Anatomy Muscle Physiology Vocab

Tendon

Attaches a muscle to a bone

Neurotransmitters

Chemicals that cross a synapse and stimulate motor neurons

Myofibrils

Parallel structures that make up a muscle fiber; multiple sarcomeres

Sarcomeres

Repeating patterns of striations that make up myofibrils

Actin filaments

Thin filaments contained within a myofibril

Myosin filaments

Thick filaments contained within a myofibril

Sarcoplasmic reticulum

Similar to the ER of other cells; stores and releases calcium ions

Fascicle

Sections of muscle tissue that contain multiple muscle fibers

Synapse

Functional connection between neurons in which chemicals can pass

Acetylcholine

Motor neurons use this neurotransmitter to control skeletal muscles

Sliding filament model

During muscle contraction, actin and myosin slide alongside each other

Neuromuscular Junction

The site where an axon and a muscle fiber meet

Type 1 Muscle fiber

Muscle with high myoglobin, lots of mitochondria and appears red

Type IIa Muscle fiber

Muscle with medium amounts of myoglobin that uses OP and glycolysis

Type IIb Muscle fiber

Muscle with low myoglobin and mitochondria that fatigues fast

I Band

Light bands (of a sarcomere) made of actin filaments

A Band

Dark bands produced when myosin and actin filaments overlap

Skeletal Muscle

Voluntary muscle that is connected to the skeleton

Cardiac Muscle

Involuntary muscle responsible for the contraction of the heart

Smooth Muscle

Involuntary muscle found in internal organs

Fascia

Layers of dense connective tissue that separate muscles

Aponeuroses

Sheet of CT that attaches muscles to other muscles

Muscle fibers

Part of the muscle that contains bundles of myofibrils

H Zone

Center of the A band composed of thick myosin filaments

Z Line

Boundary of sarcomere within the I band; anchors filaments in place

M Line

Anchors myosin filaments; within center of A band

Myoglobin

Oxygen-carrying pigment in muscle cells

Norepinephrine

Neurotransmitter required for smooth muscle contraction

Cross-bridge

Connection made when myosin heads bind to actin

Sarcolemma

The cell membrane of muscle cells