Skeletal Muscle Fiber Types Quiz

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Questions and Answers

Why is skeletal muscle referred to as striated muscle?

It is composed solely of connective tissue.

It has a smooth appearance under the microscope.

It exhibits alternating light and dark bands. (correct)

It contains a high density of capillaries.

What encases each individual skeletal muscle fiber?

The perimysium

The epimysium

The sarcolemma

The endomysium (correct)

What is the primary structural component that defines a muscle triad?

One terminal cisternae and one nucleus

Two T tubules and one sarcosome

Three T tubules and one sarcoplasmic reticulum

Two terminal cisternae and one T tubule (correct)

How does muscle enlargement occur after birth?

By the increase in the size of muscle fibers Signup and view all the answers

What is the function of the sarcoplasmic reticulum in muscle fibers?

To store calcium ions Signup and view all the answers

Which factor does NOT contribute to the structural integrity of skeletal muscles?

Epithelial tissue Signup and view all the answers

What are transverse tubules primarily associated with in muscle fibers?

Sarcoplasmic reticulum Signup and view all the answers

What key feature differentiates the sarcolemma from other cell membranes?

It contains T tubules. Signup and view all the answers

What role does lactate play in muscle metabolism after it is produced by anaerobic fast-twitch fibers?

It serves as a starting point for aerobic ATP production in slow-twitch fibers. Signup and view all the answers

Which of the following is NOT a mechanism of muscle fatigue?

Sufficient rest and recovery before exercising. Signup and view all the answers

What is the main cause of muscle soreness after vigorous exercise?

Inflammatory chemicals that affect muscle fibers. Signup and view all the answers

What characterizes the oxygen deficit phase during exercise?

A lag time before the body begins to utilize oxygen more efficiently. Signup and view all the answers

How do smooth muscle cells primarily differ from other muscle types?

They are spindle-shaped and non-striated with typically one nucleus. Signup and view all the answers

What is the effect of alternating exercise with rest in a weightlifting program?

It allows for adequate recovery and repair of muscle tissue. Signup and view all the answers

What happens to breathing rates during excess postexercise oxygen consumption?

Breathing rates return to preexercise levels with a delay. Signup and view all the answers

Which of the following statements about smooth muscle stimulating factors is true?

Hormones and neurotransmitters can influence smooth muscle activity. Signup and view all the answers

What type of muscle fibers are primarily found in the large postural muscles of the back and lower limbs?

Slow-twitch fibers Signup and view all the answers

Which process does NOT contribute to ATP production in skeletal muscles?

Electrolyte transport via Na+/K+ ATPase Signup and view all the answers

What happens to ATP production after about 15 seconds of muscle contraction?

Creatine phosphate is fully depleted. Signup and view all the answers

What is the role of creatine kinase in muscle fiber ATP production?

To transfer a phosphate from creatine phosphate to ADP Signup and view all the answers

Which fibers primarily utilize aerobic pathways during exercises?

Slow-twitch fibers Signup and view all the answers

How long can muscle fibers sustain contraction using stored ATP?

About 5–6 seconds Signup and view all the answers

During strenuous activity, what is the primary source of ATP production in fast-twitch fibers?

Anaerobic respiration Signup and view all the answers

What is generated when two ADP molecules are converted through the action of adenylate kinase?

One ATP and one adenosine monophosphate (AMP) Signup and view all the answers

What is the primary function of the trapezius muscle?

Extends the neck and head Signup and view all the answers

Which muscle is known as the 'flexing muscle' in the upper limb?

Biceps brachii Signup and view all the answers

Which muscle is located between the ribs and plays a role in elevating the ribs?

Serratus anterior Signup and view all the answers

What is the main action of the deltoid muscle?

Abducts the upper limbs Signup and view all the answers

Which of the following muscles is NOT part of the pelvic diaphragm?

Deltoid Signup and view all the answers

Which muscle is involved in the extension of the elbow?

Triceps brachii Signup and view all the answers

What group of muscles includes the levator ani?

Pelvic diaphragm muscles Signup and view all the answers

What function does the pectoralis major serve?

Flexes the shoulder and elevates the ribs Signup and view all the answers

What is the shape of a muscle that is described as being quadrate?

Square Signup and view all the answers

Which term describes fascia that runs at an angle?

