10 HUMAN ANATOMY Power Point Lecture Slides prepared

10 HUMAN ANATOMY Power. Point® Lecture Slides prepared by Leslie Hendon, University of Alabama, Birmingham PART 1 Muscle Tissue fifth edition MARIEB | MALLATT | WILHELM Copyright © 2008 Pearson Education, Inc. , publishing as Benjamin Cummings

Muscle § § 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 § Functional features § 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

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

Basic Features of a Skeletal Muscle § § Connective tissue sheaths are continuous with tendons See Figure 10. 1 a Copyright © 2008 Pearson Education, Inc. , publishing as Benjamin Cummings

Connective Tissue Sheaths in Skeletal Muscle Copyright © 2008 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 10. 1 a

Basic Features of a Skeletal Muscle § Nerves and blood vessels § Each skeletal muscle supplied by branches of § One nerve § One artery § One or more veins Copyright © 2008 Pearson Education, Inc. , publishing as Benjamin Cummings

Basic Features of a Skeletal Muscle § 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

Basic Features of a Skeletal Muscle § 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 Copyright © 2008 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 10. 3

Basic Features of a Skeletal Muscle § 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 Copyright © 2008 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 10. 4 b

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

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

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 § Sarcoplasmic reticulum § 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

Sarcoplasmic Reticulum and T Tubules § Sarcoplasmic reticulum § 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 Copyright © 2008 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 10. 6

Sarcomere and Myofibrils Copyright © 2008 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 10. 4 c

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 Copyright © 2008 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 10. 7 a

Changes in Striation During Contraction Copyright © 2008 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 10. 8 a–c

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

The Role of Titin § Titin – a spring-like molecule in sarcomeres § Resists overstretching § Holds thick filaments in place § Unfolds when muscle is stretched Copyright © 2008 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 10. 4 d

Sarcoplasmic Reticulum and T Tubules § 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

Innervation of Skeletal Muscle Copyright © 2008 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 10. 9

Innervation of Skeletal Muscle Copyright © 2008 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 10. 10

10 HUMAN ANATOMY Power. Point® Lecture Slides prepared by Leslie Hendon, University of Alabama, Birmingham PART 2 Muscle Tissue fifth edition MARIEB | MALLATT | WILHELM Copyright © 2008 Pearson Education, Inc. , publishing as Benjamin Cummings

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

Types of Skeletal Muscle Fibers § Skeletal muscle fibers § 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

Types of Skeletal Muscle Fibers § 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

Types of Skeletal Muscle Fibers § 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

Types of Skeletal Muscle Fibers § 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

Copyright © 2008 Pearson Education, Inc. , publishing as Benjamin Cummings Table 10. 2 (1 of 3)

Copyright © 2008 Pearson Education, Inc. , publishing as Benjamin Cummings Table 10. 2 (2 of 3)

Copyright © 2008 Pearson Education, Inc. , publishing as Benjamin Cummings Table 10. 2 (3 of 3)

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

Disorders of Muscle Tissue § 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

Disorders of Muscle Tissue § 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

Muscle Tissue Throughout Life § 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

Muscle Tissue Throughout Life § 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