Chapter 20 Flashcards
Deeper, Thinner, more delicate membrane that forms a double layer around the heart. It’s a shock absorber
Has an outer parietal and inner visceral layer with lubricating serous fluid in between as the heart moves.
Serous pericardium
Middle layer of heart wall made of cardiac muscle. 95% of heart wall.
Myocardium
Innermost layer of heart wall. Thin layer made of simple squamous epithelium.
Endocardium
Deoxygenated blood coming back from the body gets dumped into three veins: 2 vena cavae and coronary sinus. -right side ejects to lungs.
Pulmonary circuit
Membrane that surrounds and protects the heart. Has 2 main parts- fibrous and serous.
Pericardium
More of these appear In the heart if you workout a lot. Less appear if you don’t.
Coronary vessels.
External Layer of heart wall made of visceral serous pericardium.
Epicardium
Coronary veins collect into the ________ _________. Then empties into the ____________.
Coronary sinus; right atrium
The ends of cardiac muscle fibers connect to neighboring fibers by irregular transverse thickenings of the sarcolemma called…..
Contain desmosomes and gap junctions
Intercalated discs
Oxygenated blood coming back from the lungs gets dumped into the pulmonary veins. Left side ejects blood to body.
Systemic circuit
Contain coronary blood vessels
Sulci
Cardiac muscle fibers are _______ and ____ circular in the transverse section than skeletal muscle
Shorter; less
Set the rhythm of electrical excitation that causes contraction of the heart.
Pacemaker
Duct that attaches the aortic arch to the pulmonary trunk.
Ductus arteriosus.
Cardiac excitation normally begins in the ________
Sinoatrial node
Hold the fibers in intercalated discs together
Desmosomes
Groups of self-excitable cells spontaneously depolarize at different rates. If one group fires, all others in the area also depolarize.
Autorhythmicity
In cardiac conduction, the _________ depolarizes. Sends signal to __________. The __________ slows the signal so that ______________. Sends signal to ____________ to the _____ and _______ bundle ________ to the __________. Then…… Boom. Contraction
SA node, AV node, AV node, atrium can fill the ventricles, AV bundle, left, right, branches, purkinje fibers.
Decreases HR
ACh
These muscle fibers act as pacemakers and form the cardiac conduction system.
Autorhythmic fibers
Can alter rate and force of the heart contraction- make beat faster
Thus regulate BP, flow rate, volume required by body
ANS innervation
Increases HR- stress, excitement
Norepinephrine (adrenaline)
Decides if pressure is too high or too low.
Sensory input from baroreceptors in carotid body and in the arch of the aorta.
Response: thru sympathetic fibers (spinal cord- thoracic sympathetic ganglia-heart SA node).
Cardioacceleratory center of medulla
Unlike Autorhythmic fibers, ______ _________ have a stable Resting membrane potential of -90 mV
Contractile fibers
Opening and closing Na+ and K+ channels
AP propagation
Maintained contraction. Cannot occur in cardiac muscle. If it did, blood flow would cease.
Tetanus
Network of specialized cardiac muscle fibers that provide a path for each cycle of cardiac excitation to progress through the heart.
Cardiac conduction system