9165_ระบบกล้ามเนื้อ

22-1 • ระบบกล้ามเนือ้ (The Muscular System) พิมพรรณ รัตนโกมล พยาบาลวิชาชีพ ชานาญการพเิ ศษ © 2011 The McGraw-Hill Companies, Inc. All rights reserved.

วตั ถปุ ระสงค์การเรียนรู้ 22-2 1. ระบหุ น้าทขี่ องกล้ามเนือ้ ได้ 2. บอกชนิดตาแหน่งและคณุ สมบตั ิของกล้ามเนือ้ แตล่ ะ ชนิดได้ 3. อธิบายการทางานของกล้ามเนือ้ เรียบ กล้ามเนือ้ ลาย และกล้ามเนือ้ หวั ใจ 4. อธิบายโครงสร้างของกล้ามเนือ้ ลายได้ © 2011 The McGraw-Hill Companies, Inc. All rights reserved.

วตั ถปุ ระสงค์การเรียนรู้(ตอ่ ) 22-3 • 5.บอกความหมายของคา origin and insertion • 6.ระบกุ ารเคลื่อนทข่ี องร่างกายที่เก่ียวข้องกบั กระดกู และกล้ามเนือ้ • 7.ระบแุ ละจาแนกกล้ามเนือ้ ลายและการทางานใน สว่ นตา่ งๆของร่างกาย © 2011 The McGraw-Hill Companies, Inc. All rights reserved.

MUSCLES • Approximately 40% of your body weight • Approximately 650 muscles • Muscles only pull (they can’t push) • You have over 30 facial muscles • Eye muscles move more than 100,000 times a day © 2011 The McGraw-Hill Companies, Inc. All rights reserved.

Skeletal Muscle Functions Muscle plays six important roles in the body: 1. Produce skeletal movement 2. Maintains posture and body position 3. Support soft tissues (abdominal wall & pelvic cavity) 4. Guard entrances and exits (digestive and urinary tracts) 5. Maintain body temperature (energy is converted to heat) 6. Store nutrient reserves (proteins are broken down & amino acids are used) © 2011 The McGraw-Hill Companies, Inc. All rights reserved.

22-6 Movement • Skeletal muscles – Attached to bones by tendons – Cross joints so when they contract, bones they attach to move • Smooth muscle – Found on organ walls – Contractions produce movement of organ contents • Cardiac muscle – Produces atrial and ventricular contractions – This pumps blood from the heart into the blood vessels © 2011 The McGraw-Hill Companies, Inc. All rights reserved.

22-7 Stability • Hold bones tightly together – Stabilize joints • Small muscles hold vertebrae together – Stabilize the spinal column © 2011 The McGraw-Hill Companies, Inc. All rights reserved.

Connective Tissue Wrappings of Skeletal Muscle  Endomysium – Figure 6.1 around single muscle fiber Slide 6.4a  Perimysium – © 2011 The McGraw-Hill Companies, Inc. All rights reserved. around a fascicle (bundle) of fibers Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Connective Tissue Wrappings of Skeletal Muscle  Epimysium – Figure 6.1 covers the entire skeletal Slide 6.4b muscle © 2011 The McGraw-Hill Companies, Inc. All rights reserved.  Fascia – on the outside of the epimysium Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Skeletal Muscle Attachments  Epimysium blends into a connective tissue attachment  Tendon – cord-like structure  Aponeuroses – sheet-like structure  Sites of muscle attachment  Bones  Cartilages  Connective tissue coverings Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 6.5 © 2011 The McGraw-Hill Companies, Inc. All rights reserved.

Smooth Muscle Characteristics  Has no striations  Spindle-shaped cells  Single nucleus  Involuntary – no conscious control  Found mainly in the walls of hollow organs  Slow, sustained Figure 6.2a and tireless Slide 6.6 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings © 2011 The McGraw-Hill Companies, Inc. All rights reserved.

Microscopic Anatomy of Skeletal Muscle  Cells are multinucleate  Nuclei are just beneath the sarcolemma Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 6.3a Slide 6.9a © 2011 The McGraw-Hill Companies, Inc. All rights reserved.

Microscopic Anatomy of Skeletal Muscle  Sarcolemma – specialized plasma membrane  Sarcoplasmic reticulum – specialized smooth endoplasmic reticulum Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 6.3a Slide 6.9b © 2011 The McGraw-Hill Companies, Inc. All rights reserved.

Microscopic Anatomy of Skeletal Muscle  Myofibril  Bundles of myofilaments  Myofibrils are aligned to give distrinct bands  I band = light band  A band = dark band Figure 6.3b Slide Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings © 2011 The McGraw-Hill Companies, Inc. All rights reserved.

Microscopic Anatomy of Skeletal Muscle  Organization of the sarcomere  Thick filaments = myosin filaments  Composed of the protein myosin  Has ATPase enzymes Figure 6.3c Slide Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings © 2011 The McGraw-Hill Companies, Inc. All rights reserved.

Microscopic Anatomy of Skeletal Muscle  Organization of the sarcomere  Thin filaments = actin filaments  Composed of the protein actin Figure 6.3c Slide Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings © 2011 The McGraw-Hill Companies, Inc. All rights reserved.

