The Cardiovascular System Flashcards
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
The venous return mechanism
The skeletal pump
The respiratory pump
Pocket valves
Muscular wall
Gravity
Higher venous return means..
Higher bp
Myoglobin
Muscles form of haemoglobin , when the blood reaches the muscle it drops the o2 off, and the myoglobin picks it up to be used
The Bohr shift
- occurs when curve shifts to the rights
- allows oxygen to disassociate from haemoglobin easier
What causes this Bohr shift
- increase in blood temperature causes oxygen to drop
- increase in blood co2 levels
- a drop in blood PH causes o2 to drop
The vascular system
The vascular system is made up of blood vessels that carry blood through the body
Two types of circulation
Pulmonary - deoxygenated blood from heart to the lungs and oxygenated blood back to the heart
Systemic - oxygenated blood to the body from the heart and then the return of deoxygenated blood from the body to the heart
Blood pressure definition
The force exerted by the blood against the blood vessel wall and is often referred to as :
Blood flow x resistance
How does the redistribution of blood occur
Vascular shunt mechanism
Why does blood flow to the brain remain the same at rest and during exercise?
Brain requires oxygen
For energy
To maintain function
How is oxygen transported into the blood?
It dissolves into plasma and combines with haemoglobin to form oxy-haemoglobin
How is blood redistributed to the working muscles
Increase in co2 detected by chemoreceptors
Increase in movement detected by proprioceptors
Send impulse to medulla oblongata
Through sympathetic nerve, brain sends impulse, vasodilation and vasoconstriction
Pre-capillary sphincters relax so blood flow is increased
How does the increasing level of co2 in the blood raise HR?
Detected by chemoreceptors
Nerve impulses sent to medulla
Sympathetic nervous impulses sent to SA node
Decrease in parasympathetic nerve impulses
The impact of blood pressure on venous return
When systolic blood pressure increases, there is an increase in venous return
Decrease in systolic blood pressure, there is an decrease in venous return
The oxyhaemoglobin disassociation curve
Helps us understand how haemoglobin in our blood transports and releases oxygen
Curve represents relationship between oxygen and haemoglobin
How is blood redistributed
Vascular shunt mechanism
Vascular shunt mechanism
The redistribution of cardiac output
Redistribution of blood is important to:
- increase supply of oxygen to working muscles
- remove waste products from the muscles, such as carbon dioxide and lactic acid
- ensures blood goes to skin to regulate body temperature
- direct more blood to heart as its a muscle and requires extra oxygen during exercise
The sympathetic system
Speeds up HR
The parasympathetic system
Slows down heart rate
Stroke volume definition
the volume of blood pumped out of the left ventricle of the heart during each systolic cardiac contraction
Cardiac output definition
The volume of blood pumped out by the heart ventricles per minute
Heart rate definition
Speed at which heart beats
Cardiac output in response to exercise
During exercise there is a large increase in cardiac output due to an increase in heart rate and increase in stroke volume
Atherosclerosis
Occurs when arteries harden and narrow as they become clogged up by fatty deposits
Atheroma
A fatty deposits found in the inner lining of an artery
Angina
Chest pain that occurs when the blood supply through the coronary arteries to the muscles of the heart is restricted
Bohr shift definition
When an increase in blood carbon dioxide and a decrease in PH results in a reduction of the affinity of haemoglobin for oxygen
