heart lecture 03/23

where is the heart?

on the left side of the body inside the mediastinum of the thoracic

how many chambers are in the heart?

four, the right and left atria's and ventricles

what is the heart enclosed in?

the peridcardium

what are the pericardium layers?

the fibrous and serous pericardium

what is the fibrous pericardium?

the outermost layer of dense connective tissue

what is the function of the fibrous pericardium?

prevents the heart from overfilling and restricts its movement

what is the serous pericardium?

the layer that folds back on itself to create two specfic layers

what are the serous pericardium layer and what is between them?

parietal and visceral layer, pericardial cavity is between

what does the perietal layer of the serous pericardium adhere to?

the fibrous pericardium

what does the visceral layer of the serous pericardium adhere to?

the heart wall

what is the function of the pericardial cavity?

to reduce friction with the serous fluid it contains

what is pericardial effusion?

too much fluid in the pericardial cavity that can compress the heart and prevent its ability from pumping blood

what are the causes of pericardial effusion?

pericarditis and a trauma that causes bleeding into the pericardial cavity

what is the treatment for pericardial effusion?

drain the fluid and determine the underlying cause

what are the layers of the heart

endocardium, myocardium, epicardium

endocardium is...

the innermost layer that lines the inside of the heart and covers its valves, it is composed of simple squamous epithelium supported by connective tissue.

myocardium is...

cardiac muscle and the thickest layer

epicardium is...

the visceral layer of the serous pericardium,

composed of simple squamous epithelium and connective tissue,

often containing fat

where is cardiac muscle found?

in the myocardium of the heart

what is the cell structure of cardiac muscle?

short, cylindrical cells, some are bifurcating, have one or two centrally located nuclei, intercalated discs, and striations

what are intercalated discs?

specialized cell junctions to transmit nerve impulses

is cardiac muscle voluntary or involuntary?

involuntary (autonomic nervous system)

what is the function of cardiac muscle?

contracts to move blood through the heart

what does the coronary (atrioventricular) sulcus separate?

the atria from the ventricles

what does the interventricular sulcus separate?

the left and right ventricles, it can be seen anteriorly and posteriorly

what does the right atrium recieve?

venous blood from the superior and inferior venae cavae

what does blood flow through to get from the right atrium to the right ventricle?

the right atrioventricular (tricuspid) valve

what does the right ventricle contain?

three papillary muscles and chordae tendineae

what is chordae tendinae?

strong, fibrous cords that stretch from the papillary muscles to the 3 flaps of the right atrioventricular valves

what is the function of chordae tendineae?

to prevent the flaps from being everted into the atrium

where does the blood in the right ventricle flow to next?

the pulmonary trunk

what does blood flow through to get from the right ventricle to the pulmonary trunk?

the pulmonary semilunar valve

what does the left atrium receive?

oxygenated blood from the lungs via 3 or 4 pulmonary veins

what does blood flow through to get from the left atrium to the left ventricle?

the left atrioventricular (bicuspid) valve

what does the left ventricle do?

pump oxygenated blood into the aorta

what does blood flow through to get from the left ventricle to the aorta

the aortic semilunar valve

where does arterial circulation supply blood to the heart from?

the left and right coronary sulcus

where does the venous circulation supply blood to the heart from?

most veins of the heart unite and drain into the coronary sinus, which empties into the right atrium

what is a myocardial infarction?

a heart attack, which is the death of heart muscle

what is the cause of a myocardial infarction?

prolonged lack of blood supply, typically from plaque build up (atherosclerosis) in coronary arteries

what does it mean when they say the heart exhibits autorhythmicity?

the heart itself is responsible for initiating the heart beat

what does the heart conduction system consist of?

the sinoatrial (SA) node, atrioventricular (AV) node, atrioventricular bundle, interventricular septum, left and right bundle branches, and subendocardial branches (purkinge fibers)

the sinoatrial node is located...?

in the upper wall of the right atrium

what is the sinoatrial node function?

to initiate the heartbeat

where is the atrioventricular node located?

on the floor of the right atrium

what is the atrioventricular bundle?

a bundle of conducting muscle fibers that run through the interventricular septum

What does the atrioventricular bundle split into?

the left and right bundle branches

where do the left and right bundle branches go?

to their respective ventricle

what are the subendocardial branches?

specialized conduction muscle cells that are larger than other cardiac muscle fibers and extends through the walls of the ventricles

what are the effects of the ans on the heart?

sympathetic: increases heart rate through the sympathetic postganglionic pathway

parasympathetic: decreases heart rate though the cranial nerve X (vagus)