cardiovascular physiology part 2 fluid dynamics

Question 1

What force moves fluid from blood to tissue?

Answer 1

Hydrostatic pressure of blood = HPc

Question 2

What forces moves fluid from tissue to blood?

Answer 2

Osmotic pressure of capillaries = OPc

Question 3

What moves fluid into & out of cells?

Answer 3

Osmotic pressure only

Question 4

Where is greatest osmotic pressure?

Answer 4

Venous end of the capillaries

Question 5

Where is greatest hydrostatic pressure?

Answer 5

In the capillary (OPc)

Question 6

Which solutes move easily out of capillary under pressure?

Answer 6

Electrolytes, dissolved gases

Question 7

fluid compartments-interstitial and extracellular

Answer 7

intracellular compartment 25L

extracellular, includes plasma, interstitial fluid

Question 8

most abundant ions in body fluids

Answer 8

intracellular- cation k+, anion HPO2- 4

exreacellular-cation Na+, anion Cl-

Question 9

capillary type- continuous

Answer 9

• least permeable
• skin, muscles, lungs ans cns
• have pericytes
• -blood brain barrier cappillaries lack intercellularclefts and tight junctions.

Question 10

capillary type- fenestrated

Answer 10

• leaky
• have fenestrations (holes/windows) and very few tight junctions
• occur in the kidneys (filtration) small intestines and areas of hormone and endocrine secretion

Question 11

sinusoid cappilaries

Answer 11

• leakyist
• designed for areas with low bp
• have large intercellularclefts and fenustrations and very few tight junctions.
• irregulary shaped with large lumens
• blood flows slowly
• many macrophages
• occur in liver spleen and lymphoid tissue, and red bone marrow.

Question 12

cappilary beds

Answer 12

interwoven networks of capillaries form micro circulation between arterioles and venules. There is precappilary sphincters which control the flow through the the cappilaries. In sympathetic function only the vascular shunt (metateriole) which is thoughfare channel in the cappilay is used in parasympathetic the true cappillary is used which which involves whole bed and 10-100 exchange vessels which branch of metariole.

Question 13

vasomotor

Answer 13

is what slow and intermittent flow into cappilaries is called, reflects on/off opening of precappilary sphincter.

Question 14

hydrostatic pressure (HPc)

Answer 14

capillary hydrostatic pressure. Tends to force fluids through the capiilary walls. Is greater at arteriole end (35mmHg) and venule end (17mmhg)

Question 15

interstitial fluid hydro-static pressure (Hpif)

Answer 15

-usually assumed to be 0 because of presence of lymphatic vessels.

Question 16

colloid osmotic pressure

Answer 16

• cappillary colloid osmotic pressure (oncotic pressure, OPc)
• created by non-diffusable plasma proteins which draw water towards themselves
• always a constant 26mmHg

-intersitual fluid osmotic pressure OPif always low (1mmhg) due to low protein content.

Question 17

3 steps of Haemostatic process

Answer 17

vascular spasm
platelet plug formation
coagulation

Question 18

vascular spasm

Answer 18

injury to vascular smooth muscle cell causes vasoconstriction which can stop blood flow if injury small enough

-chemicals released by endothelial cells and platelets and reflexes initiated by local pain receptors.

Question 19

platelet plug formation

Answer 19

• damaged endothelial exposes collagen fibres
• damaged endothelial fibres release von willebrands factor (large plasma protein- acts as glue) this forms a bridge between platelets and collagen fibres.
• platelets activation- strat by clumping together and become spiked, swollen and stick to collagen
• activated platelets release chemicals which prolong vascular spasm, attract more platelets and cause degranulation of other platelets which releases chemicals

Question 20

blood clotting

Answer 20

• tranform the liquid to gel in multistep process and involves 13 clotting factors
• tissue FACTOR III made by human cells is made from….
• calcium ions from blood plasma
• other 10 factors are plasma proteins made in liver and are constantly in our blood in inactive form
• E.coli produces vit K which is required to make 4 of plasma proteins

Question 21

coagulation phase 1

Answer 21

2 pathways to prothrombin activator, usually work together.

1. intrinsic (damage to inside of blood vessel)
   - initiated by platelet
   - slower due to multiple steps(3-6 mins)
2. extrinsic (inside a tissue)
   - tissue cell trauma exposes to tissue factor
   - rapid 15 seconds bypasses some steps
   - 2 pathways merge
   - factor 10 combines with CA+ ions, platelets factor 3- from activated platelets and factor 5 form
   - this forms prothrombin activator

Question 22

coagulation phase 2

Answer 22

prothrombin activator (enzyme) acts and creates prothrombin (plasma protein)- this then converts to thrombin (enzyme)

Question 23

coagulation phase 3

Answer 23

• thrombin catalyses the soluble clotting factor fibrogen into fibrin
• fibrinmolecules join togetherinto long hair like insoluble fibres
• fibrin strands glue the platelets together and make web like mesh that traps formed elements.