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Physiology > Unit 4: Renal Physio > Flashcards

Unit 4: Renal Physio Flashcards

1
Q

the functional unit of the urinary system is the :

A

nephron within the kidney

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2
Q

Bilirubin buildup in the blood leads to:

A

jaundice

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3
Q

Each kidney is composed of around ____________ microscopic tubules called nephrons

A

1 -1.25 million

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4
Q

Define “interstitial fluid,” “plasma,” and “urine”.

[“3 zones of body fluids”]

A

Interstitial fluid- surrounds all body cells; makes up extracellular fluid; interacts w/ cytoplasm

Plasma- within blood; also makes up other part of extracellular fluid

Urine (waste)- waste material that is secreted by the kidney

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5
Q

Describe the different routes of water intake and water loss

A

3 major inputs:
60% fluids (drink)
30% moisture in food
10% metabolic water (associated w/ cell metabolism)

2 categories of outputs:
1. Sensible water loss- notice/aware of this
~sweating (10%/ variable) & urine (60%)
2. Insensible = 30%
~respiration, feces, diffusion from skin moisture

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6
Q

Describe the regulatory mechanisms regulating water intake.

A

1-2% increase in osmolarity stimulates osmoreceptors (hypothalamus- thirst center)
[primary pathway, important bc only takes a small stimulus to activate this pathway]

10% decrease in plasma volume > baroreceptors (hypothalamus- thirst center)

= thirst

Osmoreceptors also stimulate pituitary gland > produces ADH hormone> increases water reabsorption> decreased water in urine

Baroreceptors also stimulate adrenal gland > produces ALD > decreases water content in urine by increasing sodium reabsorption

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7
Q

Describe the anatomical association between the renal blood vessels and the renal tubules
(nephron).

A

The kidneys get blood through renal arteries.

Inside the kidneys, this blood goes through tiny filters called glomeruli, where the filtrate is separated.

Filtrate then travels through small tubes in the kidneys called renal tubules.

Around these tubes are tiny blood vessels that help bring back the useful things from the filtrate into the blood.

blood vessels and tubules in the kidneys work together to clean and recycle our blood

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8
Q

Name and describe the three nephron processes of urine production.

+ 1 more (?)

A

Filtration- moving of molecules from blood into the nephron [driven by filtration pressure]

Reabsorption- molecules removed from blood by filtration are put back into blood

Secretion- hydrogen/potassium molecules moved from the bloodstream to the nephron

Excretion- waste like excess water, salts, acids removed

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9
Q

Describe the role of the renal corpuscle.

A

~filtration takes place here
~contains 3 filtration barriers

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10
Q

What is glomerular filtration?

A

GFR glomerular filtration rate is the volume of fluid that filters into bowman’s capsule per unit time

average GFR is 125 ml/min or 180 L/day

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11
Q

How is glomerular filtration controlled?

A

autoregulation

sympathetic NS influence

hormonal regulation
(ALD, ANG, ADH…)

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12
Q

Describe the role of the proximal convoluted tubule (PCT).

A

60-75% of reabsorption
some secretion

~consequence of active membrane transport/ reabsorption

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13
Q

Describe the mechanism associated with sodium, glucose, and water reabsorption in the PCT.

A

Sodium reabsorption is driven by sodium potassium pump; Na is being pumped out into bloodstream > Na conc inside cell decreases (osmotic gradient pulls Na into cell from filtrate)

Na movement is needed for glucose movement; glucose moves along with the Na; moved by secondary active transport; eventually goes through a facilitative transporter > bloodstream

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14
Q

Define “renal threshold.”

What characterizes molecules that exhibit a renal threshold?

A

the amount that can be reabsorbed at maximum

[not measuring the amount being transported, but the amount in the renal tubule]

~glucose transport

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15
Q

Describe the two general functions of the loop of Henle.

How much filtrate enters and leaves the loop of Henle?

A

reabsorption of ions in excess of water to create dilute fluid in the lumen

countercurrent arrangements contribute to concentrated interstitial fluid in the renal medulla

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16
Q

Describe the function of the descending limb of the loop of Henle.

