Lecture 5 anatomy of heart Flashcards
Atrioventricular (AV) valves
incl function, right, left
Prevent blood returning to atria during ventricular
contraction.
tricuspid valve (3 leaflets)
bicuspid (mitral) valve (2 leaflets)
Semilunar valves (incl function, 2 types & cusps, Open & Close)
Prevent blood returning to the ventricle during filling (diastole).
Aortic (semilunar) valve (3 cusps)
Pulmonary (semilunar) valve (3 cusps)
Push open as blood flows out of heart.
close as blood starts to backflow.
Diastole -
valves open/closed
filling the ventricle.
AV opens,
ventricular chamber relaxed,
semilunar (outflow) valve are closed (caused by backflow towards ventricles).
Systole -
valves open/closed
Ventricles contract, AV close (to prevent back flow), pressure rises, semilunar valves opens (caused when pressure inside ventricular chamber exceeds pressure in outflow artery)
in systole what are the structures that keep the AV valve leaflet shut?
Papillary muscles (finger like projections of the myocardium that come of the wall point towards the valve leaflet)
Chordae tendinae (Attachment between papillary muscle and AV valve leaflet. heartstrings)
- Strong connective tissue can’t tear it.
- If pulled tear chordae tendernae from the papillary muscle.
2 arteries that supply the heart muscle
Right coronary artery - (groove from anterior to posterior)
Left coronary artery
First branches of the aorta / systemic circulation
Both arteries run in a groove between the atria and the ventricle (coronary groove)
Left coronary artery -
incl what does 2 branches it forms
thicker,
more blood supply,
more muscle,
runs short distance (left main stem), and
branches to form 2 branches an anterior branch (anterior interventricular artery) and the circumflex artery
anterior interventricular (coronary) artery -
runs over the interventricular system. Separates the 2 ventricular chambers.
branch forms from Left coronary artery
circumflex artery -
Runs in the left coronary groove around to the posterior of the heart.
branch forms from Left coronary artery
Venous drainage (cardiac vein) types
small cardiac vein (drains right side)
great cardiac vein (drains left side)
where do the cardiac veins end up?
in the same tubular structure (posterior of heart) called the coronary sinus
Cardiac muscle function
Beating of heart
- oxygen dependent metabolism
Cardiac Muscle Structure
made of, texture, structure, #nuclei, where nuclei is, where organelles are, how cells are connected
Isolated individual myocyte
Striated (like skeletal)
Short, fat, branched cell
1 - 2 nuclei / cell (like smooth)
Central (oval shaped) nuclei
Cytoplasmic organelles packed at poles of nuclei
Interconnected with
neighbouring cells via intercalated discs
Cardiomyocyte (sarcomeres)
how much volume of the cell does mitochondria make up?
20% of cytoplasm
Irregular branched sarcomeres (not like skeletal)
mitochondrial dependent metabolism
Aerobic oxygen dependent metabolism
Intercalated discs found where and consists of 3 junctions
only in Cardiac muscle
Adhesion belts (linking actin to actin) ~Vertical portion. - Physical propagation of contraction, generates alot of force that may pull the cells apart.
Desmosomes (linking cytokeratin with cytokeratin). (keep myocytes from pulling apart)
Gap junction (electrochemical communication) ~ Horizontal portion. Electrochemical propagation of contraction.
Cytokeratin -
cells internal cytoskeleton
Conduction System of the Heart
modified cardiac muscle
increase the efficiency of heart pumping.
responsible for the co-ordination of heart contraction and of AV valve
action.
Autonomic nerves alter the rate of conduction
impulse generation.
How do you prevent the AV valves from slamming when pressure increases?
Conduction system
The 1st part of the ventricular chamber contract are the capillary muscles which are attached to the chordae tendinae so pretension the cables attached to the AV leaflets.
Conduction pathways consists of
AV node Sinoatrial (SA) node Internodal pathways AV bundle R&L bundle branches Purkinje fibres
Sinoatrial SA node -
superior right atrium, bundle of tissue, spontaneously generates electrical impulses
Internodal pathways -
atrial pathways, spreads excitation from SA node through atrial chambers muscle
Atrioventricular AV node
gateway
only way for conduction to pass through the ventricle and into the ventricular chamber
R&L bundle branches
AV bundles split into 2
Purkinje fibres -
electrical impulse from SA node terminates,
Fuse into the cardiac muscle when conduction passes down the pathway, finds a contractile muscle and contracts
Purkinje cells consists of
fibres, nucleus, organelles, junctions, % of cardiac cells, metabolism
(some) Peripheral myofibrils. (no longer contract, redundant)
Central nucleus,
mitochondria, glycogen in cytoplasm (conduction energy dependent)
lots of gap junctions (dominates intercalated discs)
some desmosomes & few adhesion belts.
1% of cardiac cells
Oxygen dependent metabolism
semilunar
Separates ventricle from outflow artery
AV
separates atrium from ventricle
Atrioventricular (AV) valves
Prevent blood returning to atria during ventricular contraction
right side AV valve
Tricuspid valve
left side AV valve
Bicuspid (mitral) valve
semilunar vallves
prevent blood from returning to the ventricle during filling (diastole)
right side semilunar valve (# of cusps)
Pulmonary valve
3 cusps
left side semilunar valve
of cusps
Aortic valve
3 cusps
Papillary muscles
finger like projections of myocardium that tether the AV valve leaflet (from flinging back to the atria chamber) and attach to wall of ventricular chamber.
attachment between chordae tendineae and ventricle wall
Chordae tendineae
tenderness chord
Attachment between papillary muscle and AV valve leaflet.
Heart strings
Connective tissue can’t tear it
If pulled tear chordae tendineae frrom papillary muscle.
2 arteries that supply heart muscle
right coronary artery (groove from ant to post)
left coronary artery
left coronary artery
incl size, blood supply, muscle, distance, branches
Thicker more blood supply more muscle runs short distance (left main stem) form 2 branches anterior bran (anterior interventricular artery) and circumflex artery)
Anterior interventricular (coronary) artery
separates the 2 ventricular chambers
runs over the interventricular system.
