The Renal System Flashcards
1
Q
In general, how many kidneys do most humans have?
A
2
2
Q
What are the functional units of the kidney?
A
Nephrons
3
Q
What would you expect to find in your urine?
A
- Sodium
- Creatinine
- Water
- Urea
4
Q
What is filtration?
A
Filteration of 200 L of blood daily
-Toxins, metabilic wastes and excess ion leaves the body in urine
5
Q
What are the major functions of the kidney?
A
Filtration, excretion and regulation
6
Q
What is secretion?
A
Hormones and foreign substances excrete blood
7
Q
What does the kidney regulate?
A
Water, electrolytes and acids and bases
8
Q
How does the kidney regulate the concentration of following ion in plasma?
A
Increasing or decreasing excretion in urine
9
Q
What ions can be excreted via the kidney?
A
Na+, K+, Ca2+, Mg2+, Cl-, HCO3-, H+, PO4-2
10
Q
What is the endocrine function of the kidney?
A
- Long-term regulation of blood O2 carrying capacity
- Long-term blood pressure regulation
- Activation of vitamin D
11
Q
How does the kidney endocrine function allow long-term regulation of blood O2 carrying capacity?
A
RBC production by bone marrow through erythropoietin (EPO) release
12
Q
How does the kidney endocrine function allow long-term regulation of blood pressure?
A
Controlling water excretion which controls blood volume with the help of renin
13
Q
How does the kidney endocrine function allow activation of vitamin D?
A
Parathyroid hormone (PTH) activates 1α-hydroxylase in the proximal tubule which vitamin D3 is activated
14
Q
What does the renal system consist of?
A
- Diaphragm
- Kidney
- Ureter
- Bladder
- Urethra
15
Q
Which kidney is lower than another?
A
Right kidney is lower
16
Q
Why is the right kidney lower than the left kidney?
A
As the liver is above it
17
Q
What is above the left kidney?
A
Spleen
18
Q
What is on top of both kidneys?
A
Adrenal gland
19
Q
What is the adrenal gland responsible for?
A
Production of hormones e.g aldosterone
20
Q
What is the kidney composed of?
A
vascular system and renal parenchyma
21
Q
What makes up the vascular system and renal parenchyma in the kidney?
A
Renal artery
Renal vein
Renal nerves
22
Q
What is the renal artery?
A
Supplies the kidney blood
Subdivides to form afferent arteriol
23
Q
What is the renal vein?
A
Returns blood back into circulation
24
Q
What is the renal nerves?
A
Innervated by sympathetic nervous system
25
What does the afferent arteriole supply?
Blood to each and all nephrons within the kidney
26
What are the three major regions in the kidney?
- Renal cortex
- Renal medulla
- Renal pelvis
27
What is the renal pelvis?
Urine collected from major and minor calyxes to be directed towards ureter then the bladder
28
What does the renal cortex contain?
Renal corpuscles
29
What is the renal corpuscles?
- Network of capillaries surrounded by mesangial cells and encapsulated by Bowmans capsule
- Filtrated collected and directed to proximal tubule
- Distal tubule meets with afferent and efferent arterioles
30
What occurs in renal cortex?
Filtration
31
What occurs in renal medulla?
Concentration of urine
32
What does the nephron contain?
- Afferent arteriole
- Bowmans capsule
- Glomerulus
- Efferent arterioles
- Proximal convoluted tubule
- Peritubular capillaries
- Distal convoluted tubule
- Collecting duct
- Loop of Henle
- Vasa recta
33
What does each nephron has it own supply of?
Blood
34
What is the order of contents of the nephron?
- Afferent arteriole
- Bowmans capsule (Peritubular capillaries)
- Efferent arterioles
- Proximal convoluted tubule
- Distal convoluted tubule
- Loop of Henle
- Collecting duct
35
How does the blood supply the nephron?
- Blood enters through afferent arterioles
- Subdivides into capillaries where filtration occurs
- Come back together to form efferent arterioles
- Further subdivided in to peritubular capillaries
- Specialised vasa recta
- Joins back together and takes blood back to circulation via renal vein
36
What are Bowmans capsule surrounded by?
Network of capillaries
37
How many nephrons are there in the kidney?
1,00,000
38
What are the two types of nephrons?
