Anatomy & Physiology I: Skin and Muscles

Practice flashcards covering key terms and concepts from the Anatomy & Physiology I lecture notes.

Epidermis

The thin, outermost layer of skin, composed of stratified squamous epithelium.

Dermis

The deep layer of skin primarily composed of dense connective tissue, housing blood vessels and nerves.

Hypodermis

The subcutaneous layer of tissue beneath the skin, mainly composed of adipose and areolar connective tissue.

Melanocytes

Cells in the skin that produce melanin, responsible for skin pigment and UV radiation absorption.

Sebaceous Glands

Oil-producing glands in the skin that help lubricate and protect against bacterial infection.

Apocrine Sweat Glands

Sweat glands located in the axillary and anogenital areas, active post-puberty.

Skeletal Muscle

Voluntary muscle tissue attached to bones, characterized by striations and multinucleated fibers.

Cardiac Muscle

Involuntary muscle found only in the heart, striated and characterized by intercalated disks.

Smooth Muscle

Involuntary muscle found in hollow organs, lacks striations, and operates under low energy requirements.

Myofibrils

Contractile elements in muscle fibers, composed of thick (myosin) and thin (actin) filaments.

Sarcomere

The functional unit of muscle contraction, defined as the segment between two Z discs.

Sliding Filament Model

Theory that explains muscle contraction by the sliding of actin and myosin filaments past each other.

Calcium Ions (Ca2+)

Ions stored in the sarcoplasmic reticulum, released to initiate muscle contraction by binding to troponin.

All-or-None Principle

The concept that a muscle fiber will contract fully or not at all when stimulated.

Motor Unit

A motor neuron and all the muscle fibers it innervates, fundamental for muscle contraction control.

Excitation-Contraction Coupling

The process linking the action potential in a muscle fiber to muscle contraction via calcium release.

Tropomyosin

A protein that blocks the active sites on actin filaments, preventing contraction until calcium binds to troponin.

Muscle Tone

Slight, continuous contraction of muscle fibers, important for maintaining posture.

Isometric Contraction

A contraction where muscle length remains the same while tension increases.

Isotonic Contraction

A contraction where muscle changes length while maintaining constant tension, resulting in movement.