Oblique Signup and view all the answers

What is the origin of the sternocleidomastoid muscle?

Sternum and clavicle Signup and view all the answers

How many heads does a biceps muscle have?

Two heads Signup and view all the answers

Which types of muscles are responsible for abduction and adduction?

Abductors and adductors Signup and view all the answers

Which of the following muscles is NOT part of the muscles of mastication?

Sternocleidomastoid Signup and view all the answers

What type of muscle has three origins?

Triceps Signup and view all the answers

What is the primary function of abductors?

To move body parts away from the midline Signup and view all the answers

Study Notes

Skeletal Muscle Structure

Skeletal muscle, known as striated muscle, displays transverse striations microscopically.
Comprises multiple tissues: muscle, nerve, and connective tissue, functioning as complete organs (e.g., biceps brachii).

Connective Tissue Coverings

Each skeletal muscle is enveloped by epimysium.
Muscle fibers are grouped into fascicles, each wrapped in perimysium.
Individual muscle fibers are surrounded by endomysium.

Muscle Fiber Anatomy

Muscle fibers are large cells with several hundred nuclei located at their edges.
Length of muscle fibers ranges from 1 mm to 30 cm.
Striated appearance due to alternating light and dark bands; fiber number remains constant after birth, with growth resulting from increased size.

Electrical Component Structures

Sarcolemma features inward folds known as transverse tubules (T tubules) that extend into muscle fibers.
T tubules connect with terminal cisternae of the sarcoplasmic reticulum, forming muscle triads.
Sarcoplasmic reticulum plays a crucial role in muscle contraction through its Ca²⁺ concentration.

Muscle Fiber Types

Human muscles typically contain both fast-twitch and slow-twitch fibers; proportions vary.
Large postural muscles hold more slow-twitch fibers, while upper limb muscles have more fast-twitch fibers.

Energy for Muscle Contractions

Muscle fibers utilize ATP-dependent proteins, including myosin head, Na⁺/K⁺ ATPase, and Ca²⁺ pump.
ATP stores enable contractions for 5–6 seconds; continuous contraction requires ATP production through various processes.

ATP Production Pathways

ATP production occurs through:
- Conversion of ADP to ATP via adenylate kinase.
- Transfer of phosphate from creatine phosphate to ADP by creatine kinase.
- Anaerobic processes during intense exercise.
- Aerobic production during extended exercise.

Muscle Fatigue Causes

Fatigue indicates a temporary reduction in work capacity.
Mechanisms include acidosis, ATP depletion, oxidative stress, and local inflammation.

Muscle Soreness

Muscle soreness post-exercise lasts several days due to inflammatory chemical effects on fibers.
Alternating exercise with rest periods promotes muscle repair.

Oxygen Use During Exercise

Oxygen deficit is the period before enhanced breathing kicks in during exercise.
Excess post-exercise oxygen consumption refers to the delayed return to baseline breathing after ceasing activity.

Smooth Muscle Characteristics

Smooth muscle cells are non-striated, spindle-shaped, and generally contain a single nucleus.
Functional involuntarily, influenced by neurotransmitters and hormones.

Muscle Naming Conventions

Notable naming factors: shape, fascicle orientation, origin and insertion, number of heads, and specific function (e.g., abductors and adductors).

Muscle Groups

Muscles of Mastication: Temporalis, Masseter, Pterygoids.
Facial Expression Muscles and Anterior Abdominal Wall Muscles play significant roles in various actions.
Pelvic Diaphragm Muscles include Levator ani, Ischiocavernosus, Bulbospongiosus, supporting pelvic structures.

Upper Body Muscles

Trapezius: Elevates shoulders and extends neck.
Pectoralis Major: Elevates ribs, located in the chest.
Serratus Anterior: Elevates ribs between the ribs.
Deltoid: Functions as the primary abductor of the upper limb.

Upper Limb Muscles

Triceps Brachii: Named for its three heads, responsible for elbow extension.
Biceps Brachii: Known as the “flexing muscle,” facilitating flexibility in elbow and shoulder.

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Description

This quiz explores the different types of skeletal muscle fibers, including slow-twitch and fast-twitch fibers. You will learn about their distribution in various muscles throughout the human body and how they function during contractions. Test your understanding of muscle physiology and energy requirements for muscle activity.