Module 8: The Muscular System Flashcards Preview

Anatomy & Physiology MB > Module 8: The Muscular System > Flashcards

Flashcards in Module 8: The Muscular System Deck (42)
Loading flashcards...

3 types of muscle



Functions of muscles (4)

Produces movement
Maintains posture
Stabilizes joints
Generates heat


Produces movement

Skeletal muscles - walk, blink, turn around, chew, laugh etc
Smooth muscles line blood vessels and transport blood
Cardiac muscle operates as a pump for the blood


Maintains posture

Skeletal muscles defy gravity by making adjustments that allow us to sit or stand erect


Stabilizes joints

Skeletal muscles hold bones together and assist in stabilizing and strengthening joints


Generates heat

Muscle activity of ALL muscles general heat (skeletal muscles generate the most)


Coverings of skeletal muscle

-covered by fascia (layers of fibrous connective tissue)
-fascia extends beyond muscle and turns into the tendon
- Epimysium of fascia is the layer that attaches to the muscle
-Muscle fibers (cells) are grouped into fascicles (bundles)
-Perimysium surrounds each bundle
-Endomysium surrounds each muscle fiber


Structure of muscle fiber (cell)

-Elongated cells with hundreds of nucleoli
-Plasma membrane called sarcolemma
-Cytoplasm called sarcoplasm
-Each fiber is made of many myofibril which consist of myofilaments
-Sarcoplasmic reticulum surrounds each myofibril
-each myofilament is made of thin (actin) and thick (myosin) filaments
-Myfilaments arranged in sarcomeres (give muscle striated look)
- T tubules carry nerve stimulus into muscle fiber


Sliding filament mechanism

sliding of the thin filaments toward the center of the sarcomere causes the unit to shorten
Contracting muscles:
-nerve impulse stimulates sarcolemma
-t tubules allow stimulus to reach sarcolemma
-myosin heads make contact with actin to form temporary cross bridges
-myosin heads rotate, pulling actin inwards


Motor neuron

transmits nerve impulses from the brain and spinal cord to the skeletal muscles


Motor unit

a single motor neuron and the muscle fibers it stimulates


Neuromuscular Junction (NMJ)

The area where the motor neuron meets the muscle fibers
Structures include: plasma membrane @ end of neuron, Synaptic cleft (space between end of neuron and sarcolemma/plasma membrane of muscle fiber), sarcolemma/plasma membrane and its receptor sites
The neuron releases chemicals that diffuse across NMJ and stimulate the muscle fiber


Action potential

electrical impulse resulting from stimulation of the neuron to move along the neuron towards the axon terminal with vesicles (containing ACh, acetylcholine)



NMJ enzyme that breaks down ACh


What happens to the electrical signal in the sarcolemma

-signal travels along sarcolemma
-travels through T tubules and then stimulates the sarcoplasmic reticulum to release Calcium
-Calcium floods the sarcomeres and allows interaction of actin, myosin and ATP to cause muscle contraction
-Calcium is pumped back into the sarcoplasmic reticulum, away from actin and myosin causing muscle relaxation


All or none principle

The muscle fibers are either ON (contracting completely) or OFF (relaxing)


Isotonic contraction

Muscles shorten and movement occurs
ex. lifting object, walking, swimming,


Isometric contraction

Muscles DO NOT shorten and NO movement occurs
ex. pushing against a wall with arms, holding a book in your palms, TRYING to lift a piano



in skeletal muscles, when there are always some muscle fibers contracted (not the whole muscle, just some fibers)


3 types of muscle metabolism

Muscles require lots of ATP to contract
Aerobic metabolism
Anaerobic metabolism
Metabolism of Creatine Phosphate


Aerobic metabolism

In presence of oxygen
Fuels such as glucose and fatty acids are completely broken down by Aerobic Respiration
Glucose + oxygen = CO + H2O + ATP
(lots of ATP, 38 ATP per glucose)
*Provides the most ATP


Anaerobic Metabolism

In absence of oxygen
Anaerobic Respiration partially breaks down glucose to produce lactic acid and a small amount of ATP
Glucose = lactic acid + ATP
*Takes the shortest amount of time


Metabolism of Creatine Phosphate

Creatine phosphate is a high energy compound stored in muscle
Creatine phosphate + ADP = creatine + ATP


Oxygen debt

additional oxygen that is required after a physical activity to restore resting conditions
O2 needed to convert lactic acid into glycogen


Labored breathing

continues after the activity has stopped until oxygen debt has been brought back to equilibrium


Skeletal muscle origin

the end of the muscle that is attached to the STATIONARY bone (not easily movable)


Skeletal muscle insertion

the end of the muscle that is attached to the other bone (easily movable)


Prime mover

the main muscle in a particular movement
ex. during bicep curls, biceps are the prime mover


Antagonist muscle

a muscle that opposes the action of another muscle


Synergist muscle

help the prime mover by stabilizing joints or preventing awkward movement