muscular system

Muscular System

Converts chemical energy from food into mechanical energy

40%-50%

Percentage of body weight contributed by muscle

Myofibrils

gives the muscles its striped appearance

Myoglobin

Specialized protein in muscle that provides oxygen and energy required for muscle contraction

Arrector pili

Muscles in the roots of your hair that give you goosebumps

17 muscles

Number of muscles it takes to smile

42 muscles

Number of muscles it takes to frown

eye muscles

Hardest working muscle in the human body

Gluteus Maximus

Largest muscle in the body

Muscles

Responsible for all movement of the body

Skeletal, Cardiac, Smooth

Three basic types of muscle

Skeletal Muscle

Type of muscle associated with connective tissue and constitutes approximately 40% of body weight

Contractility, Excitability, Extensibility, Elasticity

Four major functional characteristics of skeletal muscle

Contractility

Ability of muscle tissue to actively shorten and generate force

Excitability

Ability of muscle tissue to respond to stimuli (irritability), typically from the nervous system

Extensibility

Capacity of muscle tissue to be stretched or extended without being damaged

Elasticity

Ability of muscle tissue to return to its original shape and length after being stretched or contracted

Skeletal Muscle

Muscle located in limbs that is striated, multinucleated, and voluntary

Cardiac Muscle

Muscle located in heart that is striated, single-nucleated, and involuntary

Smooth Muscle

Muscle located in viscera that is non-striated, single-nucleated, and involuntary

Microfilaments

Protein fibers responsible for muscle contraction due to their movement

myo and mys

Prefixes that refer to muscle

sarco

Prefix that refers to flesh

Muscle cells

Single cell organized into fasciculi containing numerous myofibrils that helps control physical forces

Myofibrils

Made up of thick and thin myofilaments that give the muscle its striped appearance

Myosin

relaxation

Actin

contraction

Tropomyosin and Troponin

Two muscle regulatory proteins located on thin filaments alongside actin

Sarcomere

Basic contractile unit of muscle fiber formed by sarcomeres joined end to end

Actin and Myosin

Two main protein filaments that compose each sarcomere

Sliding filament theory

Most popular model describing muscular contraction

Tendons

Structure that attaches most skeletal muscles to bones

Multinucleated

Condition where muscle cells have more than one nucleus

Collagen fibers

Primary fiber component of tendons

Myofibrils

Contractile elements of skeletal muscle cells measuring 50-60mm in diameter

Retinaculum

Band of connective tissue that holds down the tendon at each wrist and ankle

Origin / Head

Most stationary end of the muscle

Insertion

End of the muscle attached to bone undergoing the greatest movement

Triangular

Muscle shape group associated with shoulder and neck

Spindle

Muscle shape group associated with arms and legs

Flat

Muscle shape group associated with diaphragm and forehead

Circular

Muscle shape group associated with mouth and anus

Agonist

Muscle that accomplishes a certain movement

Antagonist

Muscle working in opposition to an agonist

Synergist

Member of a group of muscles working together to produce movement

Prime Mover

Muscle that plays the major role in accomplishing desired movement

Fixator

Muscles that hold one bone in place relative to the body while a more distal bone is moved

Spindle-shaped

Structural shape of smooth muscle cells

Peristalsis

Alternate contraction of circular and longitudinal muscle in the intestine

Genital, Reproductive/Respiratory tracts, Integument, Sensory

Body locations containing smooth muscle

Intercalated discs

Dark lines appearing as gap junctions joining adjacent cardiac muscle cells

Skeletal Muscle

Type of muscle controlled by CNS with voluntary movement

Cardiac Muscle

Type of muscle regulated by ANS with involuntary movement (e.g., heart beating)

Smooth Muscle

Type of muscle controlled by ANS with involuntary movement (e.g., peristalsis)

Twitch

Single brief contraction that is not a normal muscle function

Tetanus

Contraction immediately followed by another where the muscle never completely returns to a relaxed state

ATP

Stored energy form in muscles used at the cellular level

Cellular Respiration

Process by which organisms combine oxygen with foodstuff molecules to produce ATP

Mitochondria

Cell organelle where cellular respiration occurs

Glycolysis

First stage of cellular respiration occurring in cytoplasm without requiring oxygen

2 ATP

Net gain of ATP molecules per glucose molecule in glycolysis

Krebs Cycle

Second stage of cellular respiration requiring oxygen in the mitochondria

Electron Transport Chain (ETC)

Final stage of cellular respiration producing 28-34 ATP molecules per glucose

Oxygen

Acts as the final electron acceptor in cellular respiration to form water

Isotonic exercise

Type of exercise where muscle shortens and movement occurs

Isometric exercise

Type of exercise where tension in muscles increases but no movement occurs

Origin

Attachment point of a muscle to a movable bone

Insertion

Attachment point of a muscle to an immovable bone

650

Total approximate number of muscles in the human body

Masseter

Strongest muscle in the jaw that closes jaw and elevates mandible

Temporalis

Muscle attaching to temporal fossa that elevates and retracts mandible

Corrugator

Frowning muscle sitting inside corner of orbit creating vertical forehead wrinkles

Orbicularis Oculi

Disc-shaped muscle surrounding eye socket that closes eyelids and forms crow's feet

Procerus

Fan-shaped muscle that horizontally wrinkles skin at root of nose

Nasalis

Muscle running down sides of nose that flares nostrils

Levator labii superioris alaeque nasi

Sensibly known as LLSAN, elevates upper lip and wing of nose

Levator labii superioris

Muscle that elevates upper lip to produce a snarl

Zygomaticus Major

Cheekbone muscle that draws corner of mouth outward and upward (smile)

Zygomaticus Minor

Cheekbone muscle that draws upper lip backward, upward, and outward (sad expressions)

Orbicularis Oris

Circular muscle that closes, compresses, puckers, and protrudes mouth

Buccinator

Horizontal cheek muscle related to chewing, suckling, whistling, and dimples

Risorius

Muscle that draws corner of mouth outward and causes dimple

Epicranius

Scalp muscle containing frontalis and occipitalis bellies

Frontalis

draws the skull forward and the eyebrows upward

Occipitalis

draws the scalp backward

Epicranial Aponeurosis

dense layer of tissue that covers the upper part of the cranium

Sternomastoid

Neck muscle with two heads extending to mastoid process that flexes and rotates head

Omohyoid, Sternohyoid, Thyrohyoid

Group of strap muscles acting upon hyoid and larynx in front of neck

Platysma

Broad sheet neck muscle depressing lower jaw for fear or grimacing expressions

Trapezius

Muscle that extends head, adducts, elevates, or depresses scapula

Latissimus Dorsi

Muscle that extends, adducts, and rotates arm medially

Deltoid

Muscle that abducts, flexes, and extends arm

Pectoralis Major

Muscle that flexes, adducts, and rotates arm medially

Rectus Abdominus

Abdominal muscle that flexes abdomen

External Oblique

Abdominal muscle that compresses abdomen

External Intercostals

Intercostal muscles that elevate ribs

Internal Intercostals

Intercostal muscles that depress ribs

Diaphragm

Main muscle responsible for respiration

Flexor carpi

Forearm muscles that flex wrist

Extensor carpi

Forearm muscles that extend wrist