A

highly permeable; water reabsorption

Towards higher osmotic conc; salts enter blood; water leaves

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17
Q

Describe the function of the ascending limb of the loop of Henle.

A

permeable to IONS

away from higher osmotic conc; salts leave blood; water enters

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18
Q

What single factor distinguishes the distal convoluted tubule (DCT) and collecting ducts from all other regions of the nephron?

A

The only regions of the nephron where reabsorption is regulated by hormones

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19
Q

Describe the regulatory mechanisms that control the DCT and collecting duct.

A

ALD regulation
ADH regulation
Renin-Angiotensin-Aldosterone System (RAAS):

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20
Q

Describe the three general mechanisms for regulating blood pH.

A

Buffers (like bicarbonate)

Respiratory regulation - increasing resp rate increases the removal of Co2> lost Co2 will be pulled away from carbonic acid> pH lowered

Renal conservation of bicarbonate [saves bicarbonate so don’t lose this important buffer through urination]

Renal secretion of H+ [hydrogen ions transported out of cell in exchange of sodium ions]

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21
Q

Describe the mechanism and significance of intrinsic control over glomerular filtration.

A

At high blood pressure, autoregulation protects the glomerulus from damage

At lower blood pressure, it ensures that the kidneys receive sufficient blood flow to filter wastes.

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22
Q

Describe the role of the autonomic nervous system in regulating urine production.

A

Sympathetic nerve activity increases
>
Vasoconstriction of afferent arterioles in kidneys
>
decline of GFR
>
decline in urine production
[preserves blood volume]

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23
Q

Describe the source of antidiuretic hormone (ADH).

A

hypothalamus - posterior pituitary

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24
Q

Describe the stimuli that trigger ADH secretion (or inhibit secretion).

A

Trigger ADH secretion: increased stimulation of osmoreceptors (in hypothalamus)

Low water intake> Dehydrated>
1-2% increase in plasma osmolarity>
increased stimulation of osmoreceptors (in hypothalamus)>
Posterior pituitary is stimulated to increase ADH production

Inhibit ADH secretion: decreased stimulation of osmoreceptors

High water intake/ overhydrated>
1-2% decrease in plasma osmolarity>
decreased stimulation of osmoreceptors (in hypothalamus)>
Posterior pituitary is less stimulated, so produces less ADH

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25
Q

Describe the target cells and effect of ADH.

A

ADH acts on the kidney (distal tubule & collecting duct mainly)
> increases water reabsorption/ water permeability

ADH stimulates the epithelial cells of the collecting duct to incorporate more water pores in their membrane

Dehydration > increased water reabsorption > decreased urination

overhydration > decreased water reabsorption > increased urination

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26
Q

Describe the source of aldosterone.

A

adrenal cortex
(adrenal glands)

Zona glomerulosa

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27
Q

Describe the stimuli that trigger aldosterone secretion (or inhibit secretion).

A

Triggers ALD: = dehydrated > decreased urination
~low blood volume
~elevated potassium K+ (hyperkalemia)

Inhibits ALD: overhydrated
~high blood volume> lower stim. of jg cells > less renin > less ANG 1 and II > less adrenal cortex stimulation > less aldosterone > decreased Na and water reabsorption > increased urination

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28
Q

Describe the structure and function of the juxtaglomerular apparatus.

A

consists of
~juxtaglomerular cells of the afferent glomerular arteriole
~efferent glomerular arteriole
~extraglomerular mesangial cells
~small portion of the distal tubule known as the macula densa.

Function: activate the renin-angiotensin-aldosterone system (RAAS) when needed; This system helps regulate blood pressure and fluid balance by causing blood vessels to constrict, promoting the release of aldosterone (which retains salt and water), and adjusting how the kidneys filter and reabsorb substances.
JGA ensures the kidneys respond appropriately to changes in the body’s needs.

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29
Q

Describe all of the steps in renin-angiotensin-aldosterone pathway.

