part 4 Flashcards
(100 cards)
What will the plateua phase before repolarization do in cardiac muscle?
It sets limits on the number of beats per minute.
What is auto-rhythmicity?
Spontaneous action potentials (cardiac cells can spontaneously create action potentials)
How will cardiac muscle cells create auto-rhythmicity?
They have naturally leaky membranes that allow ions to move intracellularly.
What type of cardiac muscle cells have the fastest cycle of polariztion and repolarization?
SA node (sino-atrial node). Even though the action potential isn’t as fast in the depolarization phase.
Cardiac muscle cells are complexly covered with what? And this will lead to what?
Receptors. That make cells sensitive to hormones and neurotransmitters.
Name the 2 groups of receptors found on cardiac muscle cells?
- Adrenergic receptors 2. Cholinergic receptors
What is the primary type of adrenergic receptor found on cardiac muscle cells? What are these receptors sensitive to and where will this come from?
Beta1 receptors They are sensitive to norepinephrine released from the axons of the sympathetic fibers.
What wil norepinephrine do to cardiac muscle cells once it comes in contact with the beta1 receptors(from the adrenergic receptor group)?
Increase the excitability and strength and rate of contractions by hypo-polarizing the plasma membrane of the cell.
What is the major cholinergic receptor and what is it sensitive to and where will it come from?
Ach “muscarinic” receptors sensitive to acetylcholine. Acetylcholine is released from parasympathetic fiber axons.
What will acetylcholine released from parasympathetic fiber axons do to cardiac muscle cells when it contacts cholinergic receptors(from the cholinergic receptors)?
Decrease the excitability and strenght and rate of contraction by hyperpolarizing the membranes.
What are the main pumps of the heart?
The venticles.
What type of pump are the atria?
Priming pumps.
What is the valve of the heart that is between the right atrium and the right ventricle?
Right Atrioventricular valve aka Tricuspid.
What is the name of the valve between the left atrium and left ventricle?
Left atrioventricular valve aka mitral.
What are the right and left valves that leave the venticles?
Right and left semilunar valves Right aka pulmonic left aka aortic
What is the shape of the right ventricle?
Crescentic or “c” shaped.
What will the high pressure pump aka the left ventricle look like?
Cylindrical.
What are the 2 circulatory systems of blood flow?
- Systemic circulation= extensive body wide. 2. Pulmonary circulation= small and goes to lungs.
What are the names for the contraction and relaxation periods of the heart?
Contraction= systole relaxation= diastole
What is the cardiac cycle?
The full action of the heart per beat.
What are the 6 parts to the cardiac cycle?
- Ventricular pressure 2. Aortic pressure 3. Ventricular volume 4. Electrocardiogram 5. Phonocardiogram 6. Atrial pressure.
How will blood flow into the ventricles at rest?
75% comes from normal blood flow through the veins. 25% is done by systolic atrial contractions
Since only 25% of blood in ventricles comes from atrial contractions what is the purpose of the atrium?
Maximizes the efficiency of each ventricluar beat.
What is isovolumetric relaxation?
A very brief period of no filling of the ventricle during diastole.