the process

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39
Q

Main functions of kidney

A

Regulation of water and electrolyte balance
Regulation of arterial pressure
Filters blood

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40
Q

Kidney - homeostasis

A

Blood pressure
Water and electrolyte balance
pH
Waste product removal

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41
Q

Kidney is part of ______ system

A

Circulation

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42
Q

Kidney: When things go wrong - symptoms

A 
Swelling
High blood pressure
Shortness of breath
Fatigue
Nausea
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43
Q

Dialysis

A

Prevents build up of waste products

e.g. build up of high K+ –> heart rhythms go bizarre –> sudden death

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44
Q

Osmosis

A

The movement of water through a selectively permeable membrane
From an area of lower solute conc (high water conc) to higher solute conc (low water conc)

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45
Q

Osmotic pressure

A

The pressure required to prevent net water movement, i.e. pressure generated by the water moving inside a cell

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46
Q

Osmolarity

A

A measure of the osmotic pressure exerted by a solution across a semi-permeable membrane compared to pure water
Dependent on no of particles in solution (but independent of nature of particles)
Basically a measure of the conc of all the components in the solution

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47
Q

Osmolarity =

A

Molarity x dissociation factor

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48
Q

150mL NaCl + 1L water dissociates to give…

A

150 mM/L Na+ + 150 mM/L Cl-

= 300 mOsm/L

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49
Q

300mM urea + 1L water gives..

A

300 mOsm/L

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50
Q

Osmolarity usually refers to…

A

A container / beaker, not necessarily a cell

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51
Q

Hyperosmotic

A

A solution with a higher Osm than another

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52
Q

Isosmotic

A

2 solutions with the same Osm

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53
Q

Hyposmotic

A

A solution with lower Osm than another

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54
Q

Tonicity

A

Takes into account the conc of a solute and the ability of the particle to cross a semi-permeable membrane
i.e. ability of a solution to change shape of a cell
‘effective osmolarity’

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55
Q

NaCl - permeability

A

Low permeability

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56
Q

Urea - permeability

A

Higher permeability

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57
Q

Hypertonic

A

A solution with a higher POsm than another

Water will leave cell –> shrinkage

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58
Q

Isotonic

A

2 solutions with same POsm

Not net water movement

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59
Q

Hypotonic

A

A solution with a lower POsm than another

Water will move into cell –> swelling (and burst)

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60
Q

Disturbances in water balance: Dehydration

A

Loss of H2O from ECF
ECF osmotic pressure rises
Cells lose H2O to ECF –> cells shrink

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61
Q

Disturbances in water balance: Hydration

A

H2O enters ECF
ECF osmotic pressure falls
H2O moves into cell –> cells swell

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62
Q

Why maintaining osmolarity is important

A

Sets MP
Generates electrical activity in nerve and muscle
Provides energy for uptake of nutrients and expulsion of waste
Generation of intracellular signalling cascades

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63
Q

Fluid distribution in body - average 70kg male

A 
60% fluid = 42L
2/3 intracellular = 28L
1/3 extracellular = 14L
- 20% plasma = 2.8L
- 80% interstitial = 11.2L
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64
Q

Major sources of water intake

A

Metabolism 8%
Foods 28%
Beverages 64%

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65
Q

Major sources of water output

A

Feces 4%
Lungs 12%
Skin 24%
Urine 60%

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66
Q

Electrolyte composition: High extracellular conc

A

Na+, Cl-, Ca2+ ions have high extracellular conc

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67
Q

Electrolyte composition: High intracellular conc

A

K+ ions have high intracellular conc

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68
Q

Electrolyte composition - similarities?

A

Amount in blood plasma and interstitial fluid are usually very similar

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69
Q

About ___L of fluid enters the renal tubules each day

A

180L

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70
Q

In the average adult, the entire extracellular fluid V is filtered about __ times a day

A

12

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71
Q

How much fluid that enters the renal tubules is reabsorbed

A

~178.6L reabsorbed

~1.4L urine produced each day

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72
Q

Excretion = ?

