STRUCTURE & FUNCTION OF BODY SYSTEMS Flashcards
Actin
(Thin filament) One of the two primary myofilaments; binds with myosin to cause a muscle action.
Acetylcholine
A neurotransmitter
A-Band
The dark bands, and consist of thick filaments and some thin filaments.
Action Potential
An electric nerve impulse.
All-or-none Principle
All of the muscle fibers in the motor unit contract and develop force at the same time. There is no evidence that a motor neuron stimulus causes only some of the fibers to contract. Similarly, a stronger action potential cannot produce a stronger contraction.
Alveolar Pressure
Pressure inside the alveoli when the glottis is open and no air is flowing into or out of the lungs
Aortic Valve
Collectively with the pulmonary valve are the semilunar valves, which prevent back flow from the aorta and pulmonary arteries into the ventricles during ventricular relaxation.
Appendicular Skeleton
Skeletal subdivision that consist of the shoulder girdle, arms, legs, and pelvis.
Arterial System
Carries blood away from the heart. (closed-circuit)
Arterioles
Small branches of arteries.
Artery
Rapidly transport blood pumped from the heart
Atrioventricular (AV) Bundle
Conducts the impulse to the ventricles
Atrioventricular (AV) Node
The intrinsic pacemaker- where rhythmic electrical impulses are normally initiated.
Atrioventricular (AV) Valves
Tricuspid valve and Mitral valve collectively, prevent the flow of blood from the ventricles back into the atria during ventricular contraction.
Atrium
The upper chamber through which blood enters the ventricles of the heart. There are two atria in the human heart – the left atrium receives blood from the pulmonary (lung) circulation, and the right atrium receives blood from the venae cavae (venous circulation).
