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HLSC 128 > Renal > Flashcards

Renal Flashcards

1
Q

Kidneys are primarily responsible for..

A

maintaining the stability of ECF volume, water and electrolyte composition, blood pressure and osmolarity

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2
Q

Kidneys are main route for..

A

eliminating potentially toxic substances, metabolic wastes, and foreign compounds from the body

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3
Q

Kidney functions

A
  1. maintain water, salt and electrolytes balance in the body by urinary output e.g. maintain surplus and deficit for ECF constituents
  2. maintain the proper osmolarity of body fluids; primarily through regulating water balance (prevents disruption is osmosis)
  3. regulate and maintain the quantity and concentration of most ECF ions (Na+, Cl-, K+, HCO3-, Ca2+, Mg+, SO4-, PO4-2) e.g. minor changes in ECF K+ lead to fetal cardiac arrest or dysfunction
  4. maintain proper plasma volume to regulate long-term blood pressure
  5. help maintain proper acid-base balance in the body (urinary output of H+ and HCO-3) e.g. high H+= blood acidic= acidosis.
  6. excretion of the end products (wastes) of bodily metabolism e.g. urea, uric acid and creatinine
  7. excreting many foreign compounds (drugs, pesticides, food additives and other non-nutritive materials)
  8. produce erythropoietin to regulate RBC production
  9. produce renin (kidney enzyme) that triggers RAAS, important in salt conservation by the kidneys
  10. converting vitamin D into its active form (Calcitriol)
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4
Q

Kidneys

A
  • urine-forming organs
  • located in the back of the abdominal cavity, each kidney is supplied with a renal artery and a renal vein
  • acts on plasma flowing through it to produce urine
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5
Q

Structures that carry urine from the kidneys to the outside for elimination from the body

A
  • ureters
  • urinary bladder
  • urethra
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6
Q

The outer surface of the kidney is called the __ __, the inner surface is the __ ___

A

The outer surface of the kidney is called the renal cortex, the inner surface is the renal medulla

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7
Q

Formed urine drains into the __ __, located at the medial inner core of each kidney

A

Formed urine drains into the renal pelvis, located at the medial inner core of each kidney

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8
Q

Ureters

A
  • smooth muscle-walled duct
  • exits each kidney at the medial border near renal artery and vein
  • carry urine to the urinary bladder
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9
Q

Urinary bladder

A
  • temporarily stores urine
  • periodically empties to the outside of the body through the urethra
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10
Q

Urethra

A
  • conveys urine to the outside of the body
  • urethra is straight and short in females
  • in males: longer and follows curving course from bladder to outside
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11
Q

Dual function of the urethra

A
  1. provides route for eliminating urine from bladder
  2. passageway for semen from reproductive organs
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12
Q

Nephron

A
  • the functional unit of the kidney
  • the smallest unit that can perform all the functions of the kidney
  • approx. 1 million nephrons/kidney
  • arrangement of nephrons gives rise to 2 distinct regions: outer region, inner region
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13
Q

Outer region of nephron

A

renal cortex (granular in appearance)

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14
Q

Inner region of nephron

A

renal medulla, made up of striated triangles called renal pyramids

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15
Q

Parts of a nephron: vascular components

A

afferent arteriole, glomerulus, efferent arteriole, peritubular capillaries

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16
Q

Parts of a nephron: tubular components

A

bowman’s capsule, proximal tubule, loop of Henle, distal tubule and collecting duct

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17
Q

Afferent arteriole

A

carries blood to the glomerulus

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18
Q

Glomerulus

A

a tuft of capillaries that filters a protein-free plasma into the tubular component

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19
Q

Efferent arteriole

A

carries blood from the glomerulus

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20
Q

Peritubular capillaries

A

supply the renal tissue; involved in exchanges with the fluid in the tubular lumen

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21
Q

Bowman’s capsule

A

collects the glomerular filtrate

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22
Q

Proximal tubule

A

uncontrolled reabsorption and secretion of selected substances occur here

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23
Q

Loop of Henle

A

establishes an osmotic gradient in the renal medulla that is important in the kidney’s ability to produce urine of varying concentrations

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24
Q

Distal tubule and collecting duct

A

variable, controlled reabsorption of sodium and water and secretion of potassium and hydrogen occur here; fluid leaving the collecting duct is urine, which enters the renal pelvis

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25
Q

Combined vascular/tubular component

A

Juxtaglomerular apparatus: produces substances involved in the control of kidney function

