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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
Describe the target cells and effect of ADH.
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
26
Describe the source of aldosterone.
adrenal cortex (adrenal glands) Zona glomerulosa
27
Describe the stimuli that trigger aldosterone secretion (or inhibit secretion).
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
28
Describe the structure and function of the juxtaglomerular apparatus.
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.
29
Describe all of the steps in renin-angiotensin-aldosterone pathway.
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
30
Describe the target cells and the effect of aldosterone.
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
31
Describe the source, stimuli, and effect of atrial natriuretic hormone. ANH
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
32
the main processing center of the urinary system:
the kidneys
33
The blood coming into the kidneys is called:
dirty blood
34
the renal corpuscle is composed of 2 parts:
glomerular capillaries enclosure around them (bowman's capsule)
35
the proximal convoluted tubule drains into:
nephron loop (of henle)
36
The nephron loop of henle has 2 segments:
descending limb ascending limb
37
From the loop of henle, continues into a twisted portion called:
distal convoluted tubule
38
The distal convoluted tubule drains into
the collecting duct
39
The capillaries surrounding the entirety of the nephron are known as
peritubular capillaries
40
the peritubular capillaries allow materials to move [2 ways] :
from nephron > capillary blood [reabsorption] from blood > nephron [secretion]
41
All of the filtration takes place where?
renal corpuscle [glomerulus & bowman's capsule]
42
80% of blood flows out intact 20% of plasma :
forms filtrate
43
the glomerular capillaries are ____________ (there are perforations allowing for aggressive leakage out)
fenestrated
44
what is renal clearance?
amount of material removed from plasma per minute
45
Renal clearance is dependent on:
How much is filtered (GFR) [glomerular filtration rate] Blood flow
46
Inulin is not secreted nor reabsorbed, thus the clearance amount (that gets filtered out of the blood) is equal to:
GFR glomerular filtration rate
47
para amino-hipuric acid is completely secreted & filtered, but not reabsorbed, thus the clearance of PAH is an indicator of:
renal blood flow
48
majority of reabsorption (60-75%) occurs in the:
proximal convoluted tubule [some secretion also occurs here]
49
Function of the kidneys include regulation of: [5 things]
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
All filtration occurs in the:
renal corpuscle
51
The majority of reabsorption occurs in the:
proximal convoluted tubule
52
Water intake is driven by thirst, which occurs when:
plasma osmolarity increases by 1-2% or more or blood volume drops by 10% or more
53
what involves movement of molecules from the nephron into the blood:
reabsorption
54
What are the 2 types of renal regulation?
1) intrinsic (autoregulation) [decrease blood pressure leads to arteriole dilating] 2) extrinsic pathway (autonomic sympathetic NS) [ADH, ALD]
54
Antidiuretic hormone - regulation at the:
collecting duct
55
Antidiuretic hormone is produced by the
posterior pituitary
56
The volume change response in terms of controlling urinary output is predominantly mediated by:
juxtaglomerular cells [part of the juxtaglomerular apparatus] 2 types of cells
57
Although Renin is being secreted, it is not a hormone, but a:
enzyme
58
If renin levels increase, ANG 1 levels:
also increase [conversion is accelerated by renin]
59
Aldosterone is the hormone that acts on the kidney, predominantly on the:
distal convoluted tubule & collecting duct
60
Aldosterone is targeting:
sodium transport [sodium reabsorption increased] mechanism is the K Na pump [increased K secretion]
61
By increasing sodium reabsorption, water reabsorption is increased, so there is a decrease in
urination
62
The anti-diuretic hormone is the dominant regulatory pathway, and secondarily is:
the renin-angotensin-aldosterone system
63
Atrial natriuretic hormone ANH opposes effects of ADH and ALD, so it will lead to
increased urine production
64
What triggers ANH?
increased blood volume
65
Name the zones of the nephron in order
66
Reabsorption of water is dependent on:
permeability to water solute gradient/ osmolarity
67
Describe a way diuretics may work
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
Diuretics alter sodium reabsorption and, therefore alter
osmotic gradient
69
Most diuretics act on manipulation of ___________________ that is the driving force for water reabsorption
osmotic gradient
70
ADH only manipulates:
permeability
71
A diuretic may have less effect when there is large amounts of _____ being produced
ADH
72
Alcohol has a ___________ effect explain.
diuretic [increase pee] Alcohol depresses neurons > they produce less ADH > water permeability is blocked > reabsorption of water inhibited > increased urination
73
Excessive hydrogen ions lead to:
lowered pH altered/disruption of protein shape/function
74
If hydrogen ions are too low in concentration, it leads to
elevated pH altered protein 3d shape & function
75
Proteins are weak _________
buffers
76
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:
bicarbonate ions in circulation plasma proteins (weak buffer)
77
The pH of a solution is a measure of its
H+ concentration
78
The product secreted by the juxtaglomerular (JG) cells is _____1____, which is correctly described as a ____2____.
