Cardiovascular system Flashcards
What forms the cardiovascular system?
- Heart
- Blood
- Vessels
What is the left side of the heart responsible for?
Pumping oxygen-rich blood around the whole of the body.
What is the right side of the heart responsible for?
Pumping deoxygenated blood around to the lungs where it can be re-oxygenated and returned to the left side of the heart.
What is the order of the flow of blood through the heart?
Right atrium, AV valve (tricuspid), Right ventricle, Semi-lunar valve, Pulmonary artery, Lungs, Pulmonary vein, Left atrium, AV valve (bicuspid),Left ventricle, Semi-lunar valve, Aorta, Body, Vena cava, Right atrium.
Pulmonary circuit
Right side pumps blood to the lungs (heart,lungs,heart)
Systematic circuit
Left side pumps blood to the body (heart,body,heart)
Why is it said that the heart is two pumps working as one?
- Two pumps- One on left/ One on right
- Separated by a septum
- Right side pumps blood to the lungs- Pulmonary circuit
- Left side pumps blood to the body- Systematic circuit
- They contract in unison
What is the purpose of the valves in the heart?
To ensure blood can only flow through one direction of the heart (prevent backflow of blood)
Why is the left side of the heart thicker than the right?
Because the left side is responsible for pumping blood around the whole body so the wall of the cardiac tissue (mycocardium) surrounding the left ventricle is much thicker than on the right side of the heart.
Heart structure
- Cardiac muscle (involuntary)
- Myogenic- It can stimulate it’s own impulses and doesn’t require stimulation by the brain.
Conduction of the heart
- Conduction of the heart begins with an electrical impulse in the SINOATRIAL node.
- Spreads over the muscular walls of both atria causing them to contract together.
- Impulse reaches the atrioventricular node which holds the impulse temporarily. Delay of 0.1 seconds allows both atria to contract fully.
- Impulse then continues passing via the bundle of his down the septum wall and spreads throughout the purkinje fibres.
This allows both ventricles to contract forcing the blood out of the heart and around the body.
Systole
Contraction (forcing blood out)
Diastole
Relaxation (fill with blood)
Cardiac cycle
refers to the electrical and mechanical events that take place in the heart during 1 complete heart beat.
- Takes approx 0.8s and 72bpm.
Cardiac cycle stages
- Atrial diastole
2 Ventricular diastole - Atrial systole
- Ventricular systole
How long does atrial diastole and ventricular diastole take?
0.5 seconds
How long does atrial systole and ventricular systole take?
0.3 seconds
Atrial diastole (relaxation)
- Atria fill with blood
- Atrioventricular valves are closed
- Semi lunar valves are open
Ventricular diastole (relaxation)
- Rising pressure in the atria causes the AV valves to open and the ventricles to fill with blood.
- Atrioventricular valves open
- Semi-lunar valves closed
Atrial systole (contraction)
- Atria contract, forcing blood into the ventricles.
- Atrioventricular valves open
- Semi lunar valves closed
Ventricular systole (contraction)
- Ventricles contract, increasing pressure in the ventricles and forcing blood into the aorta and pulmonary artery.
- AV valves are forced to close
During exercise, what must the body do to meet the bodies demands for oxygen as heart rate must increase?
SA node must fire impulses more rapidly.
Stroke volume
The amount of blood that leaves the heart during 1 contraction
- Approx 70-90ml
Heart rate
The number of beats per minute
Cardiac output
The amount of blood pumped out of the heart per minute.
CO= SV X HR
Bradycardia
Slow resting heart rate <60bpm
How do you calculate moment?
Force (N) x distance from pivot (M)
Moment=Nm
How is heart rate controlled?
SA node does generate it’s own impulses.
- At approximately 100bpm
Cardiac control centre
- Located in the Medulla Oblongata
- Forming part of the autonomic nervous system.
- Central to the regulation of heart rate.
- Under involuntary control.
Two components of the Cardiac control centre
- Sympathetic nervous system
- Parasympathetic nervous system
Sympathetic nervous system
Responsible for increasing the heart rate via the cardiac accelerator nerve
Parasympathetic nervous system
Responsible for decreasing the heart rate via the vagus nerve (returning heart rate back to normal resting levels)
What sensory receptors does the cardiac control centre receive information from?
(Neural components)
- Proprioceptors
- Chemoreceptors
- Baroreceptors
Proprioceptors
- These sense movement in the muscles and inform the CCC.
- ## Exercise beings about an increase in muscular activity which requires an increase in heart rate.