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26
Q

Each nephron consists of 2 components

A

vascular and tubular components

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27
Q

Vascular component

A
  • ball-like tuft of capillaries (glomeruli)
  • water and solutes are filtered through the glomerulus as blood passes through it–> the filtered fluid then passes through the nephron’s tubular component
  • From the renal artery inflowing blood passes through afferent arterioles, which deliver blood to the glomerulus
  • Efferent arteriole transports blood from the glomerulus
  • Efferent arteriole breaks down into peritubular capillaries, which surround the tubular part of the nephron
  • Peritubular capillaries join into venules which transport blood into the renal vein
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28
Q

2 types of nephrons

A

cortical and juxtamedullary

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29
Q

Cortical nephrons

A

lie in the outer layer of the cortex, 80% of nephrons

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30
Q

Juxtamedullary nephrons

A

lie in the inner layer of the cortex, performs most urine concentration

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31
Q

3 basic renal processes

A

glomerular filtration, tubular reabsorption, tubular secretion

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32
Q

Structures involved in glomerular filtration

A

glomerulus, bowman’s capsule

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33
Q

Structures involved in tubular reabsorption

A

renal tubule (proximal, loop of Henle, distal), peritubular capillaries

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34
Q

Structures involved in tubular secretion

A

peritubular capillaries, renal tubule

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35
Q

Glomerular filtrate

A

filtrate protein free-plasma

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36
Q

Tubular reabsorption

A
  • absorb nutrients, ions, and electrolytes from kidney tubules into peritubular capillaries
  • all plasma constituents, except plasma proteins are at the same concentration in the glomerular filtrate (urine) as in the plasma
  • the quantity of each reabsorbed material is the amount required to maintain the proper composition and volume of the ECF
  • the tubules have a high absorptive capacity for substances needed by the body and little or no capacity for substances of no value
  • only excess amounts of essential electrolytes are excreted in the urine
  • the absorptive capacity may vary depending on the body’s needs
  • as the water and other valuable constituents are reabsorbed, the waste products remaining in the tubular fluid become highly concentrated, producing concentrated, less volume and yellowish urine
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37
Q

Tubular secretion

A

movement of non-filtered substances from peritubular capillaries into the kidney tubules

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38
Q

Fluid filtered from the glomerulus into Bowman’s capsule passes through 3 layers of the glomerular membrane …

A

1) Glomerular capillary wall
2) Basement membrane
3) The inner layer of Bowman’s capsule

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39
Q

Glomerular capillary wall

A
  • a single layer of endothelial cells
  • more permeable to water and solutes than capillaries elsewhere in the body
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40
Q

Basement membrane

A
  • acellular gelatinous layer
  • composed of collagen and glycoproteins (discourage the filtration of small proteins)
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41
Q

Inner layer of Bowman’s capsule

A

consists of podocyte foot processes that encircle the glomerulus tuft

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42
Q

Glomerular capillary blood pressure

A
  • the pressure exerted by the blood within glomerular capillaries
  • 55 mm Hg
  • major force producing glomerular filtration- favors filtration
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43
Q

Glomerular capillary blood pressure depends on…

A
  • contraction of the heart
  • resistance to blood flow offered by afferent and efferent arterioles
  • the smaller diameter of efferent arteriole
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44
Q

Forces involved in glomerular filtration

A

glomerular capillary blood pressure, plasma-colloid osmotic pressure and bowman’s capsule hydrostatic pressure

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45
Q

Plasma-colloid osmotic pressure

A
  • caused by the unequal distribution of plasma proteins across glomerular membrane (by osmosis)
  • opposes filtration
  • 30 mmHg
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46
Q

Bowman’s capsule hydrostatic pressure

A
  • pressure exerted by fluid in the initial part of the tubule
  • tends to push fluid out of Bowman’s capsule
  • opposes filtration
  • 15 mmHg
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47
Q

Forces involved in glomerular filtration that FAVOUR filtration

A

glomerular capillary blood pressure and net filtration pressure (GFR)

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48
Q

Forces involved in glomerular filtration that OPPOSE filtration

A

plasma-colloid osmotic pressure and bowman’s capsule hydrostatic pressure

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49
Q

Glomerular filtration rate (GFR)

A
  • the net (total force) difference favouring glomerular filtrate

= glomerular capillary blood pressure - (plasma-colloid osmotic pressure + Bowman’s capsule hydrostatic pressure)

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50
Q

Glomerular filtrate rate (GFR) depends on..