A

Filtration + secretion - reabsorption

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73
Q

Renal handling of water and solutes: Water

A 
Filtration = total
Reabsorption = most of total
Excretion = small amount of total
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74
Q

Renal handling of water and solutes: Sodium

A 
Filtration = total
Reabsorption = most of total
Excretion = small amount of total
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75
Q

Renal handling of water and solutes: Glucose

A 
Filtration = total
Reabsorption = total
Excretion = 0
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76
Q

Renal handling of water and solutes: Creatinine

A 
Filtration = total
Reabsorption = 0
Excretion = total
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77
Q

What is reabsorption

A

The idea that you’re taking fluid out of your nephron and back into blood

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78
Q

Nephrons - pathway

A 
Glomerulus
Proximal tubule
Loop of Henle: descending limb
Loop of Henle: ascending limb
Distal convoluted tubule
Collecting duct
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79
Q

Glomerular filtration rate %

A

~25% of total renal plasma flow
180 L/day
Very constant, especially over a mean pressure of 80-140

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80
Q

Glomerulus has a similar solute conc to…

A

Plasma

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81
Q

Glomerulus lacks..

A

Proteins and other high molecular weight compounds

Free from blood cells

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82
Q

Glomerulus - coming in and going out

A

Have an arteriole coming in, a capillary bed, and an arteriole going out
The only place in body to have an arteriole before and after a capillary bed

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83
Q

Glomerulus: Capillaries - holes

A

Capillaries in capillary bed have big holes in them - easy for fluid to be filtered out

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84
Q

Glomerulus: Podocytes sit on top of _____

A

Capillaries

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85
Q

Blood flow to kidneys - regulation

A

Tightly regulated, thus glomerular filtration rate is relatively constant

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86
Q

Urine output is directly proportional to….

A

Renal/blood pressure

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87
Q

Kidneys - autoregulation

A

Good autoregulation

Pressure and blood flow through glomerulus is relatively constant

88
Q

What is kidney autoregulation due to

A

Ability of arterioles to constrict - means flow through kidneys doesn’t change much
Particularly afferent arterioles

89
Q

Glomerular blood hydrostatic pressure (GBHP)

A

The major force pushing fluid and solutes out the glomerular capillaries, i.e. BP inside glomerulus
Mechanical P between afferent and efferent arterioles

90
Q

GBHP: Vasoconstriction of afferent vs efferent arterioles

A

Increases in arterial P can be buffered by vasoconstriction of afferent a
Decreases in P can be buffered by vasoconstriction of efferent a

91
Q

GBHP: Pressure at afferent vs efferent arteriole

A

P at afferent arteriole slightly higher than at efferent arteriole

92
Q

GBHP: Normal pressure inside glomerulus and arterioles

A

Glomerulus: 55 mmHg (halfway between afferent and efferent a)
Afferent: 60 mmHg
Efferent: 50 mmHg

93
Q

GBHP: Afferent arteriole vasoconstriction - pressures

A

i.e. constricts before glomerulus
Glomerulus: decreases
Afferent: decreases
Efferent: same

94
Q

GBHP: Efferent arteriole vasoconstriction - pressures

A

i.e. constricts after glomerulus
Glomerular: increases
Afferent: same
Efferent: increases

95
Q

GBHP: What happens if BP drops

A

Efferent arteriole constricts –> increases P before constriction –> efferent P and glomerular BP increases

96
Q

Glomerular filtration is dependent of…

A

Pressure gradients

97
Q

NFP = ?

