Chapter 17 Physiology of the Kidney Flashcards
1
Q
main function of the renal system
A
regulates blood volume eliminates organic waste products regulates balance of electrolytes, molecules and nutrients maintain acid base balance/pH of plasma all through urine
2
Q
kidneys
A
formation of urine
water and electrolyte balance
secretion of toxins and drugs
gluconeogenesis
3
Q
ureters
A
transfer of urine to bladder
4
Q
urinary bladder
A
storage of micturition (urination) via urethra
5
Q
urethra
A
micturition
6
Q
what does urine form from
A
filtration of blood
7
Q
outer layer of kidney
A
renal cortex
8
Q
inner layer of the kidney
A
renal medulla
9
Q
functional unit of the kidney
A
nephron
10
Q
what causes uine to flow
A
contraction of smooth muscle in urter
11
Q
base of the bladder
A
internal urethral sphincter
12
Q
surrounds urthra, contraction prevents urination
A
external urethral sphincter
13
Q
composition of nephron
A
renal corpuscle
tubule
14
Q
how does arterial blood enter the kidney
A
through renal arteries
15
Q
glomerulus
A
ball shaped capillary network
produces blood filtrate that enters tubule
16
Q
what brings blood to glomerulus and how does remaining blood leave glomerulus
A
through afferent and efferent arterioles
17
Q
how much blood leaves glomerulus again
A
80%
18
Q
veins that drain remaining blood from kidney
A
renal vein
19
Q
glomerular capsule/Bowman´s capsule
A
surrounds glomerulus
filtration
20
Q
proximal convoluted tubes of the nephron
A
reabsorbtion of salt, water, etc into peritubular capillaries
21
Q
parts of nephron
A
glomerular capsule/Bowman´s capsule proximal convoluted tubule descending and ascending limb of loop of henle distal convoluted tubule collecting duct
22
Q
fluid filtration
A
out of glomerulus into glomerular capsule
23
Q
pores in glomerular capillaries
A
fenestrae
24
Q
percent of blood that flows into glomerular capsule
A
20%
25
what makes filter through fenestrae
hydrostatic pressure of the cardiac pump
26
movement of fluid from glomerulus into glomerular capsule
glomerular filtration
27
glomerular filtration rate (GFR)
volume of filtrate produce by both kidneys per minute
28
average GFR
male: 125 ml/min
female: 115 ml/L
not equal to amount or urine production
29
what causes variation in the blood flow through glomerular and in GFR
vasoconstriction and vasodialation of afferent arterioles
30
vasoconstriction of afferent arterioles
sympathetic NS
reduced GFR
during fight or flight
31
renal autoregulation
afferent arterioles dilate when BP decreases
| constrict when BP increases
32
glomerular filtrate vs. urine production per day
glomerular filtrate 180 L
| urine 1-2L
33
filtration
movement from fluid and solutes from glomerular capillaries to capsule
34
reabsorbtion
99% of filtrate return via peritubular capillaries and through tubular cells to vascular system to maintain blood volume and pressure
35
location of reabsorbtion
65% in proximal tubule#
20% in descending limp of Henle
fine tuning for final urine concentration occurs later in the nephron
36
total solute concentration of filtrate
300 mOsm - same as plasma
37
what allos reabsorbtion via osmosis
active Na+ transport, which increases osmolarity
38
water reabsorbtion
passive via osmosis
| depends on Na+ reabsorbtion
39
how does Cl- diffuse out ob tubules
follows Na+ passively by electrical attraction
40
what does ISF must be that water can be rabsorbed by osmosis
hypertonic
41
what makes ISF hypertonic
countercurrent flow in ascending and descending limbs in nephron (Countercurrent Mulitplier System) + close proximity of limbs
42
ascending limb of loop on henle
Na+ actively pumped into ISF
Cl- follows passively
K+ diffuses passively into filtrate
water stays in -> fluid is diluted
43
descending limb of loop of henle
permeable to water
water leaves by osmosis
