Brainscape's Knowledge GenomeTM

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


See full index

SM Renal > Physiology 3 > Flashcards

Physiology 3 Flashcards

1
Q

What is the equation to calculate GFR

A

Kf x net filtration pressure

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

What are the 3 physical barriers to the process of filtration

A

1 - the wall of the capillary
2 - Basement Membrane (Basal lamina for plasma protein barrier)
3 - Slit processes of podocytes (Glomerular epithelium)

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

What is the difference between capillaries in the nephron to capillaries elsewhere in the body

A

the pores between adjacent endothelial cells are about 100 times larger than those found in capillaries elsewhere in the body

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

What forms the slit processes of the podocytes

A

The interdigitations between podocytes

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

What are the 2 main substances that do not cross from the blood into the lumen of the Bowman’s capsule

A

RBC

plasma proteins

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

Describe the basement membrane of the Bowman’s capsule

A

Acellular layer

rich in glycoproteins and collagen

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

What do the glycoproteins do to the basement membrane

A

Causes a net negative charge which then acts to repel the negatively charged plasma proteins in the filtrate

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

What is the filtrate that is initially formed

A

Modified filtrate of the blood - it lacks RBC and large plasma proteins
it does contain small solutes and salts that can cross the glomerular membrane

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

Active transport is the main way in which molecules move in the glomerular membrane. True or False

A

It is an entirely passive process

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

What are Starling Forces

A

The balance of hydrostatic pressure and osmotic forces

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

How can we calculate the net filtration

A

Add the pressures that favour filtration and subtract those that oppose it

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

What is the most important pressure in the glomerular filtration

A

Glomerular capillary blood pressure

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

What is the value of the glomerular capillary blood pressure

A

55mmHg

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

Why does the glomerular capillary blood pressure remain the same throughout the length of the capillary

A

The diameter of the afferent arteriole is larger than the efferent arteriole and therefore this causes a back pressure of blood that will be maintained

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

What is the pressure of the Bowman’s capsule hydrostatic pressure

A

15mHg

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

How does the Bowman’s capsule hydrostatic pressure occur

A

As the fluid enters the lumen, it builds up to eventually cause a pressure opposing filtration

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

What is another term for oncotic pressure

A

colloid osmotic pressure

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

What are oncotic pressures related to

A

plasma proteins

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

How does capillary oncotic pressure occur

A

plasma protein concentration acts across the membrane

They exert an osmotic effect and act to attract fluid from the Bowman’s capsule back into the blood

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

What is the value of the capillary oncotic pressure

A

30mmHg

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

What is the pressure of the Bowman’s capsule oncotic pressure
Why is this

A

0mmHg

we shouldn’t have any plasma proteins in the Bowman’s capsule and therefore it cannot pull any negative charges through

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

What pressures make up the Starling forces

A

Glomerular capillary blood pressure
Bowman’s capsule hydrostatic pressure
capillary oncotic pressure
Bowman’s capsule oncotic pressure

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

What does the net filtration do overall

A

it drives the movement of fluid and its constituents across the membrane

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

What is GFR

A

the rate at which protein-free plasma is filtered from the glomeruli into the Bowman’s capsule per unit time

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

What is Kf ?

A

The filtration coefficient

How holy the glomerular membrane is

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

What is the normal GFR rate

A

125ml/min

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

How can we change the pressure of blood flowing through the glomerular capillary

A

Vasodilation or vasoconstriction

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

What happens if we increase the GFR

A

We increase the rate at which the kidneys are filtering and therefore increases the urine production

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

What are the intrinsic regulations of GFR

A

myogenic mechanism
Tubuloglomerular
These require no hormonal or nervous stimulation

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

What is the primarily role of extrinsic regulation of GFR

A

sympathetic control via baroreceptors

increase in the sympathetic nerve activity causes an activation of the baroreceptor reflex

31
Q

Describe what happens to GFR in vasoconstriction

A

Decrease blood flow into the glomerulus

Decreases the glomerular capillary blood pressure and decreases the net filtration pressure which then decreases GFR

32
Q

What happens to GFR in vasodilation

A

Increase blood flow into the glomerulus

Increases the glomerular capillary blood pressure and Increases the net filtration pressure which then increases GFR

33
Q

Describe why the urine output decreases when a patient has a drop in blood volume e.g. Haemorrhage

A 
Decreased arterial BP 
Detected by aortic and carotid sinus baroreceptors 
Increases sympathetic activity 
Generalised arteriolar vasoconstriction
constriction of afferent arterioles 
Decrease BP in capillaries 
Decrease GFR 
Decrease urine output 
This then helps to compensate for the blood loss
34
Q

Why does changes in systemic arterial blood pressure not result in changes in GFR

A

autoregulation prevents short term changes in systemic arterial pressure affecting GFR

35
Q

What is the mean arterial Blood pressure if the BP is 120/80

A

93 mmHg

36
Q

Why is the fact that GFR is relatively constant important

A

avoid unintentional shifts in the glomerular filtration rate that could lead to an imbalance of salts and fluid or solutes

