Renal physiology Flashcards

1
Q

filtrate definition

A

liquid that has passed through a filter

urine in this case

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

lumen definition

A

inside space of a tubular structure

urinary space= tubular space

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

paracellular definition

A

between the cells

absorption between cells of the tubule

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

basolateral definition

A

surface below/to the side

surface of the tubular cell next to the bloodstream

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

osmolality definition

A

concentration of a solution

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

diffusion definition

A

movement of molecules from high to low concentration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

reabsorption definition

A

movement of substance from tubular lumen into the blood

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

secretion definition

A

movement of substance from blood into tubular lumen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

concentration of the filtrate

A

osmolality and movement of molecules along concentration gradient
also movement of molecules by active transport facilitated by transporters

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

structure of the kidneys

A

retroperitoneal
T12-L3
blood supply= renal arteries directly from aorta
25% of circulating blood
right lower than the left of to the weight of the liver

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

cross section of the kidney

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

functional unit/ nephron

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

functions of the kidney

A

filtering
reabsorption
secretion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

what is each nephron comprised of

A

afferent arteriole
glomerulus
efferent arteriole
macula densa
PCT loop
DCT
collecting duct

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

2 types of nephron

A

cortical
juxtaglomerular

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

cortical nephron

A

glomerulus that sits high in the cortex
loop that enters medullar superficially

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

juxtaglomerular nephron

A

low lying glomerulus in cortex
loops that extend deep into the medulla

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

label the image

A

purple is glomerulus
gold is arteiroles

tight proximity of glomeruli

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

3 main functions of the kidney

A

homeostatic function
hormonal influence
protein catabolism and gluconeogenesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

homeostatic function

A

blood pressure
urine production, filtering reabsorption of sodium and water
osmolality, salt and water balance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

hormonal influence

A

rennin
angiotensin 2
PG-E
endothelia
bradykinin
EPO
calcitriol

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

how much filter does the kidney receive daily and then how much urine is produced

A

180L
but reabsorb 99% filtrate so urine 1-2L per day

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

summary of actions in the connecting segment and cortical collecting duct

A

aldosterone mediated potassium secretion by principal cells
hydrogen ion secretion by alpha intercalated cells
potassium reabsorption by alpha intercalated cells
ADH-mediated water reabsorption

