Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Sem 3: Urinary > 3b.) GFR & Filtration > Flashcards

3b.) GFR & Filtration Flashcards

1
Q

State, and provide examples, the four main functions of the kidney

A
  • Regulation: concentrations of ions & small molecules
  • Excretion: waste products
  • Endocrine: renin, erythropoietin, prostaglandins
  • Metabolism: activates vitamin D, catabolism of insulin, PTH calcitonin
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

For each, state the approximate % that is recovered by the kidneys

  • Water
  • Sodium & chloride
  • Bicarbonate
  • Glucose & amino acids
A
  • 100% recovered

*Unless diabetic then there is overwhelming amount of gluose to be recovered leading to glycosuria

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

Why are some substances actively secreted into the kidney excretory system? Give an example of a substance that is actively secreted

A

Substances that we need to get rid of; active secretion gets rid of more than if we just allowed filtration. Example= hydrogen ions

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

What is the predominant cation and anion in:

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

Describe the water distribution in an average 70kg adult male

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

Define osmolality

Define osmolarity

A
  • Osmolality: number of osmoles per kg of solution/ mOsm/Kg
  • Osmolarity: number of osmoles of solute per litre of solution/ mOsm/L

Values almost same as 1L of water is almost 1kg of water

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

Define osmosis

A

Movement of water from an area of high water potential to an area of low water potential

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

Which part of the kidney is the filter?

A

Glomerulus

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

Where is the glomerulus found?

A

Only in the cortex

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

State the normal totat glomerular filtrate per day

A

140L- 180L

  • *Women tend to be lower as smaller than men*
  • *We only have about 5.5L circulating volume hence this means that our circulating volume passes through kidneys filtered many times a day*
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is the filtration fraction?

Give an approximate % for the average filtration fraction?

A

Filtration Fraction= proportion of fluid reaching the kidneys that passes into renal tubes

= fluid that passes into renal tubes/fluid reaching kidneys

=GFR/RPF

About 20% and this is important as it if was too high of a percentage our circulating volume would decrease too much

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

What is the average renal plasma flow in mL/min?

What is average glomerular filtration rate in mL/min?

A

800mL/min (amount of plasma that reaches kidneys)

125mL/min

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

Label this diagram of glomerulus

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

Describe the arteries which blood passes through as it enters renal artery and moves to the glomerulus

A
  • Renal artery
  • 5 segmental arteries
  • Interlobar arteries
  • Arcuate arteries
  • Interlobular arteries
  • Millions of afferent arterioles
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is a renal lobe?

A

Medullary pyramid and the cortex directly above it

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

Explain how/why components are forced out of the blood in the glomerulus (think about hydrostatic pressures)

A

Diameter of afferent arteriole slightly greater than diameter of efferent arteriole hence the hydrostatic pressure of blood inside glomerulus is increased. Increased hydrostatic pressure helps to force components out of glomerular capillaries

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

What substances are forced out of glomerular capillaries?

A
  • Most ofwater
  • Most/all of salts
  • Most/all of glucose
  • Most/all of urea
  • Most/all of creatinine

Ultrafilrate is identical to plasma but just doesn’t have large proteins and cells!

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

Label this image of a renal corpuscle and it’s surrounding structures

A

*Notice how lumen of proximial convulted tube looks ‘filled’ this is due to brush border which is absent in distal convulted tube

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

What is the mesangium and what is it’s role?

A

Mesangium is basement membrane like maxtrix which has glomerular capillaries embedded in it; it offers structural support to the capillaries. Mesangial cells are found in the mesangium and maintain it.

20
Q

Define a renal corpuscle

21
Q

What determines whether a molecule is filtered by glomerulus?

A
  • Size
  • Charge
22
Q

Define GFR

A

Glomerular filtration rate= volume of plasma filtered by all nephrons of both kidneys per unit time

23
Q

Why are efferent arterioles named arterioles even though they are a set of vessels leaving a capillary bed and should therefore by convention be called venules?

A

They are histologically similar to arterioles

24
Q

What is the juxtaglomerular apparatus and what does it consist of?

A

Endocrine strucutre consisting of:

  • Macula densa
  • Extraglomerular mesangial cells
  • Juxtaglomerular cells/granular cells (mainly in afferent arteriole wall)
25
What is the macula dnsa sensitive to and describe what it does in response to changes in the concentration of the substance it detects
Macula densa is sensitive to changes in NaCl concentration and affects renin release by juxtaglomerular/granular cells. If MD detects a decrease in NaCl concentration (which would cause loss of water and hence a drop in blood pressure) renin is secreted.
26
Are extraglomerular mesangial cells and juxtaglomerular/granular cells connected?
Yes, by gap junctions
27
Why do the kidneys need a high constant blood flow of about 4mL/min/g?
Water, ions, glucose and amino acids are reabsorbed back into circulating plasma; this is metabollically demanding so needs plentiful oxygen and glucose supply.
28
Approximately what % of glomerular filtrate goes on to become urine?
1% ... as the rest is reabsorbed into the blood as it passes through renal tubules (called tubular reabsorption)
29
State 3 mechanisms by which tubular reabsorption occurs
* Osmosis * Diffusion * Active transport
30
Where is the majority of the glomerular filtarte solution reabsorbed?
Proximal convulted tubules (some of water, all of glucose)
31
State some ions that are added to the glomerular filtrate in the nephron tubule
* Hydrogen ions * Potassium ions * Ammonium ions * Creatinine * Urea * Some hormones & drugs e.g. penicillin
32
Describe 3 layers of the glomerulus filtration barrier from innermost to outermost
* **Endothelial cells:** thin, highly fenestrated endothelial cells *(with negativley charged glycoproteins podocalyxin in pores)* * **Glomerular basement membrane:** acellular gelatinous layer of -ve glycoproteins * **Podocytes (found on visceral endothelial layer of Bowman's capsule):** podocytes have projections/foot processes that attach to urinary side of glomerular basement membrane. The foot processes interdigitate leaving filtration slits. A protein network forms slit pores in these filtration slits. *(Prevent passage of large molecules)*
33
Label this EM of glomerular filtration barrier
34
What is the largest molecule which can pass through glomerulus?
Inulin
35
If someone has a disease of kidney in which the negative charge of the filtration barrier is lost what may be found in their urine?
Protein (proteinuria)
36
State the two methods involved in renal autoregulation State which is faster
* Myogenic (faster) * Tubuloglomerular feedback system (slower)
37
Autoregulation is able to maintain RBF and GFR within what blood pressure range?
80 - 170 mmHg
38
Why do we need regulation of RBF and GFR?
* To prevent imbalances in substances (e.g. electrolytes) in body * Protect fragile glomerular capillaries; high perfusion may damage
39
Describe myogenic autoregulation of kidneys
Arterial smooth muscle, particulary in the preglomerular vessels (arcuate, interlobular, afferent arteriole) responds to vascular pressure/tension changes. * Increase in blood pressure: **vasoconstriction of afferent arterioles** and other preglomerular vessels or **vasodilation of efferent arteriole** * Decrease in blood pressure: **vasodilation of afferent arterioles** and other preglomerular vessels or **vasoconstriction of efferent arterioles**
40
Which arteriole, afferent or efferent, has the greatest change in resistance as part of myogenic autoregulation?
Afferent. Very little change in efferent arteriole resistance
41
Describe tubuloglomerular feedback for if GFR increases
* **Increase in GFR** * Increase tubular flow rate hence reduces time available for NaCl reabsorption in ascending loop of Henle * Results in increased NaCl delivery to distal convulted tube lumen hence more Na+, Cl- and K+ ions are transportedinto Macula densa cells by NKCC2 transporter * **Increased NaCl concentration in macula densa** * Macula densa causes **MD cells in** **juxtaglomerular appartus to release adenosinetriphosphate (ATP)** * ATP leaves MD through exit channels and is quickly converted to AMP and then to adenosine * **Adenosine binds to A1 receptor** on **extraglomerular mesangial cells** in afferent arteriole * **Activation of G proteins** * Gi inhibits adenylate cyclase, Go **increases intraellular calcium** * Calcium travels **smooth muscles cells via gap junctions** * **Vasoconstriction of afferent arteriole** ***\*NOTE:*** *ADENOSINE ALSO BINDS TO A2 RECEPTORS ON EFFERENT ARTERIOLES CAUSING VASODILATION.*
42
What does an increase in NaCl sensed by macula densa do to renin release from juxtaglomerular/granular cells?
Inhibits renin release
43
Describe the tubuloglomerular feedback if there is a decrerase in GFR
SAME MACHINERY AS FOR INCREASE * Decrease in GFR * Decrease tubular flow rate hence increases time available for NaCl reabsorption in ascending loop of Henle * Results in decreased NaCl delivery to distal convulted tube lumen hence less Na+, Cl- and K+ ions are transported into Macula densa cells by NKCC2 transporter * Decreased NaCl concentration in macula densa * Macula densa cells in juxtaglomerular appartus to release vasodilators (PGI2 & PGE2) * Vasodilation of afferent arterioles Decreased NaCl concentration in macula densa causes renin release which will then go to act on angiotensinogen to form angiotensin I. Angiotensin I converted to angiotension II by ACE.
44
There are lots sympathetic fibres innervate afferent and efferent arterioles; what do these sympathetic fibres do
Sympathetic fibres cause vasoconstriction to conserve blood volume in times of need e.g. fight or flight, ischaemia, haemorrhage
45
Describe what happens to neural regulation of GFR in fight or flight, ischaemia, haemorrhage etc...
Usually sympathetic innervation is low. In those circumstances vasoconstriction
46
Glomerulotubular balance is a 2nd line of defence against changes in GFR; explain what it is
The PCT absorbs 67% of the filtered load of an ion (GFR concentration of an ion) as oppose to a set amount; this means that if GFR increases you will increase the amount of that ion that you reabsorb so that you don't lose as much
47
Most of the energy consumed by kidneys is used in sodium reabsorption; explain why it is used in sodium reabsorption and how sodium reabsorption aids reabsorption of other substances
Cocentration of sodium in ultrafiltrate and plasma is about the same. Use Na+/K+ ATPases in the basolateral membranes of tubular cells to actively pump sodium out of ultrafiltrate and into plasma. This creates a Na+ gradient. Symporters (that transport Na+ and other substance) then allow other substances to move out of ultrafiltrate using the energy dissipated by flow of Na+ down its concentration gradient. Substances then move through cells via diffusion or active transport

Sem 3: Urinary (21 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions