Muscular System Anatomy and Physiology PDF

BACHELOR OF SCIENCE IN NURSING ANPH 111 (Anatomy and Physiology) COURSE MODULE COURSE UNIT WEEK 1 5 7 The Muscular System...

BACHELOR OF SCIENCE IN NURSING ANPH 111 (Anatomy and Physiology) COURSE MODULE COURSE UNIT WEEK 1 5 7 The Muscular System ü Read course and unit objectives ü Read study guide prior to class attendance ü Read required learning resources; refer to unit terminologies for jargons ü Proactively participate in classroom discussions ü Participate in weekly discussion board (Canvas) ü Answer and submit course unit tasks. VanPutte, Cinnamon. Regan, Jennifer. Russo, Andrew (2016). Seeley’s Essentials of Anatomy & Physiology Penn Plaza, New York, New York, McGraw-Hill Education, 10th Edition Computer device or smartphone with internet access (at least 54 kbps; average data subscription will suffice) At the end of the course unit (CM), learners will be able to: Cognitive Elaborate the functions of the Muscular System Differentiate the three types of muscles Explain the microscopic structure of a muscle Relate with how muscles have excitability, extensibility, elasticity. Delineate how muscles are named Identify different muscles in different sections of the body Affective Listen attentively during class discussions Demonstrate tact and respect of other students’ opinions and ideas Accept comments and reactions of classmates openly Psychomotor Participate actively during class discussions Follow class rules and observe compliance to Netiquette Use critical thinking to identify areas of care that could benefit from additional research or application of evidence-based practices Integrate knowledge of trends in Anatomy and Physiology Acetylcholine - Chemical messenger released from the end of a motor neuron Actin - Protein of which the thin myofilaments are composed Aerobic respiration - Process that breaks down fatty acids for energy when oxygen is present Anaerobic respiration - Process that breaks down glucose for energy when oxygen is not plentiful Antagonist - Muscles that oppose the action of a prime mover Aponeurosis - Flat, broad tendon that attaches a muscle to another muscle or to bone ATP - Adenosine triphosphate; used for energy in cells to perform various functions, including muscle contraction Atrophy - Decrease in the size of a muscle Belly - The thick midsection of the muscle Complete tetanus - Condition in which impulses arrive so fast the muscle cannot relax between stimuli and twitches merge into one prolonged contraction Creatine phosphate - Compound stored in muscle that is used for short bursts of high- energy activity Endomysium - Delicate connective tissue covering each muscle fiber Epimysium - Connective tissue covering that surrounds muscles as a whole and binds all muscle fibers together Fascia - Connective tissue surrounding the muscle Fascicles - Bundles of muscle fibers Hypertrophy - Enlargement of a muscle Incomplete tetanus - Condition of rapid muscle contraction with only partial relaxation Insertion - The end of a muscle that attaches to the more mobile bone Isometric contraction - Contraction in which the tension within a muscle increases while its length remains the same Isotonic contraction - Contraction in which the muscle changes length to move a load Motor unit - A neuron and all the muscle fibers it stimulates Muscle fiber - A skeletal muscle cell Muscle tone - Continuous state of partial muscle contraction that allows for the maintenance of posture Myofibrils - Long protein bundles that fill the sarcoplasm of a muscle fiber Myofilaments - Fine protein fibers that make up a myofibril Myosin - Protein of which the thick myofilaments are composed Neuromuscular junction - Connection between a motor neuron and a muscle fiber Origin - The end of a muscle that attaches to the more stationary bone Perimysium - Sheath of connective tissue encasing fascicles Prime mover - The main muscle triggering a movement Sarcomere - The unit of contraction of the myofibrils of a muscle Sarcoplasm - The cytoplasm of a muscle fiber Synaptic cleft - Narrow space between the end of a motor nerve and the muscle fiber Synergists - Muscles that assist in the movement of a bone Tendon - Strong, fibrous cord through which a muscle attaches to a bone Transverse (T) tubules - Tubules that extend across the sarcoplasm and allow electrical impulses to travel deep into the cell Treppe - Phenomenon in which each successive twitch contracts more forcefully than the previous one Twitch - Single, brief contraction 5.1 MUSCLES, MUSCLE TISSUES, MUSCULAR SYSTEM According to VanPutte, Regan, & Russo (2016), muscle tissues are unique enough to be modified by the ones who owns it. One can change its size and type of muscle fibers thereby enabling enhancement of strength and endurance like what we’ve been observing to athletes. Moreover, muscle cells are elongated thus the term muscle fiber for every muscle cell. 5.1.1 Functions 1. Movement of the body – everything that our mind conceives were being translated into actions through skeletal muscle contractions. 2. Maintenance of posture – with proper tone, muscles helps us to maintain posture through a steady or constant state of partial contraction. 3. Respiration – the main muscle for bathing is the diaphragm. With its contraction, it allows air to enter the lungs. Moreover, other muscles of the thorax carry out the movements necessary for respiration. 4. Production of body heat - When skeletal muscles contract, heat is given off as a by- product. This released heat is critical to the maintenance of body temperature. 5. Communication - Skeletal muscles are involved in all aspects of communication, including speaking, writing, typing, gesturing, and facial expressions. 6. Constriction of organs and vessels - The contraction of smooth muscle within the walls of internal organs and vessels causes those structures to constrict. This constriction can help propel and mix food and water in the digestive tract, propel secretions from organs, and regulate blood flow through vessels. 7. Contraction of the heart - The contraction of cardiac muscle causes the heart to beat, propelling blood to all parts of the body. 5.1.2 Types and Characteristics Muscular tissue is composed of elongated muscle cells called muscle fibers. The job of muscular tissue is to generate force, which produces motion, maintains posture, and generates heat. There are three types of muscular tissue and these are Skeletal Muscles, Cardiac Muscles and Smooth muscles.  Table 1. Types of Muscle Tissues a. Skeletal Muscle *Photo and content taken from Seeley’s Anatomy and Physiology by VanPutte, Regan & Russo (2016) Skeletal muscles are group of multi-nucleated cells with striations due to the arrangement of contractile proteins within the cells. This further helps in the generation of force during voluntary commands. As described, skeletal muscles can be found attached to the skeleton. However, the nervous system can cause skeletal muscles to contract without conscious involvement, as occurs during reflex movements and the maintenance of muscle tone b. Smooth Muscle *Photo and content taken from Seeley’s Anatomy and Physiology by VanPutte, Regan & Russo (2016) Smooth muscle contains groups of small cells with one nucleus that are capable of stretching and are part of blood vessels, the stomach, intestines, uterus, and bladder. Unlike skeletal muscles, smooth muscle tissue has no striations and contracts involuntarily. They contain less actin and myosin, with non-organized myofilaments thus the non-striated appearance  c. Cardiac Muscle Cardiac muscle has cylindrical, intermediate-sized cells that make up this tissue are connected to one another by cell junctions called intercalated discs. These intercalated discs contain specialized gap junctions helps in coordinating contractions. Cardiac muscle has striations and contracts involuntarily. 5.2 SKELETAL MUSCLE Skeletal muscles, the longest type of muscle, make up to 40% of body weight. It is named because of its attachment to bones. They also have more than one nucleus and are striated in nature. 5.2.1 Functional Characteristics Skeletal muscle has four major functional characteristics and these are contractility, excitability, extensibility, elasticity. 