Muscular System - Types and Functions PDF

Muscular system: Types and Function Present by: Dr.Nadeeka  Learning objectives At the end of the lecture, the students should be: 1.Identify the main characteristic of skeletal muscle. 2. Explain function of muscle. 3. List the three type of muscle tissue. 4.Differentiate between s...

Muscular system: Types and Function Present by: Dr.Nadeeka  Learning objectives At the end of the lecture, the students should be: 1.Identify the main characteristic of skeletal muscle. 2. Explain function of muscle. 3. List the three type of muscle tissue. 4.Differentiate between smooth, cardiac and skeletal muscle. 5.Explain the term used to name the skeletal muscle. 6.Explain function of the smooth, cardiac and skeletal muscle.  Muscle tissue Bone cannot move on its own all the movement are due to the contraction and relaxation of special cell called muscle. Muscle made up about 40% –50% of total body weight and composed of highly specialized cells. Facial Muscles Muscles of back Abdomen Muscles Muscles of leg Muscles of leg Muscles of the hand Muscles of foot Muscles of foot Function of muscular tissue 1.Produce body movement Include all type of movement which is visible or not. E.g Lifting, peristalsis, heart beating, bladder contraction. 2. Maintain body posture Body posture maintain by contraction continuously.  Function of muscular tissue 3. Storing and moving substance within body Storage is accomplished by sustaining contraction and relaxation of smooth. 4. Produce heat Need power / energy during contraction. Heat production necessary to maintain body. temperature. 80% of body heat produce by muscle contraction.  Type of muscle tissues Muscle cell also known as fiber. There are 3 types muscle tissues: 1.Cardiac muscle. 2.Smooth muscle. 3.Skeletal muscle. Each cell have different structure, location and function.  1. Cardiac muscle Involuntary. Exclusively found only in the heart. Cylindrically in shape and striated. Cell branch and interconnected to form complex network. Point where cell attach to another called intercalated disc. Has only one nucleus per cell.  2. Smooth muscle Involuntary. Non striated. Small cell with one nucleus. Lining wall of hollow organ. Tubular structure, proper substance through tract. Move in wave like contraction.  3. Skeletal muscle Also called as voluntary muscle. Striped / striated muscle. Attached to bone by tendon, to move skeleton. Forms the muscles that move the bone. Fibre are cylindrically shape. Movement can be controlled.  Site of muscle attachment Bones Cartilage Connective tissue cartilage Structure of skeletal muscle  Structure of skeletal muscle Each skeletal muscle fibre is a single cylindrical muscle cell. The cell membrane is called sacrolemma.The cytoplasma is the sarcoplasm. The smooth endoplasmic reticulum (ER) that store calcium ion is the sarcoplasmic reticulum. Cell is surrounded by  Structure of skeletal muscle 1.Endomysium– encloses a single muscle fibre. 2.Perimysium–wrap around a fassicle (bundle) of muscle fibre. 3.Epimysium –cover the entire skeletal muscle.  Structure of skeletal muscle fibre Sarcolemma– specialized plasma membrane. Myofibrils–long organelles muscle cell. Sarcopalsmic reticulum –specialized smooth endoplasmic reticulum. Muscle contraction need energy, from numerous mitochondria. Structure of skeletal muscle fibre Sarcolemma has multiple inward extension called transverse tubules. Sarcolemma packed with myofibril. Protein thread in the myofibril called myofilaments. Transverse tube  Actin filaments=thin filaments Myocine filaments=thick filaments  Nerve and blood supply Skeletal muscle have an abundant nerve and blood supply: 1.muscle fiber must receive an impulse from a nerve cell before it can contract. 2.blood vessel deliver the necessary nutrient and oxygen to produce ATP ( Adenosine triphosphate). #ATP id required for muscle contraction. 3.blood vessel remove waste product (produce as a result of muscle contraction).  Contracture Deformity A contracture deformity is the result of a stiffness or constriction in your muscles, joints, tendons, ligaments, or skin that restricts normal movement. It develops when your normally pliable connective tissues become less flexible. This means your range of motion will be limited. You may have difficulty moving your hand, stretching your legs, straightening your fingers, or extending another part of your body.  Muscular dystrophy Muscular dystrophies, or MD, are a group of inherited conditions, which means they are passed down through families. They may occur in childhood or adulthood. There are many different types of muscular dystrophy. They include: Becker muscular dystrophy Muscular dystrophy is a group of inherited diseases that damage and weaken your muscles over time. This damage and weakness is due to the lack of a protein called dystrophin, which is necessary for normal muscle function. The absence of this protein can cause problems with walking, swallowing, and muscle coordination. Thank You !! Contraction of skeletal muscle Muscle contraction is the result of a complex series of events, base on chemical reaction at muscle fiber (cellular) level. Begins with the stimulation by the nerve cell and ends when the muscle fiber is again relax. Contraction of skeletal muscle Skeletal muscles must be stimulated by a motor neuron (nerve cell) to contract. When the axon of the motor neuron reached the muscle, it will branched. Each fiber will receive the axon terminal.  Stimulus for contraction One motor neuron and all the skeletal muscle cells stimulated by that neuron called motor unit. The fibers in a motor unit stimulated at the same time, so it contract at the same time.  Neuro muscular junction Association site of axon terminal of the motor neuron and muscle is called Neuromuscular junction or Myoneural junction. Fluid-filled space between the terminal and sarcolemma is called synaptic cleft (gap). Numerous synaptic vesicles containing Acety-choline (Ach) – a neurotransmittter found in axon terminal.  Neuro muscular junction Receptor site for Acetyl-choline are located on sarcolemma. 1. When nerve impulse reaches axon terminal, Acetyl-choline is released. 2.Acetyl-choline diffuses across synaptic cleft and bind with receptor site on the sarcolemma.  Neuro muscular junction 3.in respond, the muscle impulse travel in all direction on the sarcolemma to the T- tube. 4.this will initiate physiological activity within muscle cell that result in contraction.  Sarcomere contraction In a relaxed muscle fiber: Myosin receptor sites on thin actin filaments are inactived. Cross-bridge (head) on the myosin are inactived. Calcium are stored in sarcoplasmic reticulum, and has low concentration in sarcoplasm.  Sarcomere contraction When impulses travel from axon to sacrolemma down T tubule, calcium ions are release from sarcoplasmic reticulum. The floods of calcium ion in sarcoplasm causing a change in actin filament and releases of ATP to the myosin binding site (head).  Sarcomere contraction The energized myosin head are now bound to actin to form cross bridge rotate to pull actin toward the center of the myosin to shorten the sarcomere. Because actin is firmly anchored to Z line move closer together and the sarcomere shorten.  Sarcomere contraction The length of myofilament remains the same. The actin just slides over myosin to shorten the sarcomere. This is know as sliding filament theory. The result is that the muscle is shortened (contracted).  Sarcomere contraction When there is no more nerve impulses at neuromuscular joint, muscle impulses stop and calcium ion taken back to sarcoplasmic reticulum. Without calcium, myosin detached from actin – as a result muscle relax. Label the body muscle Label the face muscle Label the head muscle Label the body muscles Label the body muscles Label the abdomen muscles Label the hand muscles Label the hand muscles Label the muscles of leg and foot Label the microscopic muscle structure Label the muscle structure Label the structure of neurotransmitter Label the neuron structure Label the muscle structure Label the microscopic muscle structure