microcirculation and oedema

Question 1

what are the layers of a blood vessel?

Answer 1

tunica intima
tunica media
tunica adventitia

Question 2

what are capillary walls made of?

Answer 2

single layer of endothelial cells

Question 3

why are capillaries known as exchange vessels?

Answer 3

site of exchange of nutrients and waste products between circulation and ISF

Question 4

how does blood enter and exit the capillary bed?

Answer 4

enters the capillary bed through the terminal arteriole and leaves via post-capillary venule

Question 5

describe the structure of capillaries

Answer 5

Composed of endothelial cells with tight junctions surrounded by basement membrane upon which the endothelium rests

Question 6

what are the types of capillaries?

Answer 6

continuous, fenestrated and discontinuous

Question 7

which type of capillary is the least permeable?

Answer 7

continuous

Question 8

describe the structure of the continuous capillary

Answer 8

sealed endothelium and basement membrane
tight junctions
only allows small molecules to go through

Question 9

what are the types of continuous capillaries?

Answer 9

numerous transport vesicles

few transport vesicles

Question 10

describe the structure of fenestrated capillaries

Answer 10

Continuous closed basal lamina but epithelium contains small circular pores
allows for free passage of small molecules

Question 11

where are fenestrated capillaries found?

Answer 11

tissues specialised for bulk exchange

Exocrine glands, intestines, glomeruli of kidneys, pancreases, intestines.

Question 12

which type of capillary is the most permeable?

Answer 12

discontinuous

Question 13

describe the structure of discontinuous capillaries

Answer 13

larger fenestrations
discontinuous basal lamina
lack pinocytotic vesicles
allows leakage between endothelial cells

Question 14

where are discontinuous capillaries found?

Answer 14

liver, spleen and bone marrow

Question 15

how does movement across a capillary endothelial cell occur?

Answer 15

diffusion
paracellular pathways
through fenestrations
calveoli

Question 16

what is fick’s law?

Answer 16

amount moved = area x conc. Gradient x diffusion coefficient

Question 17

what do surface area and diffusion distance depend on?

Answer 17

density of capillaries

Question 18

what is paracellular transport?

Answer 18

The transfer of substances across an epithelium by passing through the intercellular space between the cells

Question 19

what substances often use paracellular pathways?

Answer 19

water-soluble substances

Question 20

what are calveoli?

Answer 20

specialised pits that undergo endocytosis and form vesicle

Question 21

what pressures determine fluid movement?

Answer 21

hydrostatic and oncotic pressure

Question 22

what determines hydrostatic pressure?

Answer 22

blood pressure and the pumping of the heart

Question 23

what is the hydrostatic pressure of the capillaries normally?

Answer 23

0 mmHg

Question 24

what determines oncotic pressure?

Answer 24

number of plasma proteins in the capillary

Question 25

how is net filtration pressure calculated?

Answer 25

(HPc - HPif) - (OPc - OPif)

Question 26

what happens to fluid at the venous and arterial ends of a capillary?

Answer 26

arterial end - fluid leaves capillary | venous end - water is drawn back in

Question 27

what are lymphatic capillaries?

Answer 27

specialised vessels made up of an endothelium with large intracellular gaps surrounded by permeable b.m

Question 28

why do lymphatic capillaries have one way valves?

Answer 28

ensure lymph travels in one direction

Question 29

where can water originally from capillaries be reabsorbed?

Answer 29

at the subclavian veins | reabsorbed into circulation at lymph nodes

Question 30

what is an oedema?

Answer 30

increased volume in the interstitial compartment leads to tissue swelling

Question 31

what causes an oedema?

Answer 31

when there's too much ISF in the tissues and causes swelling to occur

Question 32

where do systemic oedemas occur?

Answer 32

in the lower body

Question 33

how are systemic oedemas recognised?

Answer 33

pitting - when firm pressure is applied in the affected area and it doesn't bounce back immediately elevated venous pressure in the legs

Question 34

what are the types of oedema?

Answer 34

systemic | pulmonary

Question 35

what factors can lead to an oedema?

Answer 35

increased capillary hydrostatic pressure decreased plasma oncotic pressure increased capillary permeabiluty lymphatic obstruction

Question 36

what complications can an increased capillary hydrostatic pressure lead to?

Answer 36

heart failure

Question 37

what is kwashiorkor?

Answer 37

severe malnutrition - deficiency in dietary protein

Question 38

what are symptoms of kwashiorkor?

Answer 38

pitting oedema | water retention in the gut

Question 39

how do you treat oedema?

Answer 39

treat the underlying cause osmotic diuretics - increase water excretion loop diuretics - increase sodium excretion

Question 40

what are symptoms of heart failure?

Answer 40

Breathlessness after activity or rest Feeling tired most of the time Swollen ankles and legs