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Physiology II - HLSC 128 > Chapter 14- Urinary System > Flashcards

Chapter 14- Urinary System Flashcards

1
Q

What are the kidney’s functions?

A

maintain H2O balance and proper osmalarity of body fluids
Regulate ECF ions
Maintain plasma volume
Maintain acid-base balance
Eliminating metabolic waste
Produce erythropoietin and renin
Converting Vit D to its active form

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2
Q

What does the urinary system consist of?

A
  1. urine forming organs
  2. Structures that carry urine from kidney to outside body
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3
Q

What are the urine forming organs?

A

Kidneys

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4
Q

What are the structures that carry urine from kidneys to outside the body?

A

Ureters
Urinary bladder
Urethra

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5
Q

What is each kidney supplied with (blood vessels)?

A

A renal artery and a renal vein

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6
Q

What do the kidneys act on to produce urine?

A

Plasma

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7
Q

What is the basic anatomy of the kidney?

A

Outer cortex and inner medulla, urine drains into the renal pelvis (medial inner core of kidney)

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8
Q

What are the ureters function?

A

Carry urine from kidneys to the bladder

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9
Q

What are the ureters walls made from?

A

Smooth muscle

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10
Q

What is the urinary bladder’s function?

A

Temporarily store urine
-Periodically empties to the outside of the body

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11
Q

What is the anatomy of the bladder?

A

Hollow, distensible, smooth muscle-walled sac

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12
Q

What is the urethra function?

A

Convey urine to the outside of the body

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13
Q

What is the nephron?

A

Functional unit of the kidney

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14
Q

How many nephrons per kidney

A

~1 million nephrons/kidney

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15
Q

What are the two coponents of the nephron?

A
  1. Vascular component
  2. Tubular component
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16
Q

What creates the two distinct regions of the kidney (Outer cortex, inner medulla)?

A

Arrangement of nephrons

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17
Q

What is the appearance of the outer region: renal cortex?

A

Granular

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18
Q

What is the inner region: renal medulla made up of?

A

Striated triangles called renal pyramids

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19
Q

What makes up the Vascular component?

A

Afferent arteriole
Glomerulus
Efferent arteriole
Peritubular capillaries

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20
Q

What makes up the tubular component?

A

Bowman’s capsule
proximal tubule
Loop of Henle
Distal tubule and collecting duct/tubule
Juxtaglomerular apparatus

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21
Q

What is the Juxtaglomerular apparatus?

A

Part of nephron that produces substances involved in the control of kidney function
-Made up of efferent and afferent arterioles, and the distal convoluted tubule

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22
Q

What is the glomerulus?

A

Ball of capillaries that filters water and solutes as the blood passes through it

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23
Q

What arterioles deliver blood to glomerulus?

A

Renal artery—-> Afferent arterioles

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24
Q

What arterioles transports blood away from glomerulus?

A

Efferent arterioles

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25
Q

What do efferent arterioles break down into?

A

Peritubular capillaries —-> Renal vein
-Surround tubular part of nephron

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26
Q

What is the tubular component?

A

Hollow, fluid-filled tube formed by a single layer of epithelial cells

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27
Q

What are the parts of the Loop of Henle?

A
  1. Descending limb
  2. Ascending limb
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28
Q

Where do all nephrons originate?

A

Cortex

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29
Q

What specifically give the granular appearance of the cortex?

A

Glomeruli
Bowman’s capsule

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30
Q

What are the kinds of nephrons?

A
  1. Cortical
  2. Juxtamedullary
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31
Q

What kind of nephrons are 80% of nephrons?

A

Cortical

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32
Q

Where do glomeruli of cortical nephrons lie?

A

Outer layer of cortex

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33
Q

Where do glomeruli of juxtamedullary nephrons lie?

A

inner layer of cortex

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34
Q

What is the Juxtamedullary nephrons function?

A

Preform most of urine concentration
20% are this type

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35
Q

What efferent arterioles belong to Juxtamedullary nephrons?

A

Long looping vasa recta

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36
Q

What efferent arterioles belong to cortical nephrons?

A

peritubular capillaries

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37
Q

What are the three basic kidney processes?

A
  1. Glomerular filtration
  2. Tubular reabsorption
  3. Tubular secretion
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38
Q

How much is filtered through glomerular filtration?

A

180L/day

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39
Q

How much is reabsorbed through tubular reabsorption?

A

178.5L/day

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40
Q

How much of cardiac output do the kidneys receive?

