Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

LSS Year 1 > Urinary System > Flashcards

Urinary System Flashcards

1
Q

What is the urinary system made up of?

A

Kidneys
Ureters
Urinary bladder
Urethra

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

Where are the kidneys located?

A

Retroperitoneal in the upper abdomen

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

What is posterior to the kidney?

A

The diaphragm

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

What is superior to the kidney?

A

Pleural cavity

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

Which kidney is lower?

A

Right

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

Where are the superior poles of the kidney?

A

Right: 11th intercostal space
Left: 11th rib

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

At what vertebral level are the kidneys?

A

L1

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

Which pole of the kidneys is angled inwards?

A

Superior

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

Under what ribs is the spleen located?

A

9 and 10

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

What muscles surround the kidney? Where

A

Posterior: Psoas major and Quadratus lumborum
Lateral: Transversus abdominis
Superior: Diaphragm

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

What fat surround the kidney? Why?

A

Perinephric fat

Protection- kidneys have a large blood supply

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

What organs surround the right kidney?

A

Liver
Hepatic flexure
Hilus
lies behind the second part of the duodenum

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

What organs surround the left kidney?

A

Stomach
Pancreas
Spleen
Splenic flexure

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

Where does the kidneys blood supply come from and drain to?

A

From abdominal aorta via the renal arteries

Renal veins drain into inferior vena cava

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

Which renal artery is is longer?

A

Right

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

Which renal vein is longer?

A

Left

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

Are the renal arteries or veins posterior?

A

Arteries

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

What is the renal pelvis?

A

The funnel-like start of the ureter where fluid drains

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

What structures does filtrate from the kidney flow through to enter the ureter?

A 
Renal papilla
Minor calix
Major calix
Renal pelvis
Ureter
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What structures are in the cortex of the kidney?

A

Glomerulus
Bowman’s capsule
Arcuate arteries and veins
Proximal and Distal convoluted tubules

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

What is located in the medulla of the kidney?

A

Loop of Henle

Collecting tubule

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

Are afferent or efferent arterioles larger in the kidney?

A

Afferent

More goes in than comes out

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

In what plane do the ureters run vertically down the posterior abdominal wall?

A

In the plane of the tips of the transverse processes of the lumbar vertebrae

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

Where do the ureters cross the pelvis brim?

A

Anterior to the sacroiliac joint and bifurcation of the common iliac arteries

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

At what level do the ureters enter the bladder?

A

The level of the ischial spine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Where do the ureters get their blood supply?

A

Renal artery
Testicular arteries
Common iliac arteries
(every major vessel is passes)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Where are the constriction points on the ureter?

A

1) Ureteropelvic junction
2) Pelvic inlet
3) Entrance to bladder

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

How is urine transported to the bladder?

A

Through the ureters by peristalsis in their smooth muscle walls

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

Where are the sites kidney stones occur in the ureters?

A

At the constriction points along the ureter

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

Where is the apex and base of the bladder?

A

Apex points anteriorly

Base points posteriorly

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

What epithelium lines the bladder? Describe it

A

Urothelium
Three layered epithelium with very slow cell turnover. Large luminal cells have highly specialised low-permeability luminal membrane.
Prevents dissipation of urine-plasma gradients

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

What ligament attaches to the apex of the baldder?

A

Median umbilical ligament

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

Why is there no ureter sphincter?

A

Ureters run obliquely so when full it puts pressure on them without the need for a sphincter. Prevents reflux

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

What separates the bladder and periuneum?

A

A diaphragm through which the urethra passes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

Where do ejaculates enter the urethra in males?

A

At the back of the prostate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

What sphincter in the bladder is under parasympathetic control?

A

Sphincter vesicae

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

What is sphincter vesicae? What causes it to open?

A

Internal sphincter- smooth muscle
At the neck of the bladder
Reflex opening in response to bladder wall tension
Controlled by parasympathetic NS

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

What sphincter in the bladder is under somatic control?

A

Sphincter urethrae

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

What is sphincter urethrae? What causes it to open?

A

External sphincter- striated muscle
In perineum
Tone maintained by somatic nerves in pudendal nerve (S2, 3, 4)
Opened by voluntary inhibition of nerves

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

What nerves innervate the sphincter urethrae?

A

S2, 3, 4

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

In a woman, what is the distance between parasympathetic and sympathetic sphincters?

A

∼5cm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

In men, what is the distance between parasympathetic and sympathetic sphincters?

A

∼20cm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

Why are females more prone to bladder infections?

A

Because the distance between their parasympathetic and sympathetic sphincters is much shorter

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

How is voluntary control stimulated when needing to empty the bladder?

