Unit 6 Renal Physiology Flashcards
1
Q
Organs of the Urinary System
A
Urinary Bladder
Urethra
Kidney
Ureter
2
Q
Kidney Function
A
Filters Blood Plasma Regulation Secretion Detoxification Gluconeogenesis
3
Q
Kidney Filtration
A
returns useful substances to blood
eliminates waste
4
Q
Kidney Regulation
A
returns useful substances to blood
eliminates waste
5
Q
Kidney Secretion
A
Renin and Erythropoeitin
6
Q
Kidney Detoxification
A
Free Radicals and Drugs
7
Q
Kidney Excretion
A
Separation of wastes from body fluids and eliminating them
8
Q
Kidney Excretion (Respiratory)
A
CO2
9
Q
Kidney Excretion (Integumentary)
A
Water, Salts, Lactic Acid, Urea,
10
Q
Kidney Excretion (Digestive)
A
water, salts, CO2, lipids, bile pigments, cholesterol
11
Q
Kidney Excretion (Urinary)
A
many metabolic wastes, toxins, drugs, hormones, salts, H+ and water
12
Q
The Lobe of the Kidney Consists of
A
Renal Pyramid and its Overlying Cortex
13
Q
Glomerular Filtrate collects in the Capsular space and flows into
A
The Renal Tubule
14
Q
PCT (Proximal Convoluted Tubule)
A
longest, most coiled, simple cuboidal with brush border
15
Q
Nephron Loop (Loop of Henle)
A
U shaped; descending and ascending limbs thick segment (simple cuboidal) initial part of descending limb and part or all of ascending limb, active transport of salts thin segment (simple squamous) very water permeable
16
Q
DCT (Distal Convoluted Tubule)
A
cuboidal, minimal microvilli
17
Q
Collecting Duct
A
Several Distal Tubules Joined
18
Q
Flow of Glomerular Filtrate
A
Glomerular (Bowman's Capsule) Proximal Convoluted Tubule Loop of Henle Distal Convoluted Tubule Collecting Duct Papillary Duct Minor Calyx Major Calyx Renal pelvis Ureter Urinary Bladder Urethra
19
Q
Functional Unit of the Kindey
A
Nephron
20
Q
Cortical Nephrons make up what percent of nephrons?
A
85%
21
Q
Cortical Nephrons
A
short nephron loops
efferent arterioles branch off peritubular capillaries
22
Q
Juxtamedullary Nephrons Make up what percent of Nephrons
A
15%
23
Q
Juxtamedullary Nephrons
A
very long nephron loops, maintain salt gradient, helps conserve water
24
Q
What is the Path of Blood through the Kidneys
A
Renal artery
—–> interlobar arteries (up renal columns, between lobes)
—–>arcuate arteries (over pyramids)
—–> interlobular arteries (up into cortex)
—–> afferent arterioles
—–> glomerulus (cluster of capillaries)
—–> efferent arterioles (near medulla vasa recta)
—–> peritubular capillaries
—–> interlobular veins —–> arcuate veins —–> interlobar veins
Renal vein
25
Filtration Membrane- Fenestrated Endothelium
70-90nm pores exclude blood cells
26
Filtration Membrane- Basement Membrane
proteoglycan gel, negative charge excludes molecules > 8nm
| blood plasma 7% protein, glomerular filtrate 0.03%
27
Filtration Membrane- Filtration Slits
podocyte arms have pedicels with negatively charged filtration slits, allow particles < 3nm to pass
28
GFR- Glomerular Filtration Rate
Filtrate Formed Per Minute
29
Amount of Filtrate Reabsorbed
99% of filtrate reabsorbed, 1 to 2 L urine excreted
30
GFR in Women
GFR = NFP x Kf 105 ml/min or 150 L/day
31
GFR in Men
GFR = NFP x Kf 125 ml/min or 180 L/day
32
In Renal Autoregulation of GFR, an increased BP will result in
Constriction of the afferent arteriole, and dilation of the efferent arteriole
33
In Renal Autoregulation of GFR, a decreased BP will result in
Dilation of the afferent arteriole and constriction of the efferent arteriole
34
What is the stable BP range in the Renal System?
80-170 mmHg
35
True or False: The urinary system can adjust to compensate for extremely low or high BP
False: It can adjust within limits, but no extremes
36
Myogenic Mechanism
An Increase in BP stretches the afferent arteriole. Afferent Arteriole constricts, and restores the GFR
37
Tubuloglomerular Feedback
Macula densa on DCT monitors tubular fluid and signals juxtaglomerular cells (smooth muscle, surrounds afferent arteriole) to constrict afferent arteriole to decrease GFR
38
Negative Feedback control of GFR
```
High GFR
Rapid FLow of filtrate in renal tubules
Sensed by macula Densa on DCT
Paracrine Secetion (Local Control)
Constriction of Afferent Arteriole
Reduced GFR
```
39
Sympathetic Control of GFR
strenuous exercise or acute conditions (circulatory shock) stimulate afferent arterioles to constrict
A Decreased GFR and urine production, redirecting blood flow to the heart, brain, and skeletal muscles
40
Hormonal Control of BP
```
Kidneys recognize a drop in BP and release Renin
Liver releases Angiotensinogen
mixes with Renin to create Angiotensin I
ACE is released from the lungs
Angiotensin II is converted
Vasoconstriction occurs
Adrenal Cortex releases Aldosterone
Hypothalamus gives Thirst Signal
Sodium and Water Retention occurs w Aldosterone
Elevated BP occurs
```
41
Effect of Angiotensin II
Constricts afferent and Efferent tubules
Reduces glomerular BP and Filtration
Reduces BP in peritubular Capillary
Reduces Resistance to Tubular Reabsorption
Tubular Reabsorption increases
Urine Volume is less but concentration is high
42
Peritubular Capillaries
Blood has unusually high COP here, and BHP is only 8 mm Hg (or lower when constricted by angiotensin II); this favors reabsorption
Water absorbed by osmosis and carries other solutes with it (solvent drag)
43
PCT (Proximal Convoluted Tubule Reabsorbs how much Glomerular Filtrate?
