Heart & Blood Flashcards
define systole
period of contraction
define diastole
period of relaxation
why is pressure on the left side of the heart higher?
it pumps blood to the rest of the body
from which to which pressure does blood flow to?
high to low pressure
what generates pressure in the heart
contractions of the cardiac muscle
describe atrial systole
- 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
describe ventricular systole
- 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
describe what happens during diastole
- 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
cardiac cycle stages in order
atrial systole
ventricular systole
diastole
how does the cardiac cycle re-start after diastole
blood from vena cava + pulmonary veins enter atria
why is it necessary for the heart rate to be modified
to need bodily demands
what controls the modification of the heart rate
nervous + hormonal systems
cardio-vascular centre
where’s the cardio-vascular located
medulla oblongata
what is heart rate determined by
the balance between sympathetic + parasympathetic nerve activity
what happens at the cardio-vascular centre?
- receives output from 4 main receptor groups
- inputs processed
- para or parasympathetic nervous system is recruited accordingly
what are the 4 receptor groups that send inputs to cardiovascular centre
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
define correlation
link/relationship between 2 things that happen
define causation
indicates 1 event is the result of the causation of another
what’s the role of coronary arteries?
supply heart with oxygen + glucose
and substances needed for respiration
describe blood clotting process
- 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
describe atherosclerosis
- 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
