Brainscape's Knowledge GenomeTM

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


See full index

Renal > GFR physiology > Flashcards

GFR physiology Flashcards

1
Q

Factors affecting GFR

A
  • Sympathetic VC causes afferent and efferent vasconstriction and decrease in GFR
  • Catacholamines - Constrict firstly the afferent
  • Angiotensin II - Constricts the efferent at low
  • Both afferent and efferent at high pressures
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the BP values the kidney can autoregulate at?

A

60-130mmHg

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

Why is reabsorption favoured in the peritubular capillaries

A
  • Due to efferent arteriole offering resistance along entire duration there is large decrease hydrostatic pressure (15mmHg)
  • Due to some plasma being filtered through capillaries there is an increase in plasma proteins and therefore plasma colloid osmotic pressure in capillaries
  • Low hydrostatic in efferent and high osmotic pressure results in the favour in absorption
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Describe the molecules involved in carrier mediated transport systems, Tm, maxiumun transport capacity system

A
  • Glucose, amino acids, organic acids, sulphate, phosphate
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the renal threshold?

A

Plasma level at which saturation occurs

e.g = 10 for glucose

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

What other substances use Tm mechanism

A

Sulphate and phosphate

  • Set at such a level that normal plasma causes saturation
  • Any increase in this normal level will cause plasma to be excreted
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What percentage of Na is absorbed in proximal tubule and by what means?

A
  • 65-75% by active transport
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Explain the absorption of sodium from the lumen to the Interstitial fluid?

A
  • Na passivley diffuses at the apical membrane due to the low concentation in the tubule cells
  • Active Na/K pumps are located on the basolateral membrane, this decreases Na within the cells providing the concentration gradient for Na to move passivley in from the tubule
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Why is Na permabile at the tubule cells and not most other places in the body

A
  • Due to large amount of Na channels and surface area offered by microvilli
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

How do anions such as Cl diffuse

A
  • Passivley due to the concentration gradient provided by the Na/K pump transporter
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Why is Na so significant in reabsorption?

A

Determines the gradient of the other ions, and establishs the gradients of the other ions, anything that decreases active transport of Na, will disrupt the whole system

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

Na reabsorption with glucose

A

Na is involved with the reabsorption of glucse

  • The SGLT2 transporter faciliates the movment of glucose into the cell against its concentration gradient
  • Passes via GLUT 1 into the intersitial fluid
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What substances are reabsorbed in the kidney tubule?

A
  • Sulphates, amino acids, sulphate, lactate, phosphate, FA

-

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

How are substances secreted?

A
  • Tm Carrier mechanisms
  • Not very specfic, ie organic acid mechainism which secretes lactic and uric acid can also be used for penicilln asprin and PAH
  • Organic base mechanisms for choline & creatinine can be used for morphine/atrophine
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the normal K value?

A
  • 4 mmoles/L
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What happens above 5.5

A
  • Resting membrane potential decreases, membrane gets excited and ventricullar vibrillation occurs
  • Calcium gluconate
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What happens when K below 3.5

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

Where is K reabsorbed and secreted

A
  • Reabsorbed in the proximal

- Excreted in the distal tubule

19
Q

How is K regulated

A
  • By aldosterone secreted in the zona glomerularis, Increased K secretion and Na reabsorption
  • H ions are also secreted to make up for losses
20
Q

How is albumin reabsorbed?

