GHH Muscle Tissues

GHH Muscle Tissues

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  General Histology andHistotechnique (1st semester 2012-2013) MUSCLE TISSUES Similarities of Muscle Tissues - Cells of muscles: fibers Myology Muscle contraction Functions of muscle movements: - Depends on two types of myofilaments (contractile proteins) 1. Produce body movements  Actin Ex. Skeletal muscle – Pull bones - Muscle movements; walking, running  Myosin - With the help of joints - Sarcolemma – plasma membrane 2. Stabilize body positions - Sarcoplasm - To sit, stand, balance position 3. Regulate organ volume - Due to smooth muscle Smooth muscle Location: Stomach – for temporary storage Uterine – Store temporarily the urine 4. Move substances within the body Ex. Cardiac muscle - blood will be pumped Smooth muscle – enzymes, food GIT Skeletal muscle – substances within the body; produces Lactic acid. 5. Produce heat - Body movement – Increases temperature Properties Contractility - To generate the pulling force - Ability of muscle to contract forcefully Excitability - Ability to respond to a certain stimuli to produce electrical signals SKELETAL MUSCLE Extensibility - To move the bones of skeleton - Ability to stretch without being destroyed - It does not consists of single muscle fiber - It form multinucleated used muscle fiber Elasticity - Form by diffusion of myoblast - Able to go back to its original shape/length  Embryonic cells of skeletal muscle
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  General Histology andHistotechnique (1st semester 2012-2013) - Striations are present  Dense irregular connective - Nucleus is found at the Peripheral – at the sides tissue - Attached to the bones c. Endomysium I. Connective Tissue components of skeletal muscle - 1 bundle of muscle - Covers the individual muscle fiber 1. Fascia – (Bandage) - Areolar tissue - Fibrous connective tissue that is deep to the skin - Separate muscle fibers from each others - Surrounds muscles and other organs of the body. 2 types: a. Superficial fascia or the subcutaneous layer - separate muscles from skin Made up of: - Areolar connective tissue - Adipose tissue Functions: 1. It provides a pathway for nerves and Blood vessels to enter and exits muscles. 2. Stores most of the triglycerides 3. Serves as good insulating layer; reducing heat loss – due to Connective tissue 4. Protects muscles from physical trauma b. Deep fascia - A dense irregular connective tissue Functions: - Lines the body wall and limbs - Holds muscles together - Allows free movement of muscles - Carries Blood vessels, nerves, Lymphatic vessels - Fills the spaces between muscles 2. Three layers of connective tissue - Extend from the deep fascia to further protect and strengthen skeletal muscle a. Epimysium - Encircles the whole muscle/covers the muscle Basic features of skeletal muscle - Dense irregular connective tissue Nerves and blood vessels b. Perimysium - Each skeletal muscle is supplied by branches of one - Encircles bundles of muscles nerve, one artery, one or more veins  Wrapped by Fascicle - Nerves and vessels branch repeatedly  10-100 or more muscle; - Smallest nerve branches serve Individual muscle fibers
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  General Histology andHistotechnique (1st semester 2012-2013)  Individual muscle fibers Tissue sheaths – extend to from the tendon - attaches muscles to bone.  Neuromuscular junction - A place in the body where nerves meet a muscle. - A synapse the motor neuron and the muscle fiber. Muscle attachments - Most skeletal muscles run from one bone to another b. The sarcolemma of the fiber encloses sarcoplasm - One bone will move – other bone remains fixed and myofibrils which are striated  Origin – less movable part of the bone  Insertion – more movable attachment c. A sac of sarcoplasm is reticulum wraps around each myofibril - Composed of a triad: is a two terminal cisterns and a T (transverse tubule). Histological features Microscopic organization and development a. Embryonic development - Fusion of myoblasts into muscle fibers Myoblast – fused to form the muscle fibers - After fusion, still with satellite cell, immature muscle fiber will lose their potential to divide hence, satellite cell retains it. - It cannot have any cell division Satellite cell – forms the muscle Functions: - Acts as a reserved population of cells - Whenever skeletal muscle is in its normal state it is inactive or quiescent; if it is injured it becomes active. - It continues to divide in order to repair and grow more muscle fibers. - Repair and maintenance of skeletal muscle
