PART 1 Muscle Tissue.

Name: PART 1 Muscle Tissue.
Uploaded: 2017-07-19T19:33:51+00:00
Duration: PTM19S26
Channel: Phoebe Norris
Description: PART 1 Muscle Tissue.

PART 1 Muscle Tissue

Muscle – a Latin word for “little mouse”
Muscle is the primary tissue in the Heart (cardiac MT) Walls of hollow organs (Smooth MT) Skeletal muscle Makes up nearly half the body’s mass Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Overview of Muscle Tissue
Functions of muscle tissue Movement Skeletal muscle - attached to skeleton Moves body by moving the bones Smooth muscle – squeezes fluids and other substances through hollow organs Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Overview of Muscle Tissue
Functions of muscle tissue (continued) Maintenance of posture – enables the body to remain sitting or standing Joint stabilization Heat generation Muscle contractions produce heat Helps maintain normal body temperature Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Functional Features of Muscles
Contractility Long cells shorten and generate pulling force Excitability Electrical nerve impulse stimulates the muscle cell to contract Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Functional Feature of Muscles
Functional features Extensibility Can be stretched back to its original length by contraction of an opposing muscle Elasticity Can recoil after being stretched Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Types of Muscle Tissue Three types of MT Skeletal muscle tissue
Packaged into skeletal muscles Makes up 40% of body weight Cells are striated Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Three types of MT (continued)
Types of Muscle Tissue Three types of MT (continued) Cardiac muscle tissue – occurs only in the walls of the heart Smooth muscle tissue – occupies the walls of hollow organs Cells lack striations Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Similarities of Muscle Tissue
Cells of muscles Are known as fibers Muscle contraction Depends on two types of myofilaments (contractile proteins) One type contains actin Another type contains myosin These two proteins generate contractile force Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Similarities of Muscle Tissues
Plasma membrane is called a sarcolemma Cytoplasm is called sarcoplasm Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Skeletal Muscle Each muscle is an organ
Consists mostly of muscle tissue Skeletal muscle also contains Connective tissue Blood vessels Nerves Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Basic Features of a Skeletal Muscle
Connective tissue and fascicles Connective tissue sheaths bind a skeletal muscle and its fibers together Epimysium – dense regular connective tissue surrounding entire muscle Perimysium – surrounds each fascicle (group of muscle fibers) Endomysium – a fine sheath of connective tissue wrapping each muscle cell Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Connective Tissue Sheaths in Skeletal Muscle
Figure 10.1a Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Nerves and blood vessels Nerves and vessels branch repeatedly Smallest nerve branches serve Individual muscle fibers Neuromuscular junction – signals the muscle to contract Draw a picture of neuromuscular junction Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Muscle attachments Most skeletal muscles run from one bone to another One bone will move – other bone remains fixed Origin – less movable attachment Insertion – more movable attachment Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Muscle Attachments Figure 10.3
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Muscle attachments (continued) Muscles attach to origins and insertions by CT Fleshy attachments – CT fibers are short Indirect attachments – CT forms a tendon or aponeurosis Bone markings present where tendons meet bones Tubercles, trochanters, and crests Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Microscopic and Functional Anatomy of Skeletal Muscle Tissue
The skeletal muscle fiber Fibers are long and cylindrical Are huge cells – diameter is 10–100µm Length – several centimeters to dozens of centimeters Each cell formed by fusion of embryonic cells Cells are multinucleate Nuclei are peripherally located Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Diagram of Part of a Muscle Fiber
Figure 10.4b Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Myofibrils and Sarcomeres
Striations result from internal structure of myofibrils Myofibrils Long rods within cytoplasm Make up 80% of the cytoplasm Are a specialized contractile organelle found in muscle tissue A long row of repeating segments called sarcomeres (functional unit of Skeletal MT) Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Basic unit of contraction of skeletal muscle
Sarcomere Basic unit of contraction of skeletal muscle Z disc (Z line) – boundaries of each sarcomere Thin (actin) filaments – extend from Z disc toward the center of the sarcomere Thick (myosin) filaments – located in the center of the sarcomere Overlap inner ends of the thin filaments Contain ATPase enzymes Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