A

Bladder fills
Stretch receptors signal the parasympathetic nervous system- bladder contracts and internal sphincter mechanically opens
At the same time stretch receptors signal motor neurons which suggests the need for voluntary control. External sphincter remains closed when motor neuron is stimulated

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

What are the different parts of a male urethra?

A 
Internal urethral oriface (bladder neck, bladder outlet)
Prostatic urethra
Membranous urethra
Bulbar urethra
Penile urethra
Navicular fossa
External urethral meatus
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

How is water excreted from the body?

A

Exhalation
Urine
Sweat

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

What does the body get rid of in the urine?

A

H2O, Na+, K+, H+, urea

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

What are the functions of the kidney?

A 
Production of urine:
- Filtration of blood plasma
- Selective reabsorption of contents to be retained
- Tubular secretion of some components
- Concentration of urine as necessary
Endocrine funtion
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

What part of the kidney has the best blood supply?

A

The cortex

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
50
Q

Which part of a kidney is most susceptible to ischaemia?

A

Papillae- fragments end up in the urine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
51
Q

What is the mechanism for urine production in the kidney?

A

Filtration of blood passing through the glomerulus (all componenets

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
52
Q

How are the cells in the filtration barrier modified for their function?

A

Fenestrated epithelia
Specialised basement membrane (basal lamina)
Podocytes with filtration slits between foot processes, producing a very fine filter (

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
53
Q

What is the fluid tonicity in Bowman’s capsule?

A

Isotonic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
54
Q

Where does fluid filtered in Bowman’s capsule go?

A

Into the proximal convoluted tubule

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
55
Q

What are the components of the renal corpuscle?

A

Bowman’s capsule
Glomerulus consists of capillaries
Podocytes associated with glomerulus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
56
Q

What is the blood supply to the renal corpuscle?

A

From afferent arteriole
Exits efferent arteriole
Glomerular capillaries at high pressure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
57
Q

In what part of the renal corpuscle is the blood supply and drainage?

A

Blood supply at vascular pole

Drains to proximal convoluted tubule at urinary pole

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
58
Q

What happens in the proximal convoluted tubule?

A

Reabsorption of ions, glucose, amino acids, small proteins and water

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
59
Q

How is the proximal convoluted tubule modified for function?

A

Brush border
Lots of mitochondria
Lots of vesicles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
60
Q

What occurs in the loop of Henle?

A

Countercurrent mechanism to create hyperosmotic fluid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
61
Q

What is the structure of the descending loop of Henle?

A

Simple squamous epithelium

Passive osmotic equilibrium (aquaporins)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
62
Q

What is the structure of the ascending loop of Henle?

A

Very water impermeable (no aquaporins)
Cuboidal epithelium, few microvilli
Lots of mitochondria (high energy requirement)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
63
Q

What is the structure and function of the vasa recta?

A

Blood vessels arranged in a loop
Blood in equilibrium with ECF
Loop structure stabilises hyper-osmotic [Na+]

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
64
Q

What occurs in the distal convoluted tubule?

A

Adjustment of the ion content of urine

Controls levels of Na+, K+, H+, NH4+

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
65
Q

What is the structure of the distal convoluted tubule?

A

Cuboidal epithelium, few microvilli
Complex lateral membrane interdigitations with Na+ pumps
Lots of mitochondria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
66
Q

Where does the concentration of urine occur in the kidney?

A

In the collecting tubule

Moves water down osmotic gradient into ECF

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
67
Q

What hormone controls the concentration of urine? What part of the kidney does it act on?

A

Vasopressin (ADH)

Works on the collecting tubule

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
68
Q

What is the structure of the collecting tubule?

A

Lots of tight junctions

Can absorb water

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
69
Q

How does the collecting tubule control water permeability?

A 
Basolateral membrane (outside) has aquaporin-3 which is not under ADH control.
Apex of cells has aquaporin-2 which is under ADH control
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
70
Q

What are juxtaglomerular cells? Where are they found?

A

Endocrine cells found around the afferent arterioles before they enter Bowman’s capsule that attach to the macula densa (modified part of the distal convoluted tubule)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
71
Q

What are the function of the juxtaglomerular cells?

A

Can sense urine input and output due to their location. Can detect low BP in the afferent arteriole and release renin.
Can also inhibit renin release due to high NaCl

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
72
Q

What is glomerular filtration?

A

The formation of an ultrafiltrate of plasma in the glomerulus
An abrupt fall in glomerular filtration is renal failure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
73
Q

What is the mechanism of glomerular filtration?

A

Fluid is drive through the semipermeable (fenestrated) walls of the glomerular capillaries into the Bowman’s capsule space by the hydrostatic pressure of the heart

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
74
Q

What is the filtration barrier in glomerulus permeable to?