A
  • net filtration pressure
  • glomerular surface area available for penetration
  • permeability of the glomerular membrane
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51
Q

Blood flow and GFR when resistance is high in afferent arteriole

A

less blood flow into glomerulus, decreased GFR

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52
Q

Blood flow and GFR when resistance is low in afferent arteriole

A

more blood flow into glomerulus, increased GFR

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53
Q

Autoregulation

A
  • prevents spontaneous changes in GFR
  • automatically adjusted without knowledge
  • myogenic mechanism
  • tubuloglomerular feedback (TGF)
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54
Q

Mechanisms that regulate GFR and how they both do that

A
  • autoregulation and extrinsic sympathetic NS
  • they are directed towards adjusting glomerular blood flow by regulating caliber/diameter and resistance in the afferent arterioles
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55
Q

Extrinsic sympathetic NS

A
  • regulates long-term blood pressure regulation
  • mediated by sympathetic nervous system input to afferent arterioles
  • baroreceptor reflex
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56
Q

If plasma colloid osmotic pressure and bowman’s capsule hydrostatic pressure remains constant, GFR is …

A

directly proportional to an increase in arterial blood pressure i.e. increase in afferent arterial BP= increase GFR, decrease in afferent arterial BP= decrease GFR

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57
Q

An increased GFR due to increased arterial pressure and net filtration pressure, can be normalized by ___ which will decrease blood flow into the glomerulus bringing the GFR back down

A

An increased GFR due to increased arterial pressure and net filtration pressure, can be normalized by vasoconstriction which will decrease blood flow into the glomerulus bringing the GFR back down

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58
Q

A decreased GFR due to decreased arteriolar pressure and net filtration pressure, can be normalized by ___ which will increase blood flow into the glomerulus bringing the GFR back up

A

A decreased GFR due to decreased arteriolar pressure and net filtration pressure, can be normalized by vasodilation which will increase blood flow into the glomerulus bringing the GFR back up

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59
Q

Intra-renal mechanisms of autoregulation

A

myogenic and tubuloglomerular feedback mechanism

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60
Q

Myogenic autoregulation

A

refers to the properties of arteriolar vasculature

(1) smooth muscles stretch automatically
(2a) if afferent arteriole’s smooth muscle constricts= decrease blood to glomerulus= decrease GFR
(2b) if afferent arteriole’s smooth muscle relax= increase blood to glomerulus= increase GFR

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61
Q

Purpose of juxtaglomerular apparatus

A
  • tubuloglomerular mechanisms are initiated by the tubules to help each nephron regulate the rate of filtration through its own glomerulus
  • it prevents dangerous imbalances of fluid, electrolytes and wastes
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62
Q

Extrinsic control of the GFR

A
  • sympathetic nervous system (can override the autoregulatory responses)
  • baroreceptors
  • filtration coefficient
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63
Q

Parasympathetic NS does/does not exert any influence on the kidneys

A

DOES NOT

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64
Q

The rate of glomerular filtration depends on..

A

filtration coefficient and net filtration pressure

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65
Q

filtration coefficient (KF) depends on..

A

surface area and the permeability of the glomerular membrane

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66
Q

Podocytes and permeability of glomerular membrane

A
  • contraction and relaxation of podocytes with foot processes increase or decrease the filtration slits in the inner membrane
  • the number of slits determines the permeability; the more slits open, the greater the permeability
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67
Q

Transepithelial transport

A

involves the transfer of substances from the kidney/renal tubular lumen into peritubular capillaries

68
Q

To be reabsorbed (move from the filtrate to the plasma i.e. transepithelial transport), a substance must transverse 5 distinct barriers…

A
  1. the luminal cell membrane
  2. the cytosol
  3. the basolateral cell membrane
  4. the interstitial fluid
  5. the capillary wall
69
Q

The 2 mechanisms to transport material across the tubules

A

passive and active

70
Q

Passive transport

A
  • no energy required
  • substances move down the electrochemical and osmotic gradients (H–> L)
71
Q

Active transport

A
  • ATP used as an energy source
  • substances move against the electrochemical gradient (L–> H_
  • e.g. glucose, amino acids, sodium, potassium, chloride, electrolytes and phosphate
72
Q

The average percentage of filtered substance reabsorbed/ excreted: Water

A

Reabsorbed= 99% (210 L/day)
Excreted= 1%

73
Q

The average percentage of filtered substance reabsorbed/ excreted: Sodium

A

Reabsorbed= 99.5% (160g/day)
Excreted= 0.5%

74
Q

The average percentage of filtered substance reabsorbed/ excreted: Glucose

A

Reabsorbed= 100% (1Kg/day)
Excreted= 0% (cannot afford to lose glucose, if >0 then diabetes/pancreas failed to produce insulin)

