Hole s Human Anatomy and Physiology Eleventh Edition Mrs. Hummer Chapter 9 Muscular System 1
Chapter 9 Muscular System Skeletal Muscle usually attached to bones under conscious control striated Three Types of Muscle Tissues Cardiac Muscle wall of heart not under conscious control striated Smooth Muscle walls of most viscera, blood vessels, skin not under conscious control not striated 2
Structure of a Skeletal Muscle Skeletal Muscle organ of the muscular system - skeletal muscle tissue - nervous tissue - blood - connective tissues fascia tendons aponeuroses- sheet of connective tissue of which certain muscles are attached to bone and facia 3
Connective Tissue Coverings muscle fascicles-bundles of skeletal muscle fibers muscle fibers myofibrils-contractile fibers thick and thin filaments 4
Skeletal Muscle Fibers sarcolemma-cell membrane sarcoplasm- cytoplasm sarcoplasmic reticulum- like E.R transverse tubule-channel that extends inward triad cisternae of sarcoplasmic reticulum transverse tubule myofibril- contractile fiber in muscle cells actin filaments (thin) myosin filaments (thick) sarcomere-unit of a myofibril 5
Myofilaments Thick Filaments composed of myosin cross-bridges Thin Filaments composed of actin associated with troponin and tropomyosin (proteins) 6
Neuromuscular Junction also known as myoneural junction site where an axon and muscle fiber meet motor neuron 7
Stimulus for Contraction acetylcholine (ACh) (neurotransmitter) nerve impulse causes release of ACh from synaptic vesicles ACh binds to ACh receptors on motor end plate generates a muscle impulse muscle impulse eventually reaches sarcoplasmic reticulum and the cisternae 8
Excitation Contraction Coupling muscle impulses cause sarcoplasmic reticulum to release calcium ions into cytosol calcium binds to troponin to change its shape position of tropomyosin is altered binding sites on actin are exposed actin and myosin molecules bind 9
Relaxation acetylcholinesterase rapidly decomposes Ach remaining in the synapse muscle impulse stops stimulus to sarcolemma and muscle fiber membrane ceases calcium moves back into sarcoplasmic reticulum myosin and actin binding prevented muscle fiber relaxes 10
Major Events of Muscle Contraction and Relaxation 11
Energy Sources for Contraction 1) Creatine phosphate; 4-6 times more abundant in muscle cells than ATP 2) Cellular respiration (ATP) creatine phosphate stores energy that quickly converts ADP to ATP 12
Oxygen Supply and Cellular Respiration Anaerobic Phase glycolysis occurs in cytoplasm produces little ATP Aerobic Phase citric acid cycle electron transport chain occurs in the mitochondria produces most ATP myoglobin stores extra oxygen (pigment that gives muscle the reddish-brown color) 13
Oxygen Debt Oxygen debt amount of oxygen needed by liver cells to use the accumulated lactic acid to produce glucose oxygen not available glycolysis continues pyruvic acid converted to lactic acid liver converts lactic acid to glucose 14
Muscle Fatigue inability to contract commonly caused from decreased blood flow ion imbalances across the sarcolemma accumulation of lactic acid cramp sustained, involuntary muscle contraction 15
Heat Production Length- Tension Relationship by-product of cellular respiration muscle cells are major source of body heat blood transports heat throughout body 16
Types of Contractions isotonic muscle contracts and changes length eccentric lengthening contraction concentric shortening contraction isometric muscle contracts but does not change length 17
Smooth Muscle Fibers Compared to skeletal muscle fibers shorter single, centrally located nucleus elongated with tapering ends myofilaments randomly organized lack striations lack transverse tubules sarcoplasmic reticula not well developed 18
Types of Smooth Muscle Visceral Smooth Muscle single-unit smooth muscle sheets of muscle fibers fibers held together by gap junctions exhibit rhythmicity exhibit peristalsis walls of most hollow organs Multiunit Smooth Muscle less organized function as separate units fibers function separately irises of eye walls of blood vessels 19
Smooth Muscle Contraction Resembles skeletal muscle contraction interaction between actin and myosin both use calcium and ATP both are triggered by membrane impulses Different from skeletal muscle contraction smooth muscle lacks troponin smooth muscle uses calmodulin (protein) two neurotransmitters affect smooth muscle acetlycholine and norepinephrine hormones affect smooth muscle stretching can trigger smooth muscle contraction smooth muscle slower to contract and relax smooth muscle more resistant to fatigue smooth muscle can change length without changing tautness 20
Cardiac Muscle located only in the heart muscle fibers joined together by intercalated discs fibers branch network of fibers contracts as a unit self-exciting and rhythmic 21
Characteristics of Muscle Tissue 22
Skeletal Muscle Actions origin immovable end insertion movable end prime mover (agonist) primarily responsible for movement synergists assist prime mover antagonist resist prime mover s action and cause movement in the opposite direction 23
Body Movement Four Basic Components of Lever 1. rigid bar bones 2. fulcrum point on which bar moves; joint 3. object - moved against resistance; weight 4. force supplies energy for movement; muscles 24
Clinical Application Myasthenia Gravis autoimmune disorder receptors for ACh on muscle cells are attacked weak and easily fatigued muscles result difficulty swallowing and chewing ventilator needed if respiratory muscles are affected treatments include drugs that boost ACh removing thymus gland immunosuppressant drugs antibodies 25
Life-Span Changes myoglobin, ATP, and creatine phosphate decline by age 80, half of muscle mass has atrophied adipose cells and connective tissues replace muscle tissue exercise helps to maintain muscle mass and function 26
Notebook Understanding Words Pg. 341 Critical Thinking: #1, 2, 3 Review Questions: #1, 8, 10, 11, 12, 13, 14, 23, 25, 29 27
Major Skeletal Muscles 28
Major Skeletal Muscles 29
Muscles of Facial Expression 30
Muscles of Mastication 31
Muscles of Facial Expression and Mastication 32
Muscles That Move the Head and Vertebral Column 33
Muscles That Move the Head and Vertebral Column 34
Muscles That Move the Pectoral Girdle 35
Muscles That Move the Pectoral Girdle 36
Muscles That Move the Arm 37
Muscles That Move the Arm 38
Muscles That Move the Arm 39
Muscles That Move the Forearm 40
Muscles That Move the Forearm 41
Muscles That Move the Forearm 42
Cross Section of the Forearm 43
Muscles That Move the Hand 44
Muscles That Move the Hand 45
Muscles of the Abdominal Wall 46
Muscles of the Abdominal Wall 47
Muscles of the Pelvic Outlet 48
Muscles of Pelvic Outlet 49
Muscles That Move the Thigh 50
Muscles That Move the Thigh 51
Muscles That Move the Thigh 52
Muscles That Move the Leg 53
Muscles That Move the Leg 54
Muscles That Move the Leg 55
Muscles That Move the Leg 56
Muscles That Move the Foot 57
Muscles That Move the Foot 58
Muscles That Move the Foot 59