A

Low blood volume stimulates JG cells

JG cells secrete Renin [enzyme]

Renin catalyzes reaction of angiotensinogen into angiotensin 1

ANG 1 is then converted into angiotensin II by ACE enzyme.

ANG II stimulates the adrenal cortex

Aldosterone production increases

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30
Q

Describe the target cells and the effect of aldosterone.

A

target cells- principal cells (P cells)

effect- controls sodium balance
increases Na+ reabsorption
& K+ secretion
[removing excess potassium]

Water retained in blood; increases blood volume

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31
Q

Describe the source, stimuli, and effect of atrial natriuretic hormone. ANH

A

Source- heart- produced by atrium in response to atrial distension

Stimuli- increased blood volume>atrial fills and walls stretch>receptors respond>some of the cells can produce and secrete ANH

Also tonic, so decreased blood volume will lead to less ANH

Effect- direct effect on glomerular filtration rate by altering constriction dilation patterns of afferent arteriole
~acts on posterior pituitary to inhibit ADH production
~acts on adrenal gland to inhibit ALD production
~The inhibitions oppose ALD and ADH effects, so there will be an increase in urine production

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32
Q

the main processing center of the urinary system:

A

the kidneys

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33
Q

The blood coming into the kidneys is called:

A

dirty blood

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34
Q

the renal corpuscle is composed of 2 parts:

A

glomerular capillaries
enclosure around them (bowman’s capsule)

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35
Q

the proximal convoluted tubule drains into:

A

nephron loop (of henle)

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36
Q

The nephron loop of henle has 2 segments:

A

descending limb
ascending limb

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37
Q

From the loop of henle, continues into a twisted portion called:

A

distal convoluted tubule

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38
Q

The distal convoluted tubule drains into

A

the collecting duct

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39
Q

The capillaries surrounding the entirety of the nephron are known as

A

peritubular capillaries

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40
Q

the peritubular capillaries allow materials to move

[2 ways] :

A

from nephron > capillary blood [reabsorption]

from blood > nephron [secretion]

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41
Q

All of the filtration takes place where?

A

renal corpuscle

[glomerulus & bowman’s capsule]

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42
Q

80% of blood flows out intact
20% of plasma :

A

forms filtrate

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43
Q

the glomerular capillaries are ____________ (there are perforations allowing for aggressive leakage out)

A

fenestrated

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44
Q

what is renal clearance?

A

amount of material removed from plasma per minute

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45
Q

Renal clearance is dependent on:

A

How much is filtered (GFR) [glomerular filtration rate]

Blood flow

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46
Q

Inulin is not secreted nor reabsorbed, thus the clearance amount (that gets filtered out of the blood) is equal to:

A

GFR

glomerular filtration rate

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47
Q

para amino-hipuric acid is completely secreted & filtered, but not reabsorbed, thus the clearance of PAH is an indicator of:

A

renal blood flow

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48
Q

majority of reabsorption (60-75%) occurs in the:

A

proximal convoluted tubule

[some secretion also occurs here]

49
Q

Function of the kidneys include regulation of:

[5 things]

A

regulation of plasma volume

regulation of plasma ionic concentration

regulation of plasma osmolarity

regulation of plasma hydrogen concentration

regulation of red blood cell production

50
Q

All filtration occurs in the:

A

renal corpuscle

51
Q

The majority of reabsorption occurs in the:

A

proximal convoluted tubule

52
Q

Water intake is driven by thirst, which occurs when:

A

plasma osmolarity increases by 1-2% or more

or

blood volume drops by 10% or more

53
Q

what involves movement of molecules from the nephron into the blood:

A

reabsorption

54
Q

What are the 2 types of renal regulation?