75
Q

The average percentage of filtered substance reabsorbed/ excreted: Urea (a waste toxic product)

A

Reabsorbed= 50%
Excreted= 50%

76
Q

Water reabsorption in the proximal tubule

A
  • out of 125 ml/min of plasma filtered, 124 ml/min plasma is reabsorbed (99% reabsorption), leaving only 1ml/min of plasma filtered and become part of the urine
  • water channels are always open in proximal tubules. However, water channels in the distal tubules of the nephron are regulated by the hormone vasopressin/ADH
77
Q

Sodium reabsorption

A
  • An active Na+- K+ ATPase pump in basolateral membrane is essential for Na+ reabsorption
  • Of the total energy spent by kidneys, 80% is used for Na+ transport
  • Na+ is not reabsorbed in the descending limb of the loop of henle
  • water follows reabsorbed sodium by osmosis which has the main effect on blood volume and blood pressure
78
Q

Tubule area: proximal tubule

% of Na+ reabsorbed: ___

Role of Na+ reabsorption: ____

A

% of Na+ reabsorbed: 67%

Role of Na+ reabsorption: Plays role in reabsorbing glucose, amino acids, water, chloride, and urea

79
Q

Tubule area: ascending limb of the loop of Henle

% of Na+ reabsorbed: ___

Role of Na+ reabsorption: ____

A

% of Na+ reabsorbed: 25%

Role of Na+ reabsorption: Plays critical role in kidneys’ ability to produce urine of varying concentrations

80
Q

Tubule area: distal and collecting tubules

% of Na+ reabsorbed: ___

Role of Na+ reabsorption: ____

A

% of Na+ reabsorbed: 8%

Role of Na+ reabsorption: Variable and subject to hormonal control; plays role in regulating ECF volume

81
Q

Glucose and amino acids reabsorption

A
  • are reabsorbed back into the blood by energy and sodium-dependent mechanisms in the proximal tubules
  • use secondary active transport by using co-transport carrier molecules within proximal tubules
  • co-transport molecules simultaneously transport glucose and amino acids from the lumen to blood and vice-versa
82
Q

Filtered load of glucose

A

100 mg/100 ml X 125 ml/min= 125 mg/min

doubling plasma glucose: 200mg/100ml X 125 ml/min= 250 mg/min

  • at constant GFR, the filtered load of glucose is directly proportional to the plasma glucose concentration
83
Q

Filtered load of a substance

A

plasma concentration x GFR

84
Q

The tubular maximum (Tm) for glucose

A
  • when the maximum reabsorption rate is reached, and when all carriers specific for a particular substance are fully “occupied/saturated”, they cannot handle any additional glucose at that time
  • Tm for glucose is 375 mg/min
  • if more glucose is absorbed than it is filtered, this will happen when,
    1. Tm will exceed above 375 mg/100ml
  1. Plasma glucose concentration must not exceed more than 375 mg/100ml
  2. It will spill into the urine
85
Q

Reabsorption moves solutes from the ____ to the ___. Secretion moves solutes from the ___ to the ___

A

Reabsorption moves solutes from the lumen of the tubule to the blood. Secretion moves solutes from the blood to the lumen of the tubule

86
Q

Passive reabsorption of urea at the end of the proximal tubule

A
  • reabsorption of sodium in the proximal tubules follow water
  • this reduces the original filtrate from 125 ml/min to only 44 ml/min at the end of the proximal tubule (i.e. 81 ml/min water is reabsorbed)
  • sodium and water create the concentration gradient for urea to be passively diffused from the tubular lumen into the peritubular capillary plasma
87
Q

One of the first chemical characteristics identified in the plasma of a patient with severe renal failure

A

elevated urea level

88
Q

Tubular secretion

A
  • transfer of substances from the peritubular capillaries into the kidney/renal tubules
  • involves transepithelial transport but reversed
  • provides a “second” route of entry into the tubule for selected substances (saves you from cardiac arrhythmia and hyperkalemia)
  • includes: hydrogen, potassium, organic anions and cations (all of which escaped filtration (glomerular filtration) and are in high quantity in the peritubular capillary )
89
Q

The most important secretory systems are for ..

