Anatomy and Physiology Chapter 5

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Questions and Answers

What are the three primary structures in the muscular system?

Skeletal, cardiac, and smooth

What does the anatomical term Fixator mean?

A muscle that holds an origin stable for another muscle

What does the anatomical term Synergists mean?

Muscles that have the same action.

What does the anatomical term prime mover mean?

The main muscle of the synergists that performs the action Signup and view all the answers

What does the anatomical term antagonist mean?

A muscle that has an opposing action Signup and view all the answers

What are Skeletal muscles?

Voluntary and contracts quickly Signup and view all the answers

What are cardiac muscles?

Voluntary Signup and view all the answers

What are smooth muscles?

Involuntary contractions are slow and sustained Signup and view all the answers

What are the intrinsic muscles?

Refers to a muscle having its origin insertion located in the same body region Signup and view all the answers

What do the terms "origin" and "insertion" indicate?

Muscle attachments Signup and view all the answers

What are Extrinsic muscles?

Refers to a muscle having its origin in different body regions and the insertion in another region Signup and view all the answers

What are the muscle actions?

Produce movement, maintain posture, stabilize joints, generate heat Signup and view all the answers

What is abduction?

Movement of a part of the body away from the midline Signup and view all the answers

What is adduction?

Movement of a part of the body toward the midline Signup and view all the answers

What is protraction?

Movement that brings part of the body forward Signup and view all the answers

What is retraction?

Movement that brings part of the body backward Signup and view all the answers

What is lateral excursion?

Movement of the jaw laterally to either side Signup and view all the answers

What is medial excursion?

Movement of the jaw back to the midline Signup and view all the answers

What is flexion?

Action that bends part of the body anteriorly Signup and view all the answers

What is extension?

Action that bends a part of the body posteriorly Signup and view all the answers

What is dorsal flexion?

The position of standing on the heels with the toes pointing up Signup and view all the answers

What is plantar flexion?

Position of standing on the tiptoes with heels off the floor Signup and view all the answers

What is inversion?

Position in which the soles of the feet are together, facing each other Signup and view all the answers

What is eversion?

Position in which the soles of the feet point away from each other Signup and view all the answers

What is opposition?

The act of bringing the thumb to the palm Signup and view all the answers

What is reposition?

The act of taking the thumb away from the palm Signup and view all the answers

What is elevation?

The act of closing the jaw or raising the shoulders Signup and view all the answers

What is depression?

The act of opening the jaw or lowering the shoulders Signup and view all the answers

What does rotation do?

The act of spinning on an axis Signup and view all the answers

What does circumduction do?

The act of making a circle with part of the body Signup and view all the answers

What is supination?

Rotation that turns the palms up Signup and view all the answers

What is pronation?

Rotation that turns palms down Signup and view all the answers

How many muscles does the sternocleidomastoid have?

Two muscles Signup and view all the answers

What is the main muscle for breathing?

The diaphragm Signup and view all the answers

What are the two accessory muscles?

The external intercostals and the internal intercostals Signup and view all the answers

What is carpal tunnel syndrome?

Prolonged repetitive motions of the fingers and hands causing inflammation of the tendons under the carpal ligaments Signup and view all the answers

A muscle has a fibrous covering called what?

Epimysium Signup and view all the answers

A muscle is composed of a bundle of what?

Fascicles Signup and view all the answers

Each fascicle is surrounded by what?

Perimysium Signup and view all the answers

A fascicle is composed of muscle cells (muscle fibers) surrounded by what?

Endomysium Signup and view all the answers

The connective tissues of the muscle come together at the end of the muscle cell, or fiber to form a what?

Tendon Signup and view all the answers

What is a sarcolemma?

A plasma membrane (cell membrane) Signup and view all the answers

The sarcoplasmic reticulum is the name given to what?

Smooth endoplasmic reticulum in a muscle cell; its job is to store calcium ions until needed Signup and view all the answers

A muscle cell is composed of what?

Myofibrils (but there is no connective tissue surrounding each of them) Signup and view all the answers

Each myofibril is composed of what?

Thick and thin myofilaments arranged in sarcomeres Signup and view all the answers

The thick and thin myofilaments are composed of what?

Protein molecules Signup and view all the answers

What do each myofibril consist of?

Sarcomeres Signup and view all the answers

Where do the sarcomeres extend from?

From the Z line to Z line Signup and view all the answers

What are filaments attached to?

They are attached to Z lines and extend towards the center of the sarcomere but do not meet Signup and view all the answers

Where do filaments reside?

They reside in the A band and do not contact the Z lines Signup and view all the answers

What is thick myofilament?

Myosin subunits look like a double-headed golf club; the head is referred to as a cross-bridge Signup and view all the answers

What is thin myofilament?

