Renal Flashcards
(135 cards)
1
Q
What are the major functions of the kidney
A
Endocrine, metabolic, pH regulation, water homeostasis, salt/ion homeostasis, reabsorption of nutrients, excretion of medications, toxins and metabolites (waste products)
2
Q
What percentage of our bodies is water
A
55% (females), 60% (males)
3
Q
How much of our total body water is ECF and ICF
A
1/3 ECF and 2/3 ICF
4
Q
What substances would be found in normal urine
A
Water, salts, urea, metabolites, hormones, small proteins
5
Q
Where are the kidneys located (rib level)
A
T12-L3
6
Q
How many lobes per kidney
A
5-11
7
Q
What are the kidneys surrounded with for support
A
Renal fat pad (adipose tissue)
8
Q
Where does filtration occur in the kidney
A
Cortex
9
Q
Where do peritubular capillaries drain to
A
Cortical radiate vein, renal vein, inferior vena cava
10
Q
How are the kidneys innervated
A
A network of autonomic nerves and ganglia called the renal plexus
(sympathetic nerves act to adjust diameter of renal arterioles and thus regulate bloodflow)
11
Q
What are the two types of nephrons
A
Cortical and juxtamedullary
12
Q
What percentage of nephrons are cortical
A
85%
13
Q
What percentage of nephrons are juxtamedullary
A
15%
14
Q
What forms the filtration barrier
A
Fenestrated capillary endothelial cells, fused basement membrane, podocytes
15
Q
What are peritubular capillaries specialised for
A
Absorption
16
Q
What are vasa recta
A
Extensions of capillaries that follow nephron loops deep into the medulla (only found with juxtamedullary nephrons)
17
Q
What is the outer layer of the glomerular capsule made of
A
Parietal simple squamous cells
18
Q
What is the inner layer of the glomerular capsule made of
A
Inner visceral podocytes
19
Q
What are podocytes
A
Specialised epithelium with many branches and intertwining foot processes called pedicels
20
Q
What are filtration slits
A
Gaps between pedicels
21
Q
What does the filtration barrier mostly filter based on
A
Size
22
Q
Urine = (in terms of filtrate)
A
Filtered - reabsorbed + secreted
23
Q
What type of epithelium is the proximal convoluted tubule
A
Cuboidal (leaky)
24
Q
How is the basolateral membrane of PCT cells described
A
Highly folded
25
How is the luminal membrane of PCT cells described
Dense microvilli brush border
26
What organelle is prominent in PCT epithelial cells
Mitochondria for active transport
27
What type of epithelium is present in the thin descending limb
Simple squamous
28
What type of epithelium is present in the thin ascending limb
Simple squamous
29
What is the purpose of the PCT
Bulk reabsorption
30
What is the purpose of the DCT
Fine tuning reabsorption
31
What type of epithelium is found in the DCT
Cuboidal, but thinner than PCT
32
What is the structure of epithelial cells in the DCT (same as collecting duct)
Few microvilli: no brush border, fewer mitochondria
33
What hormone does the kidney secrete and when
EPO, when blood oxygen levels are low. Stimulates bone marrow to produce more red blood cells
34
How do the kidneys undergo gluconeogenesis
During fasting kidneys make glucose from lactate
35
What is the blood pH range
7.35-7.45
36
What blood pH is known as alkalosis
>7.45
37
What blood pH is known as acidosis
<7.35
38
What are the two main sources of acid in the body
Acids coming from metabolism, food and drink, and carbon dioxide from metabolism
39
How is pH of the blood controlled
Lungs (exhalation of CO2), kidneys (reabsorption and secretion of bicarbonate and hydrogen ions)
40
What do kidneys secrete to maintain salt/ion homeostasis
K+
41
What medications do the kidneys secrete
Lidocaine (common local anaesthetic excreted after metabolism due to its lipophilic nature), aspirin (common pain killer excreted directly due to its hydrophilic nature)
42
What percentage of ECF is plasma
20%
43
What percentage of ECF is interstitial fluid
80%
44
What is the normal osmolarity of the ECF
275-300 mosmol/L
45
What is the normal osmolarity of the ICF
275-300 mosmol/L
46
What does hyposmotic mean
Increase in water, decrease in concentration
47
What does hyperosmotic mean
Decrease in water, increase in concentration
48
What does a loss of water from the ECF result in
Loss of water from both regions, cells shrink
49
What does a gain of water to the ECF result in
Gain of water to both regions, cells swell
50
What does a loss of isosmotic fluid from the ECF result in
No net water movement, decrease in ECF volume only
51
What does a gain of isosmotic fluid from the ECF result in
No net water movement, increase in ECF volume only
52
What is filtration
Movement of solutes from the blood to the plasma like filtrate
53
What is secretion
Movement of solutes from the peritubular capillaries into the tubular fluid
54
What is reabsorption
Movement of solutes from the tubular fluid (nephron) into the peritubular capillaries
55
What reabsorption occurs in the PCT
Bulk reabsorption of ions, water and nutrients (glucose)
56
What reabsorption occurs in the nephron loop
Bulk reabsorption of ions, water
57
What reabsorption occurs in the distal tubule and collecting duct
Fine tuning reabsorption of ions and water
58
Where does secretion occur
PCT
59
What does regulated reabsorption refer to
Regulated by hormones
60
Is sodium secreted
No
61
Where is sodium mostly reabsorbed
Most parts of the nephron
62
How much sodium is secreted in the urine
Small amount
63
Is glucose secreted
No
64
Where is glucose fully reabsorbed
PCT
65
How much glucose is secreted in the urine
None
66
Are medications and toxins secreted (e.g PAH)
Yes, entirely
67
