Renal Physiology Flashcards
1
Q
How do the renal arteries, segmental arteries, and interlobular arteries communicate with one another?
A
Arcuate arteries
2
Q
What are the branches given off by the arcuate arteries?
A
Interlobular arteries
3
Q
Where do the interlobular arteries extend into?
A
The cortex
4
Q
What makes up the capillary network surrounding the tubule system of the nephron?
A
Interlobular arteries
Afferent arterioles
Glomerulus
Efferent arterioles
5
Q
What are the collecting vessels of the nephron capillary system?
A
The interlobular veins
6
Q
What makes up each nephron?
A
Blood supply Glomerulus Loop of henle Collecting tubules Juxtaglomerular apparatus
7
Q
Renal blood flow is ____ blood flow
A
High blood flow
8
Q
How much of the cardiac output is pumped per minute through the kidneys?
A
1200ml/minute or 21%
9
Q
The glomerular capillary has _____ hydrostatic pressure
A
High
60mmHg
10
Q
The peritubular capillaries has ____ hydrostatic pressure
A
Low (13mmHg)
11
Q
Where does filtration occur in the kidneys?
A
Glomerulus
12
Q
Where does water reabsorption occur in the kidneys?
A
Proximal convoluted tubule
Descending loop of henle
END of distal convoluted tubule
Collecting ducts
13
Q
Where does solute reabsorption occur in the kidneys?
A
Proximal convoluted tubule
Ascending loop of henle
Distal convoluted tubule
Collecting duct
14
Q
Where does secretion occur in the kidneys?
A
Proximal convoluted tubule
Distal convoluted tubule
Collecting ducts
15
Q
What makes up the renal corpuscle?
A
Glomerulus and bowman’s capsule
16
Q
What makes up the juxtaglomerular apparatus?
A
Macula densa
Mesangial cells
Granular cells (Juxtaglomerular cells)
17
Q
What are the four man processes of the kidney?
A
Filtration
Reabsorption
Secretion
Excretion
18
Q
- First step of urine formation
- Bulk transport of fluid from blood to kidney tubule
A
Filtration
19
Q
Filtration is a result of ____ pressure
A
Hydraulic
20
Q
What is the normal GFR?
A
125ml/min or 180L/day
21
Q
- Process of returning filtered material to bloodstream
- May involve transport proteins
A
Reabsorption
22
Q
___% of what is filtered is reabsorbed
A
99
23
Q
What is totally reabsorbed (normally) by the kidney?
A
Glucose
24
Q
- Material added to lumen of kidney tubule from blood
A
Secretion
25
Secretion is usually ____ transport of toxins and foreign substances
Active
26
Loss of fluid from body in form of urine
Excretion
27
Equation for amount of solute excreted
Amount filtered + amount secreted - amount reabsorbed
28
Blood enters the glomerulus through the ____ _____ and filters out of the ___ ___
Glomerular capillary
| Renal corpuscle
29
What stays behind during glomerular filtration?
Large proteins and cells
30
What is the plasma-like fluid in the glomerulus?
Glomerular filtrate
31
What determines glomerular filterability?
Molecular weight
| Charges of the molecule
32
What is the favoring force in glomerular filtration?
Capillary blood pressure - 60mmHg OUT
33
What are the opposing forces in glomerular filtration?
Blood colloid osmotic pressure 32mmHg IN
| Capsule pressure - 18mmHg IN
34
What is the NET filtration pressure of the glomerulus?
10mmHg
This is the driving force
35
What will increase GFR?
Increased renal blood flow
36
What will increase GFR and cause edema?
Decreased plasma proteins
37
What will decrease GFR?
Hemmorhage
38
What 3 mechanisms regulate GFR?
Renal autoregulation
Neural regulation
Hormonal regulation
39
What are the 2 mechanisms that make up renal auto regulation?
Myogenic mechanism
| Tubuloglomerular feedback
40
What innervates the afferent and efferent arterioles? This mechanisms makes up ____ regulation of GFR
Sympathetic nerve fibers
Neural regulation of GFR
41
Activation of the sympathetic nervous system results in??
VASOCONSTRICTION!!
42
What hormones contribute to GFR regulation?
```
Angiotensin II
ANP
NO
Endothelin
Prostaglandin E2
```
43
Angiotensin II ____ GFR because it is a vasoconstrictor
Reduces
44
ANP ____ GFR because it increases capillary surface area available for filtration
Increases
45
If a substance is filtered but neither reabsorbed nor secreted, then the amount present in urine is its ___ ____
Plasma clearance
46
What are 2 agents that can be used to measure GFR?
Inulin
| Creatinine
47
Using creatinine to measure GFR is ____ accurate than inulin
Less
48
How much of the volume that enters the glomerulus is excreted to the external environment?
1%
49
What are the two pathways of absorption?
Transcellular
| Paracellular
50
What are some mechanisms of transport within the kidneys?
1. Primary active
2. Secondary active
3. Pinocytosis
4. Passive transport
51
Which part of the tubule is most likely to reabsorb large molecules like proteins with pinocytosis?
Proximal tubule
52
What occurs in the proximal tubule and thin descending segment of the loop?
Sodium, water, and chloride reabsorption
53
What is the major vehicle for reabsorption of sodium, chloride, and water in the proximal tubule?
Sodium-Potassium ATPase
54
In the first half of the proximal convoluted tubule, sodium is reabsorbed by co-transport along with??
Glucose
Amino acids
Other solutes
55
In the second half of the proximal convoluted tubule, sodium is reabsorbed with??
