AWABS - Capillary Dynamics and Interstitial Fluid

Question 1

Role of arteries

Answer 1

Transport oxygenated blood

Question 2

Role of arterioles

Answer 2

Adjust diameter to regulate blood flow
Highly muscular

Question 3

Thickness variations of arteries / arterioles vs capillaries vs venous system

Answer 3

Question 4

Types of capillary

Answer 4

Continuous (most common)
Fenestrated
Sinusoid

Question 5

Fenestrated capillaries

Answer 5

Have small gaps to allow exchange

Found in endocrine glands and intestines

Question 6

Sinusoid capillaries

Answer 6

Large gaps

Found in Bone marrow, liver and spleen

Question 7

Forces acting at capillary

Answer 7

Hydrostatic capillary pressure
Colloid osmotic pressure

(Balanced against interstitial fluid pressure and interstitial fluid colloid osmotic pressure)

Question 8

Pressures at arterial end of capillary

Answer 8

Capillary pressure 35 (out)
Interstitial fluid pressure -2

Plasma colloid osmotic pressure 27 (in)
Interstitial fluid colloid osmotic pressure 7

Net pressures act to draw out of capillaries

Question 9

Pressures at venous end of capillary

Answer 9

Capillary pressure 15 (out)
Interstitial fluid pressure -2

Plasma colloid osmotic pressure 27 (in)
Interstitial fluid colloid osmotic pressure 7

Net pressures act to draw into capillaries

Question 10

Lymphatic ducts

Answer 10

Question 11

Lymphatic drainage system movement of fluid

Answer 11

Poorly understood

Possible muscle contraction, possible mild peristalsis action

Question 12

Definition of a mole

Answer 12

Amount of a substance that contains number of molecules equal to Avogadro’s number (6.022 x10^23)

Question 13

How much does one mole weigh

Answer 13

Molecular weights added together

Eg NaCL = molecular weight of Sodium ion + Molecular weight of Chloride ion

Question 14

Osmole definition

Answer 14

Number of moles of osmotically acting particles in a solution

Question 15

Osmolality (mmol/L)

Answer 15

Number of particles (osmoles / mmol) contained in 1 litre of water / solvent

Question 16

Tonicity definition

Answer 16

The effective osmolality

Equal to the sum of concentrations of solutes which have the capacity to exert an osmotic force across a membrane

Question 17

Tonicity vs Osmolality

Answer 17

Tonicity puts osmolality in context of a relevant membrane

Question 18

Examples of isotonic fluids

Answer 18

Normal saline
Hartmann’s

Question 19

Example of hypotonic fluid

Answer 19

0.45% NaCl

Question 20

Types of transport across cell membrane

Answer 20

Passive transport
Active transport

Question 21

Active transport

Answer 21

Requires energy
Converts ATP to ADP

Works against concentration gradients

Question 22

Passive transport

Answer 22

Diffusion - Includes facilitated diffusion through aqueous channel or carrier protein

Works along concentration gradient

Question 23

Bulk transport

Answer 23

Question 24

Endocytosis vs phagocytosis

Answer 24

Endocytosis is receptor mediated using receptors on cell membrane

Question 25

Approximate CSF volume

Answer 25

~150ml

Question 26

Approximate volume of CSF production per day

Answer 26

~450ml per day

Question 27

Site of CSF production

Answer 27

4 choroid plexuses in lateral, 3rd and 4th ventricles

Question 28

Normal CSF opening pressures

Answer 28

10-15 cmH2O lying down
20-30 cmH2O sitting up

Question 29

Flow of CSF

Answer 29

Question 30

Pleural fluid, pericardial fluid and peritoneal fluid constituents

Answer 30

Ultrafiltrate of plasma

Question 31

Pleural fluid volume

Answer 31

1-10 ml

Question 32

Pericardial fluid volume

Answer 32

10-50 ml

Question 33

Peritoneal fluid volume

Answer 33

Usually <100 ml

Question 34

Pleural fluid charactersitics

Answer 34

Straw coloured
pH ~7.6