Week 7 - Muscular System PDF

Muscula r System  TRIVA FOR MUSCLES How many muscles are there in the human body?  TRIVA FOR MUSCLES What is the longest muscle in the body?  TRIVA FOR MUSCLES What is the smallest muscle in the body? Answer: The Stapedius  TRIVA FOR MUSCLES What is the biggest muscle in the...

Muscula r System  TRIVA FOR MUSCLES How many muscles are there in the human body?  TRIVA FOR MUSCLES What is the longest muscle in the body?  TRIVA FOR MUSCLES What is the smallest muscle in the body? Answer: The Stapedius  TRIVA FOR MUSCLES What is the biggest muscle in the body? Answer: The Gluteus Maximus  TRIVA FOR MUSCLES What is Ms Mhin’s Favorite muscle in the body? Answer: The Rectus Abdominis  There are about 60 muscles in the face. Smiling is easier than frowning. It takes 20 muscles to smile and over 40 to frown. Smile and make someone happy. Types of Muscle Tissue  Type of Skeletal Smooth Cardiac muscle Muscle Muscle Muscle Location Attached Wall of Heart to a hollow skeleton organs Shape Spindle- Branching Filamentou shaped filament s Control Voluntary Involuntary Involuntary Striations Yes None Yes Location Periphery Center of Center of and # of of the cell, the wall, the cell, nucleus 1 or 2 multinucleate nuclei mononucleate d d Function Movement Movement Beating of of bone of internal heart Functions of skeletal muscle tissue  Characteristics of Muscle Tissue Excitability – capacity of muscle to respond to stimulus. Contractility – ability of a muscle to shorten and generate a pulling force (not exhibited by neurons). Extensibility – muscle can be stretched to their normal resting length and beyond to a limited degree. Elasticity – ability of a muscle to recoil to original resting length after being stretched  Naming Skeletal Muscles Location of the muscle Shape of the muscle Relative Size of the muscle Direction/Orientation of the muscle fibers/cells Number of Origins Location of the Attachments Action of the muscle Classification of Muscles According to Action Muscle Action Flexor Bends a part near the joint Extensor Straightens a part near the joint Abductor Moves a part away from the midline of the body Adductor Moves a part towards the midline of the body Dilator Opens spaces or widens openings Constrictor Closes or compresses openings Levator Raises a body part Depressor Lowers a part Muscle Named by Location Bases Muscle Description Location means Tibialis anterior Muscle in front of the the nearest part tibia where the Frontalis Muscle on top of the muscles is frontal bone found Temporalis Muscle on top of the temporal bone Epicranius Around the cranium  Naming Skeletal Muscle Bases Muscle Descriptio Trapezius n Shape Deltoid triangle pertains to Deltoid the relative Serratus saw- shape of toothed the muscle. Rhomboide rhomboid, 4 us parallel sides Trapezius trapezoid, 2 parallel sides Rhomboideus Orbicularis circular major and Movement of Muscles Origin: the attachment origin of the muscle to the bone that remains stationary Insertion: the belly attachment of the muscle to the bone that moves Belly: the fleshy part of insertion the muscle between the tendons of origin and/or insertion Movement of Skeletal Muscle These muscles move when the brain sends messages to the muscle Always work in pairs 2 movements of skeletal muscle:  Contraction (shorten)  Extension (lengthen)  Major Skeletal Muscles: The Head Sternocleidomastoid Splenius capitis Pulls the head to one Rotates the head side Allows it to bend to Pulls the head to the the side chest Orbicularis oris Frontalis Allows the lips to Raises the eyebrows pucker Major Skeletal Muscles: The Head Orbicularis oculi Platysma Allows the eyes to Pulls the corners of close the mouth down Zygomaticus Masseter and Pulls the corners temporalis of the mouth up Close the jaw Major Skeletal Muscles: Upper Arm Pectoralis major Pulls the arm across the chest Rotates and adducts the arms Latissimus dorsi Extends and adducts the arm and rotates the arm inwardly  Major Skeletal Muscles: Forearm Biceps brachii Flexes the arm at the elbow Rotates the hand laterally Brachialis Flexes the arm at the elbow Brachioradialis Flexes the forearm at the elbow Major Skeletal Muscles: Forearm Triceps brachii Extends the arm at the elbow Supinator Rotates the forearm laterally (supination) Pronator teres Rotates the forearm medially (pronation) Major Skeletal Muscles: Wrist, Hand, and Fingers Flexor carpi radialis Extensor carpi and flexor carpi radialis longus and ulnaris brevis Flex and abduct the Extend the wrist and wrist abduct the hand Palmaris longus Flexes the wrist