Chapter 10: Muscle Tissue and Organization Flashcards
List and explain the 4 unique characteristics of muscle tissue.
- Excitability - responsiveness; able to be stimulated by a nerve to move
- Contractility - fibers shorten resulting in pull on bones or movement of body parts
- Elasticity - ability to return to to original length when tension is released
- Extensibility - capability to extend in length in response to contraction of opposing muscle fibers
List and describe the 3 types of muscle tissue.
- Skeletal Muscle
- striated
- voluntary
- multinucleated
i. e. muscles like biceps, quadriceps, etc - Smooth Muscle
- NOT striated
- involuntary
- only 1 nucleus
- fibers are short, fusiform shape
- takes longer to contract and relax than skeletal muscle
i. e. muscles in the digestive tract/intestines - Cardiac Muscle
- striated
- involuntary
- typically 1-2 nuclei
- fibers shorter and thicker than skeletal muscle and form Y-shaped branches
- contain intercalated discs
- autorythmic
i. e. the heart wall
List the functions of skeletal muscle (5)
- Movement
- Maintain posture
- Temp regulation (ie shivering)
- Storage and movement of materials
- Support
Describe these muscle attachments:
Tendon
Aponeuroses
Tendon - attaches muscle to: bone, skin, or another muscle; thick cordlike structure,
Aponeuroses - tendon that is a thin flat sheet
Define origin and insertion.
Origin - the less movable attachment of a muscle; typically proximal to the insertion
Insertion - the more movable attachment of a muscle; the pull is toward the origin
List and define the 4 parts of muscle cell anatomy
- Sarcolemma - plasma membrane (right under the endomysium)
- Sarcoplasm - cytoplasm
- Sarcoplasmic reticulum - similar to smooth ER
- Transverse tubules - invaginations of sarcolemma (they help spread nerve impulses for contraction)
Define a motor unit.
A motor unit is composed of a
- single motor neuron
- the muscle fibers it controls
- the neuromuscular junctions between them
Explain the all-or-none principle.
- A muscle fibers either completely contracts or it does not contract at all.
- When a motor unit is stimulated, all of it’s fibers contract at the same time
- Total force exerted by the muscle depends on the number of motor units that are activated
ie. increase motor units = increase in force of contraction
(think of lifting a box that you think will be heavier than it is)
What is muscle tone?
Resting tension in a skeletal muscle.
- some motor units are active even when a muscle is at rest
- motor units cause the muscle to be tense but produce enough force to cause movement
Define agonist.
muscle that contracts to produce a particular movement (also called “prime mover”)
Define prime mover.
muscle that contracts to produce a particular movement (also called “agonist”)
Define antagonist.
muscle action that opposes that of the agonist/prime mover
Define synergist.
muscle action that assists the agonist/prime mover in performing an action;
contributes to tension near insertion or stabilizes origin;
may assist agonist by preventing movement at a joint; therefore stabilizing origin
Define the 2 types of muscle contractions.
Isometric - length of the muscle does NOT change during the contraction; tension is generated but not enough to move the load
Isotonic - movement DOES occur; tension produced exceeds the load
Define atrophy and what happens.
Muscles is reduced in size, tone, and power. (Fibers decrease in size and become weaker.)
Occurs due to reduced stimulation.