MIDTERMS ANAPHY- Muscular system

Specialized cells called muscle fibers.

What is the muscular system composed of?

Contractility (ability to contract).

What is the main function of muscles?

Nearly all body movements result from muscle contraction.

Why are muscles important for movement?

Bones, internal organs, and blood vessel

Where are muscles attached?

1. Skeletal muscle

2. Smooth muscle

3. Cardiac muscle

What are the three major types of muscles in the human body?

Produces movements like walking and running

What is the role of muscles in body movement?

By stabilizing body position.

How do muscles help maintain posture?

How do muscles move substances inside the body?

• Heart muscle pumps blood

• Muscles move food in the digestive tract

Muscle contractions generate heat, especially during shivering.

How do muscles help regulate body temperature?

excitability

Ability of muscle to respond to a stimulus..

contractility

Ability of muscle to shorten forcefully when stimulated

extensibility

Ability of muscle to stretch without damage.

elasticity

Ability of muscle to return to its original length.

Epimysium

What covers the entire skeletal muscle?outer connective tissue layer

fascicle

A bundle of muscle fibers within a muscle.

muscle fiber

An individual muscle cell (myocyte).

myofibrils

Rod-like structures inside muscle fibers.

sarcomere

The basic contractile unit of muscle.

myofilaments

Protein filaments (actin and myosin) that make up sarcomeres.

fascia

Dense connective tissue surrounding muscles.

epimysium

Outermost connective tissue layer of muscle.

perimysium

Connective tissue surrounding fascicles.

endomysium

Connective tissue surrounding individual muscle fibers.

tendon

A cord that attaches muscle to bone.

aponeurosis

A broad flattened tendon.

sarcolemma

Cell membrane of a muscle fiber.

sarcoplasm.

Cytoplasm of a muscle cell

sarcoplasmic reticulum

Network that stores and releases calcium ions (Ca²⁺) for contraction.

Somatic motor neurons

What stimulates skeletal muscle contraction?

axon

The long part of a nerve cell that carries impulses.

They supply oxygen and nutrients to muscle fibers.

Why are capillaries important in muscles?

Before birth.

When is the number of skeletal muscle fibers determined?

Through hypertrophy (increase in cell size).

How do muscles grow after birth?

Testosterone and human growth hormone.

Which hormones stimulate muscle hypertrophy?

satellite cells

Cells that help regenerate damaged muscle fibers.

How muscles contract.

What does the sliding filament theory explain?

Actin filaments slide over myosin filaments, shortening the sarcomere.

What happens in the sliding filament theory?

ATP

What powers muscle contraction?

Myosin

What are thick filaments made of?

Actin

What are thin filaments made of?

Troponin and Tropomyosin.

What regulatory proteins control contraction?

Blocks myosin-binding sites on actin.

What does tropomyosin do?

Binds calcium to start contraction.

What does troponin do?

Z-lines

Boundaries of a sarcomere where actin attaches.

A-band

Region containing thick myosin filaments.

I-band

Region with only thin actin filaments.

H-zone

Area in the A-band without actin overlap

M-line

Structure that anchors thick filaments.

titin

Elastic protein that connects thick filaments and provides elasticity.

Nerve impulse releasing Ca²⁺ from the sarcoplasmic reticulum.

What triggers muscle contraction?

Actin binding sites are exposed.

What happens when Ca²⁺ is released?

cross-bridges

Connections formed when myosin heads bind to actin.

power stroke

Myosin pulls actin inward, shortening the sarcomere.

What causes cross-bridges to detach?

Binding of a new ATP molecule.