Cortical nephron
| Juxtamedullary nephrons
39
What % of neurones is cortical nephron?
80%
40
What % of neurones is juxtamedullary nephron?
20%
41
What are the features of a cortical nephron?
- Glomeruli located towards surface of kidney
| - Penetrate very little of medulla
42
Why is glomeruli located towards surface of kidney in a cortical nephron?
Due to arcuate artery extending renal pyramid to external cortex
43
What are the features of juxtamedullar nephron?
Glomeruli located towards medulla deeply
44
What is the difference from the cortex to the medulla?
Hypertonicity (how salty) increases from cortex to medulla
45
What facilitates filtration?
High pressure
46
What are the four fundamental mechanisms of the nephron?
1. Filtration
2. Reabsorption
3. Secretion
4. Excretion
47
What is the equation for excretion?
Excretion = filtration - reabsorption + secretion
48
Describe the filtration within renal corpuscle:
- High pressure from difference of size in diameter of afferent and efferent arterioles allow passive filtration
- Blood enters through afferent arterioles to subdivide into capillary network to leave via efferent arterial
49
What are blood vessels surrounded by?
Podocyte and renal nerves
50
What are macula densa?
- Modified distal tubule cells
| - Chemoreceptors
51
What are juxtaglomerular cells?
- Specialised smooth muscle cells
- Renin secretion
- Mechanoreceptors
52
What is contained in the glomerus filtrate?
Water, glucose, amino acids and urea
53
What is the filtration membrane of the glomerulus?
- Capillary endothelial fenestration (prevents large proteins from entering bowman space)
- Gel-like basement membrane (negatively charged so repels proteins)
- Slit diaphragm
54
What is the glomerular filtration rate?
Amount of filtrate that forms in both kidneys per minute
55
What is the average glomerular filtration rate in adult females?
105ml/min
56
What is the average glomerular filtration rate in adult males?
125ml/min
57
How much of the cardiac out is directed towards the kidneys?
22%
58
What is the daily volume of filtrate passing into nephrons in female?
150L
59
What is the daily volume of filtrate passing into nephrons in male?
180L
60
Why is it important for maintaining the glomerular filtration rate?
- Precise regulation of blood fluid volumes and solute concentration
- Excretion of waste products
61
Why is glomerular filtration rate closely maintained?
If too high: filtrate will pass through tubules too quickly and cannot be reabsorbed
If too low: waste products are not excreted
62
What could happen if glomerular filtration rate is too low?
Chronic renal failure
63
How is glomerular filtration controlled?
By action of sympathetic nervous system, hormones and intrinsic mechanisms
64
What volume of urine does a healthy person produce in a typical day?
1.5-1.8 litre
65
What is filtration coefficient?
Surface area available for filtration
| Filtration membrane permeability
66
What is net filtration pressure?
Cumulative pressure responsible for filtrate formation
67
Why is the pressure high in glomerulus ?
- Arterioles have high resistance
- Afferent diameter > efferent diameter
- Fluids and solutes forced out of blood
68
What does changes in glomerular filtration rate change?
Glomerular blood pressure
69
What is the equation for net filtration pressure?
Net filtration pressure = outward pressure - inward pressure
70
What happens to the glomerular filtration rate if afferent arteriole constricts?
Decrease in glomerular filtration rate
71
What happens to the glomerular filtration rate if efferent arteriole constricts?
Increase in glomerular filtration rate
72
What happens to the glomerular filtration rate if efferent arteriole dilation?
Decrease in glomerular filtration rate
73
What happens to the glomerular filtration rate if afferent arteriole dilation?
Increase in glomerular filtration rate
74
What is renal auto regulation?
Act locally to maintain glomerular filtration rate constant
75
How does renal auto regulation work?
- Myogenic
| - Tubuloglomerular feedback
76
What is an intrinsic controls of glomerular filtration rate?
Renal autoregulation
77
How does myogenic regulate glomerular filtration rate?
Constriction/dilation of afferent article in response to changes in blood pressure
78
How does tubuloglomerular feedback regulate glomerular filtration rate?
Contraction/dilation of afferent arteriole in response to changes in NaCl in the distal tubule (renin and adenosine)
79
What are extrinsic controls of glomerular filtration rate?
