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Flashcards in Renal Physiology Deck (67):
1

What is intracellular fluid

The largest compartment of the body (a virtual compartment)

2

How much of male and female bodies are made up of intracellular fluid

Females = 27%, males = 33%

3

What is the composition of intracellular fluid

Contains high K+ and Mg2+. Low in Na+ and Cl-. Also contains lots of negatively charged proteins

4

What does the negative charge of intracellular fluid do

Exerts a primary osmotic pressure

5

What are the two subdivisions of intracellular fluid

Plasma and interstitial fluid

6

Describe plasma

4.5% of body weight in males and females. Contains no proteins so exerts osmotic pressure

7

Describe interstitial fluid

18% of body weight in females, 21.5% in males. Contains high Na+, Cl-, HCO3(-). Has few proteins

8

What is plasma

The whole blood minus RBCs, WBCs and platelets

9

How much of plasma is water

90%

10

What is the remainder or plasma

Mineral ions: Na+, K+, Cl-, HCO3(-). Small organic molecules: amino acids, fatty acids and glucose. Plasma proteins: albumin, fibrinogen, globulins

11

What determines extracellular fluid volume

The concentration of Na+

12

What happens if there is an increase in the total body of Na+

The volume of plasma will increase

13

What are the main functions of the kidneys Unicorns Whisper Cunt Everyday

1. Clear the body of urea and other metabolic waste 2. To control the amount of water in the body 3. To regulate the composition of ECF 4. To produce erythropoietin and renin (regulates erythropoiesis and BP)

14

By forming urine what 3 important functions does the kidney perfom ERM

1.) Excretes waste products of metabolism. 2.) Regulates the body's water, sodium and potassium content. 3.) Maintains the appropriate acid-base balance of plasma

15

What are the kidneys innervated by

The sympathetic postganglionic fibres and vagal parasympathetic fibres

16

Where is the kidney located

High in the abdomen

17

How long and wide is the kidney

11cm long and 3cm wide

18

What is the hilum

Where water comes out of the kidney

19

Which two vessels is the hilum close to

Vena cava and aorta

20

What percentage of resting cardiac output do the kidneys receive

25%

21

What is renal blood flow

1.25L/min

22

Label this cross section of the kidney

Labelled diagram Hilum, ureter, renal cortex, renal medulla

23

What does a nephron consist of

Cortex and medulla; glomerulus and bowman's capsule; proximal convoluted tubule; loop of Henle; distal convoluted tubule; collecting duct

24

What are the two types of nephrons

Cortical nephrons and juxtamedullary nephrons

25

Describe cortical nephrons

Around 85% of all nephrons, located in the cortex

26

Describe juxtamedullary nephrons

Closer to renal medulla, loops of Henle extend deep into renal pyramids

27

Describe the juxtaglomerular apparatus

The ascending loop of Henle/ DCT makes contact with the afferent arteriole

28

Describe the mascula densa

Cells are more dense and sensitive to Na+ conc

29

Describe the juxtaglomerular cells

Modified cells of the afferent arteriole which release renin

30

Through which 3 processes does the nephron regulate plasma conposition

Filtration, reasbsorption and secretion

31

What is filtration

The movement of water and solutes across the filtration membrane

32

Where does filtration occur

In the renal corpuscle

33

What is reabsorption

Returning water and desirable solutes back to the body

34

Where does reabsorption occur

Primarily in the proximal convoluted tubule

35

What is secretion

Transport of undesirable material missed by filtration (waste, drugs, excess ions) from the blood into tubular fluid

36

Where does secretion occur

In the distal convoluted tubule

37

Describe ultrafiltration

Pressure in the glomerular capillaries forces a portion of plasma into the Bowman's space

38

What is able to pass during ultrafiltration

Plasma minus large proteins

39

Which cells are responsible for filtering the blood

Podocyte cells

40

What is glomerular filtration rate regulated by

Renal autoregulation, hormonal regulation and neural regulation

41

What is the amount of filtrate formed in the kidneys every minute

105-125ml/min

42

How much of the filtrate leaves the body

1%

43

Describe reabsorption that occurs in the PCT

~65% of water and 70% of Na+. Also potassium, cholride, bicarbonate, calcium, magnesium

44

In normal circumstances what does tubular reabsorption remove

All filtered glucose, lactate and amino acids

45

What does tubular reabsorption do

Reclaims useful substances from tubular fluid whilst simultaneously allowing waste products to be excreted

46

By which three mechanisms does absorption occur

Osmosis (water), active transport (Na+/ K+ ATPases), secondary active transport (glucose and amino acids coupled to sodium reabsorption)

47

How much of the filtered sodium, chloride and water are reabsorbed by the loop of Henle

20%

48

What happens as the filtrate moves down the loop of Henle

It becomes increasingly hypertonic as a result of passive movement of water out of the tubule

49

What is the only substance the descending loop is permeable to

Water

50

Where does osmolarity peak

At the hair pin bend

51

What happens as the filtrate moves up the ascending loop

Becomes increasingly hypotonic as a result of the pumping out of Na+, K+ and Cl-

52

What happens in the distal convoluted tubule

Sodium and chloride reabsorption; potassium and hydrogen secretion; calcium and magnesium handling

53

What is the unique capacity of the DCT

It can adapt to changes in hormonal stimuli

54

What are the functions of the collecting system

Adjusts final filtrate composition; determines final osmotic concentration; dtermines final volume of urine; permeable to urea

55

Only one DCT empties into one collecting duct- true/false

FALSE. Many DCTs empty into one collecting duct

56

What happens once the filtrate enters the minor calyx

The fluid is now called urine. concentration and Composition vary based on metabolic and hormonal activities

57

What 3 hormones act on the kidneys

Angiotensin II, Aldosterone and ADH

58

What does Angiotensin II do

In response to low sodium and low tubular flow juxtaglomerular cells produce renin. Renin cleaves angiotensin I from angiotensin which is converted to angiotensin II by enzymes from the lungs. Angiotensin II directly stimulates Na+ reabsorption in the PCT. Also stimulates vasocontriction of the afferent and efferent arterioles decreasing the GFR

59

What does a decrease in GFR simulate

The secretion of aldosterone

60

What part of the kidney does angiotensin II act on

Afferent and efferent arterioles and PCT

61

What does aldosterone do

Raises BP by stimulating kidneys to retain water and Na+ (increasing blood volume). Leads to production of Na+ channels and promotes Na+ reabsoprtion. Na+ reabsorption leads to water retention and limits unrianry losses

62

What part of the kidney does aldosterone affect

DCT and collecting ducnt

63

What does ADH do

Raises BP by stimulating kidneys to retain water (increasing blood volume). Increase in plasma osmolarity or decrease in blood volume causes the release of ADH from the posterior pituitary gland. ADH increases aquaporins in the renal collecting ducts

64

Where does ADH affect

Collecting duct

65

What are the most common causes of chronic renal failure

Diabetes and long term uncontrolled hypertension

66

When does CRF occur

When more than 3/4 of the functional renal tissue is lost

67

What happens during CRF

  1. Glomerular filtration rate falls substantially.
  2. Concentration of urea in blood rises (uraemia).
  3. Impaired tubular function leads to failure of normal ionic regulation, acidosis and accumulation of metabolites.
  4. Accumulation of metabolites and disturbance of ionic balance will lead to CNS depression, coma and eventually death