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Kidney > Physiology > Flashcards

Physiology Flashcards

(120 cards)

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1
Q

What are the three roles of the kidneys

A

Maintain balance of salt, water and pH

Endocrine function - secreting hormones

Excrete products

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2
Q

What is the renal blood flow

Cardiac output
Renal blood flow
Urine flow

A

Cardiac output approx. 5 L/min

Renal blood flow approx. 1L/min

Urine flow approx. 1 mL/min

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3
Q

What is the order of renal blood supply

A

Renal artery
Interlobar artery
Arcuate artery
Interlobar artery
Afferent arteriole
(Nephron) - glomerular capillary then peritubular capillary

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4
Q

What are the two capillary beds in the nephron

A

Glomerular capillary
Peritubular capillary

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5
Q

What does the passage of fluid from the blood into Bowman’s space form

A

Filtrate

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6
Q

What is the approx surface area involved in glomerular filtration

A

1m2

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7
Q

What is the distal part of the nephron responsible for

A

Secretion and reabsorption

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8
Q

What are the five determinants which effecting the movement across the filtration barrier

A
  1. Pressure
  2. Size of the molecule
  3. Charge of the molecule
  4. Rate of blood flow
  5. Binding to plasma proteins e.g. calcium, hormones such as thyroxine
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9
Q

What can freely pass the filtration barrier

A

Small molecules and ions up to 10kDa

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10
Q

Name examples of ions which are up to 10kDa

A

Glucose
Uric acid
Potassium
Creatine

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11
Q

What is restricted crossing the filtration barrier

A

Larger molecules

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12
Q

What cannot cross the filtration barrier

A

Negatively charged anions

Due to the fixed negative charge in the glomerular basement membrane repels these

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13
Q

What are the key features of Albumin

A

66kDa - molecular weight

Negatively charged

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14
Q

What is the protein called in urine which is produced by tubule

A

Tamm Horsfall protein

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15
Q

What is filtered fluid free from

A

Proteins

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16
Q

What is the renal blood flow ml/min

A

1250

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17
Q

What is the renal plasma flow ml/min

A

700ml/min

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18
Q

What is the glomerular filtration rate ml/min

A

120ml/min

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19
Q

What is the urine flow rate ml/min

A

1ml/min

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20
Q

What is the bodies normal pH (hydrogen ion) range

A

7.35-7.45

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21
Q

What is the bodies normal pH (hydrogen ion) range

A

7.35-7.45

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22
Q

What is the minimum urine hydrogen ion concentration (pH)