A

Fluids

Small solutes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
75
Q

What is the filtration barrier in the glomerulus impermeable to?

A

Cells
Proteins
Drugs etc carried bound to protein

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
76
Q

If the concentration of a solute in the blood is 1mM and 20% is filtered what is the concentration of the solute in Bowman’s capsule?

A

1mM

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
77
Q

What is the formula for net ultrafiltration pressure?

A

Puf = Pgc - Pt - 𝜋gc

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
78
Q

What two factors affect the ultrafiltration coefficient?

A

Membrane permeability

Surface area

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
79
Q

How do you calculate GFR?

A 
GFR = Puf x Kf
GFR = net ultrafiltration pressure x ultrafiltration coefficient
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
80
Q

What is GFR?

A

The amount of fluid filtered from the glomeruli into the Bowman’s capsule per unt time (ml/min)
The index of kidney function

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
81
Q

What is renal blood flow?

A

∼1L/min (1/5 of cardiac output)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
82
Q

What is renal plasma flow?

A

∼0.6L/min

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
83
Q

What is the filtration fraction?

A

0.2

Ratio between RPF and amount of filtrate filtered by glomerulus, normally 20%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
84
Q

What is normal GFR?

A

120mL/min

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
85
Q

What does the glomerular filtration rate depend on?

A

Glomerular capillary pressure (Pgc)
Plasma oncotic pressure (𝜋gc)
Tubular pressure (Pt)
Glomerular capillary surface area or permeability (Kf)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
86
Q

What would happen for your GFR if you start exercising?

A

It would not change as the body has mechanisms to regulate GFR (e.g. myogenic mechanism)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
87
Q

What is the myogenic mechanism?

A

Vascular smooth muscle constricts when stretched. Keeps GFR constant when blood pressure rises
Arterial pressure rises
Afferent arteriole stretched
Arteriole contracts (vessel resistance increases)
blood flow reduces
GFR remains constant

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
88
Q

What is the tubuloglomerular feedback mechanism?

A

NaCl concentration in fluid sensed by macula densa in juxtaglomerular apparatus
Macula densa signals afferent arteriole and changes its resistance to maintain steady GFR

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
89
Q

How does severe haemorrhage affect GFR?

A

It would fall

Due to drop in BP and CO

90
Q

How does obstruction in nephron tubule affect GFR?

A

It would fall

Increasing opposing forces

91
Q

How would reduced plasma protein concentration affect GFR?

A

It would increase

92
Q

How would a small increase in blood pressure affect GFR?

A

It would not change GFR

93
Q

What is renal clearance?

A

The extent to which a substance is removed from the blood.

Clearance is the number of litres of plasma that are completely cleared of the substance per unit time

94
Q

What is the formula for renal clearance?

A

C=(U x V)/P
U = concentration of substance in urine
P = concentration of substance in plasma
V = Rate of urine production

95
Q

Why is inulin used to predict GFR?

A

It is freely filtered and it is not reabsorbed or secreted.

It is measurable in the urine (stable, does not degrade) and is non toxic

96
Q

What is used clinically to measure GFR? Why?

A

Creatinine
Waste product from creatine in muscle metabolism
Amount released is fairly constant so amount in urine is stable
Low values of creatinine clearance may indicate renal failure
High plasma creatinine may indicate renal failure

97
Q

How does PAH have a clearance rate of 625ml/min?

A

Filtered and actively secreted in one pass of the kidney, so can be used to measure renal plasma flow.

98
Q

How do you measure renal plasma flow?

A

Use a substance which is filtered and secreted which will be removed in one pass of the kidneys

99
Q

What is the amount excreted from the kidney equal to?

A

Amount excreted = amount filtered - amount reabsorbed + amount secreted

100
Q

What does it mean is a solute is “freely filtered”?

A

It has the same concentration in the plasma and the filtrate

101
Q

Sodium is freely filtered, but the concentration of sodium in the tubule is lower than that os the plasma. Why is this?

A

Because it is reabsorbed

102
Q

Is a substance has higher clearance than inulin what can you conclude?

A

That it is secreted

103
Q

How much of the ultrafiltrate is reabsorbed?

A

∼99%

104
Q

What is osmolarity?

A

A measure of the osmotic pressure exerted by a solution across a perfect semi-permeable membrane
It is dependent on the number of particles in a solution and NOT the nature of the particles
All the concentrations of the different colutes (in mmol/L) added together. Each ion is counted separately

105
Q

What is normal plasma osmolarity?

A

285-295 mosmon/L

106
Q

What is normal urine osmolarity?

A

50-1200 mosmol/L

107
Q

What are the two types of reabsorption from one side of a cell to the other in the tubule?

A

Transcellular

Paracellular

108
Q

What are the different types of transport in the tubules of the kidney?

