Cardiovascular System Flashcards
What is the function of the cardiovascular system?
Transport essential nutrients and pass on the products of metabolism.
What does the cardiovascular system consist of?
Heart
Blood
Blood vessels
Outline the structure of the heart
Epicardium outer layer- outer layer. Pericardium (inner and outer) mostly structural and stability, connective tissue
Myocardium- middle layer. Composed of cardiac muscle. Thickest layer
Endocardium- inner layer, thin layer that lines the heart and valves
describe the chambers of the heart
Two atria Two ventricles Atria to ventricles split by valves Ventricles at apex, atria at base Split by sulci
What is the purpose of the valves and how do they work?
Prevent the back flow of blood
Work on a pressure gradient, filling of one chamber shuts previous chamber
Tricuspid, mitral, semilunar valves
describe the movement of blood through the heart
Deoxygenated blood enters the right atrium through the vena cava and is then passed to the right ventricle. Here it goes into the pulmonary arteries to the lungs. Oxygenated blood from the lungs travels through the pulmonary vein to the left atrium, to the left ventricle and then leaves the heart through the aorta.
How does the heart pump?
Myoepithelial muscle, generates own contractions through nodes.
Rhythmical contractility determines which sections of heart pump first.
What is the sinoatrial node?
Collection of myogenic muscular cells in the wall for the right atrium below the superior vena cava
Pacemaker
60-100 pulses a minute
What is the atrioventricular node?
Impulse from the SAN received by this
Situated at the septum between the atria and ventricles
Impulse passes to bundle of his and the to purkinje fibres at the apex, here the ventricles contract
What is systolic and diastolic?
Systolic- contraction
Diastolic - relaxation
Outline the cardiac cycle
Relaxation- completion of the cycle the heart is at a state of relaxation. Semilunar valves are shut due to the pressure gradient. Blood flows into atria.
Ventricular filling - tricuspid and mitral valves open due to high pressure in atria, blood flows into ventricle. Impulse from SAN assists flow
Ventricular contraction- impulse arrives at the purkinje fibres initiating contraction of ventricles
Entire cycle lasts 0.8 seconds
What is cardiac output?
The amount of blood ejected from the heart each minute
Average is 5L/min in adults
Discuss nervous control of the brain
Initiated by cardiovascular centre in the medulla of brain.
Recieves signals when the body exercises
Chemoreceptors on heart respond to chemicals in blood
Outline hormonal regulation of cardiac output
Involved adrenal glands
Exercise stimulates them to release adrenaline which increases heart rate and stroke volume
Describe the blood supply to the heart
Left and right coronary arteries branch off aorta soon after leaving the left ventricle