65% of GF to the Peritubular Capillaries
44
True or False: The PCT contains Microvilli
True: The PCT contains
| Great length, prominent microvilli and abundant mitochondria for active transport
45
Trancellular Route
Reabsorption Through Epithelial Cells of PCT
46
Paracellular Route
Reabsorption between epithelial Cells of PCT
47
Transport Maximum
when transport proteins of cell membrane are saturated; blood glucose > 220 mg/dL some remains in urine (glycosuria); glucose Tm = 320 mg/min
48
What is the Primary Function of the Loop of Henle
water conservation
generates salinity gradient, allows CD to conc. urine
also involved in electrolyte reabsorption
49
Functions of PCT and Loop of Henle
Waste removal
urea, uric acid, bile salts, ammonia, catecholamines, many drugs
Acid-base balance
secretion of hydrogen and bicarbonate ions regulates pH of body fluids
50
Principal Cells
receptors for hormones; involved in salt/water balance
51
Intercalated Cells
involved in acid/base balance
52
Function of DCT and Collecting Duct
Fluid Reabsorption here is variable, regulated by hormonal action
53
Aldosterone effects
```
Decreased BP
Renin released
Angiotensin II Formation
Angiotensin II stimulates Adrenal Cortex
Adrenal Cortex secretes Aldosterone
Promotes Na+ Reabsorption
Promotes Water Reabsorption
Decreases Urine Volume
Maintains BP
```
54
Effects of ADH (Antidiuretic Hormone)
```
dehydration stimulates hypothalamus
hypothalamus stimulates posterior pituitary
posterior pituitary releases ADH
ADH increases water reabsorption
decrease urine volume
```
55
ANP
Atrial Natriuretic Factor/Peptide
| Atria secrete ANP in response to increased BP
56
ANP actions
1. dilates afferent arteriole, constricts efferent arteriole - increases GFR
2. inhibits renin/angiotensin/aldosterone pathway
3. inhibits secretion and action of ADH
4. inhibits NaCl reabsorption
57
What Promotes Na+ and Water excretion, increases urine Volume, decreases Blood Volume, and BP
ANP/ANF
| Atrial Natriuretic Factor/Peptide
58
Effects of PTH (Parathyroid Hormone)
Increased Calcium Reabsorption in DCT (increased Blood Ca2+)
Increased Phosphate excretion in PCT, decreased new bone formation
Stimulates kidney production of calcitrol
59
Urine Concentration in the medulla vs in Collecting ducts
4x more concentrated in collecting ducts than in medulla
60
The medullary portion of the collecting duct is more permeable to
Water than NaCl
61
Producing Hypotonic Urine
NaCl reabsorbed by cortical CD
| water remains in urine
62
Producing Hypertonic Urine
```
Dehydration
INcreased ADH
Increased Aquaporin channels
increased CD water permeability
More water is reabsorbed
Urine is more concentrated
```
63
Countercurrent Multiplier
Recaptures NaCl and returns it to renal medulla
64
Decending Limb countercurrent multiplier
reabsorbs water but not salt
| concentrates tubular fluid
65
Ascending Limb Countercurrent Multiplier
reabsorbs Na+, K+, and Cl-
maintains high osmolarity of renal medulla
impermeable to water
tubular fluid becomes hypotonic
66
Recycling of Urea: Collecting Duct-Medulla
urea accounts for 40% of high osmolarity of medulla
67
Countercurrent Multiplier of Loop of Henle
More salt Continually added to PCT
The Higher osmolarity of the ECF, more water leaves by osmosis
More water leaves, saltier the fluid gets
Saltier fluid gets pumped into ECF
68
Countercurrent exchange system is formed by
Vasa Recta
69
Vasa Recta
provide blood supply to medulla
| do not remove NaCl from medulla
70
Descending capillaries of Vasa recta
water diffuses out of blood
| NaCl diffuses into blood
71
Ascending Capillaries of Vasa Recta
water diffuses into blood
| NaCl diffuses out of blood
72
Urine Appearance
almost colorless to deep amber; yellow color due to urochrome, from breakdown of hemoglobin (RBC’s)
73
Urine Odor
as it stands bacteria degrade urea to ammonia
74
Specific Gravity of Urine
density of urine ranges from 1.001 -1.028
75
Osmolarity of Urine
(blood - 300 mOsm/L) ranges from 50 mOsm/L to 1,200 mOsm/L in dehydrated person
76
Urine pH range
4.5 - 8.2, usually 6.0
77
Chemical Composition of Urine
95% water, 5% solutes
| urea, NaCl, KCl, creatinine, uric acid
