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Week 9 an phys Flashcards

1
Q

Percentage of body weight is total body fluid

A

60%

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2
Q

Percentage of body weight is intracellular fluid

A

40%

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3
Q

Percentage of body weight is extracellular fluid

A

20%

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4
Q

Percent of body weight is plasma

A

4%

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5
Q

Percent of body weight is interstitial fluid

A

16%

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6
Q

Hypertonic

A
  • Water moves out of blood cell
  • 1000 mOsm, seawater
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7
Q

Isotonic

A
  • Conditions are normal
  • 300 mOsm, 0.9% NaCl
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8
Q

Hypotonic

A
  • Water moves into cell
  • 100 mOsm
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9
Q

Calculation of Osmolarity

A
  • mM multiplied by number of particles
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10
Q

Intracellular percent of body water

A

67%

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11
Q

Interstitial percent of body water

A

27%

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12
Q

Circulating plasma percent of body water

A

6%

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13
Q

How many times do the nephrons filter the plasma per day

A

60x

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14
Q

Water filtered per day/excreted per day/% reabsorbed

A

180 L/day filtered per day
1.8 L/day excreted per day
99% reabsorped

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15
Q

Intake of water per day

A
  • Drink
  • In food
  • Metabolically produced
  • Total: 2550 mL/d
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16
Q

Output of water per day

A
  • Sweat
  • Feces
  • Urine
  • Total: 2550 mL/d
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17
Q

Key regulator of water output

A

Urine

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18
Q

If water intake doubles

A
  • Water excreted per day doubles (3.6 L/day) and only 98% is reabsorbed
  • Osmolarity decreases
  • Detected by chemoreceptors in hypothalamus
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19
Q

Sodium filtered per day/excreted per day/% reabsorbed

A
  • 630 g/day filtered
  • 3.2 g/day excreted
  • 99.5% reabsorbed
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20
Q

If sodium intake is increased

A
  • Osmolarity increases
  • Detected in Kidney
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21
Q

Glucose filtered per day/excreted per day/% reabsorbed

A
  • 162 g/day filtered
  • 0 g/day excreted
  • 100% reabsorbed
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22
Q

If glucose intake is increased

A
  • Blood glucose increases
  • Detected by Beta Cells of pancreas- insulin
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23
Q