A

hydrogen, potassium and organic ions

90
Q

Hydrogen

A
  • important in regulating acid-base balance
  • secreted in proximal, distal and collecting tubules
91
Q

Potassium

A
  • keep plasma potassium concentration at an appropriate level to maintain normal membrane excitability in muscles and nerves
  • secreted only in the distal and collecting tubules under the control of aldosterone
92
Q

Organic ions

A
  • accomplish more efficient elimination of foreign organic compounds from the body
  • secreted only in the proximal tubule
93
Q

Potassium is selectively reabsorbed in the __ tubules and is secreted in __ and __ tubules

A

Potassium is selectively reabsorbed in the proximal tubules and is secreted in distal and collecting tubules

94
Q

Dual control of aldosterone secretion of potassium and sodium

A

(1) decrease sodium/decrease ECF volume/decrease arterial pressure
(2) increase renin
(3) increase angiotensin I
(4) increase angiotensin II
(5) stimulates aldosterone secretion
(6) increases tubular sodium reabsorption and decreases urinary sodium excretion

OR

(1) increase plasma potassium
(2) stimulates aldosterone secretion
(3) increases tubular potassium secretion and increases urinary excretion

95
Q

Isotonic

A

solute concentration is equal to the water concentration

96
Q

Hypotonic

A

otherwise known as the body fluid being dilute (dilute urine), happens when more water is present than the solute load

97
Q

Hypertonic

A

otherwise known as the body fluid being too concentrated (concentrated urine), happens when there is less water than solute load

98
Q

Excretion of urine in the face of water deficit

A
  • vasopressin present: distal and collecting tubules permeable to water (allows water to leave)
  • small volume of concentrated urine excreted, reabsorbed water picked up by peritubular capillaries and conserved for body
99
Q

Excretion of urine in the face of water excess

A
  • no vasopressin present: distal and collecting tubules impermeable to water (water doesn’t leave)
  • large volume of dilute urine, no water reabsorbed in distal portion of nephron, excess water eliminated
100
Q

Countercurrent multiplication

A

passive exchange of solutes and water between the two limbs of the loop of henle

101
Q

Descending vs ascending limbs of the Loop of Henle

A
  • Descending limb is highly permeable to water but does not extrude (force out) sodium for reabsorption
  • Ascending limb actively transports NaCl out of the tubular lumen into the surrounding interstitial fluid. It is impermeable to water. Therefore, water does not follow the salt by osmosis
102
Q

Mechanism of action of vasopressin

A
  • vasopressin-controlled variable water reabsorption occurs in the final tubular segments
  • 65% of water reabsorption is obligatory in the proximal tubule. In the distal tubule and collecting it is variable based on the secretion of ADH/vasopressin
  • the secretion of vasopressin increases the permeability of the tubule cells to water. An osmotic gradient exists outside the tubules for the transport of water by osmosis
  • water deficit increases vasopressin release and more water reabsorbed
  • excess water, decreases vasopressin release, and more water is released in urine
103
Q

Effect of vasopressin/ADH on distal tubules and collecting tubules

A

posterior pituitary –> vasopressin/ADH –> blood –> kidney –> water

^controlled by negative feedback

104
Q

Functions of renin-angiotensin-aldosterone system (RAAS)

A
  1. aldosterone increases reabsorption in distal and collecting tubules
  2. promotes salt retention and resultant water retention and elevation of arterial blood pressure
  3. angiotensin-II is a potent constrictor of the systemic arterioles, thus increasing blood pressure and peripheral resistance
  4. it also stimulates thirst and vasopressin release
105
Q

Angiotensinogen

A

a plasma protein synthesized by
the liver, always present in the plasma in high concentration

106
Q

Source and role of renin

A

source: kidney

role: acts as an enzyme to activate angiotensinogen into angiotensin I

107
Q

Role of angiotensin I

A

On passing through the lungs via the pulmonary circulation, angiotensin I is converted into angiotensin II by
angiotensin-converting enzyme (ACE), which is abundant in
the pulmonary capillaries

108
Q

Angiotensin II

A

Angiotensin II is the main stimulus
for secretion of the hormone aldosterone from the adrenal
cortex

109
Q

Source and role aldosterone

A

Source: adrenal cortex

role: stimulates Na+ reabsorption by the kidneys. The resulting retention of Na+ exerts an osmotic effect that holds more H2O in the ECF. Together, the conserved Na+ and H2O help
correct the original stimuli that activated this hormonal system (low sodium/low ECF volume, low arterial blood pressure)

110
Q

Aldosterone vs Vasopressin

A

Vasopressin: opens all water channels, recruits more water channels– increases permeability and water reabsorption to prevent dehydration

Aldosterone: increases sodium reabsorption, passively reabsorbs water

111
Q

What is NOT a function of the kidneys?