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

summary of actions in the medullary collecting duct

A

potassium reabsorption or secretion
final NaCl reabsorption
ADH-mediated water ad urea reabsorption
hydrogen ion and Nh3 secretion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
summary of actions in the distal tubule
small amount of NaCl reabsorbed active regulation of calcium excretion
26
summary of actions in the loop of henle
countercurrent multiplier reabsorption of 15-25% of filtered NaCl active regulation of magnesium excretion
27
summary of actions in the proximal tubule
isosmotic reabsorption of 65-70% filtered water and NaCl reabsorption of 90% of filtered HCO3 major site of NH3 production reabsorption of almost all filtered glucose and amino acids reabsorption of potassium, phosphate, calcium, magnesium, urea and irate
28
=summary of actions in the glomerulus
filtratio
29
cells in each part of nephron
specialised tubular cells designed to optimise function at each stage
30
afferent and efferent arterioles basic
control flow of blood through glomerulus afferent= arriving efferent= exiting
31
afferent and efferent arterioles functions
able to constrict and relax repsinsbile for controlling and influencing interglomerular flow, pressure and filtration
32
what are afferent and efferent arterioles controlled by
starling forces
33
blood pressure too low, arterioles
constrict efferent arteriole to increase flow and pressure RAAS
34
blood pressure too high, arterioles
constriction of afferent to reduce hydraulic pressure in the glomerulus
35
intrinsic mechanisms for renal auto regulation
Renal autoregulation - the kidney itself can adjust the dilation or constriction of the afferent arterioles, which counteracts changes in blood pressure. This intrinsic mechanism works over a large range of blood pressure, but can malfunction if you have kidney disease includes arteriole myogenic mechanism and tubular glomerular feedback (more later)
36
extrinsic mechanism nervous control
nervous system and hormonal control can override renal auto regulation ad decrease the glomerular filtration rate when necessary large drop in BP: nervous system stimulate contraction of afferent arteriole sympathetic vasoconstriction due to epinephrine and constriction of afferent reducing urine production can also activate RAAS
37
extrinsic mechanism hormonal control
atrial natriuretic peptide is a hormone that can increase glomerular filtration rate hormone produced heart secreted when plasma volume increases increasing urine production
38
decreased resistance in afferent
increased RBF increased GFr use CCB or alpha 1 blockade
39
increased resistance in afferent
decreased RBF and GFR use NSAIDs via PG inhibition
40
decreased resistance in efferent
increased RBF and decreased GFR use ACEi or ARB
41
increased resistance in efferent
decreased RBF and increased GFR RAAS activation
42
RAAS system
43
effects of AT2
constrict efferent arteriole to maintain glomerular blood flow stimulation of ADH secretion from pituitary to reabsorb more water in collecting ducts stimulates aldosterone secretion from adrenals acts on DCT to reabsorb more water and sodium net effect is increase in BP
44
macula densa
area of closely packed specialised cells lining the wall of the distal tubule cells sense sodium chloride concentration in distal convoluted tubule
45
tubuloglomerular feedback
decreased sodium to the macula densa
46
decreased sodium to macula densa tubuloglomerular feedback
relaxes afferent arteriole increases renin from juxtaglomerular cells
47
increases renin from juxtaglomerular cells tubuloglomerular feedback
48
relaxes afferent arteriole tubuloglomerular feedback
Increases glomerular hydrostatic pressure Helps increase GFR
49
relaxes afferent arteriole tubuloglomerular feedback
Increases glomerular hydrostatic pressure Helps increase GFR
50
increases renin from juxtaglomerular cells tubuloglomerular feedbakc
Activation of RAAS Vasoconstriction of efferent arteriole Increased intraglomerular hydrostatic pressure Sodium and water reabsorption downstream
51
3 layers to filter from blood to Bowmans space
Endothelium Basement membrane Podocytes (epithelium)
52
endothelium in filter
negatively charged layer with fenestrations
53
basement membrane in the filter
produced by endothelium and podocytes negatively charged collagenous and non collagenous matrix with channels
54
podocytes in the filter
“interdigitating foot processes” that prevent large molecules from entering urinary space; phagocytic function  engulf macromoleclues trapped in slits.
55
mesangium in the filter
not a layer; but filler tissue which anchors the whole structure from the arterioles to the peritubular capillaries.
56
Bowmans capsule
collects urine
57
glomerular filtration
water freely filtered small charged particles freely filtered (Na+, K+, Cl-, glucose, urea) large particles not filtered, red blood cells minimal filtration of smallish negatively charged particles e.g. albumin. this barrier repels negatively charged proteins
58
why is the control of intraglomerular pressure crucial
too much too little causes problems
59
too much hintraglomerular pressure
breakdown of the filter leaking of larger molecules into Bowman’s space inc. blood and protein Haematuria and proteinuria
60
too little intraglomerular pressure
Not enough flow Fall in filtration and GFR
61
drugs we use in glomerulus