A

1) intrinsic (autoregulation)
[decrease blood pressure leads to arteriole dilating]

2) extrinsic pathway (autonomic sympathetic NS)
[ADH, ALD]

54
Q

Antidiuretic hormone - regulation at the:

A

collecting duct

55
Q

Antidiuretic hormone is produced by the

A

posterior pituitary

56
Q

The volume change response in terms of controlling urinary output is predominantly mediated by:

A

juxtaglomerular cells

[part of the juxtaglomerular apparatus]
2 types of cells

57
Q

Although Renin is being secreted, it is not a hormone, but a:

A

enzyme

58
Q

If renin levels increase, ANG 1 levels:

A

also increase

[conversion is accelerated by renin]

59
Q

Aldosterone is the hormone that acts on the kidney, predominantly on the:

A

distal convoluted tubule
&
collecting duct

60
Q

Aldosterone is targeting:

A

sodium transport

[sodium reabsorption increased]

mechanism is the K Na pump
[increased K secretion]

61
Q

By increasing sodium reabsorption, water reabsorption is increased, so there is a decrease in

A

urination

62
Q

The anti-diuretic hormone is the dominant regulatory pathway, and secondarily is:

A

the renin-angotensin-aldosterone system

63
Q

Atrial natriuretic hormone ANH opposes effects of ADH and ALD, so it will lead to

A

increased urine production

64
Q

What triggers ANH?

A

increased blood volume

65
Q

Name the zones of the nephron in order

A
66
Q

Reabsorption of water is dependent on:

A

permeability to water
solute gradient/ osmolarity

67
Q

Describe a way diuretics may work

A

Diuretics like mannitol work by increasing the removal of water from the body through urine.

Mannitol is an osmotic diuretic, meaning it creates an osmotic force that draws water into the urine, reducing fluid volume in the body.

When mannitol is filtered by the kidneys and reaches the renal tubules, it holds onto water molecules, preventing them from being reabsorbed.

68
Q

Diuretics alter sodium reabsorption and, therefore alter

A

osmotic gradient

69
Q

Most diuretics act on manipulation of ___________________ that is the driving force for water reabsorption

A

osmotic gradient

70
Q

ADH only manipulates:

A

permeability

71
Q

A diuretic may have less effect when there is large amounts of _____ being produced

A

ADH

72
Q

Alcohol has a ___________ effect

explain.

A

diuretic

[increase pee]

Alcohol depresses neurons > they produce less ADH > water permeability is blocked > reabsorption of water inhibited > increased urination

73
Q

Excessive hydrogen ions lead to:

A

lowered pH
altered/disruption of protein shape/function

74
Q

If hydrogen ions are too low in concentration, it leads to

A

elevated pH
altered protein 3d shape & function

75
Q

Proteins are weak _________

A

buffers

76
Q

There are buffers in the body interacting with hydrogen ions to form a weaker acid, thereby lowering the quantity of free hydrogen ions.

examples of this include:

A

bicarbonate ions in circulation

plasma proteins (weak buffer)

77
Q

The pH of a solution is a measure of its

A

H+ concentration

78
Q

The product secreted by the juxtaglomerular (JG) cells is _____1____, which is correctly described as a ____2____.

A

1- renin

2- enzyme

79
Q

How does the sympathetic nervous system alter glomerular filtration rate?

A

stimulates constriction of the afferent arteriole resulting in decreased glomerular filtration

80
Q

The function of the countercurrent multiplier results in :

the retention of ______________________________ (producing a high osmolarity) but permits water to be removed.

A

solutes in the renal medulla

81
Q

During strenuous exercise when mean arterial pressure rises, intrinsic regulation of glomerular filtration rate will cause ___________ in order to maintain a relatively constant glomerular filtration pressure

A

the afferent arterioles to constrict

82
Q

Antidiuretic hormone effects the ___________1 ________, while aldosterone effects the _____________2___________.

A

1- permeability of water necessary for reabsorption

2- osmotic gradient driving water reabsorption

83
Q

Decreased blood volume (without any change in blood osmolarity) would result in:

A

stimulation of the renin-angiotensin-aldosterone pathway resulting in increased sodium and water reabsorption

84
Q

Increased aldosterone results in increased ________1_______ from the collecting duct which results in increased _________2__________

A

1- salt reabsorption

2- osmotic reabsorption of water.

