Heart Chapter 17 Flashcards

Heart produces force that creates blood pressure which causes blood to circulate. routes blood to pulmonary and systemic

Heart is located mediastinum deep to the sternum and deep to left 2nd to 5th intercostal spaces. shaped like a blunt cone with an apex base. size of a fist

- sac surrounding heart, has fibrous/serous- fibrous holds heart in place, serous reduces friction as heart beats- parietal lines fibrous pericardium- visceral covers exterior surface of heart- pericardial cavity is btw parietal & visceral pericardium & filled with pericardial fluid

- outer(visceral) protection against friction- middle(myocardium) responsble for contractions- inner(endocardium) reduces friction from passage of blood thru heart- ventricles have ridges, trabeculae carneae- inner surface of atria is smooth. - auricles = raised areas, musculi pectinati

- each atrium has flap called auricle- coronary sulcus separates atria from ventricles, interventricular from R/L ventricle- inferior, superior vena cava, coronary sinus enter right atrium. 4 pulmonary veins enter left atrium- pulmonary trunk exits right ventricle- aorta exits the left ventricle

- fossa ovalis, where blood bypassed lungs in the fetus- interatrial septum separates atria- interventricular septum separates ventricle

- tricuspid separates R atrium & ventricle- bicuspid separates L atrium & ventricle- chordae tendineae attach papillary muscle to the atrioventricluar valve- semilunar separate aorta & pulm trunk

- blood from body flows thru right atrium into the right ventricle and then into lungs- blood returns from lungs to the left atrium, enters left ventricle, pumped back into body

- coronary arteries branch off the aorta to supply the heart.- blood returns from heart tissues to right atrium thru coronary sinus & cardiac veins

- supports the openings of the heart, point of attachment for heart muscle, & electrically insulates the atria from the ventricles

- cardiac muscle cells are branched & have centrally located nucleus- actin & myosin organized, form sarcomeres- t tubules & sarcoplasmic retic not organized like in skeletal muscle- cardiac muscle cells rely on aerobic resp - joined by intercalated disks which allow AP to move from one cell to next. func as unit

- after depolar & partial repolar, plateau phase is reached, MP slowly repolarizes- open & close of voltage chnnls produce AP- mvmt of Na thru Na chnnls cause depolar- depolar, K chnnls close & Ca begin to open- repolar, Na chnnls close, K chnls open- plateau exists b/c Ca chnls remain open- rapid repolar from Ca chnls close and the opening of many K channels

- absolute refractory, cardiac muscles cells insensitive to further stimulation- relative refractory, stronger than normal stimuli can produce AP- cardiac muscle prolonged depolar & absolute refract period, relax before AP

- cardiac muscle cells are autorhythmic b/c of development of prepotential. SA node is pacemaker of the heart.- prepotential from mvmt of Na & Ca into SA node cells, prepotential determ heart rate

- SA node & AV node are in the right atrium- AV connected to bundles in interventriclular septum by the AV bundle- bundles rise to Purkinje fibers which supply the ventricles, SA node initiates AP, go into atria and cause them to contract, AP slow in the AV node. AP travels thru AV to Purkinje fibers causing ventricles to contract, apex