MLSHH 201 – Muscular Tissue PDF

MUSCULAR TISSUE Cells are elongated. Sarcoplasm appears fibular due to the presence of myofibrils. Acidophilic staining Cells are held together by the loose areolar connective tissue containing blood vessels and nerves. 1. Mo...

MUSCULAR TISSUE Cells are elongated. Sarcoplasm appears fibular due to the presence of myofibrils. Acidophilic staining Cells are held together by the loose areolar connective tissue containing blood vessels and nerves. 1. Movement 2. Posture maintenance 3. Joint stabilization 4. Heat generation In visceral organs, the contractions are slow and uniform. 1. Able to contract Functions to alter the activity of various body parts 2. Able to extend to meet the needs of the body. 3. Able to become excitable (irritability) Activation is involuntary. 4. Elasticity Fatigue resistant 5. Conductivity It is made up of spindle or fusiform shaped cells that do not branch. Myofibrils are non-striated. Myofilaments are not distinct. Single nucleus is bulging and centrally located. Cells are somewhat compact in arrangement. 1. Muscle fibers It has the least amount of loose areolar connective 2. Muscle fibers are held together or bound together tissue. by intercellular substances in the form of loose Few, long, slender mitochondria. areolar connective tissue. Scanty ribosomes and endoplasmic reticulum. a. Epimysium: Outermost layer Sarcolemma showing pinocytic vesicles. b. Perimysium (Fascicle): Sheath of fibrous connective tissue that surrounds FUNCTIONS OF SMOOTH MUSCLE the bundles of muscle fibers. 1. Contraction of the bladder to force urine out. c. Endomysium: Sheath of reticular fibers 2. Move food through the intestines (peristalsis). 3. Peristaltic movement to move feces down the digestive system. 4. Contraction of smooth muscle in the trachea and 1. Smooth Muscle bronchi which decreases the size of the air Involuntary, spindle-shaped passageway. 2. Cardiac Muscle 5. Constriction and dilation of the blood vessels. Involuntary, striated under microscope 6. Constriction, accommodation and dilation of 3. Skeletal Muscle pupils. Voluntary, striated 7. Uterine contractions during birthing. 8. Milk letdown in the mammary gland during lactation. DISTRIBUTION OF SMOOTH MUSCLE Found mainly in the walls of hollow visceral organs like the walls of the digestive system. Bulacan State University – Main Bachelor of Science in Medical Technology (Medical Laboratory Science) 1 Rachel Bianca Llanita MUSCULAR TISSUE Middle to lower part of esophagus. CARDIAC CONDUCTION SYSTEM Internal sphincter of the anus. Made up of 5 Elements: Walls of ducts and glands associated with the 1. Sinoatrial (SA) node alimentary tract. 2. Atrio-ventricular (AV) node Walls of respiratory passages (trachea to alveolar 3. Atrioventricular Bundle of His ducts) 4. Left and Right Branches of His Urinary genital ducts 5. Purkinje Fibers Walls of arteries, veins & larger lymphatics Spleen Arrectores pilorum / Arrector pili muscle (goose flesh) Iris & ciliary bond of the eye Areola of mammary gland Subcutaneous tissue of scrotum. 1. Sinoatrial Node Has characteristics of both skeletal and smooth Location: Below the epicardium at the muscle junction of superior vena cava and right Functions to provide the contractile activity of the atrium. heart Function: Regulates the heart rate Is very fatigue resistant according to body requirements. Activation of cardiac muscle is involuntary (like smooth muscle) 2. Atrioventricular Node Made up of elongated muscle fibers that branches Location: Below the endocardium, on Has a single spherical centrally located nucleus the lower part of the interatrial septum. (branches have no nucleus). Functions: Myofibrils appears striated with distinct actin & ○ Delays cardiac impulses from myosin the sinoatrial node to allow With an intercalated disk of Eberth: serves as a the atria to contract and junction between cardiac cells. empty their contents first. With numerous Loose Areolar CT ○ Relays cardiac impulses to the Sarcoplasmic reticulum is not so well developed atrioventricular bundle. as in skeletal muscular tissue Absence of terminal cisternae 3. Atrioventricular Bundle of His Tube appears larger and situated at the Z line Location: A bundle of fibers that are Presence of bigger and numerous mitochondria located within the septum of the heart. Muscle fibers can not regenerate after being Function: Carries cardiac impulses damage down the septum to the ventricles via Purkinje fibers. DISTRIBUTION OF CARDIAC MUSCLE Muscle layer of the heart (myocardium) 4. Left