Microscopic Anatomy of Skeletal Muscle  Myosin filaments have heads (extensions, or cross bridges)  Myosin and actin overlap somewhat Figure 6.3d Slide Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings © 2011 The McGraw-Hill Companies, Inc. All rights reserved.

Properties of Skeletal Muscle Activity (single cells or fibers)  Irritability – ability to receive and respond to a stimulus  Contractility – ability to shorten when an adequate stimulus is received Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 6.13 © 2011 The McGraw-Hill Companies, Inc. All rights reserved.

Nerve Stimulus to Muscles  Skeletal muscles must be stimulated by a nerve to contract (motor neruron)  Motor unit  One neuron  Muscle cells Figure 6.4a stimulated by that neuron Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 6.14 © 2011 The McGraw-Hill Companies, Inc. All rights reserved.

Nerve Stimulus to Muscles  Neuromuscular Slide junctions – association site © 2011 The McGraw-Hill Companies, Inc. All rights reserved. of nerve and muscle Figure 6.5b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Nerve Stimulus to Muscles  Synaptic cleft – Figure 6.5b gap between nerve and Slide muscle © 2011 The McGraw-Hill Companies, Inc. All rights reserved.  Nerve and muscle do not make contact  Area between nerve and muscle is filled with interstitial fluid Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Transmission of Nerve Impulse to Muscle  Neurotransmitter – chemical released by nerve upon arrival of nerve impulse  The neurotransmitter for skeletal muscle is acetylcholine  Neurotransmitter attaches to receptors on the sarcolemma  Sarcolemma becomes permeable to sodium (Na+) Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide © 2011 The McGraw-Hill Companies, Inc. All rights reserved.

Transmission of Nerve Impulse to Muscle  Sodium rushing into the cell generates an action potential  Once started, muscle contraction cannot be stopped Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide © 2011 The McGraw-Hill Companies, Inc. All rights reserved.

The Sliding Filament Theory of Muscle Contraction  Activation by nerve Figure 6.7 Slide causes myosin heads © 2011 The McGraw-Hill Companies, Inc. All rights reserved. (crossbridges) to attach to binding sites on the thin filament  Myosin heads then bind to the next site of the thin filament Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

The Sliding Filament Theory of Muscle Contraction  This continued action causes a sliding of the myosin along the actin  The result is that the muscle is shortened (contracted) Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 6.7 Slide © 2011 The McGraw-Hill Companies, Inc. All rights reserved.

The Sliding Filament Theory Figure 6.8 Slide 6.18 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings © 2011 The McGraw-Hill Companies, Inc. All rights reserved.

Energy for Muscle Contraction  Direct phosphorylation Figure 6.10a Slide 6.24  Muscle cells contain creatine phosphate (CP)  CP is a high-energy molecule  After ATP is depleted, ADP is left  CP transfers energy to ADP, to regenerate ATP  CP supplies are exhausted in about 20 seconds Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings © 2011 The McGraw-Hill Companies, Inc. All rights reserved.

Energy for Muscle Contraction  Anaerobic glycolysis Figure 6.10b Slide  Reaction that breaks down glucose without oxygen  Glucose is broken down to pyruvic acid to produce some ATP  Pyruvic acid is converted to lactic acid Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings © 2011 The McGraw-Hill Companies, Inc. All rights reserved.

Energy for Muscle Contraction  Anaerobic glycolysis Figure 6.10b Slide (continued)  This reaction is not as efficient, but is fast  Huge amounts of glucose are needed  Lactic acid produces muscle fatigue Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings © 2011 The McGraw-Hill Companies, Inc. All rights reserved.

Energy for Muscle Contraction  Aerobic Respiration  Series of metabolic pathways that occur in the mitochondria  Glucose is broken down to carbon dioxide and water, releasing energy  This is a slower reaction that requires continuous oxygen Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 6.10c Slide 6.25 © 2011 The McGraw-Hill Companies, Inc. All rights reserved.

Muscle Fatigue and Oxygen Debt  When a muscle is fatigued, it is unable to contract  The common reason for muscle fatigue is oxygen debt  Oxygen must be “repaid” to tissue to remove oxygen debt  Oxygen is required to get rid of accumulated lactic acid  Increasing acidity (from lactic acid) and lack of ATP causes the muscle to contract less Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 6.27 © 2011 The McGraw-Hill Companies, Inc. All rights reserved.

Types of Muscle Contractions  Isotonic contractions  Myofilaments are able to slide past each other during contractions  The muscle shortens  Isometric contractions  Tension in the muscles increases  The muscle is unable to shorten Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 6.28 © 2011 The McGraw-Hill Companies, Inc. All rights reserved.

Muscles and Body Movements  Movement is attained due to a muscle moving an attached bone Figure 6.12 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide © 2011 The McGraw-Hill Companies, Inc. All rights reserved.

Muscles and Body Movements  Muscles are attached to at least two points  Origin – attachment to a moveable bone  Insertion – Figure 6.12 attachment to an immovable bone Slide Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings © 2011 The McGraw-Hill Companies, Inc. All rights reserved.

Naming of Skeletal Muscles  Direction of muscle fibers  Example: rectus (straight)  Relative size of the muscle  Example: maximus (largest) Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide © 2011 The McGraw-Hill Companies, Inc. All rights reserved.

Naming of Skeletal Muscles  Location of the muscle  Example: many muscles are named for bones (e.g., temporalis)  Number of origins  Example: triceps (three heads) Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide © 2011 The McGraw-Hill Companies, Inc. All rights reserved.

Naming of Skeletal Muscles  Location of the muscles origin and insertion  Example: sterno (on the sternum)  Shape of the muscle  Example: deltoid (triangular)  Action of the muscle  Example: flexor and extensor (flexes or extends a bone) Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 6.37 © 2011 The McGraw-Hill Companies, Inc. All rights reserved.

Cardiac Muscle Characteristics  Has striations  Usually has a single nucleus  Joined to another muscle cell at an intercalated disc  Involuntary  Found only in the heart  Steady pace! Figure 6.2b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 6.7 © 2011 The McGraw-Hill Companies, Inc. All rights reserved.

22-40 Control of Body Openings and Passages • Sphincters – Valve-like structures formed by muscles – Control movement of substances in and out of passages – Example: • A urethral sphincter prevents or allows urination © 2011 The McGraw-Hill Companies, Inc. All rights reserved.

22-41 Heat Production • Heat is released with muscle contraction – Helps the body maintain a normal temperature – Moving your body can make you warmer if you are cold © 2011 The McGraw-Hill Companies, Inc. All rights reserved.

22-42 Types of Muscle Tissue • Muscle cells – Myocytes called muscle fibers – Sarcolemma – cell membrane – Sarcoplasm – cytoplasm of cell – Myofibrils – long structures in sarcoplasm • Arrangement of filaments in myofibrils produces striations © 2011 The McGraw-Hill Companies, Inc. All rights reserved.

22-43 Types of Muscle Tissue (cont.) Muscle Major Major Mode of Group Location Function Control Skeletal Attached to Produces body Voluntary Muscle bones and skin of movements and the face facial expressions Involuntary Smooth Walls of hollow Moves contents Involuntary Muscle organs, blood through organs; vessels, and iris vasoconstriction Cardiac Wall of the heart Pumps blood Muscle through heart © 2011 The McGraw-Hill Companies, Inc. All rights reserved.

22-44 Skeletal Muscle • Muscle fibers respond to the neurotransmitter acetylcholine – Causes skeletal muscle to contract • Following contraction, muscles release the enzyme acetylcholinesterase – Breaks down acetylcholine – Allows muscle to relax © 2011 The McGraw-Hill Companies, Inc. All rights reserved.

22-45 Smooth Muscle • Multiunit smooth muscle – In the iris of the eye and walls of blood vessels – Responds to neurotransmitters and hormones • Visceral smooth muscle – In walls of hollow organs – Responds to neurotransmitters AND – Stimulate each other to contract so that muscle fibers contract and relax together in a rhythmic motion – peristalsis © 2011 The McGraw-Hill Companies, Inc. All rights reserved.

22-46 Smooth Muscle (cont.) • Peristalsis – rhythmic contraction that pushes substances through tubes of the body • Neurotransmitters for smooth muscle contraction – Acetylcholine – Norepinephrine – Will cause or inhibit contractions, depending on smooth muscle type © 2011 The McGraw-Hill Companies, Inc. All rights reserved.

22-47 Cardiac Muscle • Intercalated discs – Connect groups of cardiac muscle – Allow the fibers in the groups to contract and relax together • Allows heart to work as a pump • Self-exciting – does not need nerve stimulation to contract – Nerves speed up or slow down contraction © 2011 The McGraw-Hill Companies, Inc. All rights reserved.

22-48 Cardiac Muscle (cont.) • Neurotransmitters – Acetylcholine – slows heart rate – Norepinephrine – speeds up rate © 2011 The McGraw-Hill Companies, Inc. All rights reserved.

22-49 Production of Energy for Muscle • ATP (adenosine • Muscle cells must triphosphate) have three ways to store or make ATP – A type of chemical energy – Creatine phosphate – Needed for • Rapid production of sustained or energy repeated muscle contractions – Aerobic respiration • Uses body’s store of glucose – Lactic acid production • Small amounts of ATP © 2011 The McGraw-Hill Companies, Inc. All rights reserved.

22-50 Oxygen Debt • Develops when skeletal muscles are used strenuously for several minutes and cells are low in oxygen Pyruvic acid Converts Lactic acid to which builds up To liver for conversion to Muscle fatigue glucose, requiring more energy and oxygen to make Oxygen debt ATP © 2011 The McGraw-Hill Companies, Inc. All rights reserved.

22-51 Muscle Fatigue • Condition in which a muscle has lost its ability to contract • Causes – Accumulation of lactic acid – Interruption of the blood supply to a muscle – A motor neuron loses its ability to release acetylcholine onto muscle fibers © 2011 The McGraw-Hill Companies, Inc. All rights reserved.