A

20-25%

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41
Q

What is the total blood flow through the kidneys?

A

1L/min

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42
Q

How much of the plasma that enters the glomerulus is not filtered?

A

80%

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43
Q

Where does the non-filtered plasma leave the glomerulus?

A

Through the efferent arteriole

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44
Q

What are the 3 layers of the glomerular membrane?

A
  1. Glomerular capillary wall
  2. Basement membrane
  3. Inner layer of Bowman’s capsule
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45
Q

What kind of capillary is the Glomerular capillary wall?

A

Fenestrated

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46
Q

Why is the Glomerular capillary wall fenestrated?

A

More permeable to water and solutes than any other capillary in the body

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47
Q

What does the inner layer of the Bowman’s capsule consist of?

A

Podocytes that encircle the glomerulus tuft

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48
Q

What do podocytes surround?

A

Basement membrane of the glomerulus

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49
Q

What do podocytes terminate in?

A

Foot processes

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50
Q

What are the clefts between podocytes called?

A

Filtration slits

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51
Q

What is the purpose of filtration slits?

A

They are where the filtrate enters the Bowman’s capsule

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52
Q

What kind of process is Glomerular filtration?

A

Passive process

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53
Q

What kind of pressure forces the fluids/solute through a membrane in glomerular filtration?

A

Hydrostatic pressures

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54
Q

Why are Glomeruli efficient filters?

A

-Filtration membrane has a large surface area
-Very permeable to water and solutes
-Glomerular pressure is higher than other capillaries

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55
Q

What are the 3 physical forces involved in Glomerular filtration?

A
  1. Glomerular capillary blood pressure
  2. plasma-colloid osmotic pressure
    3.Bowman’s capsule hydrostatic pressure
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56
Q

What magnitude is Glomerular capillary blood pressure?

A

55mmHg

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57
Q

What magnitude is Plasma-colloid osmotic pressure?

A

30mmHg

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58
Q

What magnitude is Bowman’s capsule hydrostatic pressure?

A

15mmHg

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59
Q

What is Glomerular capillary blood pressure?

A

Fluid pressure exerted by blood within
glomerular capillaries

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60
Q

What does Glomerular capillary blood pressure depend on?

A

Resistance to blood flow offered by afferent and efferent arterioles

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61
Q

What is the major force producing glomerular filtration?

A

Glomerular capillary blood pressure

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62
Q

What is Plasma-colloid osmotic pressure caused by?

A

Caused by unequal distribution of plasma proteins across glomerular membrane

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63
Q

What is the effect of Glomerular capillary blood pressure?

A

Favours filtration
-forces fluid out of globular capillary into bowman’s capsule

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64
Q

What is the effect of Plasma-colloid osmotic pressure?

A

Opposes filtration
-Draws fluid into capillaries and out of the bowman’s capsule

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65
Q

What is Bowman’s Capsule Hydrostatic Pressure?

A

Pressure exerted by fluid in initial part of tubule

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66
Q

Bowman’s Capsule Hydrostatic Pressure function?

A

Push fluid out of bowman’s capsule

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67
Q

What is the effect of Bowman’s Capsule Hydrostatic Pressure?

A

Opposes filtration
-Draws fluid into capillaries and out of the bowman’s capsule

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68
Q

What is Net filtration pressure?

A

The difference between force favouring filtration and forces opposing filtration
Favouring= Glomerular Capillary BP
Opposing= Plasma-colloid pressure and Bowman’s Capsule Hydrostatic pressure

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69
Q

What is the formula for Net filtration pressure?

A

Net fil. pres.= glomerular capillary blood pressure – (plasma-colloid osmotic pressure + Bowman’s capsule hydrostatic pressure)
–> 55mmHg- (30mmHg+15mmHg)= 10mmHg

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70
Q

How much of plasma in filtered through glomerular filtration?

A

20%

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71
Q

Does glomerular filtration filter proteins?

A

No it is protein-free

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72
Q

How many millilitres is filtered per minute with glomerular filtration?

A

125mL/min

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73
Q

What does glomerular filtration rate depend on?

A
  1. Net filtration pressure
  2. Available glomerular surface area
  3. How permeable the glomerular membrane is
74
Q

What are unregulated influences on the GFR?

A

Plasma-colloid osmotic pressure
Bowman’s capsule hydrostatic pressure
-They are constant but can change (NOT CONTROLLED)

75
Q

What can cause the Plasma-colloid osmotic pressure to change?

