2.6 Flashcards
Vena cave carries blood from
Body to heart
Pulmonary artery carries blood from
Heart to lungs
Pulmonary vein carries blood from
Lungs to heart
Aorta carries blood from
Heart to body
Coronary arteries
Supply heart muscle
Oxygenated blood is pushed towards
Body
The left side of the heart pumps
Oxygenated blood to the body
The right side of the heart pumps
Deoxygenated blood to the lungs
Cardiac output formula
CO = SV x HR
What is cardiac output
The amount of blood a ventricle can pump every minute is known as cardiac output. It depends on the amount of blood your heart can move and the number of times your heart is beating.
What does HR stand for
Heart rate. How many times your heart beats in 1 minute.
Atrioventricular valve
Name of valve between atrium and ventricle
Semilunar valve
Valve that stops back flow of blood from arteries into ventricles
What is the cardiac cycle
Each heartbeat is called a cardiac cycle . It is the process by which the four chambers of the heart fill and empty of blood.
What are the main phases of the cardiac cycle
Atrial systole
Ventricular systole
Diastole
Atrial systole
The atria both contract at the same time to squeeze blood through the AV valves into the ventricles
Diastole
All chambers relax and fill with blood. Atria fill first ready for the cycle to begin again.
Ventricular systole
Both ventricles contract to squeeze blood through the pulmonary artery and aorta
What are valves used for in cardiac cycle
Preventing back flow of blood during ventricular systole and diastole
AV and SL valve in atrial systole
AV open
SL closed
AV and SL valve in ventricular systole
AV closed
SL open
AV and SL valve in diastole
AV open
SL closed
Electric nerve fibres which cause contraction of heart muscle
Sino-atrial node
Atrio-ventricular node
The purkinje fibres in ventricle walls
Explain Sino-Atrial node
Also known as peacemaker cells
Located on wall of right atrium
Auto-rhythmic, spontaneously send electrical signals across the atria causing them to contract (atrial systole)
Explains atrio ventricular node
Picks up electrical signals from SA node
Located in centre of heart between atria and ventricles
Sends electrical impulses down fibres in ventricle walls
What do fibres in ventricle walls do with nodes
Pass impulses from AV node down the middle of heart and into the ventricle side, causing ventricular contraction (ventricular systole)
Explain entire electrical pathway of heart
SA node produces wave of electrical excitation across atria - atria contracts
AV node picks up signal from atria, passes impulses down fibres in ventricular wall
Impulses travel down fibres in centre of heart
Impulses travel along ventricle walls - ventricles contract
Noradrenaline involving heart
Released when sympathetic nerve activated. Causes increase in heart rate when released at SA anode
Acetylcholine involving heart
Released when parasympathetic nerve activated. Causes decreases in heart rate when released at SA node
What is an electrocardiogram
Piece of equipment which measures the electrical activity of your heart
ECG P wave is
Electrical excitation of SA node travelling across atria (atrial systole)
ECG QRS wave is
Electrical excitation of ventricles (ventricular systole)
ECG T wave is
Electrical recovery of ventricles (diastole)
Blood pressure taken as 2 readings..
Systolic (pressure when ventricles contract)
Diastolic (pressure when heart relaxes)
Process of using a sphygmomanometer
The cuff is inflated to cut off arterial blood supply from the arm
The cuff slowly deflated until the blood starts to force its way through by ventricle contracting. You can hear pulse in arm, this is systolic bp
The cuff continues to deflate. The artery will fully open at another pressure. You cannot hear the pulse anymore, this is diastolic bp