1. Contractility – ability of a muscle to shorten with force 2. Excitability – capacity of muscles to respond to stimulus 3. Extensibility – Muscle can be stretched to its normal resting length and beyond to a limited degree 4. Elasticity – Ability of muscle to recoil to original resting length after stretched 5.2.2 Structure 5.2.2.1 Connective Tissue Coverings Epimysium – connective tissue that surrounds the entire skeletal muscle Perimysium - connective tissue around each muscle fasciculus (bundle of muscle fibers) Endomysium - connective tissue that surrounds each muscle fiber 5.2.2.2 Muscle Fiber Structure Myofibril - thread-like proteins that make up muscle fibers Myofilament - proteins that make up myofibrils (ex. actin and myosin) Sarcoplasm - cytoplasm of muscle fiber (cell) Sarcolemma - cell membrane and contains T-tubules T-tubules (transverse) - wrap around sarcomeres at A band - associated with sarcoplasmic reticulum Sarcoplasmic reticulum - type of SER. It surrounds myosin and also stores and releases Ca2+ 5.2.2.3 Actin and Myosin Myofilaments Actin - thin myofilament and resemble 2 strands of pearls Myosin - thick myofilament and resemble golf clubs Troponin - attachment site on actin for Ca2+ Tropomyosin - filament on grooves of actin and serves as an attachment site on actin for myosin 5.2.2.4 Sarcomeres Sarcomere - contractile unit. It contains actin and myosin Z disk - protein fibers that form attachment site for actin H zone - center of sarcomere. It contains only myosin I band - contains only actin A band - where actin and myosin overlap M line - where myosin is anchored ***The following illustrations will showcase the aforementioned terminologies for correlation.  Figure 5.1 Structure of a Muscle *Photo and content taken from Seeley’s Anatomy and Physiology by VanPutte, Regan & Russo (2016) (a) Part of a muscle attached by a tendon to a bone. A muscle is composed of muscle fasciculi, each surrounded by perimysium. The fasciculi are composed of bundles of individual muscle fibers (muscle cells), each surrounded by endomysium. The entire muscle is surrounded by a connective tissue sheath called epimysium, or muscular fascia. (b) enlargement of one muscle fiber containing several myofibrils. (c) a myofibril extended out the end of the muscle fiber, showing the banding patterns of the sarcomeres. (d) a single sarcomere of a myofibril is composed mainly of actin myofilaments and myosin myofilaments. the Z disks anchor the actin myofilaments, and the myosin myofilaments are held in place by the M line. (e) Part of an actin myofilament is enlarged. (f) Part of a myosin myofilament is enlarged.  Figure 5.2 Skeletal Muscle *Photo and content taken from Seeley’s Anatomy and Physiology by VanPutte, Regan & Russo (2016) (a) Organization of skeletal muscle components (b) Electron micrograph of skeletal muscle, showing several sarcomeres in a muscle fiber. (c) Diagram of two adjacent sarcomeres, depicting the structure responsible for the banding patterns 5.2.3 Excitability Figure 5.4 Ion Channels and Action Potential *Photo and content taken from Seeley’s Anatomy and Physiology by VanPutte, Regan & Russo (2016) Step 1 illustrates the status of sodium (Na+ ) and Potassium (K+ ) channels in a resting cell. Steps 2 and 3 show how the channels open and close to produce an action potential. Next to each step, the charge difference across the plasma membrane is illustrated. 5.2.4 Stimulation 5.2.4.1 Nerve Supply Motor neuron - nerve cells that carry action potentials to muscle fibers Neuromuscular junction (synapse) - nerve cell and muscle fiber meet Presynaptic terminal - end of nerve cell (axon) Postsynaptic membrane - muscle fiber membrane Synaptic cleft - space between presynaptic terminal and postsynaptic membrane Synaptic vesicle - store and release neurotransmitters Neurotransmitter - chemicals that stimulate or inhibit muscle fiber (e.g. Ach) Motor unit - group of muscle fibers that motor neuron stimulates Figure 5.5 Neuromuscular Junction *Photo and content taken from Seeley’s Anatomy and Physiology by VanPutte, Regan & Russo (2016) (a) In a neuromuscular junction, several branches of an axon junction with a single muscle fiber (b) Photomicrograph of neuromuscular junctions.  