Ch. 21 (heart) SG Flashcards
Heart location
anterior chest wall, posterior to sternum in the pericardial cavity
pericardial sac
formed by the parietal pericardium and the fibrous pericardium; contains pericardial fluid which serves as a lubricant reducing friction from heart beats
3 histological layers of the heart
epicardium (outer), myocardium (thickest), and the endocardium (inner); epicardium is aka the visceral pericardium (pericardial sac)
Cardiac muscle tissue
much smaller than skeletal muscle fibers; they resemble skeletal muscle fibers though because both have myofibrils, sarcomeres (which produce striations), dependent on aerobic respiration, short t-tubules, they contract without instructions from the NS, and they have intercalated discs
Skeleton of the heart
an extensive connective tissue that encircle the heart; layers composes of dense bands of fibroelastic tissue; functions consist of stabilizing valves of the heart, distributing forces of contraction, providing physical support for the cardiac muscle cells, providing elasticity
4 chambers of the heart
2 atriums and 2 ventricles
right atrium
receives oxygen-poor blood thru the sup. vena cava and the inf. vena cava; separated from other atrium by interatrial septum
right ventricle
oxygen-poor blood from right atrium goes into this ventricle thru the right atrioventricular (AV) valve; blood goes thru pulmonary trunk then the pulmonary arteries
left atrium
blood comes thru pulmonary capillaries which is now oxygen rich and goes thru pulmonary veins; blood goes to left ventricle via the left AV valve
left ventricle
blood leaves it from the aortic valve into the ascending aorta then the aortic arch then the descending aorta (thickest wall of any chamber - thicker so that it can develop enough pressure to force blood around the entire systemic circuit)
Right AV valve
tricuspid valve; made of connective tissue
Left AV valve
bicuspid valve; has only a pair of cusps
Function of valves
helps prevent or stop blood flow thru the heart
mitral valve prolapse
the mitral valve cusps do not close proper which causes regurgitation which causes surges and swirls known as a heart murmur
Primary function of Right side of heart
receives oxygen poor blood from the body and sends it to the lungs
Primary function of left side of heart
collect oxygenated blood from the lungs and then pump it to the rest of the body
major arteries in heart
coronary arteries which come off the base of the ascending aorta; the left coronary artery has atrial, and ventricular branches while the right one has a circumflex branch along with the other two types that were on the left one
Cardiac veins
they deliver venous blood to the coronary sinus which drains into the right atrium
Conducting system of the heart
the stimulus for contraction is generated by pacemaker cells at the Sa node; impulses follow 3 paths (internodal) thru the atrial walls to reave the AV node; after a delay the impulses are conducted to the bundle of His and then on to the bundle branches (purkinje fibers) and the ventricular myocardial cells; all this is done so the atria contract together before the ventricles and that the ventricles contract from the apex to the base
Heart innervation
heart rate is established by pacemaker cells of the SA (sinoatrial) node but it can be modified by the ANS; innervated by the glossopharyngeal and vagus nerves (norepinephrine increases haert rate while ACh decreases heart rate and force of contractions)
foramen ovale
oval opening in the interatrial septum (separates the two atriums) during the fifth week of embryonic development till birth; permits blood flow directly from right to left atriums;
Fossa ovalis
a small depression that is located at the site where the foramen ovale closes in the adult heart