Percent of blood flow going to kidney

A

22%

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24
Q

Osmolarity of Renal Cortex

A

300 mOsm

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25
Osmolarity of Renal medulla
1200 mOsm
26
Regions of the kidney
- Renal cortex (outer) - Renal medulla (inner): medulla is divided into renal pyramids in larger mammals - Renal pelvis: drainage area in center of kidney
27
Nephron
- smallest functional unit of the kidney - 1 million nephrons in human kidney - Consists of a tubule and associated vascular component
28
Juxtamedullary nephron
long looped nephron important in establishing the medullary vertical osmotic gradient
29
Juxtamedullary nephron components
1. Bowmans capsule 2. Glomerulus 3. Proximal convoluted tubule 4. Thin descending limb 5. Thin ascending limb 6. Thick ascending limb 7. Distal convoluted tubule 8. Collecting duct 9. afferent and efferent arteriole 10. Peritubular capillaries
30
Loop of Henle
Descending and ascending limbs used to establish a concentration gradient
31
Cortical vs juxtamedullary nephrons
Cortical nephrons: - Glomeruli in outer cortex - Short loops of Henle dip only into outer medulla Juxtaglomerular nephrons: - Glomeruli in inner cortex near medulla - Long loops of henli plunge into inner medulla - Peritubular capillaries from hairpin vascular loops
32
Four basic renal processes
1. Filtration 2. Secretion 3. Reabsorption 4. Osmoconcentration
33
Function of Glomerulus-Bowmans Capsule
Filtration of blood
34
Function of proximal tubule
Reabsorption
35
Function of loop of henle
Establishment of osmotic gradient
36
Function of distal tubule
Regulated reabsorption and secretion
37
Function of collecting ducts
Regulated removal of water
38
Bladder
Excretion of waste
39
How many liters of plasma enter kidney per day
900 L
40
Liters of plasma filtered into bowmans capsule per day
180 L
41
Molecular sieve layers
- Glomerular capillary wall - Basement membrane - Inner layer of Bowman's capsule
42
Glomerular capillary wall
-Single layer of flattened endothelial cells - Perforated with pores - Pores are too small for proteins to pass
43
Basement membrane
- Gelatinous layer composed of collagen and glycoproteins - Glycoproteins further limit protein movement
44
Inner layer of Bowman's capsule
consists of podocytes with filtration slits
45
Is filtration in nephron intercellular or extracellular
Extracellular
46
Driving forces of glomerular filtration
- Glomerular capillary blood pressure (higher than capillary blood pressure elsewhere) (55 mmHg) - Plasma colloid osmotic pressure (30 mmHg) - Bowman's capsule hydrostatic pressure (15 mmHg)
47
Net filtration pressure
55 - ( 30 + 15) = 10 mmHg
48
Glomerular filtration rate (GFR)
- Depends on net filtration pressure, surface area and permeability of glomerular membrane - Filtration coefficient x net filtration pressure - 20% of plasma that enters the glomerulus is filtered - GFR is an adult human is 115-125 mL/min or ~180 L/day
49
Glomerular Capillary Blood Pressure
Favors filtration - 55 mmHg
50
Plasma-Colloid Osmotic Pressure
Opposes filtration - 30 mmHg
51
Bowman's Capsule Hydrostatic Pressure
Opposes filtration- 15 mmHg
52
Net Glomerular filtration pressure
Favors filtration - 10 mmHg
53
Contents of Plasma
- Water and salts (300 mOsm) - Nutrients (Glucose and amino acids) - Small proteins and large proteins - Blood cells
54
Contents of Glomerular Filtrate
- Water and salts (300 mOsm) - Nutrients (Glucose and amino acids) - Some small proteins
55
Blood pressure in Glomerulus
55 mmHg
56
Osmotic pressure in plasma due to proteins
30 mm Hg
57
Hydrostatic pressure in Glomerular Filtrate
15 mmHg
58
Osmotic pressure due to proteins in Glomerular Filtrate
0 mmHg
59
Production of filtrate at the glomerulus occurs primarily by what
Bulk flow
60
Molecule exchange by location in nephron
- Proximal tubule: Mostly reabsorption of HCO3, NaCl, H2O, Nutrients, K+ - Descending loop: Reabsorption of H2O - Ascending loop: Reabsorption of NaCl - Distal Tubule: Reabsorption of NaCl and H2O
61
Percent of salt, water and glucose reabsorbed by mammalian tubules
- 99% salt and water - 100% glucose and amino acids
62
Where does most reabsorption occur
Proximal tubule
63
Is reabsorption passive or active
Can be either
64
What two things must a substance pass through to be reabsorbed
Renal tubular epithelial cell and capillary wall
65
Path of reabsorption
1. Luminal membrane of tubular epithelial cell 2. Cytosol of tubular epithelial cell 3. Basolateral membrane of epithelial cell 4. Interstitial fluid 5. Capillary wall
66
Where does regulation of water occur mostly
Collecting duct due to actions of ADH (Anti-diuretic hormone)
67
Is reabsorption of water passive or active
- Passive - H2O passively follows osmotic gradient across both membranes
68
Thick Ascending limp of loop of Henle and Water
Thick Ascending limp of loop of Henle is impermeable to water
69
How is reabsorption of water from collecting duct regulated
Subject to hormonal control
70
Aquaporins (AQPs)
- AQP-1 channels in proximal tubule are always open (common) - AQP-2 channels in collecting duct are regulated by ADH (vasopressin) (unique to cells of collecting duct and are hormonally regulated)
71
Where are AQP-1 channels found
Luminal membrane of tubular epithelial cell and basolateral membrane of tubular epithelial cell in proximal tubule
72
Purpose of Aquaporins
Allows water to cross membranes using osmosis
73
How much of the kidney's total energy requirement is used for Na+ transport
80%
74
Is Na+ reabsorption active or passive
- Active in most sections of the tubule but passive in some (basolateral vs luminal membrane) - Active steps involve Na+/K+ ATPase pump in basolateral membrane - Transport of Na+ across luminal membrane is passive (Na+/glucose cotransporter is located in luminal membrane)
75
Where is Na+ reabsorbed
- Proximal tubule (67%) - Loop of Henle in Ascending limb (25%) (Na+ is not reabsorbed from the descending limb) - Distal tubule (8%)
76
