Cardio Physiology.docx

Cardio Physiology.docx - Cardio Physiology Bulk flow=...

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Cardio Physiology - Bulk flow= movement of water and solutes together as a result of pressure gradient. - Needs to move from high pressure à low pressure. - Systemic circulation: blood is pumped from heart to all the parts of the body - Pulmonary circulation: blood is pumped from the heart to lungs to be oxygenated - Chordae tendineae= cord-like tendons that connect the papillary muscles of the ventricles to the tricuspid and mitral valves. They contract to prevent inversion and opening of the AV valves when the the ventricles are contracting (systole). - 4 Pulmonary veins (2 from each lung) bring in oxygenated blood from the lungs to the left atrium. - 2 Pulmonary arteries carry deoxygenated blood from the right ventricle to the lungs to be oxygenated. - AV valves – tricuspid (R) and bicuspid (L) - Semilunar valves- aortic and pulmonary (seen as 3 separate compartments). - Valves ensure unidirectional flow - Blood will be forced up against AV valve (close of flap= audible sound= LUB= at the end of S wave, second sound= DUB= semilunar valve closing) - Chordae tendineae prevent valve from flipping backwards. - Skeletal muscle cells are long, multinucleated cells. - But cardiac cells are short, forked (Y shape) cells. Connected to neighboring cells via intercalated discs made of gap junctions (joins cytoplasm of neighboring cells) and desmosomes (hold them together structurally). - When we look at the heart, it looks quite uniform in its content. - One type of cells are responsible for creating the electrical rhythm within the heart- auto rhythmic cells (initiate and conduct APs within the heart wall). The electric signals that drive heart contraction = action potentials. ; Contractile cells = cardiac muscle cells. - They depolarize on their own without any nervous system stimulation . - Neurons and skeletal muscle cells receive some sort of stimulus that causes an AP. Some graded potential brings it up to the right potential, and then depolarization occurs. - But in the heart, depolarization occurs by itself, WITHOUT any outside nervous stimulation. Heart generates its own rhythm and does not rely on input from the brain= if we cut the connection between the brain and the heart, we would be fine, but wouldn’t feel nervous for our exams. - Sino-atrial node is the pacemaker in the body. - If someone’s SA node isn’t working well, an artificial pacemaker is inserted to create the auto rhythmicity. - F-type channels/ funny channels= We have a set of channels (voltage-gated) that open at repolarization . Open at the reestablishment of a certain negative threshold. When the certain negative threshold is reached = the funny channels open (Na+ channels) = they begin depolarizing. - As soon as 1 AP is done and you start repolarizing, that certain level is reached and then the funny channels open again and start depolarizing.
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