Muscle and Nervous System Review

Flashcards covering key vocabulary terms and definitions related to muscle tissue, nervous system functions, and sensory receptors.

Muscle fiber

A single multinucleated muscle cell, long and cylindrical.

Myofibril

A long bundle inside a muscle fiber made of repeating units (sarcomeres) responsible for contraction.

Actin

Thin filament protein in the sarcomere that has binding sites for myosin.

Myosin

Thick filament protein with 'heads' that bind actin and pull to generate contraction.

Sarcolemma

The plasma membrane of a muscle fiber, which conducts electrical signals.

Sarcoplasm

The cytoplasm of a muscle fiber, containing glycogen and mitochondria.

Sarcomere

The basic contractile unit between Z-discs, with an arrangement of actin and myosin that shortens during contraction.

Sarcoplasmic reticulum (SR)

Specialized endoplasmic reticulum in muscle fibers that stores Ca²⁺ and releases it when the muscle is stimulated.

Transverse (T) tubules

Invaginations of the sarcolemma that carry action potentials deep into the fiber, signaling the SR.

Neuromuscular junction (NMJ)

The synapse between a motor neuron axon terminal and muscle fiber motor end plate.

Acetylcholine (ACh)

A neurotransmitter that binds to muscle receptors at the NMJ, triggering depolarization of the sarcolemma.

Cross-bridge cycle

The process where myosin heads bind to actin, perform a power stroke, release, and repeat as long as Ca²⁺ and ATP are available.

Agonist

The muscle primarily responsible for a movement.

Synergist

Muscle that assists the agonist in starting or stabilizing a movement.

Antagonist

Muscle that opposes the agonist, must relax to allow movement.

Somatic nervous system

Part of the nervous system that controls voluntary skeletal muscles.

Autonomic nervous system (ANS)

Involuntary control system of smooth muscle, cardiac muscle, and glands.

Dendrites

Neuronal structures that receive signals.

Axon

The part of a neuron that conducts action potentials away from the soma.

Myelin sheath

An insulating layer that increases the conduction speed of neurons.

Resting membrane potential (RMP)

The typical membrane potential of a neuron, approximately -70 mV.

Action potential (AP)

A rapid, all-or-none change in membrane potential resulting in depolarization and repolarization.

Saltatory conduction

The jumping of action potentials between nodes of Ranvier in myelinated axons.

Gyri

Ridges (folds) on the cerebral surface.

Sulci

Grooves between gyri.

Cerebrospinal fluid (CSF)

Fluid that cushions the brain and provides a stable chemical environment.

Hypothalamus

Brain region regulating body temperature, hunger, thirst, and circadian rhythms.

Limbic system

A network involved in emotion, memory formation, and motivation.

Reflex arc

The pathway that involves receptor, sensory neuron, integration center, motor neuron, and effector.

Phrenic nerve

Nerve that innervates the diaphragm, crucial for breathing.

Referred pain

Pain perceived at a location other than the site of the painful stimulus.

Sympathetic nervous system

Part of the ANS responsible for the 'fight or flight' response.

Parasympathetic nervous system

Part of the ANS responsible for 'rest and digest' functions.

Cranial nerves

Twelve nerves with mixed motor/sensory functions that originate in the brain.

Mechanoreceptors

Sensory receptors that respond to touch, pressure, and vibration.

Photoreceptors

Cells in the retina that respond to light (rods and cones).

Taste receptors

Cells within taste buds that detect chemicals in food.

Ear ossicles

Small bones in the middle ear that transmit and amplify vibrations.