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  General Histology andHistotechnique (1st semester 2012-2013) - The cytoplasm of muscle fibers - Contains a substantial amount of glycogen and myoglobin  Oxygen binding protein which is red colored globins and found only in muscle fibers. 3. Myofibrils - Contractile element of muscles - Contains overlapping thick and thin filaments - With prominent striations Alternating line and dark bands 4. Sarcoplasmic Reticulum - Fluid-filled system of membranous sacs that Structure of a skeletal muscle fiber encircles each myofibrils Function: - Releases Calcium ions to trigger muscle contraction 5. Sarcomere - Basic functional unit of myofibril - Compartment of filaments inside the myofibrils 6. Filaments - Within the myofibrils of two types: a. Thin filaments - 8 nm in diameter - Protein: Myosin b. Thick filaments Sarcoplasmic reticulo  Triad - 16 nm in diameter - Protein: Actin 1. Sarcolemma - Muscle fibers plasma membrane which is 7. Mitochondria perforated with thousands of tiny invagination - Small and less numerous skeletal muscle fiber called triad. - For cell respiration Two terminal sisters: - Powerhouse of the cell a. Terminal cisterns - For the synthesis of ATP - Structure madeup of two strands on either strands of T tubule. Zones and bands of sarcomere: b. T tubules - These are tunnels from the surface towards the 1. A-band – anisotropic center of each muscle fiber. - Darker middle portion Function of Triad: - Where thick filaments (myosin) are located To ensure that all parts of the muscle fiber become - Toward the end of the A band is a zone of overlap: excited by an action potential virtually simultaneously. where thick and thin filaments lie side by side 2. Sarcoplasm
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  General Histology andHistotechnique (1st semester 2012-2013) 2. I-band – isotropic - Lighter dense area - Where thin filaments (actin) extend - No thick filaments 3. Z-line - Distinct dark line running down the middle of the I- band - Where thin filaments are attached end to end - Zone of apposition (increase in diameter) of actin filaments belonging to two neighboring sarcomeres 4. M-line - So named because it is at the middle of sarcomere - Where thick filaments are attached end-to-end in the center of the A-band - Band of connections between myosin filaments - Supporting proteins that hold thick filaments together at the center of H-zone. 5. H-band - Appears along the middle of A-band, between the free ends of the thin filaments when muscles are stretched. - Zone of myosin filaments only (no overlap with actin filaments) within the A-band CARDIAC MUSCLE II. Cardiac muscle tissue - Principal muscular tissue in the heart wall - Shorter in length and larger in diameter - Exhibit branching which gives an individual fiber and y-shaped appearance - Nucleus centrally located
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  General Histology andHistotechnique (1st semester 2012-2013) Histological parts: - Found in wrap around sheets that form part of the 1. Sarcolemma walls of smaller arteries and veins and hollow - Plasma membrane surrounding the cardiac muscle viscera such as the stomach, intestines, uterus, and urinary bladder. 2. Sarcoplasm - The cytoplasm 2. Multiunit smooth muscle tissue - Consists of individual fibers, each with its own 3. Mitochondria motor neuron terminals and with few gap junctions - Larger and more numerous between neighboring fibers - Found in the walls of large arteries, in airways to 4. T-tubules the lungs, in arrector pili muscle that attaches to - Wider and less abundant and there is only one T- hair follicles and muscles of iris that adjust pupil tubule per sarcomere located at the Z-disc. diameter 5. Sarcoplasmic reticulum Histological features: - Few, has limited intracellular reserved of Calcium ions. 1. Endomysium - Surrounds the smooth muscle fiber 6. Myofibril - Contractile unit 2. Have a single centrally located oval nucleus 7. Sarcomeres 3. Sarcoplasm - Functional unit, same zones, bands and lines as the - Contains both thick and thin filaments skeletal muscle. 4. There is no sarcomere SMOOTH MUSCLE 5. Contains intermediate filaments 6. Have a sarcoplasmic reticulum which is scanty 7. Do not have T-tubules 8. Gap junction in visceral smooth muscles is present but not in multiunit smooth muscle. III. Smooth muscle tissue Two types: 1. Visceral smooth muscle tissue - Also known as the single unit smooth muscle tissue