A

GBHP - CHP - BCOP

~10 mmHg

98
Q

Net filtration pressure (NFP)

A

Determines how much water and small dissolved solutes leave the blood

99
Q

Capsular hydrostatic pressure (CHP)

A

Pressure exerted on plasma filtrate by elastic recoil of glomerular capsule
~15 mmHg

100
Q

Blood colloid osmotic pressure (BCOP)

A

The osmotic force which is the proteins left in the plasma - exert an increasing osmotic ‘pull’ on the water in plasma filtrate
~30 mmHg

101
Q

GBHP vs CHP

A 
GBHP = pressure inside capillaries
CHP = pressure inside capsule (opposes)
102
Q

Kidney stone affects which pressure

A

Fluid in kidney builds up –> increases CHP

103
Q

Which pressure drives fluid back into capillaries

104
Q

Regulation of glomerular filtration - types

A

Autoregulation
Neural
Hormonal

105
Q

Regulation of glomerular filtration: Autoregulation

A

Myogenic autoregulation or tubuloglomerular feedback

Blood vessels themselves respond to changes in pressure

106
Q

Regulation of glomerular filtration: Neural

A

Increased sympathetic nerve activity –> (afferent) vasoconstriction –> reduces filtration

107
Q

Regulation of glomerular filtration: Hormonal

A

Angiotensin II
Atrial natriuretic peptide

Longer term

108
Q

Regulation of glomerular filtration: Hormonal - angiotensin II acts via…

A

Vasoconstriction of afferent and efferent arterioles

109
Q

Regulation of glomerular filtration: Hormonal - atrial natriuretic peptide (ANP)

A

Responds to stretch of atria by relaxation of mesangial cells –> increases SA for filtration

110
Q

Regulation of glomerular filtration: i.e. anything that…

A
  • alters the GBHP (e.g. P in afferent artery)

- alters the SA available for filtration

111
Q

Regulation of glomerular filtration: If you stretch a blood vessel…

A

It tends to constrict around it

112
Q

Regulation of glomerular filtration: Which arterioles receive innervation from sympathetic nerves

A

Both afferent and efferent arterioles

113
Q

Regulation of glomerular filtration: BP and sympathetic activity

A

High BP = high sympathetic activity

114
Q

Natriuresis

A

The excretion of sodium

115
Q

Diuresis

A

Getting rid of lots of water

116
Q

Premature children and BP

A

Tend to develop high BP because SA available for filtration is reduced –> less glomeruli

117
Q

Tubuloglomerular feedback - cycle

A

Increased GFR –>
Increased tubular flow rate (ascending limb) –>
Increased tubular Na+, Cl-, water content sensed by macula densa cells –>
Juxtaglomerular apparatus NO release decreased –>
Afferent arteriole vasoconstriction –>
Back to top

118
Q

Macula densa

A

Sense amount of Na+ in ascending limb of nephron loop
Can give info to afferent arterioles - if lots of Na+, means there’s lots of fluid passing through tubules –> tells afferent arterioles constrict

119
Q

Juxtamedullary vs cortical nephrons

A

Cortical: dilute urine, shorter
Juxtamedullary: important in production of concentrated urine (regulating Na+ and H2O balance), extends down into medulla

120
Q

Where is interstitial fluid is very concentrated

121
Q

Where is there high conc of urea

A

Tip of nephron

122
Q

Nephron structure and function

A

Cells in diff areas look diff and have diff functions

123
Q

Where does the largest amount of solute and water reabsorption from filtered fluid occur

A

Proximal convoluted tubule

~60% glomerular filtrate
~60% NaCl and water
~100% glucose (except diabetes)

124
Q

What area of the nephron is closest to the glomerulus

A

Proximal convoluted tubule

125
Q

Do we urinate glucose

A

Generally no - all stored for later use

Exception is diabetes

126
Q

Nephron: Proximal convoluted tubule - function

A

Highly active in membrane transport processes with reabsorption of water, ions and glucose

