Heart & Blood

Question 1

define systole

Answer 1

period of contraction

Question 2

define diastole

Answer 2

period of relaxation

Question 3

why is pressure on the left side of the heart higher?

Answer 3

it pumps blood to the rest of the body

Question 4

from which to which pressure does blood flow to?

Answer 4

high to low pressure

Question 5

what generates pressure in the heart

Answer 5

contractions of the cardiac muscle

Question 6

describe atrial systole

Answer 6

• atria full of blood -> ventricles = relaxed
• both atria contract -> blood passes down to ventricles
• atrio ventricular valves open due to blood pressure
• 70% of blood flows passively down to ventricles -> ventricles don’t have to contract a lot

Question 7

describe ventricular systole

Answer 7

• atria relax
• ventricle walls contract -> blood forces atrio ventricular valves to shut which produces “lub”
• pressure of blood opens semi-lunar valves
• blood passes into aorta + pulmonary arteries

Question 8

describe what happens during diastole

Answer 8

• ventricles relax
• pressure in ventricles falls below pressure in arteries
• blood under high pressure in arteries -> causes semi-lunar valves to shut, producing dub
• all heart muscles relax during diastole

Question 9

cardiac cycle stages in order

Answer 9

atrial systole
ventricular systole
diastole

Question 10

how does the cardiac cycle re-start after diastole

Answer 10

blood from vena cava + pulmonary veins enter atria

Question 11

why is it necessary for the heart rate to be modified

Answer 11

to need bodily demands

Question 12

what controls the modification of the heart rate

Answer 12

nervous + hormonal systems

cardio-vascular centre

Question 13

where’s the cardio-vascular located

Answer 13

medulla oblongata

Question 14

what is heart rate determined by

Answer 14

the balance between sympathetic + parasympathetic nerve activity

Question 15

what happens at the cardio-vascular centre?

Answer 15

• receives output from 4 main receptor groups
• inputs processed
• para or parasympathetic nervous system is recruited accordingly

Question 16

what are the 4 receptor groups that send inputs to cardiovascular centre

Answer 16

1 - pressure receptors in the heart
2 - chemoreceptors in heart detect CO2 + O2 levels by pH changes
3 - thermoreceptors in muscles
4 - stretch receptors in muscles

Question 17

define correlation

Answer 17

link/relationship between 2 things that happen

Question 18

define causation

Answer 18

indicates 1 event is the result of the causation of another

Question 19

what’s the role of coronary arteries?

Answer 19

supply heart with oxygen + glucose

and substances needed for respiration

Question 20

describe blood clotting process

Answer 20

• blood vessel damaged and exposes lumen to collagen in its wall
• platelets activated by collagen fibres change shape to form temporary platelet plug
• activated platelets + damaged cells protein Thromboplastin
• Thromboplastin activates series of enzymes to convert Prothrombin into enzyme Thtombin (in presence of Calcium ions + Vitamin K)
• Thrombin catalyses conversion of soluble Fibrinogen into insoluble Fibrin
• when many Firbin molecules have been made they polymerise
• creates mesh of Fibrin that traps more platelets + RBC
• forms a clot + seals wound

Question 21

describe atherosclerosis

Answer 21

• plaque builds up in arteries + restricts blood flow
• endothelium damaged -> collagen fibres exposed from tunica intima
• substances travelling in blood build up in the area
• oxidation of cholesterol triggers inflammatory response -> chemicals released
• triggers phagocytes WBC -> mature monocytes + engulf cholesterol
• foam cells die -> become plaque
• plaque builds up + increases pressure
• smooth muscle cells from tunica media move to surface of plaque
• fibrous cap created -> over time can erode and release plaque into bloodstream + clot/rupture (Thrombis)
• can block arteries + stop cells getting O + glucose for resp./protein synthesis-> cell death (Ischemia)
• can affect organs -> brain, heart attack/failure, stroke