and Right Branches of Bundle of His Walls of the aorta, vena cava ( superior and Function: The right bundle carries nerve inferior) and pulmonary vessels (pulmonary artery impulses that cause contraction of the and pulmonary vein). right ventricle and the left bundle carries nerve impulses that cause contraction of the left ventricle. A specialized functional unit responsible for 5. Purkinje Fibers generating and conducting electrical impulses for Location: Beneath the endocardium on the heart, causing the heart to contract and pump either side of the cardiac septum. blood throughout the body. Bulacan State University – Main Bachelor of Science in Medical Technology (Medical Laboratory Science) 2 Rachel Bianca Llanita MUSCULAR TISSUE Function: Relays cardiac impulses to the ○ Plasma membrane of a muscle fiber ventricular cells causing the ventricles surrounding the sarcoplasm (cytoplasm) to contract. containing mitochondria, and myofibrils. CHARACTERISTICS OF PURKINJE FIBERS Sarcoplasmic Reticulum (SR) Pale in color, vesicular and transparent ○ Transverse tubule encircling a myofibril, sarcoplasm storing calcium for muscle contraction. Fewer branches, nuclei, striations,myofibril,no Myofibrils typical intercalated discs ○ Cylindrical bundles of myofilaments Abundant sarcoplasm with large amount of (two types) glycogen and big,numerous mitochondria ○ Lie parallel to one another Bigger in diameter ○ Responsible or muscle fiber contraction Shorter in size Lies in abundant amount of loose areolar Myofilaments connective tissue ○ Protein filaments (organization of these Numerous desmosomes produce alternating light/dark bands) Thin: primarily actin Thick: primarily myosin Sarcomeres ○ Repeating functional units of myofilaments ○ Responsible for muscle contraction ○ Approximately 10,000 end to end in a myofibril ○ Contain: thick/thin filaments, proteins FUNCTIONS OF SKELETAL MUSCLE Dark bands: A bands 1. Produce skeletal movement Light bands: I bands 2. Maintain posture and body position 3. Support soft tissues 1. A bands (Dark bands – Myosin) 4. Maintain body temperature Myosin consists of two twisted strands 5. Store nutrients with globular cross-bridges projected outward along the strands. DISTRIBUTION OF SKELETAL MUSCLE Thick filaments in the center Widely distributed because this type of muscle is Subdivisions: attached to the entire skeletal system of the body ○ M line – Central portion of (external urethra & external anal sphincter) each thick filament. Although the tongue & upper part of the ○ H band – regions on either esophagus are unattached to the skeletal system, side of the M line it is classified as striated voluntary. Contains only thick filaments THIN MICROSCOPIC ANATOMY OF SKELETAL MUSCLE ○ Zones of overlap – think and Myoblasts thick filaments surrounding ○ Embryonic cells that fuse to develop each other muscle fibers. Myosatellite cells ○ Unfused cells that remain in adult skeletal muscle. Sarcolemma Bulacan State University – Main Bachelor of Science in Medical Technology (Medical Laboratory Science) 3 Rachel Bianca Llanita MUSCULAR TISSUE Similar with red fibers but with smaller sarcosome (mitochondria). Speed of contraction is comparable to that of the white fibers ○ Intermediate properties between those of fast/slow ○ Contraction speed is fast ○ Can be converted to fast fibers with training 2. I bands (Light bands – Actin) Actin is a globular protein with myosin binding sites; tropomyosin and troponin. ○ Thin filaments ○ Extends from the A band of one sarcomere to the A band of the next sarcomere. ○ Z line indicates boundary 3 TYPES OF SKELETAL FIBER IN SKELETAL MUSCLE 1. Red Fibers (Slow muscle fibers) Appears red due to presence of muscle pigment (Myoglobin). Have smaller diameter & sarcoplasm (about half the diameter of fast fibers). Contain numerous large sarcosomes (mitochondria). Increase myoglobin Rich blood supply therefore higher oxygen supply Red Muscle: According to function, it contracts more slowly so fatigue less quickly Energy source: oxidative phosphorylation 2. White Fibers (Fast muscle fibers) Larger diameter Less myoglobin Pale due to less pigment With smaller & functionally sarcosome (mitochondria) Poor blood supply White muscle: It contracts faster so fatigue more quickly. Energy source: anaerobic glycolysis Most common Contain densely packed myofibrils Large glycogen reserves Very few mitochondria Fatigue rapidly 3. Intermediate Fibers Bulacan State University – Main Bachelor of Science in Medical Technology (Medical Laboratory Science) 4 Rachel Bianca Llanita