a. excretion of metabolic wastes
b. maintaining proper plasma volume
c. secreting aldosterone to regulate sodium
d. maintaining proper osmolarity of body fluids

A

C

112
Q

What is the specialized nephron capillary bed where filtration occurs?

a. afferent arteriole
b. efferent arteriole
c. glomerulus
d. peritubular bed

A

C

113
Q

Below is a listing of nephron components and associated structures:
1. descending limb of loop of Henle
2. Bowman’s capsule
3. collecting tubule
4. ascending limb of loop of Henle
5. distal tubule
6. proximal tubule

What is the correct flow of filtrate through these structures?
a. 4,6,5,3,2,1
b. 2,6,1,4,5,3
c. 2,5,6,3,1,4
d. 3,2,6,1,4,5

A

B

114
Q

Which nephron structure is especially important in the kidney’s ability to produce urine of varying concentration?

a. Bowman’s capsule
b. proximal tubule
c. distal tubule
d. loop of Henle

A

D

115
Q

Which of the following is true about blood that flows through the kidneys?

a. normally about 20-25 percent of the total cardiac output
b. all filtered through the glomeruli
c. all used to supply the renal tissue with oxygen and nutrients
d. normally about 40% percent of the total cardiac output

A

A

116
Q

Which statement is correct concerning glomerular filtrate?

a. it is a plasma-free blood
b. it is formed as a result of passive forces acting across the glomerular membrane
c. it does not contain foreign compounds because these substances are secreted by special transport mechanisms in the proximal tubule instead
d. its rate is increased by increased plasma protein level

A

B and C

117
Q

The glomerular capillary blood pressure in the nephron is 78 mm Hg. The Bowman’s capsular hydrostatic pressure is 24 mm Hg. The colloidal osmotic pressure is 18 mm Hg. What is the net filtration pressure?

a. 18 mm Hg
b. 26 mm Hg
c. 36 mm Hg
d. 42 mm Hg

A

C

118
Q

Which factor would reduce the net filtration pressure the most?

a. vasodilation of the afferent arteriole
b. vasocontraction of the efferent arteriole
c. It has a large increase in blood colloid osmotic pressure
d. It has a low capsular hydrostatic pressure

A

C

119
Q

Which statement concerning the process of glomerular filtration is correct?

a. Bowman’s capsule hydrostatic pressure opposes filtration.
b. The glomerular filtration rate is limited by a Tm.
c. All of the plasma that enters the glomerulus is filtered.
d. All of the plasma that enters the glomerulus is reabsorbed.

A

A

120
Q

What is NOT involved in autoregulation of the GFR?

a. a myogenic mechanism in which the afferent arteriole automatically constricts when it is stretched
b. a tubuloglomerular feedback mechanism in which vasoactive chemicals released from the juxtaglomerular apparatus bring about afferent arteriolar vasoconstriction
c. sympathetically induced vasoconstriction of the afferent arterioles

A

C

121
Q

Afferent arteriolar vasoconstriction _____ blood flow into the glomerulus, which causes the glomerular-capillary blood pressure to _____, leading to a(n) _____ in the net filtration pressure and a resultant _____ in the GFR.

a. increases, increase, increase, increase
b. decreases, decrease, decrease, decrease
c. increases, increase, decrease, decrease
d. decreases, decrease, increase, increase

A

B

122
Q

What occurs after stimulation of the macula densa cells?

a. vasodilation of the afferent arteriole
b. vasoconstriction of the afferent arteriole
c. increased GFR
d. secretion of erythropoietin

A

B

123
Q

When arterial blood pressure is elevated above normal, which compensatory change in renal function occurs as a result of the baroreceptor reflex?

a. afferent arteriolar vasoconstriction
b. afferent arteriolar vasodilation
c. reduction in GFR
d. efferent arteriolar vasoconstriction

A

B

124
Q

Which statement is NOT true concerning tubular reabsorption?

a. It refers to the movement of a substance from the peritubular capillary blood into the tubular fluid.
b. It occurs by either active or passive transport.
c. It involves the process of transepithelial transport.

A

A

125
Q

Which statement is NOT a step in transepithelial transport?

a. movement of the substance through the cytosol of the tubular cell
b. movement of the substance across the glomerular capillary wall
c. movement of the substance across the luminal membrane of the tubular cell
d. movement of the substance through the interstitial fluid

A

B

126
Q

Why is glucose NOT normally found in the urine?

a. Glucose does not get filtered out of glomerulus.
b. Glucose is not found in the blood.
c. Glucose is usually reabsorbed by renal tubule cells.
d. Glucose is kept in the blood.