Reabsorption of glucose and amino acids
- 100% reabsorbed, reflecting their nutritional value - Secondary active transport - Symporter in apical membrane transports Na+ down its concentration gradient and a specific organic molecule up its gradient from the lumen into the tubular cell - Basolateral Na+/K+ pump indirectly drives this cotransport system - Once inside the cell, the organic molecule is transported into ECF by facilitated diffusion
77
Renal threshold
- Max Plasma concentration of glucose in which the about of glucose reabsorbed is able to match the amount that is filtered - After renal threshold is reached, the amount of glucose excreted starts to increase from 0 - The amount reabsorbed falls below what is being filtered and slowly increases until it reaches the tubular maximum
78
Tubular maximum (Tm)
- Max amount of glucose that can be reabsorbed - Once this maximum has been reached, the amount reabsorbed remains constant and the excretion rate skyrockets
79
What causes Tubular maximum
- Plasma membrane carriers exhibit saturation
80
Glucose reabsorption in diabetes mellitus
- Plasma glucose is high in diabetes mellitus (hyperglycemia) - Glucose is filtered into Bowman's capsule at the same concentration as in plasma - When filtered glucose exceeds Tm for glucose reabsorption, the excess spills over into urine (first occurs at renal threshold) - Glucose in urine is diagnostic of diabetes mellitus
81
Where does passive transport of Na+ occur
Thin Ascending limb
82
Where does active transport of Na+ occur
- Thick Ascending limb - Collecting duct
83
Osmolarity of Proximal Tubule
300 mOsm
84
Osmolarity of Descending and Ascending Loop of Henle
600 mOsm
85
Osmolarity of bottom of loop of Henle
1200 mOsm
86
Osmolarity of Thick Ascending Loop of Henle
200 mOsm
87
Osmolarity of Distal Tubule
100 mOsm
88
Where is Urea reabsorbed
Collecting duct towards the bottom
89
Why can urine be more concentrated than plasma
- The inner medulla of the kidney has a very high osmolarity due to: - Active NaCl in thick ascending limb of loop of henle - Thick ascending limb being relatively impermeable to water so NaCl is left behind in the medulla - Urine can have variable osmolarity due to selective permeability of collecting duct to water (ADH)
90
Antidiuretic Hormone (ADH) Vasopressin
- Increases osmolarity of urine and decreases urine volume - Is secreted when there is an increase in blood osmolarity - Increases water channels in collecting duct - Water will be removed from collecting duct resulting in concentrated urine
91
What triggers release of ADH
- Osmoreceptors in hypothalamus trigger release of ADH from the hypothalamus when blood osmolarity is high and also increases thirst
92
Feedback loop of ADH
- Hypothalamus triggers release of ADH and thirst - Drinking reduces blood osmolarity and ADH increases collecting duct permeability resulting in H2O reabsorption which helps prevent further osmolarity increase - Decrease of blood osmolarity results in decrease of ADH and thirst
93
Collecting duct when no ADH is present
Collecting duct is not permeable to water
94
Collecting duct when ADH is present
Collecting duct is highly permeable to water
95
AQP-2
- Water channel regulated by ADH - Premade and packaged in vesicles - ADH stimulates exocytosis and AQP-2 insertion in Luminal membrane
96
AQP-3 and AQP-4
in Basolateral membrane
97
Process of how ADH works
- ADH from blood binds to ADH receptor located in basolateral membrane of tubular epithelial cell - ATP is used and cAMP is created in cytosol - cAMP increases permeability of luminal membrane to H2O by inserting new AQP-2 water channels
98
Decrease in Arterial Blood pressure will do what to Urine
- A decrease in glomerular capillary blood pressure (due to general arteriolar vasoconstriction) will lead to decreased urine volume and and increase in conservation of fluid and salt - This is a long-term adjustment to increase arterial blood pressure
99
Pathway of Angiotensinogen
- Liver releases angiotensinogen - Kidney releases renin - Renin converts angiotensinogen to angiotensin I - Lungs release Angiotensin converting enzyme - Angiotensin converting enzyme converts angiotensin I into angiotensin II
100
Role of Angiotensin II
- Increases vasopressin (which increases H2O reabsorption by kidney tubules) - Increases thirst (which increases fluid intake) - Causes arteriolar vasoconstriction - These three things help correct low arterial blood pressure and low ECF volume
101
Aldosterone
- Secreted by adrenal cortex - Acts on kidney to increase Na+ reabsorption by kidney tubules which increases the amount of H2O conserved when blood volume is low - Decreases K+ concentrations when K+ is high** - Acts in distal tubule and early collecting duct - Helps correct low NaCl and low arterial blood pressure
102
Two Clinical Examples of Excessive Urine Flow
-Diabetes Insipidus (rare) - Diabetes Mellitus
103
Diabetes insipidus
- High urine flow rate - not sweet - Lack/Deficiency of ADH
104
Diabetes Mellitus
- High glucose in blood - Sweet urine - high urine flow rates - High filtered glucose is not all reabsorbed in PT - Glucose reaches collecting ducts and provides osmolarity to reduce H2O reabsorption
105
Weak osmoconcentrators
- Water dwelling mammals - Have primarily cortical nephrons - Don't need to reabsorb as much water since their environment has abundant water
106
Strong osmoconcentrators
-Desert-dwelling mammals - Juxtamedullary nephrons with long loops of Henle - Elongated medulla has an exaggerated vertical osmotic gradient - Countercurrent multiplier is more active in small mammals with higher metabolic rates
107
Regulated variable of ECF volume
- Long term control of arterial pressure - Regulated via maintenance of salt balance by aldosterone and Na+ excretion
108
Regulated variable of EDF osmolarity
- Prevent detrimental osmotic movement of water from ECF into or out of cells - Regulated by maintenance of free H2O balance by ADH

AN SCI 373 (9 decks)

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