Unit 8: Muscular System

A&P

What are the 3 basic muscle types found in the body?

Skeletal muscle, cardiac muscle, smooth muscle

List all the functions of muscles in the body.

1. Supports the body, 2. Allows movement, 3. Maintains body temperature, 4. Assists cardiovascular and lymph movement, 5. Protects organs and stabilizes joints

What covers the entire skeletal muscle?

Epimysium

What surrounds a bundle of muscle fibers (fascicle)?

Perimysium

What surrounds a single muscle fiber (cell)?

Endomysium

What structures make up a muscle fiber?

Myofibrils

What is the unit of a myofibril?

Sarcomere

Which filaments are thick and which are thin?

Myosin = thick, Actin = thin

Example of a muscle named based on shape.

Deltoid, trapezius

Skeletal muscles must be stimulated by a ___ to contract.

Nerve (motor neuron)

Step 1 of nerve impulse transmission to muscle.

Nerve releases a neurotransmitter (acetylcholine)

Step 2 of nerve impulse transmission to muscle.

ACh opens membrane gates on muscle cells

Step 3 of nerve impulse transmission to muscle.

Na+ and K+ exchange causes Ca2+ release from sarcoplasmic reticulum

Step 4 of nerve impulse transmission to muscle.

Ca2+ causes actin to slide past myosin — contraction begins

An influx of ___ causes myosin to form a cross-bridge with actin.

Ca2+

What is the power stroke in muscle contraction?

Myosin pulls actin filaments toward the sarcomere center

What causes cross-bridges to detach from actin?

ATP binds to myosin head

How does the myosin head prepare for the next contraction?

It uses ATP energy to reset and bind actin again

What are the 3 ways muscles make energy (ATP)?

Creatine phosphate, cellular respiration, fermentation

Which method of ATP production is fastest?

Creatine phosphate

What provides most of a muscle's ATP?

Cellular respiration

How much ATP is produced from 1 glucose?

36 ATP

What is the reaction that breaks down glucose without oxygen?

Fermentation (anaerobic respiration)

What is muscular dystrophy?

Inherited disorder; muscles enlarge due to fat/connective tissue, fibers degenerate

What is myasthenia gravis?

Autoimmune disorder; progressive muscle weakness from lack of ACh receptors

What is a strain?

Overstretching of a muscle near a joint

What is a sprain?

Twisting of a joint causing ligament/tendon/blood vessel/nerves injury

List the functions of the nervous system.

1. Sensory input, 2. Integration, 3. Motor output

What is the central nervous system (CNS)?

Brain and spinal cord

What is the peripheral nervous system (PNS)?

Nerves outside the brain and spinal cord