127
Q

Nephron: Proximal convoluted tubule - structure

A

Highly developed brush border (microvilli) –> increases SA

128
Q

Na+/K+ ATPase - location

A

Located on basal surface

129
Q

Na+/K+ ATPase - function

A

Pumps Na+ into interstitial place

Maintains low Na+ in cell

130
Q

Na+ movement into tubule cells

A

Occurs via symporters (e.g. Na+/glucose symporter) and antiporters (Na+/H+)

131
Q

Nephron: Proximal convoluted tubule - glucose

A

Glucose and other solutes can diffuse down their conc gradient

132
Q

Nephron: Proximal convoluted tubule - water

A

Na+ movement allows water movement via osmosis

133
Q

Nephron: Proximal convoluted tubule - osmolarity

A

Similar to plasma

134
Q

Na+/Glucose sympoter

A

Na+ moves in cell down its conc gradient and glucose moves with it

135
Q

Nephron: Proximal convoluted tubule - diabetes

A

High levels of glucose –> saturate symporters –> urinate glucose

136
Q

Nephron: Descending loop of Henle - permeability

A

Low permeability to ions and urea

Highly permeable to water

137
Q

Nephron: Descending loop of Henle - water movement

A

Interstitial fluid is highly concentrated in medulla of kidney –> water moves out of tubule via osmosis –> urine becomes more concentrated

138
Q

Nephron: Descending loop of Henle - bottom

A

By the bottom of the loop, the filtrate is v concentrated

~1200 mOsmol/L, whereas ECF ~300 mOsmol/L

139
Q

Nephron: Thick ascending limb - permeability

A

Impermeable to water

Na+, K+ and Cl- actively reabsorbed

140
Q

Nephron: Thick ascending limb (of Henle) - top

A

By the time the filtrate gets to top of loop, conc of ECF decreases –> gets rid of ions via Na/K/Cl symporter –> very dilute
~100 mOsmol/L

141
Q

Nephron: Thick ascending limb - junctions

A

Very tight junctions –> water moves out

142
Q

Loop of Henle: Countercurrent mechanism

A

Descending limb impermeable to NaCl

Ascending limb impermeable to water

143
Q

Nephrons: Thick ascending loop provides…

A

Environment for thin ascending loop by pumping out ions

144
Q

Nephrons: Loop of Henle is helped by…

A

Blood vessels

145
Q

Nephrons: Descending loop of Henle is close to…

A

Descending side of capillary network

146
Q

Nephrons: Thick ascending loop is close to…

A

Ascending side of loop of Henle

147
Q

Nephrons: Does the ECF become diluted

A

Anything pumped out of the thick ascending loop is taken to thin descending loop and water coming out is taken away by veins –> doesn’t dilute the ECF

148
Q

Loop of Henle vs vasa recta

A

Vasa recta moves in an opp direction to loop of Henle to take fluid away –> keeps a high concentration medulla

149
Q

Nephron: Distal convoluted tubule and collecting duct - function

A

Additional reabsorption of NaCl

150
Q

Nephron: Distal convoluted tubule and collecting duct - ADH

A

Water permeability is dependent on antidiuretic hormone
In absence of ADH, area is impermeable to water –> more reabsorption of Na+ and Cl- –> urine produced has little Na+ and Cl- –> urine dilute

151
Q

Fluid dynamics: Water

A

Rapidly equilibrates throughout ICF and ECF

Decreases osmolarity

152
Q

Fluid dynamics: Isotonic solution

A

Remain in ECF
No effect on plasma osmolarity
No gradient in isotonic solution for H2O to move into cell - not effective for dehydration

153
Q

Antidiuretic hormone (ADH) - precursor

A

Made in hypothalamus and stored in vesicles in posterior pituitary

154
Q

ADH release: Osmoreceptors

A

Innervate the hypothalamus, sense:

  • increase in Na+ conc
  • increase in osmolarity

Signal is sent to posterior pituitary and in response to APs, ADH is released into bloodstream