Are medications and toxins reabsorbed (e.g PAH)
No
68
How much PAH is excreted in the urine
All IN BLOOD will be excreted
69
Are creatinine and inulin secreted
No
70
Are creatinine and inulin reabsorbed
No
71
How much creatinine and inulin are excreted in the urine
All filtered will be excreted
72
What is the renal blood flow
20% of CO (~1100-1200ml/min)
73
What is the magnitude of glomerular hydrostatic pressure
50 mmHg
74
What is the magnitude of blood colloid osmotic pressure
- 25 mmHg
75
What is the magnitude of capsular hydrostatic pressure
- 15 mmHg
76
What is the magnitude of net filtration pressure
10 mmHg
77
What is filtration fraction (definition)
The proportion of kidney plasma flow which actually gets filtered
78
What is filtration fraction (equation)
CO*1/5 * 0.55 * 1/5
(1/5 of plasma entering the kidneys is filtered)
79
What is the GFR (definition)
How much plasma is filtered per minute
80
How are RPF and GFR calculated
By measuring the clearance of specific substances
81
What is the GFR (equation)
RPF * FF
82
What is renal filtered load (definition)
How much of a substance in the plasma is filtered per minute
83
What is renal filtered load (equation)
GFR * solute plasma concentration
84
What is renal clearance
How much plasma is cleared of a substance per minute
85
The clearance of which substances is used to estimate GFR
Inulin and creatinine
86
The clearance of which substance is used to estimate RPF
PAH
87
How much plasma is cleared of glucose per minute
None
88
How much plasma is cleared of sodium per minute
A very small volume
89
What is the equation for renal clearance
UV / P
90
What is an average value for GFR
125ml/min, 180L/day
91
What GFR indicates kidney failure
<15ml/min
92
What percentage of water filtered load is reabsorbed in the PCT
67% (water follows sodium)
93
What percentage of water filtered load is reabsorbed in the descending limb of the nephron loop
25% (DESCENDING: water flows downhill)
94
What percentage of water filtered load is reabsorbed in the CD
2-8%
95
What percentage of water filtered load is excreted
<1-6%
96
What percentage of water absorption is bulk (obligatory), and where does this occur
92%, occurs in the PCT and descending limb of the nephron loop
97
What percentage of water absorption is regulated (facultative), and where does this occur
2-8%, CD
98
How does water cross the PCT
Trans and paracellular pathways
99
How does water cross the CD
Transcellular pathway
100
What is regulated water reabsorption regulated by
ADH
101
What percentage of sodium filtered load is reabsorbed in the PCT
67% (water follows sodium)
102
What percentage of sodium filtered load is reabsorbed in the ascending loop
25% (ASCENDING!)
103
What percentage of sodium filtered load is reabsorbed in the DCT
5%
104
What percentage of sodium filtered load is reabsorbed in the CD
2-3%
105
What percentage of sodium filtered load is excreted
<1%
106
What percentage of sodium reabsorption is accounted for by bulk sodium reabsorption
92%
107
What percentage of sodium reabsorption is accounted for by regulated sodium reabsorption
7-8%
108
What is regulated sodium absorption regulated by
Aldosterone (RAAS)
109
What creates the HOMG
Different permeabilities of descending and ascending juxtamedullary nephron loops
110
Where are TBW changes and hence changes in ECF osmolarity detected
Osmoreceptors in the hypothalamus
111
Where is ADH secreted from
Posterior pituitary
112
What does the release of ADH result in
Insertion of aquaporins into apical membrane of CD cells
113
What does an increase in ECF volume result in the secretion of (isosmotic fluid)
ANP (N)
114
What does a decrease in ECF volume result in the secretion of (isosmotic fluid)
Aldosterone (D)
115
What does the release of aldosterone result in
Insertion of sodium channels in apical membrane of DCT and CD
116
Where does creatinine come from
Muscle metabolism
117
Describe transitional epithelium
Stratified, rounded cells, flatten when stretched for protection
118
Are ureters intra or retroperitoneal
Retroperitoneal
119
Describe the muscularis of the ureters
Inner longitudinal, outer circular
120
What improves the protection of transitional epithelium
Protein plaques on its surface
121
Where do the ureters insert into the bladder
Posterolateral corners
122
Why does the ureter enter the bladder at an oblique angle
So that filling of urine doesn't go back up, compressed by increased bladder pressure
123
What are the rugae of the bladder
Folds that allow the bladder to expand without great increase in pressure
124
What is the region between the two ureters and urethra called
Trigone
125
Where does the bladder expand
Superiorly
126
Where is the male bladder located
Anterior to rectum, superior to prostate
127
Where is the female bladder located
Anterior to vagina and uterus
128
Describe the detrusor muscle
Smooth muscle layer made of oblique, circular and longitudinal muscle fibres
129
How does the epithelium change down the urethra
Transitional near bladder, then columnar, then stratified squamous near external opening
130
What is the opening of the urethra called
External meatus/orifice
131
What are the three regions of the male urethra
Prostatic, membranous, spongy/penile
132
What muscle layer does the membranous urethra pass through
Urogenital diaphragm
133
What is the internal urethral sphincter
Continuation of detrusor muscle, involuntary control
134
What is the external urethral sphincter
Skeletal muscle, voluntary control
135
What signals to the brain that you need to urinate
APs from stretch receptors in the bladder