A

Severely burned patient
Dehydrating diarrhoea

76
Q

How does a severely burned patient affect the GFR?

A

GFR increases

77
Q

How does dehydrating diarrhoea affect the GFR?

A

GFR decreases

78
Q

What can cause the Bowman’s Capsule hydrostatic pressure to change?

A

Obstructions like kidney stones

79
Q

What pressure is controlled to adjust the GFR and suit the body’s needs?

A

Glomerular capillary blood pressure

80
Q

What pressures remain constant?

A

Plasma-colloid osmotic pressure and Bowman’s capsule hydrostatic pressure

81
Q

What are the 2 major control mechanisms on glomerular blood pressure to alter GFR?

A
  1. Autoregulation
  2. Extrinsic sympathetic control
82
Q

What is the purpose of auto regulation?

A

It aims to prevent spontaneous changes in GFR
-GFR kept within a narrow range despite changes in BP

83
Q

Autoregulation is what kind of regulatory mechanism?

A

Intrinsic

84
Q

How does auto regulation work?

A

Changing the diameter of the afferent arteriole which changes BP in glomerular capillary

85
Q

If no auto regulation mechanisms what would happen to GFR?

A

Increase BP increase GFR
Decrease BP decrease GFR

86
Q

What happens when the afferent arteriole undergoes vasoconstriction? (blood flow to glomerulus decreases)

A

Decrease glomerular capillary BP —> Decreases Net filtration pressure –> Decreases GFR

87
Q

What happens when the afferent arteriole undergoes vasodilation? (blood flow to glomerulus increases)

A

Increase glomerular capillary blood pressure —> increases net filtration pressure —> Increase GFR

88
Q

What are the two intrarenal mechanisms that contribute to auto regulation?

A
  1. Myogenic mechanism
  2. Tubuloglomerular feedback TGF
89
Q

What is myogenic mechanism?

A

Stretch causes afferent arteriole smooth muscle to contract when BP is increased
-less stretch=relaxation

90
Q

What is the macula densa?

A

Area of specialised tubular cells that monitor the NaCl concentration of the tubular fluid

91
Q

What is Tubuloglomerular feedback?

A

Mechanism that involves the juxtaglomerular apparatus that allows the nephron to monitor salt level and use ATP and adenosine to regulate GFR

92
Q

What does adenosine constrict?

A

Afferent arteriole

93
Q

What happens to the TGF when salt increases (caused by GFR increase)?

A
  1. Macula Dense cells release ATP and degrade to adenosine.
  2. Afferent arteriole constricts (bc of adenosine)
  3. Glomerular blood flow is reduced and GFR lowers
94
Q

Do increases in BP that occur normally like from excercise affect GFR?

A

No, GFR doesn’t increase/decrease
-prevents needless loss of water and solutes

95
Q

What is the purpose of extrinsic sympathetic control on GFR?

A

It aims to regulate arterial blood pressure long-term

96
Q

What overrides auto regulation mechanisms?

A

Extrinsic sympathetic control
-Deliberate change in GFR despite normal BP range

97
Q

What mediates extrinsic control and where is the input sent to?

A

Sympathetic nervous system sends input to afferent arterioles

98
Q

What extrinsic control reduces urine output?

A

Barorecptor reflex
e.g Blood loss decrease plasma volume

99
Q

What substances are filtered by the kidneys?

A

Water
Sodium
Glucose
Urea (waste)
Phenol (waste)

100
Q

What is tubular secretion?

A

The transfer of substances from tubular lumen into peritubular capillaries
-highly selective and variable process

101
Q

What 5 barriers do reabsorbed substances cross during tubular secretion?

A
  1. Leave tubular fluid by crossing luminal membrane
  2. Pass through the cytosol, to get from one side of the tubular cell to the other
    3.Cross basolateral membrane (enter interstitial fluid)
    4.Diffuse through interstitial fluid
    5.Penetrate capillary wall to enter blood plasma
102
Q

All tubular fluid components are the same concentration as in plasma, EXCEPT for?

A

Proteins

103
Q

Where does waste material go?

A

It isn’t reabsorbed into blood so it stays in the tubule

104
Q

What are the two types of reabsorption?

A

Passive: No energy, down electrochemical gradient
Active: energy needed, against electrochemical gradient

105
Q

What is the essential mechanism for Na+ reabsorption?

