The Cardiovascular System Flashcards
(52 cards)
Describe how the cardiac conduction system causes the heart to contract (5 marks)
- SA node sends electrical impulses down/through the walls of the atria
- AV node receives the wave of electrical impulses causing ATRIAL SYSTOLE to squeeze blood into ventricular
- impulses travel down bundle of HIS
- perkinje fibres help spread out the impulses (ventricular systole)
- heart fills back up by the process of diastole
Medulla oblongata and example
Anything that is subconsciously controlled (e.g. heart and breathing)
How does the brain know we are exercising ? (3)
Chemoreceptors- detect changes in PH due to changes in o2 and co2
Baroreceptors- detect increases in blood pressure
Proprioceptors- detect increases in muscle movements
Stroke volume definition
The amount of blood leaving each ventricle per beat
Ejection fraction definition
The amount of blood leaving the left ventricle per beat
Venous return
The amount of blood returning to the right side of the heart via the vena cava per beat (amount of blood back to the heart)
Starlings law
- The venous return increases during exercise
- Which means more stretch in muscle walls
- More stretch means increased elastic strain and higher ejection fraction
- Starlings law is a way we manage to supply the working muscles with more oxygen to fuel them
Stroke volume and exercise
SV increases with exercise due to increased venous return
Only up to 60% of MHR because heart being too quick to allow ventricle to fully fill
Demand of o2 is met by increased HR
Heart adaptations to training
Cardiac hypertrophy
Stronger heart means increased sv and ejection fraction
Health definition
Social, mental and physical well-being
Fitness definition
The ability to carry out everyday tasks without undue fatigue/the the meet/cope with demands of the environment
What is coronary heart disease?
When the arteries that supply the heart with oxygenated bloody became blocked with fatty deposits. This process is called atherosclerosis
What causes coronary heart disease?
High blood pressure, high cholesterol, lack of exercise and smoking
What can high blood pressure cause?
Heart attack
Kidney problems
Stroke
Dementia
What can reduce high blood pressure?
Regular exercise
What is bad about high cholesterol ?
Can lead to heart disease as results in the fatty deposits building up in arteries
What are the two types of cholesterol and what do they do?
LDL (bad) - transport cholesterol to the tissues to be stored as fat
HDL (good) - transport cholesterol to the kidneys to be broken down
What is a stroke? What can it lead to?
When the oxygen supply to the brain is cut off.
Can lead to brain injury, disability or death
What are the two types of stroke?
Ischaemic strokes - blood clot stops o2 supply
Haemorrhagic strokes - caused by a burst blood vessel that supplies o2.
Describe how cardiovascular drift can occur after 10mins of steady-state exercise in a warm environment
Cardiovascular drift usually occurs after 10/20 mins of exercise
We lose body fluids from sweat which means we have a reduced blood plasma
Which means less blood able to pump through the heart equalling a reduced stroke volume
Hence why our HR increases during steady state exercise
What is the cause of cardiovascular drift?
- reduced plasma/blood volume
- reduced venous return
- starlings law
- cardiac output also increases due to more energy needed to cool body/ sweat
Arteries, veins, capillaries
Arteries- carry oxygen AWAY from the heart
Veins- carry oxygen TOWARDS the heart
Capillaries- used for diffusion of o2 and co2
What is vascular shunting?
When at rest 70% of blood is in our guts to aid digestion and distribute nutrients.
When we exercise this blood needs to get to working muscles.
Then blood also goes to the heart to be pumped to the muscles more quickly.
It also goes to the skin to help us cool down.
Redirection of blood to areas where it’s most needed
What allows the shunting of blood?
Vasoconstriction and vasodilation
