L8 -rheology

Question 1

what is blood rheology

Answer 1

deals with deformation and flow of matter so it’s about blood flow

Question 2

function of blood

Answer 2

transport stuff like gases, heat, nutriients, metabolites, signals and immune system

Question 3

constituents of blood

Answer 3

plasma, buffy coat (white blood cells and platelets) and RBCs

Question 4

structure and features of RBCs

Answer 4

biconcave disc

• has no nucleus
• has plasma membrane supported by spectrin (a protein network)
• adapted for transport, viscosity and deformability

Question 5

how does the structure of a small artery affect the flow of blood

Answer 5

the area is greater than the diameter of the RBCs so it can flow freely

Question 6

how does the structure of an arteriole affect the flow of blood

Answer 6

RBCs flowing in the column like structure

Question 7

how does the structure of a capillary affect the flow of blood

Answer 7

the cells deform so it can fit through

Question 8

how does the poiseuille’s law relate to blood flow

Answer 8

the vel of the blood in the centre is the highest but decreases as it get nearer to the edge so this is laminar flow

Question 9

what is resistance proportional to in terms of blood flow in vessels and poiseulle’s law

Answer 9

viscosity so the more viscous the blood, the higher the resistance

Question 10

what affects the resistance of the blood in a large vessel

Answer 10

blood viscosity

Question 11

what affects the resistance of the blood in a small vessel

Answer 11

plasma viscosity and the cellular properties of the RBCs

Question 12

factors controlling viscosity

Answer 12

haematocrit and plasma viscosity

Question 13

what is haematocrit

Answer 13

-ratio of RBCs to total vol of blood so around 40-45% of vol of RBCs

Question 14

how does haematocrit affect viscosity

Answer 14

as the haematocrit increases, the viscosity increases

• oxygen flux increases for a given pressure
• but if the viscosity is too great, the resistance becomes too great and this impedes the flow

Question 15

what is plasma viscosity

Answer 15

conc of other stuff like proteins, ABs, WBCs

Question 16

how does plasma viscosity affect the blood viscosity

Answer 16

if the plasma viscosity increases maybe due to an immune response , the blood viscosity increases too
-but If the viscosity is too great, the resistance is too great and this impedes the blood flow

Question 17

how does the RBC deform and aggregate in high flow condition

Answer 17

• becomes more spindle-shaped to align with the flow

- less aggregation

Question 18

how does the RBC deform and aggregate in low flow condition

Answer 18

-the cells become more stuck together and they aggregate which is mediated by plasma proteins like fibronogen

Question 19

what happens to WBC and platelets when there is RBC aggregation in the blood vessel

Answer 19

get pushed towards to the edge of the flow so they can exit to the site of inflammation

Question 20

what blood vessel is most similar to the size of the RBC

Answer 20

capillary so the cells deform and squeeze through the vessel

Question 21

when does traffic jam of RBC occur in the vessel

Answer 21

where there is or are WBCs moving in front as it is larger than the RBCs and closer to the size of the capillary or a vessel

Question 22

what happens to the shape of WBC when they get activated

Answer 22

spherical normally but deforms once activated due to bacterial infection

Question 23

factors affecting the deformation and circulation of WBC and RBCs

Answer 23

cell geometry, membrane deformability and cytoplasm and viscosity

Question 24

describe the effect of the cell geometry on the deformation and circulation of WBC and RBCs

Answer 24

• the larger the size, the larger the degree of deformation is needed so for WBCs, it’s larger than RBC
• SA:V - WBC spherical so it’s easier to deform and for RBC, It can shape w/o changing its shape

Question 25

describe the effect of the membrane deformability on the deformation and circulation of WBC and RBCs

Answer 25

• where it’s resistant to deformation) so RBC can change shape w/o being damaged)
• and disruption (having membrane skeleton provides stability)

Question 26

what is spectrin

Answer 26

• protein network supporting the RBC membrane so ti can deform
• stretches due to its coil structure then recoil

Question 27

features of RBC membrane

Answer 27

• can control the cell shape
• flexible
• stable so withstand flow stress
• have pumps and transportes to regulate haemoglobin vol and haemeostasis contents

Question 28

types of blood cells

Answer 28

RBC, WBC, platelets

Question 29

what blood cells can adhere and cant adhere to the vessel wall

Answer 29

RBC- doesnt
WBC-adhere for immune response
-platelets - adhere for clotting

Question 30

steps in WBC adhesion and migration along the wall

Answer 30

1. in contact with the vessel wall
2. captured and rolls along the wall by help of selectins
3. stops due to integrin activation
4. spreads along the vessel wall
5. migrate over the endothelium
6. move into the gap of the wall
7. then now in or under the vessel

Question 31

the blood flow is fast, how is wbc caught when it’s travelling fast too

Answer 31

-adhering causes the cells to slow down

Question 32

how is adhesion stabilised

Answer 32

with integrin activation