The Cardiovascular System Flashcards
Describe the chambers of the heart
The heart is divided into two parts by a muscular wall called the septum and each contains two chambers - atrium and ventricle
The atria are smaller than the ventricles as all they do is push the bloody down into the ventricles
The ventricles have thicker walls as they need to contract with greater force in order to push the blood out of the heart
The left side of the heart is larger as it pumps blood all around the body whereas the right side pumps deoxygenated blood to the lungs which are in close proximity to the heart
Describe the blood vessels to the heart
The vena cava brings deoxygenated blood back to the right atrium
The pulmonary vein delivers oxygenated blood to the left atrium
The pulmonary artery leaves the right ventricle with deoxygenated blood to go to the lungs
The aorta leaves the left ventricle with oxygenated blood to the rest of the body
Describe the valves of the heart
4 main valves in the heart that regulate blood flow by ensuring it moves in one direction. They open up to allow blood through but don’t allow it back
The tricuspid value is located between the right atrium and right ventricle
The bicuspid valve between the left atrium and right ventricle
The semi lunar valve can be found between the right and left ventricles and the pulmonary artery and aorta
What are the different valves in the heart ?
The tricuspid valve
The bicuspid valve
The semi lunar valve
Define myogenic
The capacity of the heart to generate its own impulses
Define sinoatrial node (SAN or SA node)
A small mass of cardiac muscle found in the wall of the right atrium that generates the heart beat. It is more commonly called a pacemaker
Define the atrioventricular node (AVN or AV node)
The node replays the impulse between the upper and lower sections of the heart
Define systole
When the heart contracts
Define the bundle of His
A collection of heart muscle cells that transmit electrical impulses from the AVN via the bundle branches to the ventricles
Define the purkinje fibres
Muscle fibres that conduct impulses in the walls of the ventricles
Describe the path of the heart muscle which causes it to contract
The electrical impulse starts at the sinoatrial node (SAN)
This impulse then spreads through the heart described as a wave of excitation (similar to a Mexican wave)
From the SAN the impulse spreads through the walls of the atria, causing them to contract and forcing blood into the ventricles
The impulse then passes through the atrioventricular node (AVN)
The AVN delays the transmission for 0.1 seconds to enable the atria to fully contract before ventricular systole begins
The impulse then passes down the bundle of His
The bundle of his branch out into smaller bundles called purkinje fibres which spread out throughout the ventricles causing them to contract
Memory tool to remember the path of an electrical impulses throughout the heart
S - SAN
A - Atrial systole
A - AVN
B - bundle of his
P - Purkinje fibres
V - ventricular systole
Define the sympathetic nervous system
A part of the automatic nervous system that speeds up HR
Define the parasympathetic nervous system
A part of the automatic nervous system that decreases heart rate
What are chemoreceptors ?
Tiny structures in the arteries that detect changes in blood acidity caused by an increase or decrease in the concentration of carbon dioxide
Chemoreceptors———-> increase in carbon dioxide ————-> increase in heart rate
What are baroreceptors ?
Special sensors in tissues and pulmonary vessels that respond to changes in blood pressure to either increase or decrease heart rate
Baroreceptors ———-> Increase in blood pressure ————-> decrease in heart rate
What are proprioceptors ?
Sensory nerve endings in the muscles, tendons and joints that detect changes in muscle movement
Proprioceptors——-> Increase in muscle movement —————-> Increase in heart rate
