Chapter 7 Notes: The Muscular System

These flashcards cover key concepts from the lecture notes on the muscular system, focusing on muscle types, structure, function, contraction processes, and the physiology of muscle fibers.

Skeletal muscle is attached to __ and moves the body by pulling on bones.

Bones

__ muscle is found only in the heart and moves blood.

Cardiac

The __ muscular tissue moves fluids and solids along the digestive tract and regulates the diameter of small arteries.

Smooth

One function of the muscular system is the maintenance of __, where skeletal muscles facilitate erect posture.

Posture

The __ encircles openings to the digestive and urinary tracts, providing voluntary control over swallowing, defecation, and urination.

Sphincters

Skeletal muscle fibers are bundled together and wrapped in connective tissue layers; the outermost layer is called __.

Epimysium

The connective tissue layer that divides skeletal muscle into bundles of fibers is called __.

Perimysium

The delicate connective tissue that surrounds and separates individual skeletal muscle fibers is known as __.

Endomysium

Tendons are bundles of __ fibers that attach muscle to bone.

Collagen

A skeletal muscle fiber is also referred to as a __.

Myofiber

The plasma membrane of a muscle fiber is called the __.

Sarcolemma

Infoldings of the sarcolemma, known as __, extend into the sarcoplasm and encircle sarcomeres.

Transverse tubules (T-tubules)

The __ is the organelle that stores calcium ions and is involved in muscle contraction.

Sarcoplasmic reticulum (SR)

During muscle contraction, calcium ions are released from the __, which triggers muscle fiber contraction.

Sarcoplasmic reticulum

The functional units of skeletal muscle fibers, called __, are made up of thin and thick myofilaments.

Sarcomeres

The binding sites for myosin on actin are covered by __ when the muscle is relaxed.

Tropomyosin

The release of __ from sarcoplasmic reticulum is crucial for muscle contraction to occur.

Calcium ions

ACh binds to ACh receptors on the __ of muscle fibers, changing membrane permeability.

Motor end plate

A twitch in muscle fibers varies in duration depending on muscle type and __ conditions.

Environmental

In the sliding filament theory, __ filaments slide past thick filaments to shorten the sarcomere.

Thin

Muscle fibers returning to their original length after contraction is caused by __, inertia, and elasticity of tissues stretched during contraction.

Gravity

During the __ contraction, muscle tension exceeds the load and results in muscle shortening.

Isotonic

Muscle tone is the __ tension that occurs even when muscles are not contracting.

Resting

Muscle hypertrophy leads to the enlargement of whole muscles due to repeated stimulation causing more __, glycolytic enzymes, and larger glycogen reserves.

Mitochondria

Muscle atrophy refers to the loss of muscle mass, tone, and decrease in __ strength.

Muscle

Rigor mortis occurs when there is no __ available to detach cross-bridges from active sites after death.

ATP

A contraction cycle in muscle fibers ends when the stimulus from the motor neuron __.

Stops

The overall effect of muscle contraction is reflected by the movement of __ caused by muscle fibers attached to tendons.

Bones

Muscle fibers activated first are typically part of __ motor units that allow for more precise movements.

Smaller

Oxygen debt is the amount of oxygen required to restore normal conditions and remove __ from muscle tissue.

Lactic acid

The breakdown of glucose without oxygen during peak activity is referred to as __ fermentation, resulting in lactic acid production.

Anaerobic

The __ phase of a muscle twitch occurs from the peak tension to the end of the twitch.

Relaxation