Extensor carpi ulnaris Flexor digitorum profundus Extends the wrist Flexes the distal Extensor digitorum joints of the fingers, Extends the fingers, but but not the thumb not the thumb  Major Skeletal Muscles: Respiratory Diaphragm Separates the thoracic cavity from the abdominal cavity Its contraction causes inspiration External and internal intercostals Expand and lower the ribs during breathing Major Skeletal Muscles: Abdominal External and internal obliques Compress the abdominal wall Transverse abdominis Also compresses the abdominal wall Rectus abdominis Flexes the vertebral column Compresses the abdominal wall  Major Skeletal Muscles: Pectoral Girdle Trapezius Raises the arms Pulls the shoulders downward Pectoralis minor Pulls the scapula downward  Major Skeletal Muscles: Leg Psoas major and iliacus Flexes the thigh Gluteus maximus Extends the thigh Gluteus medius and minimus Abduct the thighs Rotate them medially Major Skeletal Muscles: Leg Adductor longus and magnus Adduct the thighs Rotate them laterally Biceps femoris, semitendinosus, and semimembranosus Known as the hamstring group Flex the leg at the knee  Major Skeletal Muscles: Leg Rectus femoris, vastus lateralis, vastus medialis, and vastus intermedius Extend the leg at the knee Sartorius Flexes the leg at the knee and thigh Abducts the thigh, rotating the thigh laterally but rotating the lower leg medially  Major Skeletal Muscles: Ankle, Foot, and Toes Tibialis anterior Soleus Inverts the foot and Flexes the foot point the foot up (dorsiflexion) Flexor digitorum Extensor digitorum longus longus Flexes the foot Extends the toes and and toes point the foot up Gastrocnemius Flexes the foot and flexes the leg at the knee Muscle Named Muscle Named by Size by Direction of Fibers maximus Rectus (straight) (largest) –parallel to long minimis axis (smallest) longus (longest) Transverse brevis (short) major (large) Oblique  Muscle Named For : Number of Origin and Action Origins Insertion Biceps (2) Sternocleidoma Flexor carpi Triceps (3) stoid -originates radialis Quadriceps (4) from sternum and (extensor clavicle and carpi radialis) – flexes wrist inserts on Abductor mastoid process pollicis brevis Biceps of temporal bone (adductor brachii pollicis) – flexes thumb Abductor magnus – abducts thigh Extensor digitorum Arrangement of Fascicles Definition Example Parallel Strap-like Sartorius Fusiform Spindle shaped Biceps femoris Pennate Feather shaped Unipennate Extensor digitorum longus Bipennate Rectus femoris Multipennate Deltoid Convergent Pectoralis major Circular Sphincters Orbicularis oris Organization level of muscles A skeletal muscle is made up of muscle fibers, nerves, blood vessels, and connective tissues one nerve, one artery, and one or more veins serve each muscle Unlike cells of cardiac and smooth muscle tissues, which can contract without nerve stimulation Attachments of muscles Tendons: narrow bands of connective tissue that connect muscles to bone Ligaments : bands of connective tissue that join bone to bone Aponeuroses: bands of connective tissue that attach flat muscle to another muscle or to several bones  Structure of Skeletal Muscle Composed of striated muscle cells and connective tissue. Tendons anchor muscle firmly to bones. Tendons are made of dense fibrous connective tissue. Ligaments connect bone to bone at a joint. Bursae – small fluid filled sacs that lie between some tendons and the bones beneath them. They are made of connective tissue and are lined with synovial membrane that secretes synovial fluid. Connective Tissue Sheaths Fascia – on the outside of the epimysium covers and separates muscle cells Epimysium – covers the entire skeletal muscle Perimysium – wraps around a fascicle (bundle) of muscle fibers Endomysium – enclose a single muscle fibres(cell) The origins and insertions of muscles determine their actions Origin =where fixed end of a skeletal muscle attaches Most are bones Some are connective tissue sheaths or bands Typically proximal to insertion in anatomical position Insertion= where the movable end of a skeletal muscle attaches Action= specific movement produced by a skeletal muscle  Origin, insertion, and action Agonist or prime mover= muscle whose contraction is mostly responsible for producing the movement Example: biceps brachii—elbow flexion Synergist= muscle that helps larger agonist work efficiently May provide additional pull or stabilize origin Example: brachioradialisfor elbow flexion  Origin, insertion, and action Fixators= synergiststhat assist by preventing movement at another joint Antagonist= muscle whose action opposes a particular agonist Example:triceps brachiifor elbow flexion Antagonist to biceps brachii Agonist for elbow extension Microscopic Anatomy of Muscles  Structure of Skeletal Muscle The membrane that surrounds the muscle cell is called the sarcolemma.  