Anatomy and Physiology 2 - The Muscular System PDF

ANATOMY AND PHYSIOLOGY 2 THE MUSCULAR SYSTEM DR MOHAMMED BASSBOUS PALESTINE AHLIYA UNIVERSITY © 2012 Pearson Education, Inc.  Muscular system The...

ANATOMY AND PHYSIOLOGY 2 THE MUSCULAR SYSTEM DR MOHAMMED BASSBOUS PALESTINE AHLIYA UNIVERSITY © 2012 Pearson Education, Inc.  Muscular system The muscular system is a tissue that composed of specialized cells called muscle cells ( myocyte). The main character of this type of muscle is their ability for contraction. Contractibility can result in a part of the body movement by the skeletal muscles ,and can result in another functions like food transmission through the esophagus or the small intestine and others. © 2012 Pearson Education, Inc.  The Muscular System In the body there are three types of muscles : Skeletal muscle : responsible for body movement ,and they are voluntary muscles. Smooth muscle : they founded in the internal organs in general ,like G.I.T, urinary system ,respiratory and others. And they are involuntary muscle. Cardiac muscle :specific type of muscles founded in the heart. © 2012 Pearson Education, Inc.  Skeletal muscles Skeletal muscle is found throughout the body and functions to contract in response to a stimulus. In contrast to smooth and cardiac muscle ,skeletal muscle contraction is under voluntary control, receiving neural signal allowing conscious control of muscles. Skeletal muscle comprises approximately 40% of the human body weight and contains 50 to 75% of all body proteins. © 2012 Pearson Education, Inc.  Skeletal Muscles Functions Functions of the skeletal muscles: 1- Producing movement , by moving the skeleton. 2- Maintaining body posture and position. 3- Maintaining body temperature 4- Storing nutrients 5- Stabilizing joints. © 2012 Pearson Education, Inc.  The smallest unite of the muscle called myofibril, a group of myofibrils are collecting together by a membrane called Endomysium , to form what called ,myofiber. A group of myofibers are collecting together by a membrane called perimysium, to form what called fascicle. A group of fascicles ,are collecting together by a membrane called epimysium to form the muscle. © 2012 Pearson Education, Inc.  Covering of the muscles: Endomysium—encloses the myofibiles to form the myofiber Perimysium—encloses the myofibers to form the fasiclis Epimysium—encloses the fascilis to form the muscle. Fascia—on the outside of the epimysium © 2012 Pearson Education, Inc.  Muscle fiber Blood vessel (cell) Perimysium Epimysium (wraps entire muscle) Fascicle (wrapped by perimysium) Endomysium (between fibers) Tendon Bone © 2012 Pearson Education, Inc. Figure 6.1  Skeletal muscles attachment The skeletal muscle attaches to the bone at two or more places. Each muscle has two points of attachments on the bone: 1-the origin :bone that remains immobile during muscles contraction 2-the insertion : the bone that moves during the contraction. Muscle attached to the bone by a cord like structure of connective tissue called tendon. © 2012 Pearson Education, Inc.  Muscle contracting Origin Brachialis Tendon Insertion © 2012 Pearson Education, Inc. Figure 6.12  Muscle contracture Sarcomere : the basic structure unite of the muscular cell ,that make it able to contract. The sarcomere composed of : 1-myosin filaments (Thick) 2-actin filament (Thin) 3- bands (between the actin and myosin). © 2012 Pearson Education, Inc. © 2012 Pearson Education, Inc.  Mechanism of contarction How muscle contracts: Muscle contraction : means shortening of the muscle. 1- nerve gives the signal to the muscle through the neuromuscular junction , by releasing neuropeptide (acetylcholine). The neuromuscular junction : It is the site of connection between the neuron and the sarcomere. © 2012 Pearson Education, Inc.  2- acetylcholine will bind to receptors in the surface of the sarcomere, this binding will lead to the entry of the sodium ions to the sarcomere. 3- entry of the sodium ions will lead to the exposure of the myosin heads ,which are binding sits on the myosin surface that can bind with actin. 4-Myosin heads binding with actin, and pull the actin to the center of the sarcomere ,causing shortening of the muscle (contraction) © 2012 Pearson Education, Inc. © 2012 Pearson Education, Inc.  Energy for Muscle Contraction Initially, muscles use stored ATP for energy, ATP breaks down to give Energy +ADP. Only 4–6 seconds worth of ATP is stored by muscles. Second way for energy: Muscle cells store creatine phosphate (CP) CP is a high-energy molecule CP supplies are exhausted in less than 15 seconds © 2012 Pearson Education, Inc.  Energy for Muscle Contraction Third way : Aerobic way Glucose is broken down ,releasing energy (about 32 ATP) , This is a slow reaction that requires continuous oxygen. Fourth way : Anaerobic way and lactic acid formation Reaction that breaks down glucose without oxygen This reaction is not as efficient, but is fast Glucose is broken down ,releasing energy (only 2 ATP) © 2012 Pearson Education, Inc.  Types of Body Movements Flexion Decreases the angle of the joint Brings two bones closer together from the joint. Extension Opposite of flexion © 2012 Pearson Education, Inc. © 2012 Pearson Education, Inc. Figure 6.13a  Types of Body Movements Rotation Movement of a bone around its longitudinal axis. Like head rotation from side to side. © 2012 Pearson Education, Inc.  Types of Body Movements Abduction Movement of a limb away from the midline Adduction Opposite of abduction Movement of a limb toward the midline © 2012 Pearson Education, Inc. © 2012 Pearson Education, Inc. Figure 6.13d  Special Movements Dorsiflexion Lifting the foot up Plantar flexion Depressing the foot down. © 2012 Pearson Education, Inc.  Special Movements Supination Forearm rotates so palm faces anteriorly Pronation Forearm rotates so palm faces posteriorly © 2012 Pearson Education, Inc. © 2012 Pearson Education, Inc. © 2012 Pearson Education, Inc. © 2012 Pearson Education, Inc.  VASTUS LATERALIS MUSCLE Deltoid muscle © 2012 Pearson Education, Inc. Figure 6.19  The smooth muscles Smooth muscles are an involuntary non-striated muscle that is present throughout the body. It is founded in the G.I.T, where it helps with mechanical digestion , and food transportation from one part to another. It founds in the urinary system, and help in urine transportation, sphincter control , urinary bladder contraction. It is present throughout arteries and veins, where it plays a role in the regulation of blood pressure. © 2012 Pearson Education, Inc.  Innervation of the smooth muscles According to the way of innervation , Smooth muscles are grouped into two types: 1- single-unit smooth muscle : Most common type, and is found in the walls of most internal organs; like the urinary tract, and the digestive tract, gallbladder ,urethra ,esophagus … 2-multiunit smooth muscle : it is the type of innervation of the tunica media, iris of the eye and others.. © 2012 Pearson Education, Inc.  The single unite smooth muscles In single-unit smooth muscle a single cell in a bundle is innervated by a nerve fiber. The nerve signal is transmitted from one cell to the next cell through what called (gap junctions)between the cells. Due to this property, single-unit bundles contracts in a coordinated fashion like a squeezing , making it possible to push and in the same time transferring the materials, in the proper direction. © 2012 Pearson Education, Inc. © 2012 Pearson Education, Inc. © 2012 Pearson Education, Inc.  multiunit smooth muscle These muscles are innervated individually , means that each muscle cell has its own nerve fiber, and means that all muscles in this type are contracted and relaxed in the same time. This type of muscles found in : 1- The iris 2-The arteries wall (tunica media) © 2012 Pearson Education, Inc. © 2012 Pearson Education, Inc.