SOPHIA Human Biology Unit 2 Challenge 2: Skeletal Muscles

Muscle Cramps

a type of muscle spasm that doesn't immediately release

Skeletal Muscle

a voluntary muscle that contains long, striated (striped appearance), multi-nucleated cells (fibers); attached to skeleton to allow movement, stabilize joints, produce body heat, and protect deeper internal organs; largest and most common muscle type in the body

Anabolic Steroids

synthetic substance that mimics testosterone; used to build muscle and enhance physical performance

Action Potential

technical term for nervous impulse sent by motor neurons to muscle fibers

Tetanus

term to describe prolonged muscle contraction/sustained muscle contraction caused by repeated muscle twitches; disease caused by microbes that cause muscles to continuously spasm (nervous and muscular systems don't properly communicate, causes uncontrollable spasms)

Motor Unit

term used to describe one motor neuron and all of the muscle fibers it innervates at once

Sarcomeres

the basic units of muscle contraction; functional and contractile units of skeletal and cardiac muscles; created by specific arrangements of myofilaments (actin and myosin)

Fibers

multi-nucleated cells that compose skeletal muscles; composed of myofibrils

Muscle Strain

muscle fiber tears or is stretched too far

Voluntary Muscles

muscle form we have conscious control of

Involuntary Muscles

muscle form we have no conscious control over

Capillaries

allow more blood to flow to muscles; delivers more oxygen and takes carbon dioxide as muscles work

Slow Skeletal Muscles

also called Red Skeletal Muscles; type of muscle that can contract slowly for long periods of time; have more myoglobin and capillaries (both allow sustained activity)

Fast Skeletal Muscles

also called White Skeletal Muscles; type of muscle that can contract quickly for short periods of time (ie. hands); have less myoglobin, capillaries, and mitochondria (in cells)

Cardiac Muscle

an involuntary type of muscle that contains short, striated (has striped appearance), single-nucleated cells; found only within the heart and pumps blood throughout cardiovascular system

Smooth Muscle

an involuntary type of muscle that contains short, tube-like, single-nucleated cells (has a smooth appearance; small, organized sheets); compose the inside of the walls of hollow organs and tubes

Reciprocal Innervation

nervous system controlling muscle groups that appose and work against one another; when one muscle contracts, no nervous system signals are sent to opposing muscle (it relaxes); allows for antagnostic contractions to occur

Contraction

occurs when muscle fiber generates tension, causing muscle to shorten

Muscular System

one of 11 body systems; allows movement, body heat production, and the flow of blood and other substances throughout the body

Antagnostic Contraction

opposing muscle on opposite side of joint contracts to create opposing movement to its muscle counterpart; allowed by reciprocal innervation; ex. biceps and triceps

Neuromuscular Junction

place where end of a motor neuron reaches/comes close to muscle fibers

Troponin

protein found on actin that helps to regulate when myosin can bind to actin; calcium is released from the SR and binds to this protein, causing tropomyosin to expose actin to myosin for binding, leading to a contraction

Tropomysoin

protein in skeletal muscles that shields actin, preventing myosin from binding unless there's a nerve signal (prevents random contractions from occurring)

Myoglobin

protein that binds to oxygen to carry more oxygen to cells to produce more ATP/cell energy

Sarcoplasmic Reticulum (SR)

specialized form of smooth endoplasmic reticulum found within skeletal muscles used for calcium storage; releases calcium during muscle contractions

Creatine

substance found naturally in muscles that can be used to supplement/replace ATP while working out to sustain activity for longer periods of time

Synergistic Contraction

when muscle groups work together to create same movement

Neurotransmitters

chemical messengers that carry signals across the synapse and between cells

Myofilaments

compose myofibrils; made of proteins (mostly actin and myosin)

Jaundice

disorder associated with liver function that can be caused by steroid use

Insertion

end of muscle that attaches to moveable bone; fixed, moveable end of skeletal muscle

Origin

end of muscle that attaches to stable bone; fixed, non-moveable end of skeletal muscle

Synapse

gap between end of a motor neuron and muscle fiber; where electrical signal gets translated into a chemical signal that the muscle fiber can understand

Muscular Dystrophy

genetic disorder that causes the gradual breakdown of skeletal muscle fibers

Sliding Filament Mechanism

theory used to describe muscle contraction

Myosin

thick filament of sarcomere; contains double head and single tail; heads pull on actin filaments to create movements

Actin

thin filament of sarcomere; protein that interacts with myosin to create movement

Tendons

tough band of fibrous connective tissue; connects muscle to bone

Aerobic Exercise

type of exercise that gradually conditions slow/red muscles to work for longer periods of time; builds endurance; exercises that increase heart rate (ie. swimming, running, biking, etc.); increase the size and quantity of mitochondria in muscle cells

Strength Training

type of exercise that increases the size of fast/white muscles; increases the force muscles can exert; causes more myofibrils to be produced

Twitch

type of muscle contraction where sarcomeres quickly pull inward and create quick, jerky motion

Muscle Spasm

type of muscle disorder where involuntary muscle contractions occur; often caused by potassium deficiencies

Motor Neurons

type of neurons that deliver signals to muscles or glands

Muscular Atrophy

wasting away of muscle tissue leading to very weak muscles; often occurs to people on bedrest

Myofibrils

what muscle cells/fibers contain; long chains of myofilaments; also contain sarcomeres (the basic unit of muscle contractions)