Presentation on theme: "ST110 Concorde Career College, Portland"— Presentation transcript:
1ST110 Concorde Career College, Portland Muscular System
2Objectives Define the term muscle. Describe the functions of the muscular system.List and identify the structures of the muscular system and describe the function of each.Identify the types of muscle.
3Objectives Understand the physiology of muscle contraction. Identify muscles according to their action, location, number of divisions, or according to the direction that the fibers run.Describe the mechanism by which the muscular system helps to maintain homeostasis.
4ObjectivesDescribe common diseases, disorders, and conditions of the muscular system including signs and symptoms, diagnosis, and available treatment options.Demonstrate knowledge of medical terminology related to the muscular system verbally and in the written form.
5Three Types of Muscle1. Skeletal 2. Smooth 3. Cardiac
15Muscle Structure Fascicles - bundles of muscle fibers Each bundle held together with connective tissueSeveral bundles encased in tough connective tissue called fascia
16Microscopic Structure Each skeletal muscle fiber is one muscle cell.Sarcolemma- electrically polarized membrane covering each fiber.Sarcoplasm- found underneath the sarcolemma and contains the nuclei and mitochondria.Each muscle fiber is further broken down into myofibrils that are composed of myofilaments.Myofibrils: further broken down into sarcomeres- the functioning unit
18Microscopic Structure 2 types of monofilaments:Myosin- thick filamentActin- thin filament, contains 2 proteinsTropomysoinTroposinThe 2 filaments produce striations in skeletal and cardiac muscle.Striations are composed of:I Band (light band)A Band (dark band)
19Microscopic Structure Sarcoplasmic reticulum (SR): system of tubules and sacs surrounding each myofibril.Stores and releases calcium ions which regulates the calcium ion concentration with myofibrils.Transverse tubules (T tubules) are attached to surface of SR & have openings to surface of skeletal muscle fiber.
22Muscle ActionSkeletal muscle action is stimulated by nerve impulses from the brain and spinal cord.The point where the nerve and the muscle fiber meet is called the neuromuscular junction.A chemical called a neurotransmitter (usually acetylcholine) is released from the nerve stimulates muscle contraction.
23Muscle Action Dendrites Synapse Synaptic cleft Vesicles Motor end plateExcitabilityAction potential
26ContractionThe capacity of muscle to shorten and thicken is called contractility.Muscle fibers contain two types of proteinsActinMyosin
27Role of Calcium Necessary for muscle contraction. Calcium is stored in the ER of the muscle cell and is released into the cytoplasm when the cell is stimulated.Calcium exposes the sites on the actin where the crossbridges form with the myosin to cause contraction.
28ATP Muscle contraction requires energy in the form of ATP. ATP is produced in the cell by a process called oxidation (“burning”) of nutrients.Oxygen and a nutrient (usually glucose) are necessary to produce ATP.Myoglobin stores oxygen in the muscle.Glucose is stored in the form of glycogen.
29Muscle ContractionTone - A property of muscle in which a steady or constant state of partial contraction is maintained.Isotonic contraction - Muscles become shorter and thicker and tone remains the same (movement)Isometric contraction - Muscles remain at a constant length while tension against the muscle increases (no movement).
31Smooth muscleThe mechanism of smooth and cardiac muscle contraction is the same as that of skeletal muscles.The difference is in the structure and function of the cells.
32Smooth Muscle Fiber Structure Cells are shorter and have single, centrally located nucleus.The cells are elongated and taper at both ends.Myofibrils contain actin and myosin & are randomly arranged, not striated.
33Smooth Muscle Fiber Structure Visceral smooth muscle: most common type, located in the walls of hollow organs.2 layers:Outer-fibers travel in longitudinalInner- fibers are arranged in a circular patternThe multi-layer arrangement of fibers allows the organ to change in shape and size.EXAMPLE: stomach after a meal (3 layers).Peristalsis- wavelike motion (like intestines)
35Cardiac Muscle aka myocardial muscle The only smooth muscle that has striations.Muscle cells are arranged end to end to form fibers that are interconnected.Muscle cells have a centrally located single nucleus and have actin & myosin filaments.Endomysium-located between muscle fibers & contains capillaries and lymphatics.
36Cardiac MuscleCells are joined at each end by intercalated disk. This allows for rapid transfer of impulses from cell to cell“all or nothing manner”Myogenic: spontaneous, involuntary contractions of the heart.The rate of contractions is controlled by nerve impulses from the ANS.
40Attachments of Skeletal Muscles Tendons - Attach muscle to boneAponeurosis - broad and flat tendon
41Tendons & Ligaments Tendons - attach muscle to bone. Ligaments - attach bone to bone.
42TendonsDense fibrous connective tissue. Consists of parallel fibers held together by tenosynovium. Fibers of the tendon come together with the periosteum of bone. This attatches muscle to bone. Typically inserted at the distal end of bone.TendinitisTenosynovitis
44LigamentsFibrous connective tissue consisting of parallel collagenous bundles that bind bone to bone, forming joints.
45FasciaAponeuroses: special type of fascia that binds muscle to muscle.EXAMPLE: external abdominal oblique muscle
46FasciaFascia – fiberous connective tissue that covers and supports muscle.3 types-Deep: surrounds muscle to hold them together and provide support.Forms fascial compartments: contain groups of muscles that have nerves and blood vessels.Compartment SyndromeFasciotomy- surgical incision through a fascia to relieve tension or pressure.Subcutaneous: continuous layer of connective tissue over the entire body. Between skin and deep fascia.Subserous: located between internal layer of deep fascia and the serous membranes.
47Attachments of Skeletal Muscles OriginThe more fixed and stationary attachment that serves as a basis for actionproximalInsertionMovable attachment where effects of contraction are seendistal
48Terminology of Movement Agonists - Perform the main action (also called prime movers)Antagonists - Opposite action of the agonistSynergists - Assist prime moversFlexion - BendingExtension - Straightening
50Extension & FlexionAntagonistic muscle pair of the upper arm in action. During extension of the elbow (shown at left), the triceps is contracted and the biceps is relaxed. During flexion of the elbow (shown at right), the triceps is relaxed and the biceps is contracted.
58Muscles of the Trunk Abdomen – Three layers Respiratory muscles External oblique (outer most)Internal obliqueRectus abdominisRespiratory musclesIntercostal muscles (important for respiration)Diaphragm (separates the thoracic and abdominal cavities)