37
Q

What is the myogenic auto regulation

A

If vascular smooth muscle is stretch (e.g exercise increasing the arterial BP) it contracts thus constricting the arteriole
It is related to the amount of stress caused to the smooth muscle found within the wall of the afferent arteriole

38
Q

What does the tubuloglomerular feedback involve

A

The juxtaglomerular apparatus

If the GFR rises, more NaCl flows through the tubule leading to constriction of afferent arterioles

39
Q

What do the macula densa cells do

A

Sense the NaCl content of the tubular fluid

40
Q

Where is the juxtaglomerular apparatus

A

The part of the distal tubule passes between the afferent and efferent arterioles

41
Q

What happens if an increase in salt has been detected by the macula densa

A

Vasoactive chemical messengers are released which will bring about a contraction of the smooth muscle which will bring about a reduced amount of blood flowing into the capillary and GFR will decrease.

42
Q

What type can over ride the other type of control

A

Extrinsic control of GFR can override the 2 mechanisms that control the intrinsic control

43
Q

What happens to GFR in a patient that has a kidney stone and how

A

It decreases - blockage downstream in the nephron causes a build up of fluid which will increase the hydrostatic fluid pressure - this causes an increase in the pressures opposing filtration

44
Q

What happens to GFR in a patient that has diarrhoea and how

A

Patient is dehydrated and this increases the concentration of plasma proteins. This then increases the capillary oncotic pressure which opposes filtration. This then decreases the net filtration pressure and therefore decreases GFR

45
Q

What happens to GFR in a patient that has severe burns and how

A

Los plasma proteins from the site of injury which causes a decrease in capillary oncotic pressure which results in an increase in GFR

46
Q

What is plasma clearance

A

a measure of how effectively the kidneys can clean the blood of a substance
It equals the volume of plasma completely cleared of a particular substance per minute

47
Q

How can we calculate the clearance of a substance

A

Rate of excretion / plasma concentration

48
Q

What are the normal units for plasma clearance

A

ml/min

49
Q

What is inulin

A

exogenous compound that is not produced naturally by the body
found in onions and garlic

50
Q

Inulin is metabolised by the kidney. True or False

A

False

51
Q

Why is inulin important in terms of calculating GFR

A

As it is not metabolised, absorbed or secreted, we can calculate the GFR based on the inulin clearance.
all inulin would leave the body in urine

52
Q

What is the normal level of inulin clearance

A

125ml of inulin-free plasma is returned to the circulation per minute

53
Q

What is the draw back of measuring inulin

A

we have to infuse it into the subject and is therefore not ideal

54
Q

What substance can be measured instead of inulin

A

creatinine - it gives us a close approximation of GFR level

55
Q

What is the clearance rate of glucose

A

0

All glucose is reabsorbed and none should be in the urine

56
Q

What is the clearance for substance which are filtered, partly reabsorbed and not secreted.
Give an example of this type of substance

A

Less than GFR (we excrete less than what was initially filtered)
Urea

57
Q

What is the clearance for substance which is filtered, secreted but not reabsorbed.
Give an example of this type of substance

A

More than GFR. More ions are added to the initial tubular fluid
H+ ions

58
Q

What happens to the substance if the clearance is less than GFR

A

substance is reabsorbed

59
Q

What happens to the substance if the clearance is more than GFR

A

Substance is secreted into the tubule

60
Q

What happens to the substance if the clearance is equal to the GFR

A

The substance is not reabsorbed or secreted

61
Q

How can we calculate the clearance

A

concentration of substance in urine x urine flow rate all divided by the concentration of substance in plasma

62
Q

What is Para-amino hippuric acid (PAH)

A

exogenous organic anion

63
Q

Why is PAH used clinically

A

To measure renal plasma flow

64
Q

How is PAH cleared

A

it is freely filtered at the glomerulus
secreted into the tubule from the blood (not reabsorbed)
completed cleared from the plasma

65
Q

How is PAH unique

A

all the PAH in the plasma that escapes filtration is secreted from the peritubular capillaries into the tubular fluid

66
Q

What is the normal clearance value of PAH

What does this also equal

A

650ml/min

Renal plasma flow (RPF)

67
Q

What criteria does a substance have to make in order for it to be used as a clearance marker

A

Non-toxic
Inert (i.e. not metabolised or broken down in the kidney)
Easy to measure in urine and plasma

68
Q

What should a GFR marker also be

A

Filtered freely

NOT secreted or reabsorbed as it passes along the nephron

69
Q

What should a RPF marker also be

A

filtered and completely secreted

70
Q

What is the filtration fraction

A

The fraction of plasma flowing through the glomeruli that is filtered into eh tubules

71
Q

How can we calculate the filtration fraction

A

GFR/ Renal plasma flow

72
Q

What is the filtration fracture in healthy individuals

A

20%
20% of the plasma that enters the glomeruli is filtered. The remaining 80% moves on to efferent arterioles and then the peritubular capillaries

73
Q

How much of the cardiac output do the kidneys receive

A

24%

SM Renal (23 decks)

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