A

C

127
Q

Which statement regarding the proximal tubule is NOT true?

a. It reabsorbs about 65 percent of the filtered water.
b. It is the site of action of renin.
c. It is the location where glucose is reabsorbed.

A

B

128
Q

Which statement regarding tubular maximum (Tm) is NOT true?

a. It is the maximum amount of a substance that the tubular cells can actively transport within a given time period.
b. It is the maximum rate at which a substance is filtered at the glomerulus.
c. It occurs when the membrane carrier becomes saturated.

A

B

129
Q

Which plasma constituent is NOT regulated by the kidneys?
a. Glucose
b. Na+
c. H+
d. Phosphate

A

D

130
Q

What is the major waste product of nitrogen metabolism?
a. plasma proteins
b. Urea
c. Glucose
d. amino acids

A

B

131
Q

Given the following data for substance X (GFR = 125 mL/min, Tm = 125 mg/min, at a plasma concentration of 200 mg/100 mL), how much of substance X is filtered, reabsorbed, and excreted?

a. 125 mg/min filtered, 125 mg/min reabsorbed, 0 mg/min excreted
b. 200 mg/min filtered, 125 mg/min reabsorbed, 75 mg/min excreted
c. 250 mg/min filtered, 125 mg/min reabsorbed, 125 mg/min excreted
d. 250 mg/min filtered, 200 mg/min reabsorbed, 50 mg/min excreted

A

C

132
Q

Which statement about Na+ reabsorption is INCORRECT?

a. It uses 80 percent of the energy requirement of the kidney.
b. It is under control of the hormone aldosterone in the distal portions of the nephron.
c. It is not linked to the reabsorption of amino acids and urea.

A

C

133
Q

What happens when blood volume becomes abnormally low?

a. Sodium reabsorption is diminished.
b. Dilute urine is formed.
c. Renin catalyzes the conversion of angiotensinogen.
d. Aldosterone is secreted by the kidney.

A

C

134
Q

What is the energy required for glucose reabsorption used for?

a. to run the Na+–K+ ATPase pump
b. to run the Na+-glucose co-transport carrier
c. to maintain the Tm for glucose
d. to produce aldosterone-induced protein, which increases the permeability of the proximal tubular cells to glucose

A

A

135
Q

What are the distal and collecting tubules the site of?

a. the co-transport carriers for glucose and amino acid reabsorption
b. the organic ion secretory systems
c. aldosterone and vasopressin action
d. glucose reabsorption

A

C

136
Q

Which statement regarding tubular secretion is NOT true?

a. It involves transepithelial transport.
b. It is the movement of a substance from the peritubular capillary blood into the tubular fluid.
c. It always occurs by active transport.
d. a and b.

A

C

137
Q

Which statement with regards to plasma clearance is correct?

a. It is the time required to filter blood in the glomerulus.
b. It is the amount of a substance appearing in the urine in one minute.
c. It is the amount of a substance filtered in one minute.
d. It is the volume of plasma that is completely cleared of a substance by the kidneys in one minute.

A

D

138
Q

What establishes the medullary vertical osmotic gradient by means of countercurrent multiplication?

a. loops of Henle of juxtamedullary nephrons
b. loops of Henle of cortical nephrons
c. vasa recta of juxtamedullary nephrons
d. vasa recta of cortical nephrons

A

A

139
Q

Which of the following is true about the ascending limb of the loop of Henle?

a. NaCl passively leaves the tubular fluid down its concentration gradient.
b. NaCl is actively transported into the interstitial fluid, leaving water behind because the tubular cells are not permeable to water.
c. K+ is secreted.
d. aldosterone stimulates Na+ reabsorption.

A

B

140
Q

Which statement with regards to vasopressin is correct?

a. It can completely halt urine production during periods of water deprivation to conserve water for the body.
b. It activates the cyclic AMP second-messenger system within the tubular cells.
c. It renders the distal and collecting tubules impermeable to water.
d. It increases Na+ reabsorption by the distal portions of the nephron.

A

B

141
Q

What enable the kidneys to produce urine of varying concentrations and volumes depending on the body’s needs?

a. Na+–K+ ATPase pump and co-transport carriers
b. juxtaglomerular apparatus and vasa recta
c. podocytes and peritubular capillaries
d. medullary vertical osmotic gradient and vasopressin

A

D

142
Q

What happens when the bladder of an infant is filled with urine?

a. Stretch receptors in the bladder wall are inhibited.
b. Parasympathetic nerve supplying the bladder is inhibited, allowing the bladder to relax.
c. A motor neuron supplying the external urethral sphincter is stimulated, causing the sphincter to open.
d. A motor neuron supplying the external urethral sphincter is inhibited, allowing the sphincter to open.