A 
Osmosis
Active transport
Passive transport
Counter transport
Co-transport
Movement down electrochemical gradient
109
Q

In protein dependent transport what type of molecules does this move? What is it dependent on?

A

Hydrophilic molecules

Dependent on the number of proteins

110
Q

What types of transport of solutes across tubules have saturable kinetics?

A

Direct ATP dependent
Indirect ATP dependent
Protein dependent

111
Q

How are proteins reabsorbed?

A

Binding them to low-affinity, high variability receptors on the cell surface, internalise into a vesicle and recycle the receptor

112
Q

Why is glucose present in the urine in diabetes mellitus?

A

Glucose in the blood increases so amount of glucose being filtered increases
Amount being reabsorbed increases until transporters become saturated at which point no more glucose can be reabsorbed and it starts to be excreted

113
Q

What is secretion in the kidneys?

A

Moving substances from the peritubular capillaries into the tubular lumen

114
Q

How much of what goes into the kidney ends up in the tubule system?

A

20%

115
Q

How much sodium is absorbed in the different parts of the kidney?

A

Proximal convoluted tubule: 65%
Loop of Henle: 25%
Distal convoluted tubule: 8%
Collecting duct:

116
Q

Where is glucose reabsorbed in the kidney?

A

In the proximal convoluted tubule

117
Q

What is most of the ATP used in resorption used for?

A

Pumping Na+ to generate a large concentration gradient

118
Q

What is Na+ transport used for in reabsorption?

A

Reabsorbing Cl-, glucose and amino acids in the proximal convoluted tubule
Reabsorbing bicarbonate and to excrete protons

119
Q

What occurs in the descending limb of the loop on Henle?

A

Water is passively reabsorbed through squamous epithelium which draws in Na+ and K+

120
Q

What happens in the ascending limb of the loop of Henle?

A

Chloride is actively reabsorbed
Sodium is passively reabsorbed and with it bicarbonate is reabsorbed
Impermeable to water. High energy requirement
By now 85% water and 90% sodium and potassium have been reabsorbed

121
Q

What is the osmolarity of the tubular fluid leaving the loop of Henle with respect to plasma?

A

Hypoosmolar

122
Q

What cotransporter is present in the distal convoluted tubule?

A

Na⁺K⁺ATPase on the apical side

NA+Cl- on the basal (tubule) side

123
Q

In the distal convoluted tubule and collecting tubule sodium reabsorption is dependent on what?

A

Aldosterone

124
Q

Is the distal part of the nephron permeable to water?

A

No, unless there is ADH

125
Q

What are the two cell types in the distal tubule and collecting duct?

A

Principle cell

Intercalated cell

126
Q

What are the roles of principle cells in the distal tubule and collecting duct?

A

Important in sodium, potassium and water balance (mediated via Na/K ATP pump)

127
Q

What is the role of intercalated cells in the distal tubule and collecting duct?

A

Important in acid-base balance (mediate via H-ATP pump)

128
Q

What is renal tubule acidosis?

A 
Single gene defect
Hypercholermic metabolic acidosis
Impaired growth
Hyperkalemia
Caused by an inability to excrete protons or extra protons leak out after being pumped out causing an acidosis
Mutation in Na+H+ cotransporter
129
Q

What is (Antenatal) Bartter syndrome?

A 
Excessive electrolyte secretion
Premature birth, polyhydraminos
Severe salt loss
Moderate metabolic alkalosis
Hypokalemia
Renin and aldosterone hypersecretion
Mutation in Na+2Cl-K+ transport protein
130
Q

What is Fanconi Syndrome?

A

Increased excretion of uric acid, glucose, phosphate, bicarbonate
Increased excretion of low MW protein
Disease of the proximal tubules associated with renal tubular acidosis
Proton pump won’t dissociate so can’t relocate transporter

131
Q

What do the water balance and salt in the body determine?

A

Water balance regulates plasma osmolarity

Salt determines the ECF volume

132
Q

What are the volumes of different compartments of body water?

A

Intracellular fluid: 25L (65%)

Extracellular fluid: 15L (35%) mainly interstitial fluid, also plasma, lymph and transcellular

133
Q

What methods does the body use to get rid of water? How much is lost in this way? What are these methods affected by?

A

Sweat ∼450ml/day (fever, climate, activity)
Faeces ∼100ml/day (diarrhoea)
Respiration ∼350ml/day (activity)
Urine output ∼1500ml/day

134
Q

Where is water absorbed in the kidneys?

A

Proximal convoluted tubule: 60-70%
Decending loop of Henle: ∼30%
Distal convoluted tubule: ∼20%

135
Q

How much water do we excrete based on what we filter?