85
Q

Loop diuretics increase urination by ____________1________ at the expense of _________2___________.

A

1- increasing filtrate osmolarity

2- increased potassium excretion

86
Q

The only region(s) of the nephron where reabsorption is regulated by hormones:

A

distal convoluted tubule and collecting duct

87
Q

The counter-current multiplier creates a mechanism for retaining salt while eliminating water from the:

A

medulla of the kidney

88
Q

The kidneys regulate water loss via urination in response to:

A

blood volume changes detected by stretch receptors in the atria

blood volume changes detected by stretch receptors in the kidney (JG cells)

osmotic changes detected by osmoreceptors in the hypothalamus

89
Q

Antidiuretic hormone (ADH) is secreted from

A

posterior pituitary

90
Q

What does ADH do (action)?

A

increased water reabsorption
[increases water permeability by increasing concentration of aquaporins w/in collecting duct]

91
Q

ADH effects are:

A

1 degree- decreased plasma osmolarity
2- increased plasma volume & pressure [decreasing urine volume]

92
Q

Aldosterone is a hormone secreted from

A

adrenal cortex

93
Q

ADH stimuli are

A

increased osmolarity
[monitored by hypothalamic osmoreceptors]

94
Q

ALD stimuli are

A

increased plasma K+ conc.
[& decreased blood volume/ pressure]

95
Q

Action of ALD:

A

Na+ retention
K+ secretion (loss)

96
Q

ALD effect:

A

increased plasma Na+
maintains plasma volume (decreasing urine volume)

97
Q

Renin-angiotensin-Ald system stimuli?

A

decreased blood volume/ pressure in afferent arteriole

& increased filtrate Na+ via Macula densa cells

98
Q

R-A-A system action:

A

secretion of enzyme renin into blood

renin converts angiotensinogen into angioten 1 > ACE converts that to Ang II > this stimulates release of ALD

99
Q

R-A-A system effect:

A

Ald stimulates Na+ retention & K+ secretion

blood volume conserved (decreasing urine volume)

100
Q

Atrial natriuretic hormone is secreted by

A

the heart

101
Q

Atrial natriuretic hormone stimuli?

A

increased blood volume

[stretching of atrial chamber]

102
Q

Atrial natriuretic hormone action

A

Increase Na+ & water excretion [induces vasodilation]

103
Q

Atrial natriuretic hormone effect?

A

decreased Na+ conc., blood volume, pressure
[increasing urine volume]f

104
Q

Antidiuretic hormone (ADH) acts primarily on the ________1________ and specifically stimulates _______2_______

A

1- collecting duct

2- increased water permeability

105
Q

Increased aldosterone results in ________1_______ reabsorption from the collecting duct which results in _________2________.

A

1: increased salt

2: increased osmotic reabsorption of water

106
Q

Loop diuretics increase urination by __________1________ at the expense of _________2_______.

A

1: increasing filtrate osmolarity

2: increased potassium excretion

107
Q

what type of cell are osmoreceptors?

A

neurons

108
Q

no aquaporins means:

A

no permeability to water

109
Q

Angiotensin 2 role on adrenal cortex

A

Aldosterone

[down, decreases] or [up, increases]

110
Q

Aldosterone target is

A

collecting duct & distal convoluted tubule

111
Q

The aldosterone pathway is induced by

A

blood volume

112
Q

If blood volume is too high, aldosterone will be:

A

decreased by the pathway

(less JG cell stimulation, less renin > less ANG, less adrenal cortex stimulation > less ALD)

113
Q

Lack of potassium effects

A

very low resting membrane potential

harder to reach threshold

no heartbeat [less/ no AP]

114
Q

What is steatorrhea?

A

excessive fat in stool

“stinky fatty floater”

due to decreased fat digestion

115
Q

bile salts help emulsify:

A

fats

[not digest]

116
Q

lipases do what with fats?>

A

digest

117
Q

name the fat soluble vitamins

A

A, E, D, K

Physiology (20 decks)

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