Muscle Tissue Overview

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Questions and Answers

What is the primary function of calcium in muscle tissue?

To help muscle fibers regenerate

To provide energy for muscle contraction

To facilitate the contraction of muscle tissue (correct)

To transport oxygen to muscle cells

Which connective tissue layer surrounds an entire skeletal muscle?

Perimysium

Epimysium (correct)

Endomysium

Fascia

What is the primary type of cell that skeletal muscle develops from?

Myoblasts (correct)

Sarcoblasts

Fibroblasts

Chondrocytes

Which part of a muscle fiber's structure is responsible for the organization of protein filaments?

Myofibrils Signup and view all the answers

What is the role of satellite cells in skeletal muscle tissue?

To aid in limited regeneration after damage Signup and view all the answers

Which characteristic is unique to skeletal muscle tissue?

Multinucleated structure Signup and view all the answers

What type of muscle tissue is associated with involuntary rhythmic movements?

Cardiac muscle tissue Signup and view all the answers

Which muscle type does NOT have striated fibers?

Smooth muscle tissue Signup and view all the answers

How are cardiac muscle cells connected to each other?

Through intercalated discs Signup and view all the answers

What is the main function of smooth muscle tissue?

Involuntary movements Signup and view all the answers

What structure is defined as the functional unit of a skeletal muscle fiber?

Sarcomere Signup and view all the answers

What initiates the contraction cycle in a muscle fiber?

Release of calcium from the sarcoplasmic reticulum Signup and view all the answers

Which protein is NOT part of the thin filament in skeletal muscle?

Myosin Signup and view all the answers

Which characteristic is unique to cardiac muscle tissue?

Connected via intercalated discs Signup and view all the answers

What type of muscle tissue does not exhibit striations?

Smooth muscle Signup and view all the answers

Which component contributes to the transfer of contractile forces in smooth muscle tissue?

Dense bodies Signup and view all the answers

What is the primary source of energy for cardiac muscle cells?

Fatty acids Signup and view all the answers

Which type of junction is primarily responsible for communication between cardiac muscle cells?

Gap junctions Signup and view all the answers

What stimulates smooth muscle contraction?

Hormones and secretions Signup and view all the answers

What structure is characterized by branched cells and is surrounded by endomysium?

Cardiac muscle Signup and view all the answers

Study Notes

Muscle Tissue

Three types of muscle tissue: skeletal, cardiac, and smooth
Muscle tissue is responsible for movement through contraction using calcium
All muscle cell parts include the prefix "sarco-", such as sarcoplasm, sarcoplasmic reticulum, and sarcolemma

Skeletal Muscle Tissue

Striated, multinucleated (fusion of many cells)
Movement is voluntary and organized into long muscle fibers
Muscle fibers can be 1 mm to 30 cm in length and are 10-100 µm in diameter
Satellite cells are "reserve cells" and are responsible for limited regeneration after damage

Organization of Skeletal Muscle

Endomysium: very thin layer of connective tissue that surrounds individual muscle fibers; contains capillaries and nerve endings
Perimysium: thin connective tissue layer surrounding a bundle of muscle fibers; acts as a functional unit where fibers work together and are innervated by one nerve
Epimysium: dense connective tissue that surrounds the entire muscle; contains nerves, blood, and lymph vessels

Skeletal Muscle Fiber Organization

Muscle fibers have highly organized myofibrils, which are long bundles of protein filaments
Thick filaments: myosin proteins
Thin filaments: actin proteins (includes troponin and tropomyosin)
Sarcomere: the functional unit of muscle fibers, extending from Z-line to Z-line
Contraction: Actin and myosin slide past each other, bringing Z-lines closer together

Contraction of a Muscle Fiber

Contraction is initiated by a signal from the neuromuscular junction (NMJ) that releases acetylcholine (ACh)
ACh depolarizes the sarcolemma (T-tubules), causing the release of calcium (Ca2+) from the sarcoplasmic reticulum (SR)
Ca2+ initiates the contraction cycle
T-tubules are infoldings of the sarcolemma
Branched sarcoplasmic reticulum (SR) helps regulate calcium levels
Triad is formed by a T-tubule and two SRs
Mitochondria provide energy for contraction

Cardiac Muscle Tissue

Cells are branched, striated, and connected via intercalated discs
Surrounded by endomysium and many capillaries
Groups of cardiac muscle cells are surrounded by perimysium, which is continuous with the connective tissue of the heart: endocardium and epicardium
Signal transfer is similar to skeletal muscle but less organized
Contains many mitochondria (up to 40%) for aerobic respiration
Primarily uses fatty acids as energy source

Cardiac Intercalated Discs

Strong adhesion through desmosomes
Communication through gap junctions

Smooth Muscle Tissue

Individual cells with many gap junctions
Endomysium contains basal lamina and collagen fibers, transferring contractile forces
Slow contraction using actin and myosin
No striations
Cells pack closely together in layers with different alignments
Dense bodies serve as attachment points (similar to Z-lines)
Uses calmodulin and MLCK instead of troponin and tropomyosin

Muscle Tissue and Movement

Skeletal muscle tissue: movement is initiated by motor nerves releasing acetylcholine (ACh)
Cardiac muscle tissue: movement is initiated by the autonomic nervous system and the pacemaker heart
Smooth muscle tissue: movement is initiated by the autonomic nervous system, hormones, and secretions

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Description

This quiz covers the three types of muscle tissue: skeletal, cardiac, and smooth. You will learn about their functions, structures, and the organization of skeletal muscle, including connective tissue layers like endomysium, perimysium, and epimysium. Test your knowledge on muscle contraction and cell regeneration.