Muscular System Unit V PDF

UNIT V The Muscular System Functions of Muscle Tissue https://www.youtube.com/watch?v=rMcg9Yz NSEs 1. Movement Gives rigidity for the muscles so that person can pull, walk, run, lift, chew, manipulate objects picking noses and others. 2. Maintenance of Posture Without much conscio...

UNIT V The Muscular System Functions of Muscle Tissue https://www.youtube.com/watch?v=rMcg9Yz NSEs 1. Movement Gives rigidity for the muscles so that person can pull, walk, run, lift, chew, manipulate objects picking noses and others. 2. Maintenance of Posture Without much conscious control, muscles generate a contractile force that allow us to maintain an erect or seated position. 3. Respiration The muscular system automatically drives movement of air into and out of our body. 4. Heat generation Contraction of muscle tissue generates heat, which is essential for maintenance of temperature homeostasis. 5. Communication Muscle tissue allows us to talk, gesture, write, and convey our emotional state by doing such things as smiling or frowning. 6. Constriction of organs and blood vessels Nutrients move through our digestive tract, urine is passed out of the body, and secretions are propelled out of glands by contraction of smooth muscle. Constriction or relaxation of blood vessels regulates blood pressure and blood distribution throughout the body. 7. Pumping blood Blood moves through the blood vessels because our heart tirelessly receives blood and delivers it to all body tissues and organs. 8. Other functions Muscles help protect fragile internal organs by enclosing them, and are also critical in maintaining the integrity of body cavities. Properties or Characteristics of Muscle Contractility is the ability of muscle cells to forcefully shorten. To flex the elbow, the person need to contract (shorten) muscles. Excitability (responsiveness) is the ability of a muscle fiber to respond rapidly to a stimulating agent. Elasticity is the ability to recoil or bounce back to the muscle's original length after being stretched. Extensibility is the ability of a muscle to be stretched. In order to be able to flex extremity, other muscles must extend in order to allow flexion to occur. Three types of muscle tissues in the body 1. Skeletal Muscles The best-known feature of skeletal muscle is its ability to contract and cause movement. Skeletal muscles act not only to produce movement but also to stop movement, like resisting gravity to maintain posture. Muscles also prevent excess movement of the bones and joints, maintaining skeletal stability and Preventing skeletal structure damage or deformation. Skeletal muscles are located throughout the body at the openings of internal tracts to control the movement of various substances. Each skeletal muscle is an organ that consists of various integrated tissues. Tendon is a fibrous connective tissue which attaches muscle to bone and serves to move the structure. Fascia is connective tissue to provide support, shape, and suspension for most of the soft tissues of the body. Aponeuroses can act as fascia. An aponeurosis is made of layers of delicate, thin sheaths. Epimysium is the fibrous tissue surrounding the skeletal muscle, allows a muscle to contract or move powerfully while maintaining its structural integrity. Perimysium is a sheath of connective tissue that groups muscle fibers into bundles (between 10 & 100 or more) or fascicles which plays in transmitting lateral contractile movements. Endomysium (meaning within the musles) is the key element that separates single muscle fibers from one another. Allows autonomous gliding in contraction and is highly deformable tissue that adapts changes during the muscle contraction. Fascicle arrangements determine what type of movement a muscle can make and they work in tandem. Biceps brachii flexes the forearm and the triceps brachii extends it. Fascicle, a group of muscle fibers “bundled” as a unit within the whole muscle. They are covered by a layer of connective tissue called perimysium.  The hamstrings flex the leg, whereas the quadriceps femoris extend it. https://www.youtube.com/watch? v=58gI3jXNnPI Flexor digitorum superficialis and flexor digitorum profundus flex the fingers and the hand at the wrist, whereas the extensor digitorum extends the fingers and the hand at the wrist. Every muscle fiber is supplied by the axon branch of a somatic motor neuron, which signals the fiber to contract. Skeletal muscle fibers are made when myoblasts (muscle cells) fuse together. This means that each muscle cell has more than one nucleus because it is made of several combined cells. It acts as a barrier between the extracellular and intracellular compartments, defining the individual muscle fiber from its surroundings. These muscle fiber is surrounded by a plasma membrane called the sarcolemma, which contains sarcoplasm, the cytoplasm of muscle cells. Sarcoplasmic Reticulum is a series of closed saclike membranes, that forms a cufflike structure surrounding a myofibril. It serves as the storage of intracellular calcium needed for the initiation of muscle contraction. Myofibrils are made up of thick (myosin) and thin (actin) myofilaments, which help give the muscle its striped appearance. Myofibrils are very long chains of sarcomeres, that are the contractile units of the cell. There are two other muscle proteins: tropomyosin and troponin.  Along with actin and myosin. There are two other muscle proteins: tropomyosin and troponin. Skeletal Muscle Contraction: (c/o Video) © Motor neuron released Stimulu acetylcholine, a s neurotransmitter Protein receptors in the motor end plate detect the presence of a neurotransmitter Muscle impulse spreads to the sarcolemma, T tubules and sarcoplasmic reticulum Sarcoplasmic reticulum releases calcium to the sarcoplasm Calcium in the sarcoplasm interacts with troponin and tropomysin molecules, which move aside, exposing the myosin sites on the actin filaments Myosin cross-bridges bind and pull actin causing sarcomeres to shorten and contract. After the nervous impulse has been received, the acetylcholinase (enzyme) decomposes the acetylcholine Calcium returns to the sarcoplasmic reticulum and the linkages between myosin and actin are broken Relaxation occurs Energy sources for muscle contraction A. AdenosineTriphosphate (ATP) is the critical source for muscle