Cardiovascular System 2 Flashcards
The heart, Blood Flow, CHD & Electrical Impulses
Function of the cardiovascular system
To provide an adequate circulation of blood around the body
This helps to provide self with oxygen and essential nutrients and to remove waste products from these cells
Double Circulatory System
The heart pumps blood twice in one cycle to help maintain a high-pressure and movement of blood
Systematic Circulation
Blood flow between the heart and the whole/rest of the body
Pulmonary Circulation
Blood flow between the heart and the lungs
Cardiac Muscle
The muscle which makes up the heart it never fatigues
Myogenic cardiac muscle
Cardiac muscle is myogenic. This means that it can contract and relax on its own accord without the need for nerve impulses as some other muscles do
Septum
The muscular wall separating the left and right sides of the heart
Left chambers of the heart
the left atrium is above, receiving blood from the PV
and the left ventricle is below, forcing blood out the aorta
Right chambers of the heart
the right atrium is above, receiving blood from the vena cava
and the right ventricle is below, forcing blood out the PA
Ventricles Vs Atria
The wall of the ventricles are thicker than the walls of the atria. This is because the atria only need to pump blood down to the ventricles whereas the ventricles need to pump blood out of the heart (further distances)
Vena Cava
The blood vessel (vein) which carries deoxygenated blood from the body to the heart (right atrium)
Aorta
The blood vessel (artery) carrying oxygenated blood from the heart (left ventricle) to the rest of the body
Pulmonary Vein
The blood vessel carrying oxygenated blood from the lungs to the heart (left atrium)
Pulmonary Artery
The blood vessel carrying deoxygenated blood from the heart (right ventricle) to the lungs
Coronary Arteries
Blood vessels found on the surface of the heart which provide the heart muscle with its own blood flow for essential gases & nutrients such as (oxygen and glucose)
Atrioventricular Valves
They separate the atria and the ventricles and prevent back flow of blood from the ventricles into the atria (during ventricular systole)
Semilunar Valves
Separate the ventricles and the arteries, prevent back flow of blood from the arteries into the heart (during ventricular systole)
Opening and closing of valves
The only open one way dependent on the pressure, when pressure is higher behind the valve it is forced open and when pressure is higher in front of a valve it is forced closed this maintains a one directional flow in the heart
Cords
Cords are attached to the atrioventricular valves from the ventricles. They stop the ventricles being forced upwards into the atria when the ventricles contract. Therefore preventing blood from back flowing
The order of blood flow through the heart
Atrial Systole
Ventricular Systole
Diastole
Atrial Systole
Both atria contract in unison, this decreases the volume of the atria and increases the pressure.
This forces the atrioventricular valves to open and blood flows down its pressure gradient into the ventricles causing the ventricles to (slightly) increase in pressure and volume
Ventricular Systole
Both ventricles contract in unison, this decreases the volume and increases the pressure in the ventricles.
The higher pressure in the ventricles then the atria causes the AV valves to close
The higher pressure in the ventricles then the arteries forces the semilunar valves to open, blood flows into the arteries.
Diastole
All chambers of the heart relax, the arteries higher pressure than the ventricles which forces the semilunar to shut.
Blood flows into the atria slowly filling them up as the veins have slightly more pressure than the atria.
The increase atria pressure causes the AV valves to open and some blood passively flows into the ventricles.
Sinoatrial node (SAN)
Found in the right atrium, & releases an electrical signal which coordinates the cardiac cycle and initially results in atrial contraction
(aka the pacemaker)
Atrioventricular node (AVN)
Found towards the centre of the heart at the point where all four chambers of the heart are in close proximity.
It releases an electrical signal which is passed on to the bundle of His.
Bundle of His
Found in the septum of the heart and carries the electrical signal from the AVN into several separate signals which are sent through the purkinje fibres
Purkinje Fibres
Found in the walls of the ventricles, (receive electrical impulses from the bundle of his) and cause ventricles to contract
Pathway of electrical signals through the heart
SAN/Sinoatrial Node (RA)
AVN/Atrioventricular Node (Septum)
Bundle of His (Septum)
Purkinje Fibres (walls of ventricles)
Decreasing heart rate
Low CO2/high O2 is detected by Chemoreceptors, medulla and carotid arteries.
Impulses are sent to the heart resulting in fewer impulses between the sinoatrial and the AV node this leads to a decreased heart rate
Increasing heart rate
High CO2/Low O2 detected by chemoreceptors, medulla and carotid arteries
Impulses sent to the heart result in more impulses between the sinoatrial node and the AV note