Actin subunits make up a double chain of beads twisted together Signup and view all the answers

What is tropomyosin?

A thread that holds the actin chained together Signup and view all the answers

What is troponin?

A calcium regulatory molecule (a small protein attached to the tropomyosin) Signup and view all the answers

What is excitability?

A muscle cell that can be stimulated by a nerve to contract Signup and view all the answers

What is conductivity?

The stimulation from the nerve moves quickly along the length of the muscle cell Signup and view all the answers

What is contractility?

A muscle cell can shorten with force. Muscles can only pull; they cannot push Signup and view all the answers

Stimulation of a muscle cell by a nerve happens at a what?

Neuromuscular junction also known as a synapse Signup and view all the answers

An electrical stimulation along the nerve cell results in the release of what?

Acetylcholine Signup and view all the answers

Acetylcholine fits into receptors on the muscle cell to do what?

Stimulate it to contract Signup and view all the answers

What is extensibility?

A muscle can be stretched; muscles are stretched by the contraction of other muscles Signup and view all the answers

What is elasticity?

If a muscle cell is stretched, it will return to its original shape Signup and view all the answers

Very little what is needed in order for the muscle to respond?

Stimulus/threshold Signup and view all the answers

As long as the threshold is reached, the cell will do what?

Contract in an 'all or nothing manner' Signup and view all the answers

What is the sliding filament theory?

Involves the contractions of muscles grabbing thick and thin myofilaments and pulling them toward the center of the sarcomere Signup and view all the answers

As all of the sarcomeres are shortened, what happens to the muscle cell?

The muscle cell shortens as well Signup and view all the answers

What is a twitch?

It is a contraction of a muscle cell in response to a single nerve stimulus Signup and view all the answers

How many phases does a twitch have?

Four (latent phase, contraction phase, relaxation phase, refractory phase) Signup and view all the answers

What is a tetany contraction?

It is a sustained contraction due to repetitive nerve signals Signup and view all the answers

It is the frequency of the nerve impulses that determines whether the contractions will be what?

Twitch or tetany Signup and view all the answers

Energy contained in ATP is needed for the contraction to happen and to actively transport calcium ions back where?

To the sarcoplasmic reticulum so that the muscle can relax Signup and view all the answers

A motor unit is defined as what?

A single nerve cell and all of the muscle cells it stimulates Signup and view all the answers

Small motor units are needed for what?

For fine, precise movements Signup and view all the answers

Getting more motor units involves what?

Recruitment Signup and view all the answers

More and more motor units can achieve what?

Larger motion Signup and view all the answers

What is an isotonic movement?

Tension in the muscle remains constant as the muscle shortens Signup and view all the answers

What is isometric contractions?

Tension in the muscle increases, but there is no shortening of the muscle Signup and view all the answers

How many parts are there to a lever system?

Three Signup and view all the answers

Muscles move bones in what type of system?

A lever system Signup and view all the answers

What is resistance?

A weight to be lifted Signup and view all the answers

What is Effort?

The force applied to lift weight; in a muscle system, the effort is the insertion of the muscle Signup and view all the answers

What is fulcrum?

A pivot point on the lever that does not move; in muscle lever systems, the fulcrum is a joint Signup and view all the answers

Levers are classified as what?

First, second, or third based on the location of the fulcrum, effort, and resistance Signup and view all the answers

Most levers in the body are what?

Third class levers Signup and view all the answers

Muscle cells can do what two things?

Aerobic or anaerobic respiration to process energy Signup and view all the answers

Aerobic is a many-step process that produces enough energy to generate how many ATP molecules?

36, but requires the addition of oxygen Signup and view all the answers

Anaerobic is a shorter process that produces enough energy to generate how many ATP molecules?

2, and does not require oxygen Signup and view all the answers

What is creatine phosphate?

Storage form of readily available energy (stores excess ATP) Signup and view all the answers

Creatine phosphate is formed by what?

By aerobic respiration when the muscle is resting and depleted quickly is rapidly contracting muscle; energy is transferred back to ADP when ATP levels decrease Signup and view all the answers

What is muscle fatigue?

It is the inability of a muscle to fully respond to a nerve stimulus Signup and view all the answers

What is physiological contracture?

It is the complete fatigue in which the muscle appears to be stuck; it can no longer contract or relax Signup and view all the answers

Fatigue can result from what?

The build-up of lactic acid, the lack of acetylcholine, or the lack of glucose Signup and view all the answers

What are twitch fibers specially adapted for?

Aerobic respiration, so they do not fatigue quickly Signup and view all the answers

What are fast-twitched fibers specially adapted for?

Anaerobic respiration, and therefore fatigue quickly Signup and view all the answers

What is cardiac muscle tissue composed of?

