Urinary Physiology Flashcards
1
Q
Three Basic Renal Processes
A
- Glomerular Filtration (fluid into tubule)
- Tubular Reabsorption (tubule to blood)
- Tubular Secretion (blood to tubule)
2
Q
Substance Fates
A
- Filtered and secreted
- Secreted only
- Filtered and reabsorbed
- Filtered and partially reabsorbed
3
Q
What is Filtered During Glomerular Filtration
A
Everything except for RBCs and proteins because they are too big
4
Q
What is reabsorbed from the tubules
A
- Na
- Cl
- Ca
- PO4
- Water
- Glucose
5
Q
What is secreted into the tubules
A
- K
- H
- Large organics such as medications
6
Q
Glomerular Filtration
A
- Filtrate passes through glomerular capillary wall, basement membrane, and podocytes that can change shape to control GFR
- Moves filtrate into the tubules
- Urine is less than 1% of the filtrate
7
Q
Average Glomerular Filtration Rate
A
- 160-180 L/day
- 125 mL/min
8
Q
Podocytes
A
- Change shape to control filtration
- Create large slits during renal failure that allows proteins and RBCs to enter
- This is why proteinuria and blood in the urine is a symptom of renal failure
9
Q
Forces Involved in Glomerular Filtration
A
- Glomerular capillary pressure (favours filtration)
- Plasma-colloid osmotic pressure (opposes filtration)
- Bowman’s Capsule hydrostatic pressure (opposes filtration)
10
Q
Factors Affecting GFR
A
- Net filtration pressure
- Glomerular surface area
- Glomerular membrane permeability (podocyte shape)
- Tuboglomerular feedback controls glomerular blood flow
- Size of afferent and efferent arterioles
- Sympathetic control
11
Q
How is GFR Measured
A
- Inulin is not reabsorbed or secreted
- Inulin excretion rate = GFR
11
Q
Movement Across Cells
A
- Trans-cellular transport is active or passive, and transports Na, Glucose, etc.
- Paracellular transport is passive only and is fueled by diffusion of water and ions
12
Q
Sodium Reabsorption
A
- Na/K pumps create gradients
- Water (via osmotic gradient), Cl (via electrical gradient), and glucose (via carriers) all follow
13
Q
Glucose Reabsorption
A
- Tubular Maximum is the point where all carriers are full and glucose is forced to remain in urine
- This should not happen
- 100% of glucose should be reabsorbed
- Renal Threshold is the blood glucose level where the tubular maximum will be reached
14
Q
Urea Reabsorption
A
- Urea is small and diffusible, which means it is a passive process
- This means urea is reabsorbed to equilibrium (50%)
15
Q
Aldosterone
A
- Controls Na/K pumps
- Released with low blood volume
- Increases pump speed, Na reabsorption, and water reabsorption
- Decreases urine output
16
Q
Renin-Angiotensin System
A
- Regulates Na volume and blood pressure
- Increases thirst
- Increases vasoconstriction
- Increases reabsorption
17
Q
ANP
A
- Antagonistic to aldosterone
- Inactivates Na/K pump
- Inhibits Na reabsorption
- Secreted with increased BP, Na concentration, and blood volume (stretch)
18
Q
Secretion
A
- Transfer of materials from extracellular fluid into tubule
- Active process
- Uses Na/K pumps
- H is secreted for acid/base balance
- Large organics are secreted if they cannot be filtered
19
Q
Collecting Ducts
A
- Site of water reabsorption via ADH
- Concentrates urine
- Requires osmotic gradient from cortex to medulla
20
Q
Descending Loop of Henle
A
- Permeable to water
- Impermeable to salts
- Filtrate becomes more concentrated
21
Q
Ascending Loop of Henle
A
- Permeable to salts
- Impermeable to water
Filtrate becomes less concentrated
22
Q
ADH
A
- Causes insertion of water pores into the apical membrane
- Allows water through to be reabsorbed into the blood
- Released if blood osmolarity is high (water content is low)
23
Q
Apical Membrane
A
- Cell surface facing the lumen of the tubule
24
Effects of Dehydration on Hormone Levels, Water reabsorption, and Urine Output
- Increased ADH and Aldosterone
- Decreased ANP
- Increased water reabsorption
- Decreased urine output
- More concentrated urine
25
Effects of Water Loading on Hormones, Water Reabsorption, and Urine Output
- Decreased ADH and Aldosterone
- Increased ANP
- Decreased water reabsorption
- Increased urine volume
- More dilute urine
26
Clearance
- The rate at which solutes disappear from the body
27
Detrusor and Sphincter States During Bladder Filling
- Detrusor is relaxed
- Sphincters are contracted
28
Micturition
- Stretch receptors increase their firing rate
- Sphincters relax
- Detrusor contracts
29
Acute Causes of Renal Failure
- Infections/toxins
- Inappropriate Immune Responses
- Obstruction of flow
- Insufficient blood supply
30
Chronic Causes of Renal Failure
- Hypertension
- Diabetes
- Chronic exposure to toxins or drugs
31
Effects of Renal Failure
- Buildup of wastes to toxic levels
- Loss of calcium
- Na/K imbalance
- Loss of proteins
- Loss of RBCs
- Low blood pressure due to low renin
32
Symptoms of Renal Failure
- Vomiting, diarrhea, cellular necrosis (due to toxins)
- Osteoporosis (due to Ca loss)
- Nerve and muscle effects (due to Na/K)
- Edema (due to protein loss)
- Anemia (due to RBC loss)
- Dizziness (due to low blood pressure)
33
Kidney Stones
- Due to crystallization of minerals in kidney, ureters, or bladder
- Made of calcium and oxalates, meaning vegetables like spinach and beets can be a cause
- Can be due to dehydration, especially with binge drinking
34
Acid-Base Balance
- Normal pH is 7.38-7.42
- H concentration is closely regulated to control balance
35
Abnormal pH Effects
- Altered protein structure
- Nervous system effects
36
Acidosis
- Low pH
- Metabolic can be due to exercise (lactic acid buildup), ketoacid buildup, or organic acid intake
- Respiratory can be due to decreased ability to expel CO2
- Both can depress the nervous system, making neurons less excitable
37
Alkalosis
- High pH
- Metabolic can be from bases in the diet, and can cause vomiting and pyloric stenosis
- Respiratory can be from hyperventilation such as at high altitudes
38
pH Homeostasis
- Buffers can combine with or release H as needed, fastest response, can include phosphates, proteins such ad HB, and bicarbonate
- Ventilation balances H levels by changing rate and depth of breathing
- Renal regulation is the slowest, but also balances H
39
Intercalated Cells
- Type A function in acidosis, secrete H, and reabsorb bicarb
- Type B function in alkalosis, secrete bicarb, and reabsorb H