A

Na-K ATPase pump
-Active transport

106
Q

How much of the kidney’s total energy is spent on Na transport?

A

80%

107
Q

What follows reabsorbed sodium by osmosis?

A

Water

108
Q

What mainly effected by water following reabsorbed sodium?

A

Has an effect on blood volume and blood pressure

109
Q

Why is Na reabsorption important?

A

If body Na is controlled, ECF water volume is controlled which controls blood volume and blood pressure

110
Q

What other substances are coupled to the movement of Na reabsorption?

A

Glucose, amino acids and Cl-

111
Q

What is the most abundant cation in filtrate and ECF?

A

Sodium Na+

112
Q

Where is the fine tuning of Na reabsorption carried out? (too much or too little Na)

A

Distal tubule
Too much Na—>Less reabsorbed, more excreted in urine

Too little Na—>More reabsorbed

113
Q

What do ECF volume changes affect?

A

Blood pressure

114
Q

How is Na reabsorption fine-tuned?

A

RAAS

115
Q

What is RAAS?

A

Renin-angiotensin-aldosterone system
Most important Hormone system involved in Na regulation through use of Juxtaglomerular apparatus granular cells

116
Q

What do JGA granular cells release?

A

Renin

117
Q

What is Renin?

A

Hormone that helps regulate BP and maintain normal sodium levels

118
Q

What does Renin do?

A

Converts angiotensinogen into angiotensin I

119
Q

What is angiotensin-converting enzyme?

A

Enzyme that converts Angiotensin I into angiotensin II

120
Q

What does Angiotensin II stimulate the secretion of?

A

Aldosterone

121
Q

What are the functions of the RAAS?

A
  1. Increases Na absorption, promotes water retention (negative feedback system)
  2. Potent constrictor of systemic arterioles
    3.Stimulates thirst
  3. Stimulates vasopressin secretion
122
Q

What is aldosterone?

A

Hormone that acts on last portion of distal convulsed tubules and collecting ducts

123
Q

What does aldosterone do?

A

Increases apical membrane Na channels
Creates more basolateral Na/K ATPase pumps

124
Q

What happens to Na reabsorption when there is Low ECF volume and Low BP?

A

More renin is released which leads to more aldosterone released. More aldosterone=more Na reabsorbed and greater volume in ECF

125
Q

What happen when there is High ECF volume in Na reabsorption?

A

Less renin is released which leads to less aldosterone released. Less aldosterone= Less Na reabsorbed and more body volume lost in urine

126
Q

What is Atrial Natriuretic peptide (ANP)

A

Hormone opposite to aldosterone, it INHIBITS Na reabsorption

127
Q

What secretes ANP?

A

Atria

128
Q

What is ANP secreted in response to?

A

Being stretched by Na retention
Expansion of ECF volume
Increase is arterial pressure

129
Q

What does ANP release promote?

A
  1. Natruresis (Loss of Na)
  2. Diuresis (Increase urine production)
  3. Hypotensive effects
    All help to correct the OG stimulus that brought about release of ANP (negative feedback)`
130
Q

What is reabsorption of glucose and amino acids dependent on?

A

Sodium, they are reabsorbed by secondary active transport

131
Q

How much water reabsorbed is UNCONTROLLED?

A

80%
65%- reabsorbed in proximal tubule
15%-Reabsorbed in loop of henle

132
Q

How is the other 20% of water reabsorbed in a controlled way?

A

Under hormonal control of Vasopressin or ADH

133
Q

What do the proximal tubule and loop of henle contain to allow water reabsorption?

A

Aquaporins (water channels)

134
Q

How is bulk flow enhanced?

A

increased plasma colloid osmotic pressure of peritubular capillaries

135
Q

Which part of the nephron regulates H2O reabsorption via vasopressin?

A

Distal portion

136
Q

What happens to waste products the more water is reabsorbed?

A

Waste products become more concentrated, remain in tubular fluid and are excreted in urine

137
Q

Why can’t waste products be reabsorbed?

A

They cannot permeate the tubular wall

138
Q

Where is Hydrogen secreted?

A

proximal, distal and collecting tubules

139
Q

Where are potassium ions secreted?

A

Only is distal and collecting tubules under the control of aldosterone

140
Q

Why is potassium ion secretion important?

A

Keeps plasma K at appropriate concentration to maintain normal membrane excitability

141
Q

Where are organic ions secreted?

A

Only in proximal tubules

142
Q

What is potassium ion secretion?

