Physiology lecture Flashcards
1
Q
renal artery–> segmental artery –> ?
A
interlobar artery
2
Q
the interloper arteries are connected by:
A
arcuate arteries
3
Q
the ______ veins are the collecting vessel of the nephron capillary system
A
interlobar
4
Q
- high blood flow
2. 2 capillary beds
A
renal blood flow
5
Q
_____% of cardiac output goes to the kidneys
A
21
6
Q
high hydrostatic pressure in
A
glomerular capillary
7
Q
low hydrostatic pressure in
A
peritubular capillaries
8
Q
- filtration
- reabsorption
- secretion
- excretion
A
4 main processes of renal physiology
9
Q
- first step in urine formation
- bulk transport of fluid from blood to kidney tubule
- result of hydraulic pressure
- GFR = 180 L/day
A
Filtration
10
Q
- process of returning filtered material to bloodstream
- 99% of what is filtered is reabsorbed
- may involve transport proteins
A
Reabsorption
11
Q
Is glucose normally totally reabsorbed?
A
YES
12
Q
- material added to lumen of kidney tubule from blood
* active transport (usually) of toxins and foreign substances (saccharine, penicillin)
A
Secretion
13
Q
*loss of fluid from body in form of urine
A
Excretion
14
Q
(Amount filtered + amount secreted) - amount reabsorbed =?
A
Amount of solute excreted
15
Q
Occurs as fluids move across the glomerular capillary in response to glomerular hydrostatic pressure
A
glomerular filtration
16
Q
- blood enters glomerular capillary
- filters out of renal corpuscle
- large proteins and cells stay behind
- everything else is filtered into nephron
- glomerular filtrate
- plasma like fluid in glomerulus
A
glomerular filtration
17
Q
- molecular weight
2. charges of the molecule
A
factors that determine glomerular filterability
18
Q
Mechanism: Bulk flow
Direction of movement : From glomerular capillaries to capsule space
Driving force: Pressure gradient (net filtration pressure, NFP)
A
glomerular filtration
19
Q
Types of pressure:
Favoring Force: Capillary Blood Pressure (BP) Opposing Force: Blood colloid osmotic pressure(COP) and Capsule Pressure (CP)
A
Glomerular filtration
20
Q
Amount of filtrate produced in the kidneys each minute.
**125mL/min = 180L/day
A
GFR
21
Q
what does increased renal blood flow do to GFR?
A
increases GFR
22
Q
what does increased plasma protein do to GFR?
A
increase GFR, causes edema
23
Q
what does hemorrhage to do GFR?
A
decreases GFR (bc decreased capillary BP)
24
Q
- Renal Autoregulation
- Neural regulation
- Hormonal regulation
A
Regulate GFR
*all adjust renal blood pressure and resulting blood flow
25
Sympathetic nerve fibers innervate afferent and efferent arteriole
Normally sympathetic stimulation is low but can increase during hemorrhage and exercise
Vasoconstriction occurs as a result which conserves blood volume(hemorrhage)and permits greater blood flow to other body parts(exercise)
Neural regulation of GFR
26
Several hormones contribute to GFR regulation
* Angiotensin II. Produced from Renin, released by JGA cells is a potent vasoconstrictor. Reduces GFR
* ANP(released by atria when stretched) increases GFR by increasing capillary surface area available for filtration
* NO
* Endothelin
* Prostaglandin E2
Hormonal regulation of GFR
27
If a substance is filtered but neither reabsorbed nor secreted, then the amount present in urine is its.....
plasma clearance
*amount in plasma cleared/min by glomerulus
28
125ml of plasma is cleared/min in glomerulus, which is about how many L per day?
180L/day
29
```
Freely filterable at glomerulus
Does not bind to plasma proteins
Biologically inert
Non-toxic, neither synthesized nor metabolized in kidney
Neither absorbed nor secreted
Does not alter renal function
Can be accurately quantified
Low concentrations are enough (10-20 mg/100 ml plasma)
```
Inulin
*can measure GFR
30
End product of muscle creatine metabolism
Used in clinical setting to measure GFR but less accurate than inulin method
Small amount secrete from the tubule
Creatinine
31
Transcellular pathway
| Paracellular transport
2 pathways of absorption
32
1. Primary Active Transport
2. Secondary Active Transport
3. Pinocytosis
4. Passive Transport
Mechanisms of transport
33
Some parts of the tubule, especially the proximal tubule, reabsorb large molecules such as proteins by...
pinocytosis
34
Sodium, water and chloride reabsorption in proximal tubule, including....
1. proximal convoluted tubule
| 2. thick descending loop
35
Sodium, water and chloride are reabsorbed in the...
proximal tubule
36
proximal tubule REABSORBS about __% of filtered sodium, chloride, bicarb and potassium.
*also reabsorbs almost all of the filtered glucose and amino acids
65%
37
Proximal tubule ______ organic acids, bases and hydrogen ions into tubular lumen
secretes
38
major vehicle for reabsorption of sodium, chloride and water
Soidum-potassium ATPase
39
in the first half of the PROXIMAL tubule, Na+ is reabsorbed by co-transport along with..
Glucose
AAs
other solutes
40
in the second half of the PROXIMAL tubule, sodium is reabsorbed mainly with...