Composed of branched, striated cells with a single nucleus and junctions between cells called intercalated disks Signup and view all the answers

The cells in cardiac muscle tissue are what?

Auto rhythmic (rely on aerobic respiration) Signup and view all the answers

What is skeletal muscle tissue composed of?

Composed of long, striated cells with multi nuclei pushed off to the side Signup and view all the answers

The cells in skeletal muscle tissue are what?

Voluntary and rely on aerobic or anaerobic respiration for energy and are associated with bones, skin, and body openings Signup and view all the answers

What are smooth muscle tissues composed of?

Composed of spindle-shaped cells with a single nucleus Signup and view all the answers

The cells in smooth muscle tissue are what?

Are not under voluntary control, rely on aerobic and anaerobic respiration for energy, and are located in the walls of blood vessels and hollow organs Signup and view all the answers

Study Notes

Muscular System Overview

Primary structures of the muscular system: skeletal, cardiac, and smooth muscles.
Muscle types based on control: voluntary (skeletal) and involuntary (cardiac and smooth).

Muscle Terminology

Fixator: Stabilizes origin of another muscle during movement.
Synergists: Muscles that work together to produce the same movement (e.g., diaphragm and intercostal muscles).
Prime mover: The main muscle responsible for an action.
Antagonist: Opposing muscle that performs the opposite action.

Muscle Types and Characteristics

Skeletal muscles: Voluntary, contract quickly, attached to bones.
Cardiac muscles: Involuntary, auto-rhythmic, found in the heart, relies on aerobic respiration.
Smooth muscles: Involuntary, slow and sustained contractions, located in walls of hollow organs and blood vessels.

Muscle Actions

Key muscle actions include:
- Abduction: Moving a body part away from the midline.
- Adduction: Moving a body part toward the midline.
- Flexion: Bending a part of the body anteriorly.
- Extension: Straightening a part of the body posteriorly.
- Elevation: Raising a structure (e.g., shoulders).
- Depression: Lowering a structure (e.g., opening the jaw).

Muscle Attachment and Structure

Origin and insertion: Terms indicating muscle attachments; origin is fixed, insertion moves.
Intrinsic muscles: Origin and insertion within the same body region (e.g., biceps).
Extrinsic muscles: Origin located in a different region from insertion.
Muscle fiber components:
- Epimysium: Covers the entire muscle.
- Fascicles: Bundle of muscle fibers surrounded by perimysium.
- Muscle fibers: Surrounded by endomysium.

Functional Properties of Muscles

Excitability: Ability to respond to stimulation.
Conductivity: Rapid transmission of stimulus along the muscle cell.
Contractility: Ability to shorten and generate force.
Extensibility: Can be stretched by the contraction of other muscles.
Elasticity: Returns to original shape after being stretched.
All-or-nothing principle: Muscle contracts fully or not at all, once threshold is reached.

Contraction Mechanisms

Sliding filament theory: Thick and thin myofilaments slide over one another, pulling toward the center of the sarcomere.
Twitch: Contraction of a muscle fiber in response to a single nerve stimulus with four phases (latent, contraction, relaxation, refractory).
Tetany: Sustained muscle contraction from rapid nerve impulses.

Energy and Metabolism

Aerobic respiration: Produces up to 36 ATP molecules and requires oxygen.
Anaerobic respiration: Produces only 2 ATP molecules without additional oxygen.
Creatine phosphate: Serves as a readily available energy reservoir, converting back to ATP.

Muscle Fatigue and Types of Fibers

Muscle fatigue: Inability to respond fully to stimulus, caused by factors like lactic acid buildup.
Twitch fibers: Adapted for aerobic respiration, fatigue-resistant.
Fast-twitch fibers: Adapted for anaerobic respiration, fatigue quickly.

Types of Muscle Tissue

Cardiac muscle: Branched, striated, single nucleus, interconnected by intercalated disks.
Skeletal muscle: Long, striated, multi-nucleated, controlled voluntarily.
Smooth muscle: Spindle-shaped, single nucleus, operates involuntarily, found in blood vessel walls and hollow organs.

Lever Systems in Muscle Movement

Muscles function within a lever system consisting of:
- Fulcrum: Pivot point (joint).
- Effort: Force applied (muscle insertion).
- Resistance: Weight being lifted.
Most body muscles operate as third-class levers, facilitating large movements with smaller muscle contractions.

These key points provide a structured overview of chapter 5 covering the muscular system's anatomy, physiology, and functional properties.

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Test your knowledge of the muscular system with these flashcards covering key terms and definitions. From the primary structures to specialized muscle functions, this quiz will enhance your understanding of chapter 5 in Anatomy and Physiology.