155
Q

Where is ADH made

A

Nerve cells in hypothalamus

156
Q

ADH: Osmoreceptors detect osmolarity in ____

157
Q

Osmoreceptors - structure

A

Have ‘stretch-inhibited’ cation channels

Like a pyramid tethered with long arms - when cell shrinks, lots of stretch on arms –> opens stretch-activated channels

158
Q

Osmoreceptors - channels

A

When cell shrinks due to hypertonic stimulus, cation channels open
Na+ enters cells and triggers APs

159
Q

ADH AKA

A

Arginine vasopressin (AVP)

160
Q

Plasma ADH and osmolarity

A

Plasma ADH increases as osmolarity increases

161
Q

ADH release - blood volume

A

Increased blood volume = less ADH

162
Q

ADH - threshold

A

Threshold for ADH release ~280 mOsm
Normally plasma osmolality is 290 mOsm
So, we usually have ADH circulating in our body with ability to increase or decrease

163
Q

ADH - increased threshold results in…

A

Thirst (dehydration)

164
Q

What hormone is most sensitive to osmolarity

165
Q

What does ADH act on

A

The last part of the convoluted distal tubule and the collecting duct (i.e. end of nephron)

166
Q

ADH - storage vesicles

A

ADH stimulates insertion of aquaporin-2 containing vesicles into the apical membrane
Aquaporin-2 is a water channel, so water can move from tubule into cell (water pore)

167
Q

ADH - basolateral membrane

A

Always relatively permeable to water, so water can move via osmosis back into blood

168
Q

ADH - steps

A
  1. ADH binds to membrane receptor
  2. Receptor activates cAMP second messenger system
  3. Cell inserts aquaporin-2 water pores into apical membrane via exocytosis
  4. Water is absorbed by osmosis into blood
169
Q

ADH - ADH receptors

A

Detect and bind to ADH and sends a message into cell

170
Q

ADH - apical vs basolateral membrane permeability

A

Normally apical membrane not permeable to water (but presence of water pores allows permeability)
Basolateral permeable to water

171
Q

ADH - urine

A

ADH facilitates reabsorption of water in distal tubule and collecting duct –> concentrated urine

172
Q

Collecting ducts move through the ____ of the kidney

173
Q

As we move down the collecting duct, there’s a gradient for water to…

A

Move out of it, so water pores allow them to easily move out to dilute the medulla

174
Q

End of collecting duct - osmolarity

A

Can get up to 1200 mOsm

175
Q

ADH release - types of baroreceptors

A

Both arteriole and cardiopulmonary baroreceptors

176
Q

ADH release - baroreceptors, blood P and blood V

A

Decreased baroreceptor activity, decreased blood V or P = ADH release

177
Q

Overall, what factors affect ADH release

A

Anything that causes an increase in osmolarity, an increase in conc, or a decrease in blood V

178
Q

Renin-Angiotensin-Aldosterone (RAA) system - functions

A

Maintaining Na+ balance

BP regulation

179
Q

ADH: Dehydration

A

Increase in osmolarity and change in blood V = ADH increases

180
Q

ADH: Drinking too much water

A

ADH decreases

181
Q

Juxtaglomerular apparatus

A

Where distal tubule borders the glomerulus

182
Q

Juxtaglomerular apparatus: Macula densa cells

A

Respond to a decrease in NaCl content by increasing prostaglandins
Baseline regulation to keep it even - not involved in blood P regulation, just prevents damage of kidneys

183
Q

Juxtaglomerular apparatus: Juxtaglomerular (granular) cells

A

In afferent arteriole

Release renin

184
Q

Juxtaglomerular apparatus: Pressure

A

Decrease in pressure in afferent arteriole acts on juxtaglomerular cells –> release renin

