Physiology chap 12 and 13 – Flashcards

Arteries are vessels that always carry oxygenated blood

An ECG detects the electrical activity occurring in a single cardiac muscle cell

Blood enters the aorta throughout the entire cardiac cycle

The proximity of the sarcoplasmic reticulum to each sarcomere permits the nearly simultaneous delivery of calcium to all sarcomeres of the muscle fiber.

During recording of an ECG, a depolarization that travels toward a positive lead will cause an upward deflection.

An electrocardiogram records the waves of depolarization and repolarization as they travel along the entire heart.

There are no slow glycolytic fibers

Thick filaments have many protrusions along their middle (head of the myosin filaments) but none at their ends.

The speed with which smooth muscle cells contract is similar to fast glycolytic skeletal muscle cells.

The contraction phase of a twitch lasts longer than the relaxation phase

There is no summation of cardiac muscle.

As skeletal muscle shortens with contraction, the length of the I band remains constant as the length of the A band decreases

Action potentials travel more quickly through the ventricular contractile cells than the conduction pathway.

Alpha motor neurons innervate extrafusal muscle fibers

Spontaneous depolarization of smooth muscle cells is mediated by pacemaker cells.

Calcium entering the cell during the plateau phase of the ventricular cell action potential triggers calcium release from the sarcoplasmic reticulum.

Ryanodine receptors are calcium channels in the sarcoplasmic reticulum

All veins return blood to the heart

Blood exits the aorta throughout the entire cardiac cycle

Aortic and left ventricular pressures are nearly identical throughout the entire cardiac cycle

Slow-wave potentials are caused by cyclical fluctuations in opening and closing of potassium channels.

The biceps cause flexion of the arm, whereas the triceps cause extension

Deoxygenated blood is blue.

An ECG detects the electrical activity occurring in a single cardiac muscle cell

Hemoglobin in skeletal muscle acts as an oxygen buffer

The AV node autorhythmic cells are the fastest depolarizing cells in the heart.

Ventricular contraction begins at the top of the heart and travels downward to its apex

Action potentials in cardiac muscle last longer than action potentials in skeletal muscle

Pacemaker activity occurs in certain smooth muscle cells and cardiac muscle cells

A skeletal muscle cell produces force for only a small portion of its contractile cycle because only a small portion of the crossbridge cycle involves force generation.

To initiate cardiac muscle contraction, calcium binds to troponin, causing a shift in tropomyosin that exposes the myosin binding sites on actin.

Skeletal muscle fibers are formed by the fusion of multiple cells during embryonic development, resulting in the presence of numerous nuclei per fiber.

Atrial pressure exceeds aortic pressure

The first heart sound coincides with the beginning of this period.

Ventricular pressure exceeds aortic pressure

All 4 valves of the heart are open

AV valves are open and semilunar valves are closed

The second heart sound coincides with the beginning of this period.

Semilunar valves are open and AV valves are closed

All 4 valves are closed and pressure in the ventricle is decreasing

Contraction of the heart is triggered by the central nervous system.

Skeletal muscle and cardiac muscle are multinucleated cells, whereas smooth muscle cells each have one nucleus.

The muscular wall of the right ventricle is thicker than that of the left ventricle because it develops a greater pressure in order to deliver blood to the organs of the body

Prolapse involves improper alignment of the atrioventricular valve such that one or more of the cusps are pushed into the atrium by the pressure developed in the ventricle.

Intrafusal muscle fibers contribute directly to the tension produced during muscle contraction

According to Starling's Law, as venous return increases, end-systolic volume increases

Parasympathetic activity enhances the closing of funny channels

The contractile cycle of the heart normally originates from a pacemaker cell within the sinoatrial node.

The end diastolic volume is proportional to the length of ventricular contractile cells.

Receives deoxygenated blood from veins

This chamber is connected to the pulmonary arteries.

Receives blood from the pulmonary veins

The mitral valve separates this chamber from its associated ventricle

The SA node is located here

This chamber has the thickest myocardium

This chamber empties into the aorta

During isovolumetric contraction, this chamber has the greatest pressure

Ventricular diastole

Ventricular repolarization.

AV nodal conduction time.

Atrial depolarization

Ventricular depolarization-

Ventricular systole

The velocity of shortening during an isometric contraction is zero.

The first heart sound occurs during the transition from systole to diastole

Activation of Golgi tendon organs during overstretching of a muscle protects the muscle by inhibiting its contraction

Contraction of smooth muscle cells is driven by binding of calcium to calmodulin.

Binding of ATP to myosin increases myosin's affinity for actin

Responsible for ion movement during the depolarization phase of the autorhythmic cell action potential.

These channels open during the plateau phase of the cardiac contractile cell action potential

Allows sodium movement into the cell during the early spontaneous depolarization in autorhythmic cells.

Allows calcium movement into the cell during the late spontaneous depolarization in autorhythmic cells.

Opening of these channels is responsible for the depolarization phase of the cardiac contractile cell action potential.

Allows ion movement out of the cell during repolarization of the autorhythmic cells.