Figure 5.6 Function of the Neuromuscular Junction *Photo and content taken from Seeley’s Anatomy and Physiology by VanPutte, Regan & Russo (2016) 5.2.5 Contraction Contraction of skeletal muscle tissue occurs as actin and myosin myofilaments slide past one another, causing the sarcomeres to shorten. Many sarcomeres are joined end-to-end to form myofibrils. Shortening of the sarcomeres causes myofibrils to shorten, thereby causing the entire muscle to shorten. The sliding of actin myofilaments past myosin myofilaments during contraction is called the sliding filament model of muscle contraction. During contraction, neither the actin nor the myosin fibers shorten. The H zones and I bands shorten during contraction, but the A bands do not change in length. Figure 5.7 Summary of Skeletal Muscle Contraction *Photo and content taken from Seeley’s Anatomy and Physiology by VanPutte, Regan & Russo (2016)  5.2.5.1 Sliding Filament Theory Table 2. Steps in a Muscle Contraction (Sliding Filament Theory) 1. An action potential travels 2. Ca2+ causes synaptic down motor vesicles to release neuron to acetylcholine into presynaptic synaptic cleft. terminal causing Ca2+ channels to open. 3. Acetylcholine 4. Na+ causes binds to receptor sarcolemma and t- sites on Na+ tubules to increase channels, Na+ the permeability of channels open, sarcoplasmic and Na+ rushes reticulum which into postsynaptic releases stored terminal calcium. (depolarization). 5. Ca2+ binds to troponin which is 6. Ca2+ binding to troponin causes tropomyosin to attached to actin. move exposing attachment sites for myosin. 8. ATP is released from myosin heads and heads 7. Myosin heads bind to actin. bend toward center of sarcomere. 10. Acetylcholinesterase (enzyme breaks down acetylcholine) is released, Na+ channels close, and muscle contraction 9. Bending forces actin to slide over myosin. stops 5.2.5.2 ATP and Muscle Contraction Energy for muscle contractions supplied by ATP Energy is released as ATP → ADP + P ATP is stored in myosin heads ATP help form cross-bridge formation between myosin and actin New ATP must bind to myosin before cross-bridge is released Rigor mortis: person dies and no ATP is available to release cross-bridges Other Information: o ATP is made in mitochondria from aerobic or anaerobic respiration. o During a muscle contraction, H zone and I band shorten but A band stays the same. o Striations of skeletal and cardiac muscle are due to sarcomeres (actin and myosin). Terms o Threshold - weakest stimulus needed to produce a response o All or None Law - muscle contracts or doesn’t (no in between) o Twitch - rapid contraction and relaxation of a muscle o Tetanus - muscle remains contracted o Isometric - amount of tension increases (weight) o Isotonic - amount of repetitions increases o Tone - constant tension over a long period of time 5.2.5.2.1 Slow and fast Twitch Fibers Slow Twitch Fibers Contract slowly Fatigue slowly Long distance runners Use aerobic respiration Energy from fat Dark meat Red or dark because of myoglobin Myoglobin: helps O2 bind in muscle Fast Twitch Fibers Contract quickly Fatigue quickly Sprinters Use anaerobic respiration Energy from glycogen White meat Other Facts about Twitch Fibers Humans have both types of fibers Distribution of fibers is genetically determined Neither type can be converted but capacity can be increased through intense exercise Figure 5.8 Breakdown of ATP and Cross-Bridge Movement During Muscle Contraction *Photo and content taken from Seeley’s Anatomy and Physiology by VanPutte, Regan & Russo (2016) 5.1 MUSCLE SYSTEM AND NOMENCLATURE 5.1.1 General Principles Origin – non-movable end Insertion - movable end Belly - middle Synergists - muscles that work together Antagonist - muscles that oppose each other 5.1.2 Nomenclature Muscles are named according to Location Ex. tibialis anterior Origin/insertion Ex. sternocleidomastoid Size Ex. gluteus maximus Shape Ex. deltoid (triangular) Function Ex. Masseter 5.1.3 Muscles of Head and Neck 5.1.3.1 Facial Expression and Mastication Occipitofrontalis - raises eyebrows (forehead) Orbicularis oculi - allows blinking (eyes) Orbicularis oris - kissing muscle (mouth) Zygomaticus - smiling muscle (cheek) Masseter - chewing (mastication) muscle Figure 5.9 Muscles of Facial Expression and Mastication *Photo and