A
136
Q

How do the kidneys produce hyperosmolar urine?

A

Using a countercurrent mechanism
1) Salt is pumped into the interstitium from the ascending limb creating a 200mmol gradient
2) Water flows out of descending limb to equilibrate the gradient
3) Flows round loop of Henle so the new fluid entering is of lower concentration
4) Salt again pumped out making 20mmol gradient which is even higher now
5) Water pumps out descending
Salt concentration continues to get lower as the gradient becomes larger.
This creates a low concentration fluid at the end of the ascending limb and a high concentration filtrate at the end of the descending limb

137
Q

What part of the nephron is permeable to urea?

A

The bottom of the collecting duct and the bottom of the loop of Henle

138
Q

How does urea increase the concentration of urine?

A

As the filtrate travels along the collecting duct water is reabsorbed into the interstitium. This part is impermeable to urea so the concentration increases. When in the permeable area urea moves out into the interstitium down the concentration gradient.
Urea then moves down the concentration gradient into the loop of Henle back into the filrates and recirculates
This continues creating very highly concentrated filtrate

139
Q

What are the urea transporters? Where are they located?

A

UT-A2 in the thin descending limb of the loop of Henle
UT-A1 and UT-A3 in the inner medullary collecting duct
UT-B1 in the vasa recta

140
Q

How is the vasa recta specialised for function?

A

Follows the same path as the loop of Henle. Permeable to water and solutes
Descending limb: Water diffuses out and solutes diffuse in
Ascending limb: Water diffuses in and solutes diffuse out

141
Q

What is vasopressin? Where is it synthesised and where does it work?

A

Peptide hormone
Synthesised in the hypothalamus and packages into granules
Secreted from the posterior pituitary (neurohypophysis)
Binds to specific receptors on basolateral membrane of principle cells in the collecting ducts

142
Q

What is the mechanism of action of vasopressin?

A

Causes insertion of aquaporins into the cells membrane (predominantly AQP2 into the luminal membrane)
Also stimultes urea transport from IMCD into thin ascending limb of loop of Henle and interstitial tissue by increasing membrane localisation of UTA1 in the inner medullary collecting duct

143
Q

What triggers ADH release?

A

Plasma osmolarity >300mOs regulated by osmoreceptors
Also stimulated by a marked fall in blood volume or pressure (monitored by baroreceptors or stretch receptors)
Ethanol inhibits ADH release, which leads to dehydration as urine volume increases

144
Q

What is the response mechanism to low plasma osmolarity?

A 
↓ Plasma osmolarity
(Hypothalamic receptors)
↓ ADH release
↓ Collecting duct water permeability
↑ Urine flow rate
Increased fluid loss will raise plasma osmolarity
145
Q

What is the response mechanism to high plasma osmolarity?

A

↑ Plasma osmolarity
(Hypothalamic receptors)
↑ ADH release
↑ Collecting duct water permeability
↓ Urine flow rate
Decreased fluid loss will lower plasma osmolarity
Hypothalamus also stimulates thirst centre- increased water intake will lower plasma osmolarity

146
Q

What different disorders of water balance can you have?

A

1) No/insufficient production of ADH
2) No detection of ADH (mutant ADH receptor)
3) No response to ADH signal (mutant aquaporn)

147
Q

What is diabetes insipidus?

A

Excretion of large amounts of watery urine (as much as 30 litres each day)
Unremitting thirst
Due to a disorder with ADH

148
Q

What four components of the nephron allow the generation of a hyperosmolar environment?

A

1) Counter current mechanism
2) Descending loop impermeable to salt but permeable to water
3) Ascending loop impermeable to water but ‘permeable’ to salt
4) Urea permeability of the bottom of the loop and collecting duct

149
Q

How does dietary sodium affect blood pressure?

A

Increased dietary sodium
Increased osmolarity
Increased ECF volume
Increased blood volume and pressure

150
Q

What happens to sodium reabsorption if you increase GFR?

A

↑ Na reabsorption

151
Q

What happens to sodium reabsorption if you decrease GFR?

A

↓ Na reabsorption

152
Q

How does the sympathetic nervous system increase sodium retention?

A
  • Causes vasoconstriction of the kidney tubular blood vessels predominantly the afferent arteriole (decreasing pressure gradient across glomerulus goes down)
  • Increase sodium uptake mechanisms in the proximal convoluted tubule
  • Stimulates juxtaglomerular cells to release renin and produce angiotensin
153
Q

If you want to increase Na retention what mechanism does this?

A

Increase sympathetic activity

Decrease GFR

154
Q

What stimulates juxtaglomerular cells to release renin?

A

1) Sympathetic nervous system

2) Low tubular Na

155
Q

How is sodium reabsorption decreased?