A

4.5

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23
Q

Define Base

A

Accepts hydrogen ions

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24
Q

Define acid

A

Donates hydrogen ions

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25
Carbohydrates + fats =
Carbonic acid
26
Number the buffers involved in dietary acid load
Plasma protein Haemoglobin Extracellular bicarbonate Intracellular carbonate Phosphate
27
What is the name of the protein which is present in urine produced by the tubule
Tamm Horsfall
28
What is the renal corpuscle made up of
Glomerulus (tuft capillaries) + Bowman's capsule
29
What goes is the blood flowing into the glomerulus
Afferent arteriole
30
What is the blood flowing out of the glomerulus
Efferent arteriole
31
What does the glomerulus contain
Endothelial layer Glomerular basement membrane
32
What does the endothelial layer contain
Fenestrated capillaries
33
What is the role of fenestrated capillaries
Cannot filter formed elements e.g. blood cells Can filter elements less than 100nm in diameter
34
What are the layer of the glomerular basement membrane and its role
Lamina rara interna (heparin sulphate) Lamina Densa (type 4 collagen with laminas) Lamina rare externa (heparin sulphate)
35
What is the role of the glomerular basement membrane
Negatively charged on both sides Cannot pass negative molecules e.g. plasma proteins Easily pass positively charged molecules e.g. sodium Can pass (but not as well as positively charged) negatively charged molecules e.g. chloride
36
What is the Bowman's capsule made up of
Parietal layer Visceral layer (podocytes)
37
What is the role of podocytes
Slit diaphragm in-between made of nephrin Only allows less than 10nm through
38
What can pass through the renal corpusal
Charged ions less than 10nm
39
What can pass through the endothelial layer
Most substances 50-100nm
40
What cannot pass through the glomerular basement membrane
Negative molecules repelled
41
What can pass through the visceral layer of the renal corpuscle
Less than 10nm
42
What happens in the Renal corpuscle if a macromolecule e.g. plasma protein was to get stuck in the slit diaphragm
Phagocytosed by mesangial cells
43
What are the role of mesangial cells
Phagocytosis Control the amount of blood flow Gap junctions with juxtaglomerular cells
44
Define glomerular filtration rate
Filtration rate per unit of time (minutes)
45
What percentage of blood that passes into the renal corpuscle will be filtered
20%
46
What happens to hydrostatic pressure along the length of the capillary
Constant along the length
47
What happens to osmotic pressure along the length of the capillary
Rises along the length
48
What affects GFR
Net filtration rate Surface area Permeability of glomerulus
49
Define Osmolality
The concentration of a solution expressed as the total number of solute particles per kilogram
50
What is the volume of urine
400ml-20L in 24 hours
51
What is the pH of urine
4.5-8
52
What is the concentration of sodium in urine
100-300 mmol/24 hours
53
What is the concentration of potassium in urine
50-450 mmol/24 hours
54
What is the concentration of glucose in urine
less than 1 mmol/24 hours
55
What is the amount of amino acids in urine
Very little
56
What is the concentration of HCO3 in urine
1 mmol/24 hours
57
How much filtrate is there per day
180 L/day
58
What is the main principle of the proximal convoluted tubule
Bulk absorption (leaky)
59
What is the main principle of the distal convoluted tubule
Fine tubing (impermeable)
60
What is the order of the nephron segments
Proximal convoluted tubule Proximal straight tubule Thin descending limb Loop of Henle Thin ascending limb Thick ascending limb Collecting tubule Distal convoluted tubule Collecting
61
What parts of the nephron segments are in the cortex
Proximal convoluted tubule Proximal straight tubule Thick ascending limb Collecting tubule Distal convoluted tubule
62
What parts of the nephron segments are in the medulla
Think ascending limb Loop of Henle Thin ascending limb Collecting duct
63
What is the functions of the proximal tubule
Bulk reabsorption of - Na - Cl - Glucose - Amino acids - HCO3- Secretion of organic ions
64
What is the functions of the Loop of Henle
More Na reabsorption Urinary dilution Generation of medullary hypertonicity
65
What is the function of the Distal convoluted tubule
Fine regulation of Na, K, CA, Pi Separation of Na from H2O
66
What is the function of the collecting duct
Similar to distal tubule More acid secretion Regulated H2O reabsorption concentrating urine
67
What is bulk reabsorption in the proximal tubule driven by
Basolateral NaKATPase
68
Where is the majority of bulk reabsorption achieved in the proximal tubule
Mostly achieved in the first half
69
What permeability is the proximal convoluted tubule to H2O
Highly
70
What is the basolateral layer
Between the cell and the capillary
71
What is the apical layer
Between the cell and the lumen (of the proximal convoluted tubule)
72
What is secondary active transport
A molecule which is going against its concentration uses a molecule is going with its concentration gradient to move across the cell
73
What is the movement of potassium and sodium in ATPase
3 Na+ out 2 K+ IN
74
Which molecules move across the apical membrane using secondary active transport (into the cell)
2Na+ and glucose Na+ and phosphate Na+ and amino acids
75
What molecules in the proximal convoluted tubule make there way through the basal lateral membrane
Glucose Amino acid Lactate
76
What percentage of glucose, amino acids and lactate are reabsorbed into the capillary
100%
77
What is the process of bicarbonate filtration in the proximal convoluted tubule