1- renin 2- enzyme
79
How does the sympathetic nervous system alter glomerular filtration rate?
stimulates constriction of the afferent arteriole resulting in decreased glomerular filtration
80
The function of the countercurrent multiplier results in : the retention of ______________________________ (producing a high osmolarity) but permits water to be removed.
solutes in the renal medulla
81
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
the afferent arterioles to constrict
82
Antidiuretic hormone effects the ___________1 ________, while aldosterone effects the _____________2___________.
1- permeability of water necessary for reabsorption 2- osmotic gradient driving water reabsorption
83
Decreased blood volume (without any change in blood osmolarity) would result in:
stimulation of the renin-angiotensin-aldosterone pathway resulting in increased sodium and water reabsorption
84
Increased aldosterone results in increased ________1_______ from the collecting duct which results in increased _________2__________
1- salt reabsorption 2- osmotic reabsorption of water.
85
Loop diuretics increase urination by ____________1________ at the expense of _________2___________.
1- increasing filtrate osmolarity 2- increased potassium excretion
86
The only region(s) of the nephron where reabsorption is regulated by hormones:
distal convoluted tubule and collecting duct
87
The counter-current multiplier creates a mechanism for retaining salt while eliminating water from the:
medulla of the kidney
88
The kidneys regulate water loss via urination in response to:
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
Antidiuretic hormone (ADH) is secreted from
posterior pituitary
90
What does ADH do (action)?
increased water reabsorption [increases water permeability by increasing concentration of aquaporins w/in collecting duct]
91
ADH effects are:
1 degree- decreased plasma osmolarity 2- increased plasma volume & pressure [decreasing urine volume]
92
Aldosterone is a hormone secreted from
adrenal cortex
93
ADH stimuli are
increased osmolarity [monitored by hypothalamic osmoreceptors]
94
ALD stimuli are
increased plasma K+ conc. [& decreased blood volume/ pressure]
95
Action of ALD:
Na+ retention K+ secretion (loss)
96
ALD effect:
increased plasma Na+ maintains plasma volume (decreasing urine volume)
97
Renin-angiotensin-Ald system stimuli?
decreased blood volume/ pressure in afferent arteriole & increased filtrate Na+ via Macula densa cells
98
R-A-A system action:
secretion of enzyme renin into blood renin converts angiotensinogen into angioten 1 > ACE converts that to Ang II > this stimulates release of ALD
99
R-A-A system effect:
Ald stimulates Na+ retention & K+ secretion blood volume conserved (decreasing urine volume)
100
Atrial natriuretic hormone is secreted by
the heart
101
Atrial natriuretic hormone stimuli?
increased blood volume [stretching of atrial chamber]
102
Atrial natriuretic hormone action
Increase Na+ & water excretion [induces vasodilation]
103
Atrial natriuretic hormone effect?
decreased Na+ conc., blood volume, pressure [increasing urine volume]f
104
Antidiuretic hormone (ADH) acts primarily on the ________1________ and specifically stimulates _______2_______
1- collecting duct 2- increased water permeability
105
Increased aldosterone results in ________1_______ reabsorption from the collecting duct which results in _________2________.
1: increased salt 2: increased osmotic reabsorption of water
106
Loop diuretics increase urination by __________1________ at the expense of _________2_______.
1: increasing filtrate osmolarity 2: increased potassium excretion
107
what type of cell are osmoreceptors?
neurons
108
no aquaporins means:
no permeability to water
109
Angiotensin 2 role on adrenal cortex
Aldosterone [down, decreases] or [up, increases]
110
Aldosterone target is
collecting duct & distal convoluted tubule
111
The aldosterone pathway is induced by
blood volume
112
If blood volume is too high, aldosterone will be:
decreased by the pathway (less JG cell stimulation, less renin > less ANG, less adrenal cortex stimulation > less ALD)
113
Lack of potassium effects
very low resting membrane potential harder to reach threshold no heartbeat [less/ no AP]
114
What is steatorrhea?
excessive fat in stool "stinky fatty floater" due to decreased fat digestion
115
bile salts help emulsify:
fats [not digest]
116
lipases do what with fats?>
digest
117
name the fat soluble vitamins
A, E, D, K

Physiology (20 decks)

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