- Hormonal regulation
| - Autonomic regulation
80
When does extrinsic controls take over to maintain glomerular filtration rate?
If systematic blood pressure is <80 or >180
81
What would happen to the glomerular filtration rate if a person suffered from severe malnutrition?
increase
82
What happens in an increase in blood pressure?
- Afferent arterioles contrics
- Glomerular capillary blood pressure decreases
- Net filtration pressure decreases
- Glomerular filtration rate decreases
83
What happens in a decrease in blood pressure?
- Afferent arterioles dilates
- Glomerular capillary blood pressure increases
- Net filtration pressure increases
- Glomerular filtration rate increases
84
Where does most of water, electrolytes and nutrients filtered get reabsorbed?
Proximal tubule
85
How much water is reabsorbed is reabsorbed in the proximal tubule?
65%
86
What essential nutrients are reabsorbed back into the blood within the proximal tubule?
Water, glucose, amino acids and electrolytes
87
What does reabsorption in the proximal tubule rely on?
Secondary active transport of Na+ across the apical membrane powered by basolateral Na+/K+ ATPase pumps
88
Is the descending loop permeable or impermeable to water?
Permeable to water
89
Is the ascending loop permeable or impermeable to water?
Impermeable
90
How does reabsorbing occur in the loop of Henle?
- Water reabsorbed by osmosis along descending loop
- Na+ is actively reabsorbed along ascending loop by Na+/K+/2Cl-/ cotransportes (powered by basolateral Na+/K+ ATPase pumps)
- Smaller volume of dilute filtrate leaving the loop of Henle and entering the distal tubule
91
What gradient does the long loop of Henle in juxtamedullary nephrons establish in the renal medulla?
Vertical osmotic gradient
92
Why is it important for the juxtamedullary nephrons to establish a vertical osmotic gradient?
- Allows extra water reabsorption from collecting duct into salty environment of inner medulla when needed
- Water to be conserved during states of dehydration
93
What controls the vertical osmotic gradient?
Anti-diuretic hormone (ADH)
94
How does reabsorption occur in distal tubule and collecting duct?
- Aldosterone = binds to receptors on the distal tubule and collecting duct to promote Na+ and water reabsorption and K+ secretion
- Anti-diuretic hormone = binds to receptors on the collecting duct to promote water reabsorption through aquaporins
95
What happens if over hydration of water?
- No water conversation required
- No ADH released from posterior pituitary
- Large volume of dilute urine
96
What happens if dehydration of water?
- Water conversation required
- ADH release from posterior pituitary
- Small volume of concentrated urine
97
What is the role of the kidney in long-term blood pressure regulation?
- Juxtaglomerular apparatus
| - Tubuloglomerular feedback
98
How does the juxtaglomerular apparatus help in long-term blood pressure regulation?
- Monitors and responds to a fall in blood pressure and GFR
| - Decrease in filtered Na+ by activating renin-angiotensin-aldosterone system (RAAS)
99
How does tubuloglomerular feedback help in long-term blood pressure regulation?
Adjusts afferent article diameter which affects the glomerular filtration rate
100
Describe the renin-angiotensin-aldosterone system (RAAS) when the blood pressure decreases:
- Juxtaglomerular apparatus senses decreases
- Renin is released from juxtaglomerular cells
- Renin cleaves to angiotesinogen to angiotensin I
- Converted to angiotensin II (occurs with help my angiotensin converting enzyme)
- Promotes constriction of blood vessels
- Acts on adrenal gland to release aldosterone (increase in Na+ and H2O reabsorption into blood from distal tubule and collecting duct --> increases blood volume
- Blood pressure increases
101
What does ADH target within the nephron?
Collecting duct
102
What does aldosterone target within the nephron?
Distal tubule and collecting duct
103
What does atrial natriuretic peptide target within the nephron?
Glomerulus, distal tubule and collecting duct
104
What is the mechanism of ADH?
Increase insertion of aquaporins, to promote the reabsorption of water
105
What is the mechanism of aldosterone?
Enhances activation of Na+ transports to increase reabsorption of Na+ and water
Increases secretion of K+ ion
106
What is the mechanism of atrial natriuretic peptide?
Increases GFR by promoting vasodilation of the afferent arteriole; opposes the action of aldosterone and ADH