A

Atrial naturitic peptide decreases absorption of sodium in the proximal convoluted tubule and the collecting duct and also decreases stimulation of juxtaglomerular cells

156
Q

What is the renin-angiotensin-aldosterone system?

A 
Liver releases angiotensinogen
JGA release renin
Converts angiotensinogen to angiotensin I
ACE (lungs) converts to angiotensin II
Stimulates the release of aldosterone
157
Q

What stimulates the release of renin?

A

↓ Blood pressure
↓ Fluid volume
↑ β1-Sympathetic

158
Q

What inhibits the release of renin?

A

↑ Blood pressure
↑ Fluid volume
↓ β1-Sympathetic
Production of ANP (atrial naturitic peptide)

159
Q

What are the effects of angiotensin II?

A

1) Proximal tubule, ↑ Na uptake, ↑ water reabsorption, ↑ ECF, ↑ BP
2) Vascular system, vasoconstriction, ↑ BP
3) Adrenal gland, aldosterone synthesis

160
Q

What is aldosterone? Why is it released? What does it do?

A

Steroid hormone synthesised and released from the adrenal cortex
Released in response to angiotensin II due to a decrease in blood pressure (via baroreceptors) or decreased osmolarity of ultrafiltrate.
Stimulates:
- ↑ Na reabsorption
- ↑ K+ secretion
- ↑ H+ secretion

161
Q

What is caused by excess aldosterone?

A

Leads to hypokalaemic alkalosis

162
Q

How does aldosterone work?

A

1) Enters cell and binds to steroid hormone receptor in the cytoplasm (which is bound to inhibitory protein)
2) When aldosterone binds to receptor the inhibitory protein is released
3) Steroid hormone receptors dimerises and translocates to the nucleus and drives transcription
4) Increases expression of Na channel in the collecting duct and induces formation of Na-K-ATPase pumps

163
Q

What is hypoaldosteronism?

A 
Reabsorption of sodium in the distal nephron is reduced
Increased urinary loss of sodium
ECF volume falls
Increased renin, angiotensin II and ADH
Causes:
Dizziness
Low BP
Salt craving
Palpitations
164
Q

What is hyperaldosteronism?

A 
Reabsorption of sodium in the distal nephron is increased
Reduced urinary loss of sodium
ECF volume increases (hypertension)
Reduced renin, angiotensin II and ADH
Increased ANP and BNP
Causes:
High BP
Muscle weakness
Polyuria
Thirst
165
Q

What is Liddle’s syndrome?

A

An inherited disease of high blood pressure

  • mutation in the aldosterone activated sodium channel
  • channel is always ‘on’
  • results in sodium retention leading to hypertension
166
Q

Where are the baroreceptors that detect low blood pressure?

A

In the atria and some in the right ventricle

In pulmonary vasculature

167
Q

Where are the baroreceptors that detect high blood pressure?

A

Carotid sinus
Aortic arch
Juxtaglomerular apparatus

168
Q

What happens in the low pressure baroreceptors when they detect low blood pressure?

A

Signal through afferent fibres to the brainstem

Stimulates sympathetic activity and ADH release

169
Q

What happens in the low pressure baroreceptors when they detect high blood pressure?

A

Atrial stretch

Stimulates ANP, BNP release

170
Q

What happens in the high pressure baroreceptors when they detect low blood pressure?

A

Signals through afferent fibres to the brainstem
Stimulates sympathetic activity and ADH release

Stimulates JGA cells which stimulates renin release

171
Q

What is ANP? What does it do?

A

Atrial natriuretic peptide
Small peptide made in the atria (also make BNP)
Release in response to atrial stretch (i.e. high blood pressure)
Causes:
- Vasodilation of renal (and other systemic) blood vessels
- Inhibition of sodium reabsorption in proximal tubule and in the collecting ducts
- Inhibits release of renin and aldosterone
- Reduces blood pressure

172
Q

What are the different types of diuretic?

A

1) Osmotic diuretics
2) Carbonic anhydrase inhibitors
3) Loop diuretics
4) Thiazides
5) K+ sparing diuretics

173
Q

How do osmotic diuretics work? Where do they work in the nephron?

A

Glucose as in diabetes mellitus or mannitol

In the proximal convoluted tubule

174
Q

How do loop diuretics work? Give an example

A

Blocks triple co-transporter (Na+Cl-K+)

e.g. furosemide

175
Q

How to thiazides work? Where do they work in the nephron?

A

Block Na/Cl co-transport

In the distal convoluted tubule

176
Q

Give two examples of K+ sparing diuretics and how they work? Where do they work in the nephron?

A

1) Amiloride- block Na channels
2) Spironolactone- aldosterone antagonist
They work in the distal convoluted tubule and into the collecting duct

177
Q

Where do carbonic anhydrase inhibitors work in the nephron? How do they work?