content taken from Seeley’s Anatomy and Physiology by VanPutte, Regan & Russo (2016)  5.1.3.2 Tongue and Swallowing Muscle Figure 5.10 Tongue and Swallowing Muscles *Photo and content taken from Seeley’s Anatomy and Physiology by VanPutte, Regan & Russo (2016) Table 3. Tongue and Swallowing Muscles Muscles Origin Insertion Action Tongue muscles Intrinsic Inside tongue Inside tongue Changes shape of tongue Extrinsic Bones around oral cavity or Onto tongue Moves tongue soft palate Hyoid muscles Suprahyoid Base of skull, mandible Hyoid bone Elevates or stabilizes hyoid (e.g. geniohyoid, stylohyoid, and hyoglossus) Infrahyoid (e.g.thyrohyoid) Sternum. Larynx Hyoid bone Depresses or stabilizes hyoid Pharyngeal muscles Elevators Soft palate and auditory tube Pharynx Elevate pharynx Constrictors Larynx and hyoid Pharynx Constrict Pharynx Superior Middle Inferior  5.1.4 Trunk Muscles 5.1.4.1 Thoracic Muscles External intercostals: elevate ribs for inspiration Internal intercostals: depress ribs during forced expiration Diaphragm: moves during quiet breathing Figure 5.11 Muscles of the Thorax (a) Anterior view shows a few selected intercostal muscles and the diaphragm. (b) Lateral view shows the external and internal intercostals *Photo and content taken from Seeley’s Anatomy and Physiology by VanPutte, Regan & Russo (2016)  5.1.4.2 Abdominal Wall Muscles Rectus abdominis: center of abdomen; compresses abdomen External abdominal oblique: sides of abdomen; compresses abdomen Internal abdominal oblique: compresses abdomen Transverse abdominis: compresses abdomen Figure 5.12 Muscles of the Anterior Abdominal Wall (a) In this anterior view, windows reveal the various muscle layers. (b) A cross-sectional view of the muscle layers *Photo and content taken from Seeley’s Anatomy and Physiology by VanPutte, Regan & Russo (2016) 5.1.5 Upper Limb Muscles Trapezius: shoulders and upper back; extends neck and head Pectoralis major: chest; elevates ribs Serratus anterior: between ribs; elevates ribs Deltoid: shoulder; abductor or upper limbs Triceps brachii: 3 heads; extends elbow Biceps brachii: “flexing muscle”; flexes elbow and shoulder Brachialis: flexes elbow Latissimus dorsi: lower back; extends shoulder  Figure 5.13 Arm Muscles *Photo and content taken from Seeley’s Anatomy and Physiology by VanPutte, Regan & Russo (2016) 5.1.6 Lower Limb Muscle 5.1.6.1 Hips and Thighs Iliopsoas: flexes hip Gluteus maximus: buttocks; extends hip and abducts thigh Gluteus medius: hip; abducts and rotates thigh 5.1.6.2 Muscles of Upper Leg Quadriceps femoris 4 thigh muscles Rectus femoris: front of thigh; extends knee and flexes hip Vastus lateralis: extends knee Vastus medialis: extends knee Vastus intermedius: extends knee Gracilis: adducts thigh and flexes knee Biceps femoris, semimembranosus, semitendinosus: hamstring, back of thigh; flexes knee, rotates leg, extends hip  Figure 5.14 Muscles of the Hip and Thigh *Photo and content taken from Seeley’s Anatomy and Physiology by VanPutte, Regan & Russo (2016) 5.1.6.3 Muscles of Lower Leg Tibialis anterior: front of lower leg; inverts foot Gastrocnemius: calf; flexes foot and leg Soleus: attaches to ankle; flexes foot  Figure 5.15 Superficial Muscles of the Leg *Photo and content taken from Seeley’s Anatomy and Physiology by VanPutte, Regan & Russo (2016)  Figure 5.16 Overview of the Superficial Body Musculature Red is muscle, white is connective tissue, such as tendons, aponeurosis and retinacula *Photo and content taken from Seeley’s Anatomy and Physiology by VanPutte, Regan & Russo (2016) Rizzo, D. C. (2016). Fundamentals of Anatomy and Physiology (Fourth ed.). Boston, Massachussetts: Cengage Learning. Thompson, G. S. (2015). Understanding Anatomy & Physiology: A Visual, Auditory, Interactive Approach,2nd Edition. Philadelphia: F. A. Davis Company. Tortora, G. J., & Freudenrich, C. C. (2011). Visualizing Anatomy & Physiology. John Wiley & Sons, Inc.. VanPutte, C., Regan, J., & Russo, A. (2016). Seeley's Essentials of Anatomy & Physiology. New York, New York: McGraw-Hill Education. To set the tone right, we will help each other in the appreciation of the initial phase of Anatomy and Physiology by accomplishing the Course Task/s in Canvas