Brainscape's Knowledge GenomeTM

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


See full index

Urinary > Lecture 5 - GFR and filtration > Flashcards

Lecture 5 - GFR and filtration Flashcards

1
Q

What is reabsorbed in the kidney?

A 
Water
Na+
Cl- 
HCO3- 
Glucose
Amino acids
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What substance is actively secreted

A

H+ - lose more than filtered

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

Ultrafiltrate

A

water, ions and all small molecules - plasma without plasma proteins

Not:
RBCs
WBCs
Albumin

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

Filtration rate

A

180 L/ day filtered 10 x

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

Average urination a day

A

1.5 L

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

Total body water

A

42 L

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

ECF water

A

1/3rd - 14 L

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

Intracellular water

A

2/3rds - 28 L

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

Interstitial water

A

3/4 of ECF - 10.5 L

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

Plasma water

A

1/4 of ECF - 3.5 L

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

Haematocrit

A

2 L RBC
3.5 L plasma

5.5 L circulating volume

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

Predominant ion in intracellular fluid

A

K+

Less Na+
Many large organic anions

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

Predominant ion in extracellular fluid

A

Na+

Less K+
Main anion = Cl- and HCO3-

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

Osmolarity

A

number of osmoles in 1 L of fluid

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

Osmolality

A

Solute per kg of solvent

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

Water in regards to cell membranes

A

Can cross cell membranes freely

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

Glomerulus

A

Tuft of capillaries between the afferent and efferent arteriole in the renal cortex

18
Q

Renal plasma flow (RPF)

A

800ml/ min

19
Q

GFR

A

125ml/min

20
Q

Filtration fraction

A

Proportion of fluid from the renal artery that passes into the renal tubules
GFR/RPF
Normally 20%

80% of the blood from the renal artery exits through the efferent arteriole and is unfiltered

21
Q

Basement membrane

A

Acellular gelatinous layer of glycoproteins

Negatively charged

22
Q

Podocytes

A

Wrap around the outside of the capillary loop

Gaps in podocytes = filtration slits - increases filtering capacity

23
Q

What is the basement membrane selective against?

A

Large negatively charged substances such as proteins

24
Q

What makes the basement membrane selective?

A

Podocytes
Negatively charged
Fenestrations in the capillary endothelium

25
Q

What is the largest substance that can pass through the basement membrane?

A

Insulin

26
Q

Proteinuria

A

In some disease processes, the negative charge of the basement membrane is lost so proteins are more readily filtered.

Therefore protein in the urine.

27
Q

Pressures in the glomerulus

A

P(GC) - Hydrostatic pressure in the glomerulus capillary
P(BC) - Hydrostatic pressure in the Bowman’s capsule
π(GC) - Oncotic pressure in the glomerulus capillary

28
Q

Net filtration pressure

A

Net filtration pressure = PGC - (PBC + πGC)

29
Q

Oncotic pressure in Bowman’s capsule

A

Proteins do not get filtered into the Bowman’s capsule so there is no oncotic pressure exerted here

30
Q

Where is oncotic pressure highest?

A

Efferent arteriole as less water

31
Q

Autoregulation of GFR

A

Maintains GFR when blood pressure is within the physiological limits (80-180)

By constricting or dilating the afferent and efferent arteriole

32
Q

Tubular secretions

A 
H+
K+
NH4+ - ammonium ions 
Creatinine
urea
drugs e.g. penicillin 
hormones - insulin
33
Q

Arteriole response to high BP

A

Afferent arteriole constricts

34
Q

Intrinsic autoregulation responses of the kidney

A

Myogenic response

Tubuloglomerular feedback

35
Q

Myogenic renal autoregulation

A
  1. High BP
  2. Opens stretch sensitive, non-selective cation channels in the afferent arteriole smooth muscle.
  3. Influx of Na+ causes depolarisation
  4. Ca2+ influx causes contraction

Rapid
In pre-glomerular blood vessels i.e. arcuate - afferent arteriole

36
Q

Tubuloglomerular feedback

A
  1. High BP
  2. Increased NaCl and H2O delivery to the distal convoluted tubule and cortical collecting duct
  3. The macula densa cells sense an increase in GFR (salinity sensing)
  4. Move more Na+ and Cl- and K+ ions intracellularly visa NKCC2 into macular densa which causes ATP release
  5. ATP converted to adenosine once it leaves the macula densa cells.
  6. Adenosine binds to A1 receptors located on the mesangial cells in the afferent arteriole causing activation of G proteins.
  7. Gi inhibits adenylate cyclase and Go leads to an increase in intracellular calcium which spreads to mesangial cells SM via gap junctions
  8. Contraction of afferent arterioles which decreases PGC and GFR

(NaCl also inhibits renin release in granular cells)

37
Q

Why does GFR decrease in response to high BP

A

To protect the distal tubule and collecting duct from overloading

38
Q

Autoregulation when GFR decreases

A
  1. Less NaCl is delivered to the macula densa cells of the distal convoluted tubule
  2. Prostaglandins are released from the macula densa cells
  3. Causes vasodilation of the afferent arteriole
  4. PGC and GFR increases
39
Q

RAAS

A
  1. Prolonged decrease in BP
  2. Renin released from granular cells
  3. Renin converts angiotensinogen to Angiotensin I
  4. Ang I to Ang III
  5. Ang II causes vasoconstriction of the efferent arteriole
  6. Increases PGC and GFR
40
Q

Sympathetic regulation

A

Normally sympathetic innervation is low

  1. Low BP due to e.g. severe haemorrhage
  2. Increase in sympathetic nerve activity
  3. Stimulates constriction of the afferent arteriole via noreadrenaline.
  4. PGC and GFR decreases (preserves blood volume as blood is diverted to the muscles and heart)
41
Q

Parasympathetic regulation

A
  1. High BP
  2. Ach release
  3. Release of NO from endothelial cells
  4. Efferent arteriole dilation
  5. Decrease PGC and GFR
42
Q

Glomerulotubular balance

A

The PCT absorbs 67% of filtered load therefore depends on GFR.

Blunts sodium excretion

Urinary (23 decks)

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