185
Q

Juxtaglomerular apparatus: Macula densa cells - fast or slow

A

Buffers quick changes

186
Q

Juxtaglomerular apparatus: Renin release - fast or slow

A

Slow - long-term effect that respond to more subtle changes

187
Q

Renin is released primarily due to…

A

Low Na+ in nephron

188
Q

Hormones - speed

A

Usually take a while

189
Q

Triggers for renin release from juxtaglomerular (granular cells

A

Low NaCl conc in distal tubule (Na+ depletion)
Decreased perfusion pressure (by granular cells, afferent arteriole)
Increased sympathetic activity (e.g. via baroreflect)

i.e. low BP, low BV, low Na+

190
Q

Renin release: Macular densa cells are sensing…

191
Q

Renin-Angiotensin System: Active hormone

A

Angiotensin II

Others (angiotensinogen and angiotensin I) are precursors

192
Q

Renin is a(n) _______

193
Q

Renin-Angiotensin System: Rate limiting step

A

Renin is the rate limiting step of the production of angiotensin II

194
Q

Renin-Angiotensin System: ACE

A

Usually lots present

Usually the target when wanting to reduce angiotensin II because less side effects

195
Q

Aldosterone - release

A

From adrenal cortex in response to angiotensin II

196
Q

Aldosterone - what does it act on

A

Distal tubule and collecting ducts to increase transcription of Na/K ATPase pumps –> increases Na+ reabsorption and K+ excretion

197
Q

Aldosterone - water

A

Water reabsorption may also increase via osmosis if ADH is present

198
Q

Aldosterone - main functions

A

Na+ and water retention

199
Q

Angiotensin II - high levels

A

Quite a potent vasoconstriction in kidney and smooth muscle

Can stimulate thirst

200
Q

RAA system summary - dehydration

A

Na+ deficiency and haemorrhage –> decrease blood V –> increase renin –> increase angiotensin II –> vasoconstriction of arterioles –> increase BP until norm
OR:
increase aldosterone –> increase Na+ (and water) reabsorption in –> increase blood V -> BP increase until norm

201
Q

Angiotensin II and salt

A

Increased salt –> reduced angiotensin II –> reduced renin because of change in arteriole P

202
Q

Chips (increased salt) - effects

A

Increased intake of NaCl in ECF –> water moves out of cell –> increased blood V and osmolarity (?)

203
Q

ADH and chips

A

Increase in blood V is major trigger so ADH doesn’t help much

204
Q

Salt vs water balance

A

ADH: important in maintaining water balance
RAA system: important in maintaining salt balance

2 systems allow for independent control of water and salt levels in body

205
Q

Haemorrhage - fluid loss is…

A

Isosmotic

Lose both water and salt so need both RAA system and ADH

206
Q

Blood loss is…

A

Hypovolemic / isotonic

207
Q

What is blood loss sensed by

A

Juxtoglomerular cells and arterial baroreceptors

208
Q

Blood loss leads to increased…

A

Sympathetic activity
ADH
Renin / angiotensin II / aldosterone

–> vasoconstriction and conservation of water and Na+

209
Q

Atrial natriuretic peptide (ANP) - acts to..

A

Reduce renin, ADH and aldosterone release
Increase GFR
Reduces Na+ and water reabsorption

210
Q

Timescale:

A

Baroreceptors = second
Osmolarity = ~1-2 min
ADH at least half an hour, 3 hours before any change in blood levels
Aldosterone ~4 hours

211
Q

Where are glomerular capillary endothelial cells found

A

In renal corpuscle

212
Q

Gradient for transport of many substances is produced by…

A

The Na/K ATPase pump

213
Q

Perfusion P and blood flow

A

Decreased perfusion P –> decreased NV –> decreased renal blood flow

214
Q

Renin and GFR

A

Decreased GFR = increased renin

215
Q

Selective vasoconstriction of the efferent arteriole leads to….

A

Increased P in glomerular capillary network

216
Q

Dehydration - aquaporins

A

Dehydration –> more aquaporins inserted into membrane collecting ducts

217
Q

The countercurrent exchange in the vasa recta maintains..

A

High conc of NaCl in ECF

MEDSCI 142 (9 decks)

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