Chloride ions
56
What are the 3 functionally distinct segments of the loop of henle?
Thin descending
Thin ascending
Thick ascending
57
The thin descending loop of henle is highly permeable to? Moderately permeable to?
Highly permeable to water
Moderately permeable to most solutes
58
Which part of the loop of henle has no active reabsorption?
Thin descending loop
59
Which segment of the loop of henle secretes hydrogen ions into the tubule?
Thick ascending loop
60
Where is glucose reabsorbed? What is it reabsorbed with?
Reabsorbed with Na+ in the early portion of the proximal tubule
61
The amount of glucose reabsorbed is proportionate to the ____ ______ ____
Plasma glucose level
62
The plasma level at which glucose first appears in the urine
Renal threshold for glucose
63
Where and how does hydrogen secretion occur?
Proximal tubules
Loop of henle
Early distal tubules
Secondary active transport
64
Where does primary active transport begin?
Late distal tubules and continues through the remainder of the tubular system
65
What is important for forming a maximally acidic urine?
Hydrogen secretion
66
What allows for the excretion of excess hydrogen and the generation of new bicarbonate?
Ammonia buffer system
67
Calcium is both filtered and reabsorbed by the kidneys but is NOT ??
Secreted!
68
Where does PTH increase calcium reabsorption?
Thick ascending loop of henle and distal tubules
69
PTH reduces ??
Urinary excretion of calcium
70
Regulates permeability of the distal tubules and collecting ducts to water
Antidiuretic hormone
71
What provides the osmotic gradient necessary for water reabsorption to occur in the kidneys?
High osmolarity of the renal medullary interstitial fluid
72
What determines whether or not water leaves the collecting duct by osmosis?
ADH
73
ADH makes the walls of the collecting duct more ??
Permeable to water
74
______ in the hypothalamus detect low levels of water (high osmolarity)
Osmoreceptors
75
If the osmoreceptors detect high osmolarity, the hypothalamus sends a signal to the ____ ____ which released ADH into the bloodstream
Pituitary gland
76
When ADH is present, more water is _____ and less is _____
More water is reabsorbed
Less is secreted
77
Obligatory water resorption uses?
Sodium and other solutes
78
Water resorption is strongly influenced by ___ ___ because it follows it back to the interstitial fluid
Sodium reabsorption
79
Occurs mostly in collecting ducts
Through the water poles (channel)
Regulated by ADH
Facultative (selective) water resorption
80
Occurs with large amounts of poorly reabsorbed solutes such as glucose, mannitol, or urea
Solute diuresis or osmotic diuresis
81
Osmotic diuresis results in ____ saline
Hypotonic
82
The constant fraction of the filtered Na+ and water are reabsorbed in the proximal tubule despite variation of GFR
Glomerulotubular balance
83
Why is glomerulotubular balance important?
To prevent overloading of the distal tubular segments when GFR increases
84
What is the first line of defense to buffer the effect of spontaneous changes in GFR on urine output? What is the second?
First line = auto regulatory mechanism
Second line = glomerulotubular balance
85
How do nerves from the renal plexus regulate blood pressure and distribution throughout the kidney?
They innervate smooth muscle of the afferent and efferent arterioles
86
Sensory nerves located inside the renal pelvic wall that are activated by stretch of the renal pelvic wall
Renerenal reflex
87
What does the renorenal reflex cause?
Increase in afferent renal nerve activity
Decrease in efferent renal nerve activity
Increase in urine flow rate and urinary sodium secretion
88
Increases the release of substance P via activation of N-type calcium channels in the renal pelvic wall
PGE2
89
Retention of water is controlled by ??
ADH
90
ADH release is stimulated by ?
Decrease in blood volume
Decrease in blood pressure
Increase in extracellular fluid osmolarity
91
Sodium balanced is controlled by ??
Aldosterone
92
Where is aldosterone synthesized?
Adrenal cortex
93
Where does aldosterone cause sodium resorption and K+ secretion?
DCT and CD
94
What is the mechanism of aldosterone?
Stimulates the Na+K+ ATPase pump on the basolateral side of the cortical collecting tubule membrane
95
What is the primary site of aldosterone action?
Principal cells of the cortical collecting duct
96
What releases renin and what stimulates the release of renin?
Juxtaglomerular apparatus stimulated by fall in NaCl, extracellular fluid, or arterial BP
97
Released by the atrium in response to atrial stretching due to increased blood volume
Atrial natriuritic peptide (ANP)
98
What does ANP inhibit?
Inhibits Na+ and water resorption, also inhibits ADH secretion
99
What does ANP promote?
Sodium excretion (natriuresis) and water excretion (diuresis)
100
The process of emptying the urinary bladder
Micturition
101
What two processes are involved in micturition?
1. Bladder fills progressively until the tension in its wall rises above threshold level
2. Micturition reflex occurs and empties bladder
102
How does aging affect the renal system?
1. Decline in number of functional nephrons
2. Reduction of GFR
3. Reduces sensitivity to ADH
4. Problems with micturition reflex
103
What is the myogenic reflex?
Type of auto regulation
Increase in blood pressure causes afferent arterioles to stretch, opening "stretch-activated channels", which in turn opens voltage gated channels. Calcium enters the voltage gated channels and binds to the actin chain to contract myofilaments back to their normal shape
104
What is tubuloglomerular feedback?
Type of auto regulation
Macula densa cells detect increase in Na+, creates action potential that travels to afferent arterioles and causes contraction/vasoconstriction of the afferent arteriole
