cardiovascular week 1 Flashcards
Describe cardiac muscle
form an interconnecting network
joined to each other by intercalated disks
central nuclei and regular cytoplasmic cross-striations
highly vascularised
long cylindrical cells with one or at most two nuclei
What are the similarities between cardiac muscle and skeletal and smooth muscle?
skeletal - strong contractions that use large amounts of energy
smooth - the contractions are continuous and initiated by inherent mechanisms although they are moderated by external autonomic and humeral control
What are intercalated disks?
specialised intercellular junctions that provide both mechanical and electrophysiological coupling, allowing cardiac cells to function as a functional syncytium
describe the difference in the way that cardiac cells contract as compared to skeletal muscle
in cardiac muscle there is a slow release of calcium ions from the sarcoplasmic reticulum after recovery from the previous contraction; this causes a succession of autonomic contractions independent of external stimuli
Describe the sarcomeres in cardiac muscle
they form a branching myofibrillar network, continuous in three dimensions throughout the cytoplasm.
The branding columns of sarcomeres are separated by sarcoplasm containing rows of mitochondria and sarcoplasmic reticulum
Describe the composition of the intercalated disks
3 types of membrane to membrane contact;
mainly fascia adherens (FA) - actin filaments - transmit contractile forces
Desmosomes - anchorage for intermediate filaments of the cytoskeleton
Gap junctions - sites of low electrical resistance through which excitation passes from cell to cell
Describe the mitochondria of cardiac cells
elongated or spheroidal and have abundant closely packed cristae rich in oxidative enzyme systems.
The sarcoplasm within and between the sarcomeres is rich in glycogen granules
Give an overview of the coronary circulation of the heart
two coronary arteries arise from the aortic sinuses in the initial portions of the ascending aorta and supply the muscle and other tissue of the heart
They circle the heart in the coronary sulcus, with marginal and interventricular branches, in the inter ventricular sulki, converging toward the apex of the heart
The returning venous blood passes through cardiac veins, most of which empty into the coronary sinus
Describe the coronary sinus
a large venous structure located in the coronary sulcus on the posterior surface of the heart between the left atrium and left ventricle.
The coronary sinus empties into the right atrium between the opening of the inferior vena cava and the right atrioventricular orifice.
What are the branches of the right coronary artery?
sino-atrial node branch
right marginal branch
small branch to AV node
posterior inter ventricular branch
What does the right coronary artery supply?
right atrium and ventricle
sion-atrial and AV nodes
interatrial septum
portion of the left atrium
posteroinferior 1/3 of the inter ventricular septum
a portion of the posterior part of the left ventricle
What are the branches of the left coronary artery?
inter ventricular
circumflex - left marginal artery
What does the left coronary artery supply?
most of the left atrium and ventricle
most of the inter ventricular septum - including AV bundle and its branches
What are the cardiac veins called?
great
middle
small
posterior
Describe the great cardiac vein
begins at apex and agents in the anterior atrioventricular sulcus - often termed anterior inter ventricular vein
greatly enlarges to form the coronary sinus and enters the right atrium