ACE inhibitors and Angiotensin 2 Receptor Blockers ACE is the enzyme to convert AT1 to AT2 AT2 causes efferent vasoconstriction to increase pressure and filtration in the glomerulus ACEi  no AT2  no effect on efferent arterioles, and also no knock-on BP Reduction in intraglomerular pressure -> reduction in GFR Long term protective effect and preservation of renal function
62
measuring GFR
Creatinine is product of creatine muscle metabolism Almost constant rate of production Freely filtered Minimally reabsorbed and secreted  Allows estimation of GFR when adjusted for muscle mass, age and sex CKD EPI – eGFR 
63
proximal convoluted tubule, how to think pf it
as heavy lifter of the nephron receives 180L per day of filtrate that is iso-omotic with plasma no RBC's virtually no protein
64
iso-osmotic
approx same number of small molecules and ions
65
proximal convoluted tubule
Bulk of the reabsorption (60%) of the filtrate 90-100% reabsorption of glucose and amino acids Transporters (sodium – glucose, sodium – phosphate, sodium –amino acid)  Paracellular reabsorption Reabsorption AND secretion, e.g. Sodium – hydrogen antiporter  Na/H antiporter aids in bicarbonate reabsorption 
66
glucose handling in the kidney
early proximal tubule late proximal tubule
67
early proximal tubule
High capacity-low affinity Na-Glu symporter – SGLT2 Reabsorbs most of filter glucose Diffusion out of cell across basolateral membrane via GLUT2 transporter
68
late proximal tubule
Low capacity-high affinity Na-Glu symporter - SGLT21 Reabsorbs remaining glucose Diffusion out of cell across basolateral membrane via GLUT1 transporter
69
glycosuria and diabetes
Glucose is freely filtered at glomerulus and reabsorbed in PCT High plasma glucose levels (10-12 mmol/L) saturates SGLT transporters Overspill of glucose into urine Osmotically active particle Diuresis (increased urine production)
70
water reabsorption in the PCT
Interstitium now hyperosmotic Osmotic movement of water across tight junctions and aquaporins  Hydrostatic pressure in interstitium increases High oncotic pressure within peritubular capillaries (proteins) Push and drag of water into capillaries Fluid in PCT is now iso-osmotic with plasma again
71
polyuria
excessive urination
72
polydypsia
excessive thirst
73
loop of henle how to think of it
engine of the nephron descending into the medulla hairpin turn back out and into the cortex
74
loop of henle function
Starts at end of PCT and finishes at the macula densa. Remaining 40-45% of filtrate not handled by PCT Reabsorption of 25-35% of Na⁺ and Cl⁻ First time we’re seeing salt and water reabsorption separated Water is passive in the descending limb, sodium is active in the ascending limb
75
loop of henle NKCC
The main channel in the Loop used to reabsorb Na⁺, K⁺ and Cl⁻ 1. Na⁺, K⁺, 2Cl⁻ enter 2. K⁺ spat back out 3. Paracellular transport
76
recycling ROMK channel
that spits potassium back into the tubule creating a negative change within the cell and a positive charge inside the tubule allowing the paracellular reabsorption of positively charged sodium, calcium and magnesium
77
counter current mechanism in the loop of henle
steep concentration ngradient maximise Na+ reabsorption filtrate leaving the loop of henle is hypo-osmotic with plasma
78
drugs used in loop of henle
Loop diuretics (as the name suggests) Furosemide Bumetanide Act on the NKCC to inhibit reabsorption of Na⁺, K⁺ and Cl⁻ Increases the osmolality of the filtrate Reduced concentration gradient less water reabsorbed by diffusion diuresis and natriuresis.
79
what to think of the distal convoluted tubule as
nephron site of intelligent and qualitative sodium and water reabsorption for what is beneficial to the body
80
distal convoluted tubule function
Starts from the macula densa and ends at connecting segment “Fine tuning” of remaining 5% of Na⁺ and Cl⁻ Sodium-chloride co-transporter (NCCT) Na⁺/H⁺ exchanger and Cl⁻/HCO₃⁻ exchanger NO water reabsorption here 
81
transport mechanisms in the distal convoluted tubule
NCCT – does exactly what it says on the tin - Also powered by Na⁺K⁺ATPase - Blocked by thiazide diuretics e.g. bendroflumethiazide, indapamide Na⁺/H⁺ exchanger = Na⁺ in, H⁺ out Cl⁻/HCO₃⁻ exchanger = Cl⁻ in, HCO₃⁻ out H⁺ + HCO₃⁻ = H₂CO₃ ⇌ H₂O + CO₂ 10-15% of calcium reabsorption occurs here under influence of PTH and vitamin D (mostly in Loop)
82
distal convoluted tubule Na+
Low intracellular Na+ NCCT takes up sodium Impermeable to water Filtrate leaving the DCT becomes more dilute - 50 mosm/L
83
brief function of collecting ducts
fine tuning reabsorption and secretion
84
2 main segments of collecting dust
cortical medullary
85
collecting ducts
Potassium excretion and sodium reabsorption (ENaC and Na,K,ATPase) – principle cells Acid-base handling – intercalated cells Hormonal influence – aldosterone and ADH Urea reabsorption via UT-A1 and UT-A3 (urea recycling)
86
water reabsorption in CD
Tubular side is impermeable to water BUT Permeability can be increased Insertion of aquaporins (water channels) into tubular membrane Under ADH influence Basolateral surface is permeable Water moves into the interstitium via osmosis This osmotic gradient has been set up by the LoH countercurrent multiplier
87
ENaC function
reabsorb sodium and water in response to aldosterone -> potassium secretion 
88
drugs used in collecting ducts
Mineralocorticoid antagonists (MRAs) e.g. spironolactone reduce sodium and water reabsorption in the distal nephron  drop in BP MRAs cause hyperkalaemia
89
overexpresison of ENaC
Liddle’s syndrome (Autosomal dominant cause of hypertension associated with hypokalaemia)
90
diabetes insipidus
Non-response of ADH to V2 receptors = Nephrogenic diabetes insipidus Reduced production of ADH = Cranial diabetes insipidus