BMS10-1029 Microcapillaires

Question 1

Microcirculation

Answer 1

Terminal arterioles, capillaries and post capillary venules

Question 2

Function of the microcirculation

Answer 2

Transfer gas, water, nutrients and waste between blood and tissues

Question 3

Describe the microcirculation organisation (5)

Answer 3

Arteriole
Terminal arterioles
Capillaries
Post capillary venules
Venule

Question 4

What control terminal arterioles flow?

Answer 4

They aren’t innervated so local factors control

Question 5

Which sections are surrounded by pericytes?

Answer 5

Capillaries and post capillary venules

Question 6

Give 2 functions of the lymphatic capillaries

Answer 6

Take microorganisms to lymph glands

Absorb fluid and protein to return to the blood

Question 7

What is vasomotion?

Answer 7

The relaxing and contracting of terminal arterioles, different areas normally have different levels of dilation but when exercising they are all the same, dilated

Question 8

Where are continuous capillaries found?

Answer 8

Lung
Skeletal muscle 
Skin
Myocardium
CT
Fat

Question 9

Where are fenestrated capillaries found?

Answer 9

Kidneys, intestine and joints

Question 10

Where are discontinuous capillaries found?

Answer 10

Bone marrow
Spleen
Liver

Question 11

Routes allowing substances through the capillary wall

Answer 11

Transcellular (straight through)
Vesicular transport protein
Trans endothelial channel 
Fenestrations
Between cells

Question 12

What are the 2 ways water cross?

Answer 12

Intercellular junctions and water channels

Question 13

If plasma leaves circulation what happens?

Answer 13

The lymph returns it back to the bloodstream

Question 14

How do you calculate overall pressure?

Answer 14

Hydrostatic - (omega x oncotic)

Question 15

How to calculate hydrostatic pressure?

Answer 15

Capillary - Interstitium

Question 16

How to calculate oncotic pressure?

Answer 16

Capillary - Interstitium

Question 17

What is the omega?

Answer 17

0.8-0.95 which corrects for the endothelium as its not a perfect barrier and sometimes protein will cross it

Question 18

What does a high omega mean?

Answer 18

The solute is less permeable

Question 19

Why do we filter 8litres a day?

Answer 19

The entire body normally has a small outward pressure gradient

Question 20

How can swelling feet make this vary?

Answer 20

Increased capillary pressure so more leaves increasing filtration
Arterioles then constrict reducing the capillary pressure

Question 21

How can exercise make this vary?

Answer 21

Arterioles are constricted so there less filtration so fluid is absorbed

Question 22

What makes up lymphatic vessels?

Answer 22

Continuous overlapping endothelial
Interrupted basal lamina
Anchoring filaments
Elastic

Question 23

What does the efferent lymph connect to?

Answer 23

Thoracic duct and then the subclavian vein

Question 24

Oedema

Answer 24

Fluid leaving the capillaries and going into the interstitium is greater than the uptake by lymph- this causes swelling due to the excess fluid

Question 25

How can heart failure cause oedema?

Answer 25

CVP can increase due to a decrease CO as fluid is backed up AND due to increased fluid retention - this all increases hydrostatic pressure

Question 26

How can inflammation cause oedema?

Answer 26

There is vasodilation and increase permeability so lots of proteins leave making the oncotic pressure gradient less

Question 27

What other cause is there for oedema?

Answer 27

Lymph blocked e.g. elephantiasis has a worm impairing lymphatic function