Cl-
41
The second half of the proximal tubule has a relatively ____ concentration of chloride compared with the early proximal tubule
HIGH
| 140 mEq/L vs 105 mEq/L
42
In the second half of the proximal tubule, the higher chloride concentration favors the _____ of this ion from the tubule lumen through the intercellular junctions into the renal interstitial fluid.
diffusion
43
3 functionally distinct segments of Loop of Henle
1. thin descending
2. thin ascending
3. thick ascending
44
Glucose is reabsorbed along with Na+ in the early portion of the
proximal tubule
45
Glucose is typical of substances removed from the urine by secondary
active transport
46
The amount of glucose reabsorbed is proportionate to the amount ______
filtered
47
is the plasma level at which the glucose first appears in the urine.
renal threshold for glucose
48
The actual renal threshold for glucose is about 200 mg/dL of arterial plasma, which corresponds to a venous level of about
180 mg/dL
49
Hydrogen secretion through secondary
active transport
50
Secretion occurs mainly at the proximal tubules, loop of Henle, and early distal tubule
H+ secretion (via secondary active transport)
*more than 90% of HCO3 is passively reabsorbed in this manner
51
Beginning in the late distal tubules and continuing through the reminder of the tubular system
* It occurs at the luminal membrane of the tubular cell
Primary active transport
52
Hydrogen ions are transported directly by...
hydrogen transporting ATPase
53
- accounts for only about 5 percent of the total hydrogen ion secreted
- important in forming a maximally acidic urine
- hydrogen ion concentration can be increased as much as 900-fold in the collecting tubules
- decreases the pH of the tubular fluid to about 4.5, which is the lower limit of pH that can be achieved in normal kidneys
Hydrogen secreted through proton pump
54
Excretion of Excess Hydrogen Ions and Generation of New Bicarbonate by the...
ammonia buffer system
55
Calcium is both filtered and reabsorbed in the kidneys but not
secreted
56
Only about 50 per cent of the plasma calcium is
ionized
*remainder being bound to plasma proteins
57
Parathyroid hormone (PTH) _____ calcium reabsorption in the thick ascending Loop of Henle and distal tubules
increases
58
PTH ______ urinary excretion of calcium
reduces
59
When there is excess water in the body and body fluid osmolarity is reduced, the kidney can excrete urine with an osmolarity as low as __ mOsm/liter, a concentration that is only about one sixth the osmolarity of normal extracellular fluid
50
60
when there is a deficit of water and extracellular fluid osmolarity is high, the kidney can excrete urine with a concentration of about _______ mOsm/liter
1200-1400
61
regulates the permeability of the distal tubules and collecting ducts to water
ADH
62
a high osmolarity of the renal medullary interstitial fluid, which provides the osmotic gradient necessary for water reabsorption to occur in the presence of high level of
ADH
63
loop of henle
DCT
collecting duct
..all impermeable to?
Urea
64
Whether the water actually leaves the collecting duct (by osmosis) is determined by
ADH
65
in the hypothalamus detect the low levels of water (high osmolarity), so the hypothalamus sends an impulse to the pituitary gland which releases ADH into the bloodstream.
Osmoreceptors
66
ADH makes the wall of the collecting duct more permeable to
water
* Therefore, when ADH is present more water is reabsorbed and less is excreted.
67
Using sodium and other solutes.
Water follows solute to the interstitial fluid (transcellular and paracellular pathway).
Largely influenced by sodium reabsorption
Obligatory water resorption
68
Occurs mostly in collecting ducts
Through the water poles (channel)
Regulated by the ADH
Facultative (selective) water resorption
69
Nerves from the renal plexus (sympathetic nerve) of the autonomic nervous system enter kidney at the
hilus
70
Sensory nerves located in the renal pelvic wall are activated by stretch of the renal pelvic wall (which may occur during diuresis or ureteral spasm/occlusion).
renorenal reflex
71
Activation of these nerves leads to an increase in afferent renal nerve activity, which causes a decrease in efferent renal nerve activity and an increase in urine flow rate and urinary sodium excretion
Renorenal reflex
72
1. ADH
2. aldosterone
3. ANP
humoral regulation of kidneys
73
retention of water is controlled by...
ADH
74
Decrease in Blood Volume
Decrease in Blood Pressure
Increase in extracellular fluid (ECF) Osmolarity
stimulates ADH release
75
Sodium balance is controlled by...
Aldosterone
76
Steroid hormone
Synthesized in Adrenal Cortex
Causes resorption of Na+ in DCT & CD
Also, K+ secretion
Aldosterone
77
The primary site of aldosterone action is on the principal cells of the cortical...
collecting duct
78
The net effect of ______ is to make the kidneys retain Na+, water resorption and K+ secretion
aldosterone
79
The mechanism of ______ is stimulating the Na+K+ ATPase pump on the basolateral side of the cortical collecting tubule membrane.
aldosterone
80
is released by atrium in response to atrial stretching due to increased blood volume
ANP
81
* inhibits Na+ and water resorption, also inhibits ADH secretion
* promotes increased sodium excretion (natriuresis) and water excretion (diuresis) in urine
ANP
82
The bladder fills progressively until the tension in its wall rises above a threshold level, and then
A nervous reflex called the micturition reflex occurs that empties the bladder.
2 processes of micturition
83
The _____ reflex is an automatic spinal cord reflex; however, it can be inhibited or facilitated by centers in the brainstem and cerebral cortex.
micturition
84
Decline in the number of functional nephrons
Reduction of GFR
Reduced sensitivity to ADH
Problems with the micturition reflex
changes with aging
