Heart Flashcards
(42 cards)
The heart
A hollow involuntary muscle pump-contains a one way valve system and it’s purpose is to generate pressure which moves blood
Endocardium
Inner most covering of heart, covers valves and tendons, continuois with lining of blood vessels
Myocardium
The muscle interlacing fibres
Has own blood supply e.g coronary circulation
Pericardium
Outer mist layer forms a prrcardial sack
Visceral pericardium is attached to heart
Fused parirtal and fibrous pericardium attach around the great vessels
Pericardial cavity between the layers contain serous fluid to reduce friction
Systemic
Left
Recieves from lungs and pumps around body
Pulmonary circuit
Right
Recieves blood from body and pumps to lungs
Atrioventricular valves
Valves between atrium and ventricle
Tricuspid valve 3 cusps right hand side- anchors to ventricular wall via choedae tendanae which attaches to papillary muscles
Bicuspid left and 2 cusps
Semilunar valves
Open and close with blood flow prevents blood from going going back into ventricular chamber Include Aortic valve Pulnorany valve Both have 3 cusps
Intristic conduction system
1) sinoatrial node (pacemaker of heart located in top right atrium) sodium rushes in- if enough comes in then electrical charge changes and an action potential generated
2) AP SPREADS through left and right atrium and down the internodal pathway- atria contract
3) the internodal pathway leads AP to atrioventricular node (AV node) action potential pauses because of repolarisation- heart relaxes
4) atrioventricular node (bundle of His) is reached and splits into left and right AP runs down branches
5) hits purkenje fibres AP wraps up each side of ventricle causing contractual cells to depklarise and therefore contract
Why can atria and ventricles not contract at same time
Because pressure would be to high…. so atria does then ventricles do
Diastole
heart relaxation- blood is filling vebtricles
Syastole
heart contraction - blood is ejected from ventricles
Cardiac output
Amount of blood pumped out of each ventricle in 1 minute
Stroke volume
Amount of blood pumped our of ventricle with each heartbeat
Preload
Change in degree of ventricular stretch
Contractility
Change in cardiac cell contractile force
Afterload
Change in back pressure exerted by blood in large arteries leaving heart
Blood pressure
Force exerted on inner wall of blood vessel, is measured on systemic arteries near the heart.
Largest blood pressure occurs at
Aorta then arterioles, capillaries, venues, veins, vena cava
Blood pressure
Neural control
Baroceptors in neck a receptors which change diameter of blood vessels (vasoconstriction etc) in order for arterial pressure to be achieved
Blood pressure
Hormonal control
Adrenaline (epinphrine) a blood borne chemical acts on smooth muscle- is released from heart when pressure is to high
Also increase sodium output which decreases water retention
Blood pressure
Renal control
Baroceptors adapt and change to chronic high or low bp .
Increased bp stimulates kidneys to eliminate water thus reducing bp
Decreased bp stimulates kidneys to increase blood volume and bp
What r the lower chambers of the heart called
Ventricles
What is the end diastolic volume
The volume of blood in the ventricles before it contracts movement from high concentration to low) this is a passive transport process.