Sarcomere Sarcomeres: Myofibrils are composed of repeating units The smallest functional unit of the muscle fiber Interaction between the thick and thin filaments of sarcomeres are responsible for muscle contraction Parts of Sarcomere A band – area where myosin (thick) filaments are may include regions with overlapping actin filaments I band – area between thick filaments where only thin filaments are present Parts of Sarcomere Striations, a repeating series of dark and light bands, are evident along the length of each myofibril Z disc – protein that actin (thin) filaments are connect to M line – protein that myosin (thick filaments are connected to H zone – area surrounding M line where myosin (think filaments are but actin filament dont reach  Myofilaments. : Within each sarcomere, there are two types of myofilaments: thick filaments (composed of the protein myosin) and thin filaments (composed of the protein actin). Sarcoplasmic Reticulum: Sarcoplasmic Reticulum: A network of endoplasmic reticulum that stores calcium ions, essential for muscle contraction. Molecular Composition of Myofilament s Actin Protein of thin filament Binding sites for myosin  Molecular Composition of Myofilament s Myosin Head Myosin molecule consists of 2 myosin heads that are facing outwards Binds to active sites on the actin molecules to form cross bridges Retain all the motor functions of myosin Has 2 binding sites; one for actin and one for ATP Molecular Composition of Myofilament s Tropomyosin Protein of thin filament Tropomyosin is a protein involved in skeletal muscle contraction and that wraps around actin and prevents myosin from grabbing it.  Molecular Composition of Myofilament s Troponin Troponins are proteins needed for the contraction of cardiac muscles and skeletal muscles Has 3 regions/subunits Troponin I: binds to actin; facilitates inhibition of myosin binding to actin by tropomyosin Troponin T: binds tropomyosin Troponin C: has 4 binding sites for calcium ions. (1 troponin : 7 G-actin monomers) Neuromuscular Junction https://www.youtube.com/ watch?v=NfEJUPnqxk0 https://www.youtube.com/ watch?v=BVcgO4p88AA  Muscle contraction Excitation-contraction coupling– the process by which depolarization of muscle fiber initiates contraction: 1. Action potential travels to neuromuscular junction, reaches muscle fiber. 2. Action potential travels along sarcolemma (muscle fiber membrane), causing release of Ca+2 from sarcoplasmic reticulum. 3. Ca+2 initiates interaction of myosin and actin, causing muscle contraction. 4. Ca+2 is pumped back into the sarcoplasmic reticulum, causing muscle relaxation III. Muscle Contraction Step 1: Neuromuscular junction Action potential reaches end of motor neuron inc. Ca+2 influx release of Ach Ach binds with Ach receptor of muscle membrane  Na+ influx local potential opens voltage gated Na+ channels action potential Ach degraded by acetylcholinesterase  RYR (Ca+2 Muscle release channel) Contraction Release DHP of Ca+2 Step 2: Sarcolemma R and SR into Action potential travels myofibr T- il through T-tubules activates tubule dihydropyridine DHP receptors (DHPR)  R activates ryanodine receptors (RYR) in terminal cisternae  RYR (Ca+2 release of Ca+2 into release myofibril channel) *DHPR also known as Terminal the L-type Ca+2 cisterna channel Silverthorn. and of Boron Human SR An integrated Boulpaep, Physiology MedicalApproach 6 th ed. Pearson  RYR (Ca+2 Muscle release channel) Contraction Release DHP of Ca+2 How do DHPR and RYR interact? R into In heart muscle, DHPR myofibr opens, causes Ca+2 influx, T- il then Ca+2 influx causes RYR tubule to open In skeletal muscle, DHPR is DHP mechanically attached to R RYR. So if DHPR changes shape, RYR opens. Clinical application: RYR (Ca+2 Calcium channel blocker release drugs (e.g. amlodipine, channel) nifedipine) work on heart muscles, not on skeletal Terminal muscle. cisterna Boron and of SR Boulpaep, Medical  Muscle Contraction Terminal cisternae? Several Ca+2 binding proteins Calsequestrin Histidine-rich calcium- binding protein (HRC) Sarcalumenin Triadin, junction= Anchors calsequestrin near RYR SERCA (Sarcoplasmic or ER calcium ATPase)= pumps Ca+2 into SR Sliding Filament theory Power stroke Sliding Filament theory III. Muscle Contraction Step 4: Muscle relaxation SERCA: Pumps 2 Ca+2 back into terminal cisternae per ATP hydrolyzed ↓Ca+2 Tropomyosin blocks actin binding site again ↓actin- myosin interaction The Muscle Twitch Myogram: the recording of electrical activity during muscle contraction Latent - cross bridges begin to cycle but muscle tension is not yet measurable so the myogram does not show a response. Period of contraction - cross bridges are active, from the onset to the peak of tension development Period of relaxation – the pumping of Ca2+ back into the SR. Because the number of active cross bridges is declining, contractile force is declining  Type of Skeletal Muscle Fibers The speed of contraction of L.R.