contractions because it breaks the myosin- actin cross-bridge, freeing the myosin for the next contraction. In the process of regeneration of ATP, creatine phosphate transfers a high- energy phosphate to ADP. As ATP decomposes, the energy from creatinine phosphate can be transferred to ADP (adenosine diphosphate molecules converting them back to ATP. B. Creatine phosphate (Phosphocreatine) serves as high- energy reservoir in striated muscle, brain, retina, inner ear, spermatozoa, and, to a lesser degree, smooth muscle, which are tissues that can consume ATP rapidly. C. Creatinine phosphokinase promotes the synthesis of creatinine Oxygen supply and cellular respiration phosphate. Supply of oxygen gas is important to life, for this, the chemical process inside the cells that consume oxygen to produce usable energy is known as cellular respiration https://www.youtube.com/watch? v=WsqP1O7388g. During this process, energy is converted from glucose, in the presence of oxygen, into ATP molecules. ATP is the energy source in cells so if the bodies will not produce ATP cellular respiration would stop working. The cells start to die and eventually the organism itself. Phosphocreatine (creatine phosphate) is stored inside muscle cells and it is readily available to produce ATP quickly. Hemoglobin carries blood to the muscles. Oxygen in blood located in the muscle is termed as myoglobin. During rest or moderate activity, there is enough oxygen to support aerobic respiration. Oxygen deficiency may develop during strenuous exercise, and lactic acid accumulates as an end product of anaerobic respiration. Anaerobic respiration produces an oxygen debt. This is the amount of oxygen needed to oxidize lactic acid to glucose, carbon dioxide and water. The existence of an oxygen debt explains why we continue to breathe deeply and quickly for a while after exercise. Muscle Weakness (muscles loses its ability to contract) Causes Strenuous Decreased activity flow Heart failure Sepsis of blood and Lactic Acid oxygen Accumulation (prolong relaxation)  This burning sensation (soreness) is associated Lactic acid build with a buildup of acid in the muscles during intense exercise, up in the and lactic acid has long been thought to be the culprit in bloodstream as that acid buildup, known as acidosis compared to glucose High lactic acid Intracellula accumulation in r acidosis the blood stream (fatigability ) Why is lactate bad? As the person indulge on strenuous activity, the muscles burn more CHO and produce more lactic acid, which quickly breaks down into a good guy (lactate) and a bad guy (hydrogen ions). The hydrogen ions are bad because they lower the muscle pH, decreasing muscle efficiency, and causing that awful burning sensation. Muscle https://www.youtube.com/watch?v=Fb3kmH yXtM4 Cramps Causes of Muscle Cramps Inadequate ATP in the muscle cells Failure of calcium ions to return back to the sarcoplasmic reticulum so muscle can relax Prolong muscle contraction (muscle cramp) Isotonic VS Isometric Contraction Muscular Responses Threshold stimulus: refers to the minimum intensity required from a stimulus to produce a response from a person. All or None Response. When a muscle contracts, it contracts to its full extent or none at all. 2. Cardiac Muscles Cardiac muscle is striated muscle that is present only in the heart. They are branched, and joined to one another by intercalated discs (gap junctions) for depolarization between cells and desmosomes to hold the fibers together when the heart contracts. Characteristics of a Cardiac Muscles A. Cardiacmuscles B. Cardiac musclesareareintrinsically involuntary controlled (the ability of the heart to control its rate). D. Cardiac muscles are branched. Allows cardiac muscle tissue to contract very quickly in a wave- like pattern to effectively pump blood throughout the body. E. Cardiac muscles are single nucleated.  Marked by transverse dark and light bands These striations are caused by lighter I bands composed mainly of a protein called actin, and darker A bands composed mainly of myosin. 3. Smooth Muscles Smooth muscle is composed of involuntary muscles found within the walls of organs and structures such as the esophagus, stomach, intestines, and blood vessels. These muscles push materials like food or blood through organs. Chemical Composition of a Muscle 1. Flexion, movement that decreases the 2. angle between two Extension, body parts. movement that increases the angle, or the distance, between two bones or parts of the body. 3. Rotation, movement of a bone around a longitudinal axis (ball-and-socket joints). 5. Circumduction is a combination of flexion, extension, abduction, and adduction commonly seen in ball-and-socket joints. 4. Abduction, moving the limb away from the midline, or median plane, of the body. 5. Adduction, it is the movement of a limb toward the body midline.  eversion. To invert the foot, turn the sole medially; to evert the foot, turn the sole laterally. 6. Dorsiflexion and plantar flexion. Lifting the foot so that its superior surface approaches the shin is called dorsiflexion, whereas depressing the foot is called plantar flexion. 9. Supination and pronation. Supination occurs when the forearm rotates laterally so that the palm faces anteriorly and the radius and ulna are parallel; Pronation occurs when the forearm rotates medially so that the palm faces posteriorly. Muscle Interaction Of a group of muscles, the one doing the majority of the work is the prime mover. Quadriceps femoris in the movement of extending knee joint. Biceps and triceps in arm flexion and extension. Helper muscles are called synergists; opposing muscles are called antagonists.  Major Skeletal Muscles Muscles that move the face Skeletal Muscle Actions: Types of Body Movements Origin. Muscle is attached to the immovable or less movable bone. Insertion. Muscle is attached to the movable bone, and when the muscle contracts, the insertion moves toward the origin. Muscles that move the head Muscles of the abdominal wall Muscles that move the wrist, hand, and fingers Muscles that move the forearm Muscles that move the arm Muscles that move the pectoral girdle Muscles that move the leg Muscles that move the thigh Muscles that move the ankle, foot and toes Muscles of the pelvic outlet  The Muscle Song (Optional) https://www.youtube.com/watch?v=hY2fa6Q98 -k