A

In the proximal convoluted tubule
If you block carbonic anhydrase the protons cannot be pumped into the cell which then prevent Na from being pumped into the cell using a co-transporter

178
Q

What does high potassium cause?

A

Depolarises membranes and action potentials

Causes heart arrhythmias

179
Q

What does low potassium cause?

A

Heart arrythmias

180
Q

What is the intracellular and extracellular K+ concentration?

A

Intracellular: 150mmol/L
Extracellular: 3-5mmol/L

181
Q

What happens to K+ when you ingest it in a meal?

A

K+ aborption
↑ plasma K+
Tissue uptake (stimulated by insulin, aldosterone and adrenaline)
Pumped into cells via Na⁺K⁺ATPase

182
Q

What is K+ secretion stimulated by?

A

↑ plasma [K+]
↑ aldosterone
↑ tubular flow rate
↑ plasma pH

183
Q

How much of the K+ from the filtrate is secreted?

A

1-80%

184
Q

What cell is responsible for potassium secretion? How does it do it?

A

Principle cells

Moves K+ into cell through Na⁺K⁺ATPase then into tubule through K+ channels

185
Q

How does aldosterone stimulate K+ secretion?

A

Stimulates Na⁺K⁺ATPase pump and also stimulates Na+ channels (Na from tubule into cell) and K+ channels (K from cell into tubule)

186
Q

How does flow stimulate the secretion of K+?

A

1) Flow stimulates the primary cilium which activates PDK1.
2) PDK1 activation causes an increase in intracellular calcium
3) Ca2+ stimulates the activity of the K+ channels

187
Q

What are the most common electrolyte imbalances?

A

Hypokalaemia

Hyperkalaemia

188
Q

What are the symptoms of hypokalaemia? What causes it?

A 
Causes:
Diuretics due to increased tubular flow rate
Surreptitious vomitting
Diarrhoea
Genetic (Gitelman's syndrome)
189
Q

What is Gitelman’s syndrome?

A

Mutation in the Na/Cl transporter in the distal nephron

Causes hypokalaemia

190
Q

What is hyperkalaemia?

A

Seen in response to K+ sparing diuretics
ACE inhibitors
Elderly

191
Q

When ADH is high is renin secretion increased?

A

No

192
Q

When ADH is high are the principle cells permeable to water?

A

Yes

193
Q

When ADH is high are aquaporins relocated to the plasma membrane of the principle cells?

A

Yes

194
Q

In the loop of Henle does the ascending limb reabsorb K+?

A

Yes

195
Q

In the loop of Henle is Na+ reabsorption required for the uptake of glucose?

A

No

None left all reabsorbed in the proximal convoluted tubule

196
Q

Are body sodium levels used to regulate osmolarity?

A

No water levels are

197
Q

What is the mechanism of maintaining acid base balance if you hyperventilate?

A 
↑ ventilation
CO2 'blown off'
↑ pH (↓H+)
Respiratory alkalosis
Compensatory change in renal function
H+ gain / HCO3- loss
↓ pH (↑H+)
198
Q

What is the mechanism of maintaining acid base balance if you hypoventilate?

A 
↓ ventilation
CO2 retention
↓ pH (↑H+)
Respiratory acidosis
Compensatory change in renal function
H+ loss / HCO3- gain
↑ pH (↓H+)
199
Q

What is the mechanism of acid base homeostasis when a change in GI/renal function results in H+ gain or HCO3- loss?

A 
↓ pH (↑ H+)
Metabolic acidosis
Compensatory change in lung function
↑ ventilation
CO2 'blown off'
↑ pH (↓ H+)
200
Q

What is the mechanism of acid base homeostasis when a change in GI/renal function results in H+ loss or HCO3- gain?

A 
↑ pH (↓ H+)
Metabolic alkalosis
Compensatory change in lung function
↓ ventilation
CO2 retention
↓ pH (↑ H+)
201
Q

Where is bicarbonate reabsorbed in the nephron?

A

Proximal CT: 80%
Loop of Henle (↑): 10%
Distal CT: 6%
Collecting duct: 4%

202
Q

In the Henderson-Hasselcalch equation what is pK?

A

The ratio of whether bicarbonate is in carbonic acid form or bicarbonate and protons

203
Q

What type of cells line the proximal convoluted tubule?

A

Cuboidal epithelial cells

204
Q

How is bicarbonate reabsorbed in the proximal convoluted tubule?