A bands – full length of the thick filament
Sarcomere Structure A bands – full length of the thick filament Includes inner end of thin filaments H zone – center part of A band where no thin filaments occur Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Sarcomere Structure (continued)
M line – in center of H zone Contains tiny rods that hold thick filaments together I band – region with only thin filaments Lies within two adjacent sarcomeres Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Sarcoplasmic Reticulum and T Tubules
A specialized smooth ER Interconnecting tubules surround each myofibril Some tubules form cross-channels called terminal cisternae Cisternae occur in pairs on either side of a t-tubule Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Contains calcium ions – released when muscle is stimulated to contract Calcium ions diffuse through cytoplasm Trigger the sliding filament mechanism Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Sarcoplasmic Reticulum and T Tubules in the Skeletal Muscle Fiber
Figure 10.6 Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Sarcomere and Myofibrils
Figure 10.4c Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Mechanism of Contraction
Sliding filament theory Myosin heads attach to actin in the thin filaments Then pivot to pull thin filaments inward toward the center of the sarcomere PLAY Sliding Filament Theory Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Sliding Filament Mechanism
Figure 10.7a Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Changes in Striation During Contraction
Figure 10.8a–c Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Microscopic and Functional Anatomy of Skeletal Muscle Tissue
Muscle extension Muscle is stretched by a movement opposite that which contracts it Muscle fiber length and force of contraction Greatest force produced when a fiber starts out slightly stretched Myosin heads can pull along the entire length of the thin filaments Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Titin – a spring-like molecule in sarcomeres
The Role of Titin Titin – a spring-like molecule in sarcomeres Resists overstretching Holds thick filaments in place Unfolds when muscle is stretched Figure 10.4d Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Muscle contraction Ultimately controlled by nerve-generated impulse Impulse travels along the sarcolemma of the muscle cell Impulses further conducted by T tubules T tubule – a deep invagination of the sarcolemma PLAY Anatomy Review: Skeletal Muscle Tissue Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Innervation of Skeletal Muscle
Motor neurons innervate skeletal muscle tissue Neuromuscular junction is the point where nerve ending and muscle fiber meet Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

PART 2 Muscle Tissue

Types of Skeletal Muscle Fibers
Skeletal muscle fibers are categorized according to How they manufacture energy (ATP) How quickly they contract Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Are divided into 3 classes Slow oxidative fibers (Type I) Red Slow twitch Fast glycolytic fibers (Type IIx) White fast-twitch Fast oxidative fibers (Type IIa) Intermediate fibers Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Slow oxidative fibers (Type I) Red color due to abundant myoglobin Obtain energy from aerobic metabolic reactions Contain a large number of mitochondria Richly supplied with capillaries Contract slowly and resistant to fatigue Fibers are small in diameter Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Fast glycolytic fibers (Type IIx) Contain little myoglobin and few mitochondria About twice the diameter of slow-oxidative fibers Contain more myofilaments and generate more power Depend on anaerobic pathways Contract rapidly and tire quickly Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Fast oxidative fibers (Type IIa) Have an intermediate diameter Contract quickly like fast glycolytic fibers Are oxygen-dependent Have high myoglobin content and rich supply of capillaries Somewhat fatigue-resistant More powerful than slow oxidative fibers Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Disorders of Muscle Tissue
Muscle tissues experience few disorders Heart muscle is the exception Skeletal muscle Remarkably resistant to infection Smooth muscle Problems stem from external irritants Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Muscular dystrophy A group of inherited muscle destroying disease Affected muscles enlarge with fat and connective tissue Muscles degenerate Types of muscular dystrophy Duchenne muscular dystrophy Myotonic dystrophy Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Myofascial pain syndrome Pain is caused by tightened bands of muscle fibers Fibromyalgia A mysterious chronic-pain syndrome Affects mostly women Symptoms – fatigue, sleep abnormalities, severe musculoskeletal pain, and headache Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Muscle Tissue Throughout Life
Muscle tissue develops from myoblasts Myoblasts fuse to form skeletal muscle fibers Skeletal muscles contract by the seventh week of development Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Cardiac muscle Pumps blood three weeks after fertilization Satellite cells Surround skeletal muscle fibers Resemble undifferentiated myoblasts Fuse into existing muscle fibers to help them grow Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

With increased age Amount of connective tissue increases in muscles Number of muscle fibers decreases Loss of muscle mass with aging Decrease in muscular strength by 50% by age 80 Sarcopenia – muscle wasting Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

PART 1 Muscle Tissue.

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