A

Movement of K from capillaries to interstitial fluids into tubular cell via the pump and out via ion channels into urine

143
Q

Where are K channels located?

A
  1. Basolateral membrane (proximal tubule and loop of Henle)
  2. Luminal membrane (Distal portions)
144
Q

What happens to K if channels are on basolateral membrane?

A

K is recycled

145
Q

What happens to K is channels are on luminal membrane?

A

K is secreted

146
Q

What two separate things does aldosterone dually control?

A

K secretion and Na reabsorption

147
Q

What does Dual control mean?

A

If one pathway is activated it still affects the other one

148
Q

If the aldosterone pathway is activated for decreased Na what would happen to K concentrations?

A

They would decrease

149
Q

What is the Body fluids osmolarity when there is normal fluid balance and solute concentration?

A

300mOsm/L
=body fluids (ECF) are Isotonic

150
Q

When there is too much H2O relative solutes?

A

ECF is hypotonic
Cells>ECF
-too dilute

151
Q

When there is a water deficit relative to solutes?

A

ECF is hypertonic
Cells<ECF
-too concentrated

152
Q

What does the kidneys urine secretion concentration depend on?

A

Body’s state of hydration

153
Q

Where is the vertical osmotic gradient maintained?

A

Interstitial fluid of renal medulla

154
Q

What is the vertical osmotic gradient?

A

Concentration of interstitial fluid of the medulla of each kidney and progressively increases
300mOsm/L —> 1200mOsm/L

155
Q

What does the vertical osmotic gradient follow?

A

Hairpin loop of Henle deeper and deeper into medulla
deeper=higher mOsm/L

156
Q

What establishes the medullary vertical osmotic gradient ?

A

Countercurrent multiplication system

157
Q

What is Countercurrent multiplication ?

A

Fluid in one tube flows the opposite way in
the adjoining tube

158
Q

What is the descending limb highly permeable to?

A

Water

159
Q

What is the descending limb NOT highly permeable to?

A

Sodium

160
Q

What does the ascending limb actively transport out of the tubular lumen and into the surrounding interstitial fluid?

A

Sodium chloride NaCl

161
Q

What is the ascending loop impermeable to?

A

Water
-Water doesn’t follow salt via osmosis

162
Q

What is the role of Vasopressin?

A

increases the permeability of the tubule cells to water

163
Q

Where is 65% if water reabsorption obligatory?

A

proximal tubule

164
Q

Why does water reabsorption vary in the distal tubule and collecting duct?

A

It is based on secretion of vasopressin

165
Q

Where is vasopressin produced and released?

A

produced in the hypothalamus
and released from the posterior pituitary

166
Q

What does vasopressin act on?

A

Distal tubule
Collecting duct

167
Q

How does Vasopressin work on tubule cells?

A

cyclic AMP mechanism

168
Q

What happens to urine excretion during a water deficit?

A

vasopressin is increased so H2O can b reabsorbed by peritubular capillaries and conserved for odies
-small quantity of Concentrated 1200mOsm/L urine leaves collecting tubules

169
Q

What happens to urine excretion during a water excess?

A

Vasopressin is decreased so no water is reabsorbed in collecting tubule and large quantity of dilute urine is excreted 100mOsm/L

170
Q

What is osmotic diuresis?

A

Increased urine production containing increased excretion of water AND solute

171
Q

In diabetes mellitus what solute is excreted?

A

Glucose (not reabsorbed as it excels reabsorption capacity)
-Sweet urine

172
Q

What is water diuresis?

A

Increased urine with little increased solute
Caused by: excess water intake or diabetes insipius

173
Q

What is Micturition?

A

The action of urinating

174
Q

What controls micturition (urine release)?

A

Sphincters:
1. Internal urethral sphincter
2. External urethral sphincter

175
Q

What is the internal urethral sphincter made from?

A

Smooth muscle

176
Q

What controls the internal urethral sphincter?

A

parasympathetic nervous system contracts it
Relaxed bladder causes it to close

177
Q

What is the external urethral sphincter made from?

A

Skeletal muscle
-Its under voluntary control, somatic motor

178
Q

Elimination of urine is a combination of what?

A

reflex and voluntary control

179
Q

During reflex control urine in bladder stimulates what?

A

Stretch receptor

180
Q

What allows urine to pass though urethra?

A

Relaxation of external sphincter muscle

Physiology II - HLSC 128 (7 decks)

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