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Muscular System
Anatomy & Physiology I Lab
| Term | Definition |
|---|---|
| What is the Latin origin of the word “muscle” and its meaning? | “Mus,” meaning “little mouse.” |
| Name the three types of muscle tissue and their characteristic | Skeletal – striated, voluntary; Cardiac – branched, striated, involuntary; Smooth – visceral, non-striated, involuntary. |
| What is excitability in muscle tissue? | Ability to receive and respond to a stimulus, usually a neurotransmitter. |
| What is contractility in muscle tissue? | Ability to shorten forcibly when adequately stimulated. |
| How do muscles produce movement? | Skeletal muscles – locomotion; Cardiac & smooth – rhythmic beating of heart, constriction/dilation of blood vessels; Smooth – propel substances in digestive, renal, reproductive tracts. |
| How do muscles help maintain posture? | Counteract gravity’s downward pull. |
| What role do muscles play in joint stabilization? | Strengthen and stabilize skeletal joints |
| How do muscles generate heat? | Contraction produces heat, regulating body temperature. |
| Define extensibility in muscle tissue. | Ability to be stretched beyond resting length when relaxed. |
| Define elasticity in muscle tissue. | Ability to recoil and resume resting length after stretching. |
| What connective tissues surround muscles? | Epimysium & perimysium – dense irregular connective tissue; Endomysium – areolar connective tissue. |
| What is a myofibril and what does it contain? | Long contractile unit inside muscle fiber; contains sarcomeres. |
| Sequence of events in muscle contraction (first step). | Action potential arrives at axon terminal of motor neuron. |
| What happens at the neuromuscular junction (NMJ)? | Acetylcholine released → action potential generated in sarcolemma. |
| How does the action potential propagate into the muscle cell? | Travels along sarcolemma and down T-tubules → Ca²⁺ released by sarcoplasmic reticulum. |
| What does calcium do in muscle contraction? | Binds to troponin → removes tropomyosin block → exposes myosin-binding sites on actin. |
| What forms cross-bridges during contraction? | Myosin heads bind to actin filaments. |
| What microscopic changes occur in a sarcomere during contraction? | I bands shorten, Z discs move toward M line, H zones disappear, A bands stay the same length. |
| What four factors affect the force of a muscle contraction? | Frequency of stimulation, number of fibers, size of fibers, degree of muscle stretch. |
| Define a lever in muscle movement. | A rigid bar moving on a fulcrum when effort is applied to move a load. |
| Mechanical advantage vs. disadvantage? | Advantage (power lever): small effort moves large load; Disadvantage (speed lever): load moves rapidly, wide range of motion. |
| First-class lever | one where the joint (fulcrum) is located between the muscle (effort) and the load |
| Second-class lever | a lever system in the body where the load is positioned between the fulcrum and the effort |
| Third-class lever | a type of lever system in the human body where the effort is applied between the fulcrum (pivot point) and the load |
| What is the difference between origin and insertion of a muscle? | Origin – immovable/less movable bone; Insertion – movable bone that moves toward origin during contraction. |
| Define antagonists. | Muscles opposing or reversing a movement (e.g., triceps brachii during elbow flexion). |
| Define synergists. | Muscles adding force or reducing unwanted movement during action. |
| Define fixators. | Synergists that immobilize a bone or muscle origin during contraction. |
| How are muscles named based on fiber direction? | Rectus – straight, Transverse – across, Oblique – angled. |
| How are muscles named based on location? | By bone or region they associate with (e.g., tibialis anterior). |
| How are muscles named based on size? | Maximus – largest, Minimus – smallest, Longus – long (e.g., gluteus maximus) |
| How are muscles named based on number of origins? | Biceps – 2 origins, Triceps – 3 origins. |
| How are muscles named based on attachment points? | According to origin or insertion (e.g., sternocleidomastoid). |
| How are muscles named based on shape? | Example – deltoid (triangular). |
| How are muscles named based on action? | Flexor or extensor (e.g., adductor magnus). |
Created by:
mdonovan8742
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