A

1) H+ moved into filtrate via H+ATPase
2) H+ binds to HCO3- using carbonic anhydrase (in the membrane) to form (H2CO3 then) CO2 and H2O
3) CO2 diffuses across the membrane
4) Carbonic anhydrase catalyses CO2 + H2O to produce (H2CO3 then) H+ and HCO3-
5) H+ pumped back into the filtrate by H+ATPase and Sodium proton antiporter (loop)
6) HCO3- pumped into the interstitium by chloride bicarbonate exchanger and sodium bicarbonate cotransporter
7) Sodium potassium ATPase pumps Na into the interstitium

205
Q

How is acid secreted in the collecting duct?

A

1) Hydrogen potassium ATPase move H+ inot the filtrate and K+ into cell
2) Carbonic anhydrase converts H+ and HCO3- to H2O and CO2
3) CO2 diffuses into cell and carbonic anhydrase converts CO2 + H2O to H+ and HCO3-
4) H+ATPase and Hydrogen potassium ATPase pumps H+ into the filtrate
5) AE1 (Chloride bicarbonate exchanger) pumps HCO3- into the interstitium in exchange for Cl-

206
Q

How is bicarbonate secreted in the collecting duct

A

1) Carbonic anhydrase in the intercalated cell converts CO2 + H2O to HCO3- + H+
2) HCO3- exchanged with Cl- in the filtrate using a chloride bicarbonate exchanger
3) H+ inside the cell is pumped into the interstitium

207
Q

How is HCO₃⁻ generated in the proximal convoluted tubule using carbonic anhydrase?

A

1) Carbonic anhydrase converts CO₂ + H₂O to H⁺ + HCO₃⁻
2) HCO₃⁻ pumped into interstitium via chloride bicarbonate exchanger (AE1) in exchange for Cl⁻
3) H+ pumped into filtrate via H+ATPase
4) Binds to phosphate (HPO₄²⁻) to form H₂PO₄

208
Q

How can HCO₃⁻ be generated in the proximal convoluted tubule using glutamine?

A

1) Glutamine split into 2NH₄⁺ and 2HCO₃⁻
2) NH₄⁺ pumped into the filtrate in exchange for Na⁺
3) HCO₃⁻ pumped into the interstitium via a chloride bicarbonate exchanger (AE1)
4) Na⁺K⁺ATPase pumps Na⁺ into the interstitium and K⁺ into cell

209
Q

What happens when the kidney stops working?

A

1) Loss of excretory function
- Accumulation of waste products
2) Loss of homeostatic function
- Disturbance of electrolyte balance
- Loss of acid-base control
- Inability to control volume homeostasis
3) Loss of endocrine function
- Loss of erythropoietin production
- Failure to 1α-hydroxylase vitamin D
4) Abnormality of glucose homeostasis
- Decreased gluconeogenesis

210
Q

What are the most common symptoms that patients with chronic kidney disease (renal dysfunction) present with?

A

Hypertension
Oedema
Pulmonary oedema
(Fluid overload)

211
Q

In chronic kidney disease which has particularly affected the medulla what can patients present with? Why is this?

A

Salt and water loss in patients with tubulointerstitial disorders which damage the concentrating mechanism

212
Q

What would show on an ECG in a patient with hyperkalaemia

A

1) T wave peaks
2) P wave disappears
3) Frankles sign (bradycardia)
4) Broadening of the QRS

213
Q

What are the implications of hyperkalaemia?

A

Caused by failure of distal tubule to secrete potassium
Exacerbated by acidosis- causes shift of potassium from intracellular to extracellular space
Can cause cardiac arrythmias (usually initial loss of p waves and bradycardia) and arrest
Can effect neural and muscualr activity
Clinical features of hyperkalaemia are dependent on the chronicity of the hyperkalaemia

214
Q

What are the consequences of chronic renal failure?

A

Phosphate retention
Low levels of calcitriol
Hypocalcaemia
Hyperparathyroidism

215
Q

In kidney failure there is decreased erythropoietin production. What does this cause?

A

Anaemia

216
Q

In kidney failure you have low 1-25 vitamin D. What does this cause?

A

Poor intestinal calcium absorption
Hypocalcaemia (short term)
Hyperparathyroidism (longer term)

217
Q

What is the major outcome of patients with chronic kidney disease?

A

Cardiovascular disease

218
Q

How do you distinguish between acute and chronic kidney disease?

A

Renal size in chronic is usually reduced
Check previous creatinine (if previously abnormal it is chronic)
Chronic uraemic symptoms (nocturia)

219
Q

What is the initial management of a patient with chronic renal failure?

A

IV saline to correct fluid depletion
IV sodium bicarbonate to correct acidosis
IV insulin and dextrose to lower plasma potassium (drives K⁺ ions back into cells)
Dialysis

220
Q

How do you estimate GFR?

A

MDRD equation

LSS Year 1 (4 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions