week 8 (cardiac system, heart function/structure, cardiac physiology, circulation) Flashcards
pericaridum
The membrane that surrounds and protects the heart
It confines the heart to its position in the mediastinum, while allowing sufficient freedom of movement for vigorous and rapid contraction.
two main parts:
(1) the fibrous pericardium
(2) the serous
pericardium
fibrous pericardium
composed of tough, inelastic, dense irregular connective tissue
prevents overstretching of the heart, provides protection, and anchors the heart in the
mediastinum
serous (partieal and visceral pericardium)
layers of the serous pericardium is a thin film of lubricating serous fluid known as pericardial fluid which reduces friction between the layers of the serous pericardium as the heart moves
The space that contains the few milliliters
of pericardial fluid is called the pericardial cavity
significant of pericardial space
mechanical protection for the heart and big vessels, and a lubrication to reduce friction between the heart and the surrounding structures
endocardium
thin layer of endothelium overlying a thin layer of connective tissue. It provides a smooth lining for the chambers of the heart and covers the valves of the heart. The smooth endothelial lining minimizes
the surface friction as blood passes through the heart
myocaridum
is responsible for the pumping action of the heart and is composed of cardiac
muscle tissue.
The cardiac muscle fibers are organized in bundles that swirl diagonally around the heart and generate the strong pumping actions of the heart
epicardium
epicardium is composed of two tissue
layers. The outermost is the visceral layer of
the serous pericardium and is composed of mesothelium. Beneath the mesothelium is a variable layer of delicate fibroelastic tissue and adipose tissue.
imparts a smooth, slippery texture to the outermost surface of the heart. The epicardium contains
blood vessels, lymphatics, and vessels that supply the myocardium.
why is the is the myocardium of ventricles thicker than the myocardium of the atrium
This is because blood is pumped out of the heart at greater pressure from these chambers compared to the atrium
how does endocardium serve protective function for the heart
A tissue covering the inside of the heart, the endocardium keeps the blood flowing through the heart separate from the myocardium,
difference between normal and the specialized tissue of the conduction system in the heart
specialized cardiac muscle fibers called autorhythmic fibers
They act as a pacemaker, setting the rhythm of electrical excitation
that causes contraction of the heart.
They form the cardiac conduction system
cardic cycle
Atrial and Ventricular diastole (chambers are relaxed and filling with blood) Atrial systole (atria contract and remaining blood is pushed into ventricles) Ventricular systole (ventricles contract and push blood out through aorta and pulmonary artery)
systole
During atrial systole, which lasts about 0.1 sec,
the atria are contracting. At the same time, the ventricles are relaxed
During ventricular systole, which lasts
about 0.3 sec, the ventricles are contracting
diastole
ventricles relax in ventrical disstole
artia relax during atrial distole
sinoartial node (SA)
generates an electrical signal that causes the upper heart chambers (atria) to contract
atriventricular node (AV)
controls the passage of the heart’s electrical signal from the atria to the ventricles
atrioventricular bundle
specialized for electrical conduction that transmits the electrical impulses from the AV node
right and left bundle branchesx
The bundle of His is an important part of the electrical conduction system of the heart, as it transmits impulses from the atrioventricular node, located at the anterior-inferior end of the interatrial septum, to the ventricles of the heart.
purkinje fibres
electrical conduction of impulse to the ventricular muscle
autorhythmicity
Contractions of the heart (heartbeats) are controlled by specialized cardiac muscle cells called pacemaker cells that directly control heart rate
conduction pathway
sinoatrial (SA) node
atrioventricular (AV) node
atrioventricular
(AV) bundle
right and left bundle branches
location of heart (cavity)
The heart is located in the mediastinum, with two-thirds of its mass to the left of the midline.
it is by the thoriac cavity
apex
You can visualize the heart as a cone lying on its side. The pointed apex is formed by the tip of the lef ventricle (a lower chamber of the heart) and rests on the diaphragm. It is directed anteriorly, inferiorly, and to the lef .
base
base of the heart is opposite the apex and is its posterior aspect. It is formed by the atria (upper chambers) of the heart, mostly the lef atrium
blood supply to and from the myocardium
The coronary arteries provide the main blood supply to the heart. The coronary arteries also supply the myocardium with oxygen to allow for the contraction of the heart and thus causing circulation of the blood throughout the body
coronary circulation
part of the systemic circulatory system that supplies blood to and provides drainage from the tissues of the heart. … Deoxygenated blood is returned to the chambers of the heart via coronary veins; most of these converge to form the coronary venous sinus, which drains into the right atrium.