Cardiorespiratory

Question 1

what initiates haemostasis?

Answer 1

Occurs when a tissue or blood vessel is directly damaged and causes bleeding.

Question 2

Facts about platelets?

Answer 2

They are circulating, contain actin and myosin so can change shape, have mitochondria, dense and alpha granules (have lots of proteins), no nucleus, produce ATP and ADP, can manufacture enzymes and has glycoprotein surface receptors.

Question 3

what is VWF?

Answer 3

Von Willebrand factor is a large glycoprotein (alpha granule) produced by vascular endothelium at the injury site. It circulates in plasma and binds to exposed collagen which causes platelet activation.

Question 4

how is fibrin formed?

Answer 4

in response to a damaged vessel, a cascade of enzymes causes the generation of the enzyme thrombin which converts soluble fibrinogen to insoluble fibrin.

Question 5

what is calcium used for during haemostasis?

Answer 5

to prevent blood coagulating in storage

Question 6

what are the several functions of thrombin?

Answer 6

1) removal of small fibrinopeptides from fibrinogen to form fibrin.
2) activation of XIII
3) activation of platelets
4) catalyses activation of factors ….

Question 7

what are the limitations of coagulation?

Answer 7

[Thrombin] must be carefully controlled. Intact endothelium secrets a vasodilator which prevents platelet activation.

Question 8

what is cardiac integration?

Answer 8

The nature of interactions between the heart, vasculature and other biological systems to optimise function.

Question 9

what things can modify smooth muscle contraction (aka raise intracellular Ca+ levels)?

Answer 9

Chemical -> metabolism, hormones, paracrine effects.

Physical-> blood pressure and flow.

Question 10

Classic Principles of flow regulation?

Answer 10

• Re-active hyperaemia
• Active hyperaemia
• Myogenic tone
• Flow-dependant vasodilation (NO)

Question 11

How does Nitric Oxide effect blood flow?

Answer 11

It is a vasodilator. Nitric oxide increases blood flow and lowers blood pressure.

Question 12

define vasodilation?

Answer 12

Increase in internal diameter of a blood vessel due to relaxation within the wall of the vessel. This causes an INCREASE in blood flow but a DECREASE in resistance and pressure.

Question 13

define vasodilatation?

Answer 13

Increased calibre of the blood vessel.

Question 14

what is transmural pressure?

Answer 14

The pressure exerted across the vessel wall.

Question 15

what are the four main factors which effect blood flow?

Answer 15

Diameter, Length, Pressure and Viscosity.

Question 16

what are structural adaptations of the coronary circulation?

Answer 16

High capillary density. Large endothelial area. Reduced diffusion distance.

Question 17

what are the functional adaptations of the coronary circulation?

Answer 17

High flow and O2 extraction.

Question 18

what is metabolic hyperaemia?

Answer 18

Condition where the muscle is working hard and release metabolites, uses ATP and breaks it down to the vasodilator (adenosine).

Question 19

what are the structural adaptations of cerebral circulation?

Answer 19

high capillary density. Grey matter has large exchange area. Blood brain barrier (lipophilic things can’t get out of brain).

Question 20

what are functional adaptations of cerebral flow?

Answer 20

High basal blood flow (grey matter).
Self preservation.
Cerebral auto regulation.

Question 21

what are risk factors for stroke?

Answer 21

Modifiable -> Diabetes, hypertension, cigarette smoking, atrial fibrillation.
Unmodifiable -> sex, gender, age, ethnicity, genetics.

Question 22

what is destroyed during. stroke?

Answer 22

120 million neurons, 830 billion synapses, 447 miles of myelinated.fibres.

Question 23

what does the rate of transfer in diffusion depend on?

Answer 23

area, distance and driving force (conc. gradient).

Question 24

what conditions arise at high altitude?

Answer 24

reduced barometric pressure, reduced partial pressure of oxygen, decrease in air temp and water vapour pressure. High exposure to UV.