A

D

143
Q

True/False: The kidneys are the organs that are primarily responsible for maintaining constancy of the volume and electrolyte composition of the internal fluid environment.

A

True

144
Q

True/False: The afferent arteriole is the blood vessel that carries blood to the glomerular capillaries.

A

True

145
Q

True/False: Glomerular filtration occurs primarily by active transport

A

False

146
Q

True/False: The glomerular filtrate is almost identical in composition to the plasma

A

True

147
Q

True/False: The glomerular filtrate contains only substances that are not needed by the body.

A

False

148
Q

True/False: If a kidney stone blocked the renal pelvis and consequently caused a buildup of fluid pressure in the tubules and Bowman’s capsule, the net filtration pressure across the glomerular capillary membrane would increase.

A

False

149
Q

True/False: The pores in the glomerular membrane are too small for albumin to pass through.

A

False

150
Q

True/False: Contraction of mesangial cells closes off a portion of the filtering capillaries, which leads to a decrease in GFR if the filtration pressure remains unchanged.

A

True

151
Q

True/False: Transepithelial transport occurs only for substances that are actively reabsorbed

A

False

152
Q

True/False: The amount of glucose reabsorbed is directly proportional to the plasma glucose concentration at all plasma glucose concentrations.

A

False

153
Q

True/False: The secretion of aldosterone stimulates the tubular reabsorption of sodium and the tubular secretion of potassium.

A

True

154
Q

True/False: Water reabsorption cannot occur from any portion of the nephron in the absence of vasopressin.

A

False

155
Q

True/False: Angiotensinogen is produced by the kidney.

A

False

156
Q

True/False: A plasma clearance of 135 mL/min for a substance when the GFR is 125 mL/min indicates that net secretion of the substance occurs.

A

True

157
Q

True/False: In the tubular segments permeable to H2O, solute reabsorption is always accompanied by comparable H2O reabsorption

A

True

158
Q

True/False: When tubular fluid enters the distal tubule, it is hypotonic

A

True

159
Q

True/False: A pure loss or gain of H2O that is not accompanied by comparable solute deficit or excess in the body leads to changes in ECF osmolarity.

A

True

160
Q

The functional unit of the kidneys is the ____________________.

A

nephron

161
Q

Tubular ____________________ and tubular ____________________ are selective processes that occur in the nephron

A

reabsorption, secretion

162
Q

The specialized cells of the ____________________ within the ____________________ detect changes in the rate at which fluid is flowing past them through the tubule. In response, they secrete vasoactive chemicals that influence the GFR by making adjustments in the calibre of the ____________________ arterioles. This is known as the ____________________ feedback mechanism.

A

The specialized cells of the macula densa within the juxtaglomerular apparatus detect changes in the rate at which fluid is flowing past them through the tubule. In response, they secrete vasoactive chemicals that influence the GFR by making adjustments in the calibre of the afferent arterioles. This is known as the tubulo-glomerular feedback mechanism.

163
Q

If the plasma concentration of substance X is 200 mg/100 mL and the GFR is 125 mL/min, the filtered load of this substance is ____________________.

A

250 mg/min

164
Q

On average, of the 125 mL/min of plasma filtered, ____________________ mL/min is reabsorbed, and ____________________ mL/min is excreted as urine.

A

124 mL/min, 1 mL/min

165
Q

____________________ percent of the filtered H2O is variably reabsorbed under the control of the hormone ____________________ in the distal and collecting tubules

A

20%, vasopressin/ADH

166
Q

Two means by which substances can enter the renal tubules are ____________________ and ____________________. Two means by which substances can leave the kidney tubules are ____________________ and ____________________.

A

Two means by which substances can enter the renal tubules are glomerular filtration and tubular secretion. Two means by which substances can leave the kidney tubules are tubular reabsorption and urine excretion.

167
Q

Match the renal function with the correct characteristic by using the answer code:

a. movement of substances from the peritubular capillary blood into the tubular lumen
b. movement of substances from the glomerular capillary blood into the tubular lumen
c. everything filtered or secreted that is not subsequently reabsorbed
d. movement of substances from the tubular lumen into the peritubular capillary blood

  1. glomerular filtration
  2. tubular reabsorption
  3. tubular secretion
  4. urine excretion
A
  1. B
  2. D
  3. A
  4. C

HLSC 128 (7 decks)

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