In lumen Proton (H+) reacts with bicarbonate (HCO3-) to make carbonic acid Carbonic anhydrase breaks this into CO2 and H2O CO2 moves into the cell and reacts with water (using carbonic anhydrase) inside the cell to form carbonic acid Carbonic acid is not stable Dissociates into bicarbonate and proton Bicarbonate used sodium to move into capillary
78
Within the proximal convoluted tubule the reaction of bicarbonate from the lumen to capillary how many bicarbonate ions are secreted into the capillary
3
79
Define glucose: Tubular maximum
As plasma glucose increases at a specific amount the amount of glucose reabsorbed will stay the same and the amount of glucose excreted will increase
80
How does some potassium and chloride ions move across the cell in the proximal convoluted tubule
Using tight junctions between cells
81
How are endogenous compounds (creatinine, urate and bile salts) and drugs transported in the proximal convoluted tubule
Active transport Uses organic cation/anion transporters
82
Define glomerulotubular balance
More filtered load is matched by more proximal tubular reabsorption
83
What does a greater filtration factor in the proximal convoluted tubule cause
Increases osmotic pressure in downstream peritubular capillaries Sucks more back
84
What does efferent arteriolar constriction in the proximal convoluted tubule cause
Reduces peritubular capillary hydrostatic pressure
85
What are the two ways that glomerulotubular balance is achieved
Greater filtration factor Efferent arteriolar constriction
86
What is the osmolality in the glomerulus compared to when entering the proximal convoluted tubule
Same Isotonic with the blood plasma
87
What is the osmolality when entering the Loop of Henle
Same as the glomerulus Isotonic with the blood plasma Na+ and water are reabsorbed in the same amounts
88
Where does solute reabsorption occur within the loop of Henle
Thick ascending limb
89
What is the aim of countercurrent in the loop of Henle
Generate a hypertonic medullary interstitium so that H2O can be sucked out of the tubule in impermeable segments, thus concentrating the urine
90
What is another word for high osmolality
Hypertonic
91
What is another word for low osmolality
Hypotonic
92
How does counter current multiplier mechanism work
1. Ascending limb lowers luminal osmolality and increases the medullary interstitial osmolality 2. Increased interstitial osmolality draws H2O out of the descending limb, luminal osmolality increases 3. Continuous flow of fluid pushes the hyperosmotic fluid from end of the thin limb to the ascending limb
93
What does the counter current multiplier mechanism create
Medullary interstitial osmotic gradient
94
What are the reasons why blood flow does not wash of the osmotic gradient achieved in the counter current multiplier mechanism
Vasa recta Long capillaries extend into the medulla Permeability to solute/water
95
What allows water to move out of the descending limb in the counter current multiplier mechanism
Aquaporin type 1 channels Passive
96
Is the descending limb permeable to water
Yes
97
Is the descending limb permeable to solute
No
98
Is the ascending limb permeable to water
No
99
Is the ascending limb permeable to solute
Yes
100
How do solutes move out of the cell in the ascending limb
Na+/K+/2Cl- co-transporters Move Na+ K+ 2Cl- Out of the cell
101
What also contributes to medulla hypertonicity (Loop of Henle)
Back leak of urea out of the medullary collecting duct
102
What is the gradual medullary interstitial osmotic gradient
From 300 700 1000 1200 Moving down the lumen
103
Osmolarity
The concentration of a solution expressed as the total number of solute particles per litre
104
What is the role of the distal tubule
Continues the active dilution of urine by reabsorption of Na+ in water impermeable setting
105
What are the two divisions of the distal convoluted tubule
Early Late
106
What is the late distal convoluted tubule responsive too
On hormones
107
What happens in the early distal convoluted tubule
Parathyroid hormone - works out how much Ca2+ is in the blood Parathyroid actives Ca2+ transporters to get into the cell Pumps out Ca2+ into the bloodstream
108
How does sodium get into the cell in the early distal convoluted tubule
Sodium chloride symporter (same direction) Na+ and Cl-
109
What happens in the late distal convoluted tubule
Aldosterone responding cells Allows the pumping of Na+ out of the cell and K+ into the cell
110
Is the collecting duct permeable to water
Impermeable
111
What is the collecting duct surrounded by
Hypertonic medullary insterstitium
112
What is collecting duct regulated by
Na reabsorption K secretion Acid secretion Water reabsorption
113
What are the two types of cells found in the collecting duct
Principal cell Intercalated cell
114
What is the mechanism of ADH on the collecting duct
ADH acts on receptor Increases cAMP - kinases - vesicle shuttling H2O enters the cell by the aquaporin 2 into the cell and leaves into the blood
115
What is the action of aldosterone on the collecting duct
Increases transcription (steroid receptor) of ENaC (and NaKATPase) Increases apical Na influx Charge movement facilitates K efflux
116
What does aldosterone drive in the collecting duct
Na reabsorption K secretion
117
What cell does ADH (vasopressin) act on
Principal cells
118
What is the action of ADH in the collecting ducts
Adenylyl-cyclase coupled vasopressin receptor (V2R) Kinase actions culminate in insertion of vesicles containing aquaporin 2 into the apical membrane Increases water permeability
119
Define osmolaRity
Number of particles per litre of fluid NUMBER of particles
120
Define osmolaLity
Total solute concentration within a specific volume of solute expressed in osmoles per litre (osm/L)

Kidney (7 decks)

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