hypertonic fluid enters ascending limb creating diluted tubular fluid and concentrated ISF
44
vasa recta
blood vessels in medulla
45
urea
waste product of amino acid metabolism that is excreted in urine
46
due to what diffuses ura out the terminal portion of the collecting duct
countercurrent exchange
47
what surrounds collecting ducts
hypertonic ISF
48
fluid in collecting ducts
hypotonic
49
permeability of collecting ducts
permeable to water but not salt
50
what happens when plasma osmolarity increases
ADH increases permeabilty of collecting duct to water
51
due what increases ADH the permeability of collecting ducts to water
insertion of aquaporin channels
52
what creates a hypertonic renal medulla
countercurrent multiplier system and vasa recta
53
where does reabsorbed liquid go to
pertubular capillaries into ISF and then into tubule lumen
54
which receptors control plasma osmolarity
hypothalamic osmoreceptor
55
dehydration
high plasma osmolarity - high ADH - high water reabsorbtion - smaller urine volume (less water in urine)
56
over-hydration
low plasma osmolarity - low ADH - low water reabsorbtion - high urine volume (more water in urine)
57
obligatory water loss
400 ml/day
58
Excretion rate
(filtration rate + secretion rate) - reabsorbtion rate
59
substance that is filtered but not reabsorbed or secreted
filtered substance = GFR
60
Secretion
substance actively transported from peritubular capillaries to tubular cells and into filtrate
61
location of most reabsorbtion and secretion
proximal tubule
62
what can inulin be used for
estimate glomerular filtration rate (120ml/min)
63
why can inulin be used for the filtration rate estimation (Einschätzung)
because it is filtered but not reabsorbed or secreted
| excreted amount per minute = amount filtered per minute
64
clearance
```
mass of substance excreted per unit time/plasma concentration of substance
C(S)= VU(S)/P(S)
V= urine volume per min
U(S)= urine concentration of S
P(S)= plasma concentration of S
```
65
renal plasma clearance
volume of plasma that is cleared of a substance by kidneys per unit of time
66
amount of filtered Na+ and K+ reabsorbed
85% - 90%
67
waht does the final concentration of Na+ and K+ in urine depend on
physiological needs/homeostasis
68
decreased plasma Na+
activates renin-engiotension-aldosterone system due to decreased blood volume
69
alosterone
stimulates Na+ reabsorbtion in distal tubule and corticol collecting duct
stimulates K+ secretion in distal tubule and corticol collecting duct
Na+/K+ pump
70
K+
reabsorbed and secreted
71
what forms the intersection of the distal tubule with the afferent and efferent arterioles
juxtaglomerular apparatus
72
responsibilities of juxtaglomerular apparatus
secrets renin into blood in afferent arterioles
73
ADH
affects water reabsorbtion in collecting ducts to controle urine and blood volume
74
Atrial natriuretic peptide (ANP)
stimulates salt excretion when blood volume increases
75
role of kidneys in blood ph control
excreting H+ in urine
76
reabsorbtion of bicarbonate in proximal tubule to control urine pH
1. Na+/H+ pump transports H+ into filtrate and Na+ out of filtrate. Most of the H+ secreted into the filtrate is used for reabsorption of bicarbonate.
2. Bicarbonate combines with H+ to form carbonic acid in the filtrate.
3. Carbonic acid in the filtrate is converted to CO2 and H2O in the filtrate
4. CO2 diffuses into tubule cells, where CO2 and H2O form carbonic acid.
5. Carbonic acid dissociates to HCO3- and H+ in tubule cells.
6. The bicarbonate from the tubule cells diffuses into blood
77
amount of reabsorbed bicarbonate
80-90%
78
what is H+ in urine buffered by
ammonia and phosphate buffer
79
alkalosis
pH > 7.45
less [H+] in plasma and filtrate
less bicarbonate reabsorbed
80
acidosis
pH < 7.35
increased [H+] in plasma in filtrate
increased bicarboneate made in proximal tubule and reabsorbed