= lateral rectus different muscles of eye vary widely. G.= gastrocnemius S.= soleus Why? Because we have several different types of skeletal muscle fibers. Type of Skeletal Muscle Fibers  TETANUS Summation of twitches that occur at high frequency stimulations. How we are able to have smooth, continuous movements i. Incomplete (UNfused) – individual contractions are observed Interval for muscle contractions allow twitches for brief relaxation between contractions, peak tension increases but oscillates ii. Complete (fused) – individual contractions are indistinguishable. Interval between successive stimuli decreases, twitches observed fuse on top of one another wherein a sustained, smooth higher force is obtained  MOTOR UNIT smallest functional unit of a muscle; basic unit of movement smallest amount of muscle that can be activated voluntarily consists of a motor neuron and the muscle fibers that innervates it Types of muscle fiber Extrafusal fiber – innervated by alpha motor neurons fibers comprise the bulk of muscle and form the major force- generating structure. Intrafusal fibres : innervated by gamma motor neuron. buried in the muscle, and they contain afferent receptors for stretch, but they also contain contractile elements  Fiber Length (length-tension relation) The effect of muscle fiber length on FACTORS the amount of tension the fiber can develop DETERMINI Tension is generated when a muscle contracts and decreases its length NG MUSCLE Kinds of contraction: TENSION Isometric – muscle length is held constant when tension is generated Isotonic – force or tone is held constant but there is a change in muscle length FACTORS DETERMINING MUSCLE TENSION Fiber Diameter Diameter of fiber is directly proportional to the force produced (smaller fiber = smaller force) Diameter of fiber is directly proportional to the threshold (smaller fiber = lower threshold) FACTORS DETERMINING MUSCLE TENSION Number of Active Fibers Number of fibers per motor unit The fewer the fibers = finer the movement The more fibers = more gross movement Number of active motor units The more units activated = stronger force produced  Types of Muscle Contraction Type of Contracti Length of Mechanis External on Muscle Tension m Work Example Trying to lift heavy Sarcomeres weights which (when the shorten weights are Isometri Remains the stretch those No external not actually c same Increases which do not work lifted) Shortening of individual sarcomeres adds up to the Shortening shortening of  Types of Muscle Contraction 1. Isotonic contraction Length changes while contracting Concentric (shortening) Eccentric (lengthening) Contributes most to cellular damage after exercise Load pulls muscle back even though cross-bridges are being formed Types of Muscle Contraction 2. Isometric contraction Muscle contracts but does not change in length Load is too heavy/ immovable How?  Type of fatigue Featur Peripheral e Fatigue Central Fatigue Central nervous system (brain Location Muscle fibers and spinal cord) Accumulation of Decreased ability of the central metabolic waste (e.g., nervous system to activate Cause lactate, hydrogen ions) motor neurons Feeling tired, difficulty Symptom Muscle soreness, concentrating, reduced s weakness, cramping motivation Rest, hydration, Recovery nutrition Rest, sleep, stress management Intense exercise, Production of Energy for Muscle ATP (adenosine Muscle cells must triphosphate) have three ways A type of chemical to store or make energy, needed for ATP sustained or Creatine repeated muscle phosphate contractions -Rapid production of energy Aerobic respiration -Uses body’s store of glucose Lactic acid production  Production of Energy: Oxygen Debt Develops when skeletal muscles are used strenuously for several minutes and cells are low in oxygen Conver Lactic acid Pyruvic acid ts to which builds up To liver for conversion Muscle fatigue to glucose, requiring more energy Oxygen debt and  Production of Energy: Muscle Fatigue Condition in which a muscle has lost its ability to contract Causes:  Accumulation of lactic acid  Interruption of the blood supply to a muscle  A motor neuron loses its ability to release acetylcholine onto muscle fibers Muscle Remodeling Muscle undergoes continuous remodeling Hypertrophy vs Atrophy Increase/decrease in mass Adjusts number of contractile proteins, energy-supplying enzymes, no. of sarcomeres Atrophy occurs rapidly following denervation Hyperplasia Production of more muscle fibers Rare; under extreme conditions  Muscle Strains and Sprains Strains – injuries due to over-stretched muscles or tendons Sprains – more serious injuries that result in tears to tendons, ligaments, and/or cartilage of joints RICE is recommended treatment for either Rest Ice Compression Elevation TREATMENT OF MUSCLE STRAINS AND SPRAINS  Muscle Strains and Sprains Prevention Warm up muscles - A few minutes before an intense activity raises muscle temperature and makes muscle more pliable Stretching - Improves muscle performance and should always be done after the warm-up or after exercising Cooling down or slowing down - Before completely stopping prevents pooling of blood in the legs and helps remove lactic acid from muscles  Aging Contractions become slower and not as strong Dexterity and gripping ability decrease Mobility may decrease Assistive devices helpful Routine exercise Swimming Physical therapy  Diseases and Disorders of the Muscular System Disease Description Botulism Affects the gastrointestinal tract and various muscle groups Fibromyalgia Fairly common condition that causes chronic pain primarily in joints, muscles, and tendons Muscular Inherited disorder characterized Dystrophy by muscle weakness and a loss of muscle tissue Myasthenia Autoimmune condition in which gravis patients experience muscle weakness  Diseases and Disorders of the Muscular System Disease Description Rhabdomyol A condition in which the kidneys ysis become damaged after serious muscle injuries Tendonitis Painful inflammation of a tendon (lockjaw) and the tendon-muscle attachment to a bone Torticollis Acquired or congenital; spasm or (wryneck) shortening of the sternocleidomastoid muscle; head bends to affected side and chin rotates to opposite side  Clinical application Muscular Dystrophy Mutated dystrophin- glycoprotein complex X-linked disorder Progressive weakness of muscle Malignant hyperthermia In susceptible persons, some anesthetics may cause uncontrolled release of Ca+2 Due to mutated RYR Results in rigidity; rise in temperature https://www.pinterest.com/pin/534661786987294988/ Tx: Dantrolene  Activity of the day Make an infographics about different muscular related illness: For each disorder, include: A brief description of the disorder. Key facts or statistics (e.g., prevalence, genetic inheritance). Common symptoms or manifestations. Diagnostic methods. Treatment options or management strategies. Citations APA No repetitions to your classmates Question! In which of the following situations may temporal summation leading to tetany be occurring? A. Standing in a relaxed manner B. Standing at attention C. Carrying a very light load D. Carrying a very heavy load E. B and D only F. All of the above Question! In which of the following situations may temporal summation leading to tetany be occurring? A. Standing in a relaxed manner B. Standing at attention C. Carrying a very light load D. Carrying a very heavy load E. B and D only F. All of the above Question Time! Which of the following might be true of Olympic medalist Hidilyn Diaz? A. The act of her lifting the barbell is primarily an isometric contraction B. Her muscles might insert nearer to the fulcrum compared to most people C. She experiences less central fatigue compared to most people D. Her muscles have primarily undergone lengthening hypertrophy E. B and C are true Question Time! Which of the following might be true of Olympic medalist Hidilyn Diaz? A. The act of her lifting the barbell is primarily an isometric contraction B. Her muscles might insert nearer to the fulcrum compared to most people C. She experiences less central fatigue compared to most people D. Her muscles have primarily undergone lengthening hypertrophy E. B and C are true  References https://www.youtube.com/watch?v=V9S6I_W3ZlE https://www.slideshare.net/zernwoman/a-p-ch-6-musclular -system-student-ppt https://slideplayer.com/slide/10341017/ https://slideplayer.com/slide/4680737/ Berne, 6th ed. Guyton, 13th ed. Ganong, 23rd ed. Silverthorn, Human Physiology: An Integrated Approach, 6th ed.