A

Via the Tm mechanism in the proximal tubule

21
Q

How are drugs not reabsorbed considering the are highly nonpolar and not lipid soluble

A
  • The liver metabolises them to polar compounds
22
Q

What substances are reabsorbed 100%

A
  • Glucose, amino acids, FA’s
23
Q

Maximum concenration of urine that can be produced

A

1200-1400 mOsmoles

24
Q

What is the obligotory waste product and water loss values

A

600mOsmoles / 500mOsmoles

25
Q

Describe the loop of henle

A
  • Removes water on descending

- Removes NaCl on the ascending

26
Q

Describe the fluid entering into the loop of henle

A

Enters at 300mOsmoles
Leaves at 100mOsmoles
200mOsmoles difference at any level between intestitium and ascending limb

27
Q

What has the loop of henle achieved

A
  • It has concentrated the interstitial gradient

- 2

28
Q

Describe the counter current exchangers

A
  • The vesa recta acts as a counter current exchanger,
  • Arranged as a hairpin loop, means it does not interfere with the interstitial gradient
  • They reabsorb the water while not interfering with the interstitial gradient
29
Q

What are the functions of the counter current exchanger

A
  • Provide O2 to the medulla
  • Do not disturb the interstitial gradient
  • Removes volume from the interstitium 36/L day
30
Q

What type of hormone is ADH and where is it released from?

A
  • ADH is a peptide hormone released from the posterior pituitary of the hypothalamus
  • It is secreted by the Supraoptic and paraventricular nuclei
31
Q

Where are osmoreceptor located

A
  • The anterior pituitary gland
32
Q

What triggers the release of ADH

A
  • A Increase in osmolarity via stretch sensitive ion channels
  • Cell dehydration due to trying to balance the hypertonic fluid
33
Q

What is the normal plasma osmorality

A

280 - 290

34
Q

Describe the sensitivity of plasma regulatirty

A
  • A mere change of 2.5% outside of the normal 280-290 will result in a large secretion of ADH
35
Q

Describe effective osmorality

A

Osmorality - Non penetrating and penetrating solutes
Tonicity - Non penetrating solutes
- An increase in osmorality that does not increase in tonicty will not cause in increase in ADH secretion

  • i.e Freely permable substances like urea will not create and osmotic drag are not produce osmotic drag or increase ADH secretion
36
Q

How is water reabsorbed at the collecting ducts?

A
  • ADH binds to receptors triggering exocytosis or aquaporin 2 pores into the apical membrane
  • Water is then absorbed via osmosis
37
Q

If ADH is present maximally

A
  • Water is reabsorbed into the interstitum due to the high concentration created by the multipliers
  • H20 is then reabsorbed back via the vasa recta\
  • Highly concentrated, small volume of urine created
38
Q

In the absence of ADH

A
  • ## Collecting duct is impermeable to H20, creating a large volume of dilute urine compensating for ADH excess
39
Q

Explain urea recycling

A
  • Movement of H20 out of the CD greatly concentrates the urea
  • CD membranes are relatively permeable to urea particullarly towards tips
  • Urea is reabsorbed back down its concentration gradient at medullary tips where it acts to reinforce the the intertitium gradient
  • The occurs in an anti-diuresis where high levels of ADH, urea is reaborbed to the thin ascending LoH, Ureamia occurs
  • Urea also has an osmotic effect on water so its important its reabsorbed
40
Q

Describe the other way osmorlatiy is regulated

A

Low and high pressure receptors

  • Low located in the L and R atria of the great veins
  • High located in the Carotid and aortic arch baroreceptors
41
Q

Describe the effect of decrease of volume on receptors

A
  • They normally have a constant inhibitory discharge on ADH, when ECF decreases this discharge stops
  • A moderate decrease in blood pressure will effeect the L and R atria receptors
  • When there is a change in MBP the carotid and aortic baroreceptors will be affected
  • This will increase ADH secretion
42
Q

What other stimuli increase ADH

A
  • Pain, emotion, stress, exercise, nicotine, morphine, following traumatic surgery
43
Q

What main stimuli depresses ADH release

A
  • Alcohol depresses ADH secretion
44
Q

Describe average volumes of fluid

A

Bowmans capsule - 180L/day, 300mOsm
End of proximal tubule - 54L/day, 300mOsm
End of loop of henle - 16L/day, 100mOsm
Collecting duct - 1.5L/day, 50-1200 mOsm

Renal (2 decks)

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