Honors Muscular System Notes PDF

Muscular System Anatomy & Physiology  Period 2 how do we get cramps? how many muscles in the body? what is a muscle sprain or tear? how do muscles grow bigger with exercise? how does protein affect muscles how are muscles named how are muscles formed what are the ty...

Muscular System Anatomy & Physiology  Period 2 how do we get cramps? how many muscles in the body? what is a muscle sprain or tear? how do muscles grow bigger with exercise? how does protein affect muscles how are muscles named how are muscles formed what are the types of muscles what are the strongest muscles in the human body what are the functions of muscles what can causes muscles to lose mass? is there a place in the human body with no muscles  Major Muscles ON QU IZ There are about 650 human muscles – Difficult to differentiate muscles – Scientists do not agree on a set number You will have to know about 20 muscles – Identify these muscles during the bullfrog dissection Click for “Twitching Frog Legs” video [2min] Click for “Muscle Song” video [3.5min] Click for “Kids Health” video [7min]  Function of Muscles Click for “Cadaver Muscle Dissection” video [15 min] Muscles produce movement or generate tension (text 6.1)  Function of Muscles ON QU IZ 1. Skeletal Movement 2. Communication 3. Body Position and Posture 4. Protects Soft Tissues 5. Guard Entrances and Exits 6. Maintain Body Temperature Skeletal Movement Contracts and moves the bones  Communication Faces Lemon Muscles in your face help you express your inflections and emotions to other people  Body Posture Continuous muscle contractions maintain body posture. Without the constant action, you could not sit upright without collapsing or stand without toppling over.  Support and Protection The abdominopelvic wall and the floor of the pelvic cavity consist of layers of skeletal muscle These muscles support the weight of visceral organs and shield internal tissue from injury FRIENDS  Guards Circular muscle groups that guard entrances and exits → Sphincter Maintain Body Temp. Muscle contractions require energy and whenever energy is used in the body, some of it is converted to heat. The heat released by working muscles keeps the body temperature in the range required for normal functioning.  Characteristics of Muscles Muscle cells are elongated (muscle cell = muscle fiber) Contraction of muscles is due to the movement of proteins called myofilaments All muscles share some terminology – Prefix myo refers to muscle – Prefix mys refers to muscle – Prefix sarco refers to flesh “Flesh” is a combination of muscle and fatty connective tissue  Skeletal Muscles and Body Movements Movement is attained due to a muscle moving an attached bone Muscles are attached to at least two points – Origin – attachment to an immoveable bone – Insertion – attachment to a movable bone  BONE MUSCLE RELATIONSHIP LEVER SYSTEMS LEVER SYSTEM-CONSISTS OF A – RIGID BAR ( LEVER) WHICH MOVES ON A – FIXED POINT ( FULCRUM) WHEN A – FORCE IS APPLIED( EFFORT) TO MOVE A – RESISTANCE( LOAD) THE BONES AND MUSCLES IN THE BODY ACT AS LEVER SYSTEMS ❖ BONES ❖ JOINTS ❖ MUSCLES CONTRACTING ❖ BONE ITSELF + overlying tissues + other material you are trying to move LEVER SYSTEM  TYPES OF LEVERS FIRST CLASS LEVERS- -FULCRUM LIES BETWEEN THE EFFORT AND THE LOAD( SEE-SAW) - EFFORT IS APPLIED AT ONE END AND LOAD LIES ON THE OTHER END SECOND CLASS LEVERS -LOAD LIES BETWEEN EFFORT AND FULCRUM( WHEELBARROW) GREATER STRENGTH, LESS SPEED AND RANGE OF ACTION THIRD CLASS LEVERS - EFFORT LIES BETWEEN LOAD AND FUNCTIONFAST LARGE MOVEMENTS WITH LITTLE EFFORT - MOST SKELETAL MUSCLES ARE OF THIS TYPE  1st CLASS LEVER Muscle= Splenius  Let’s go to the weight room! What Elbow extension muscle? Where is fulcrum? Where is effort? Where is load? Second class levers 2nd class lever Plantar flexion to raise body on toes- What are the muscles being used for the effort? Load Effort THIRD CLASS LEVERS  rd 3 Class Levers Load or resistance Effort fulcrum Skeletal Muscles and Body Movements During Movements different muscles serve different functions – The Agonist - The primary muscle that moves the bone – The Antagonist - The muscle that opposes the agonist – Synergists - Assist the prime mover muscles – Fixators - Help by hold bones in place  Tendons & Aponeuroses Tendons Both Aponeuroses Thick & rope Connect muscle Flat sheet to bone like Made of dense like structures connective structures tissue  ON Five Golden Rules of Gross QU IZ Skeletal Muscle Activity 1. all muscles cross at least one joint 2. bulk of muscles lies proximal to the joint crossed 3. all muscles have at least 2 attachments: origin & insertion 4. muscles only pull (never push) 5. during contraction the muscle insertion moves toward the origin The Muscular System Muscles are responsible for all types of body movement –Involuntary/Voluntary Three basic muscle types are found in the body –Skeletal muscle –Cardiac muscle –Smooth muscle Click for “Muscle Types” video [2.5min] Cardiac and smooth muscle have special features (text 6.4)  ON QU IZ Skeletal Muscle Characteristics Most are attached by tendons to bones Cells are multinucleated Striated – have visible banding Voluntary – subject to conscious control Cells are surrounded and bundled by connective tissue  Cardiac Muscle Characteristics ON QU IZ Has striations Has a single nucleus Involuntary Found only in the heart Contracts at a fairly steady rate set by the heart’s pacemaker Neural controls allow the heart to respond to changes in bodily needs  ON QU Smooth Muscle Characteristics IZ Has no striations Spindle-shaped cells Single nucleus Involuntary – no conscious control Found mainly in hollow internal structures (eg. intestines, stomach, bladder) Pushes food and other substances through the body  ON QU IZ Draw the three types of tissue: Skeletal Muscle Smooth Muscle Cardiac Muscle Muscle Anatomy ON QU IZ MUSCLES ARE LIKE OGRES  Microscopic Anatomy of Skeletal Muscle ON Within each muscle cell, several QU IZ organelles can be found – Nuclei are found just beneath the cell’s membrane (sarcolemma) – Thousands of mitochondria can be found in each fiber – Sarcolemma: Muscle cell membrane  Microscopic Anatomy of Skeletal Muscle Muscle Cells also have specialized organelles, some that parallel organelles found in regular cells – Transverse Tubule (T Tubule): Channels that extend between the sarcoplasm and the sarcolemma – Sarcoplasmic Reticulum: Muscle Smooth ER Also contain enlarged portions called Cisternae that border the T Tubules The two cisternae & T tubule together make up the TRIAD  Microscopic Anatomy of Skeletal Muscle ON QU Myofibril IZ – Bundles of myofilaments (proteins) – Myofibrils are aligned to give distinct bands I band = light band A band = dark band Microscopic Anatomy of Skeletal Muscle ON Sarcomere QU IZ – Contractile unit in a myofibril – Segment between two Z discs One Sarcomere  Microscopic Anatomy of Skeletal Muscle ON Organization of the sarcomere QU IZ – Thick filaments = myosin filaments Composed of the protein myosin Has ATPase enzymes - stored in myosin heads – Thin filaments = actin filaments Composed of the protein actin  Microscopic Anatomy of Skeletal Muscle ON H zone: Zone of thick filaments QU IZ without superimposed thin filaments M line: Center of the H zone H zone Actin-myosin crosslinking: the bridge connecting actin & myosin filaments Myosin heads: myosin structure which attaches and detaches to actin, resulting in contraction of the muscle Skeletal Muscle Anatomy Small to Large Bundles of myofilaments (actin & myosin) make up a myofibril. Myofibrils are divided into segments called sarcomeres that span from Z-line to Z-line. Bundles of myofibrils form Muscle Fibers which included other organelles and are surrounded by a cell membrane called a sarcolemma. Skeletal Muscle Anatomy Small to Large Muscle fibers are surrounded by Endomysium Bundles of muscle fibers make up Muscle Fascicles Muscle Fascicles are surrounded by Perimysium Many Fascicles group together to create the whole Muscle Which is surrounded by the Epimysium  Muscle Contraction The act of muscle contraction can be broken down into steps called the Sliding Filament Model In this process nerve impulses send signals into the muscle which triggers myosin to pull actin filaments closer together  Sliding Filament Model There are 2 parts to the sliding filament model. – Part 1 shows how the release of calcium removes guard proteins around the actin to reveal binding sites – Part 2 shows how myosin heads break down ATP and use energy to bind and pull on the actin.  Neuromuscular Junction The Neuromuscular junction is where a motor neuron meets the muscle cell. The end of the motor neuron meets the muscle cell at a motor end plate. end plate (purple line)  PART 1 1. Nerve impulses are sent through a neuron to the muscle to begin contraction 2. Acetylcholine (Ach) is released from the neuron 3. Ach binds receptor to a receptor on the motor end plate  PART 1 4. The binding of Ach allows positively charged ions to enter the muscle fiber. (i.e. Na+, Ca2+) 5. Positive ions send a signal down the T tubule to the Sarcoplasmic Reticulum (SR) 6. The signal tells the SR to open releasing Calcium into the muscle fiber  PART 1 7. Calcium Binds to the Troponin 8. The calcium binding causes the Troponin to pull Tropomyosin away from the cross bridge binding sites PART 2  Nerve Stimulus to Muscles Nerves attached to muscle fibers will stimulate groups of fibers at a time A group of fibers controlled by the same neuron is called a Motor Unit As more strength is needed, motor units with increasing numbers of fibers will be stimulated in a process called recruitment  Contraction of a Skeletal Muscle Muscle fiber contraction is “all or none” Within a skeletal muscle, not all fibers may be stimulated during the same interval Different combinations of muscle fiber contractions may give differing responses – Muscle force depends upon the number of fibers stimulated More Fibers More Strength Muscles can continue to contract unless they run out of energy  Graded Responses Different degrees of skeletal muscle shortening – Twitch – Tetanus Unfused (incomplete) Fused (complete)  Types of Graded Responses Twitch – Single, brief contraction caused by a single stimuli Click for “Why Do We Twitch?” video [1min]  Types of Graded Responses Tetanus (summing of contractions) – One contraction is immediately followed by another – The muscle does not completely return to a resting state  Types of Graded Responses Unfused (incomplete) tetanus – Only about 300 milliseconds apart – Some relaxation occurs between contractions – The results are summed  Types of Graded Responses Fused (complete) tetanus – No evidence of relaxation before the following contractions – The result is a sustained muscle contraction – If this occurs for too long, fatigue sets in  Energy for Muscle Contraction Initially, muscles used stored ATP for energy – Bonds of ATP are broken to release energy – Only 4-6 seconds worth of ATP is stored by muscles After this initial time, other pathways must be utilized to produce ATP  Energy for Muscle Contraction Aerobic Respiration – Series of metabolic pathways that occur in the mitochondria – Glucose is broken down to carbon dioxide and water, releasing energy 36 ATP per C6H12O6 – This is a slower reaction that requires continuous oxygen  Energy for Muscle Contraction Anaerobic glycolysis – Reaction that breaks down glucose without oxygen – Glucose is broken down to pyruvic acid to produce some ATP 2 ATP per C6H12O6 – Pyruvic acid is converted to lactic acid – This reaction is not as efficient, but is fast Huge amounts of glucose are needed Lactic acid produces muscle fatigue Muscle Fatigue and Oxygen Debt When a muscle is fatigued, it is unable to contract The common reason for muscle fatigue is oxygen debt – Oxygen is required to get rid of accumulated lactic acid – Oxygen is being used from other areas of the body and must eventually be “repaid” Increasing acidity (from lactic acid) and lack of ATP causes the muscle to contract less  Effects of Exercise on Muscle Aerobic exercise results in stronger muscles due to increase in blood supply Muscle fibers increase mitochondria and oxygen storage Muscle becomes more fatigue resistant Heart enlarges to pump more blood to body Does not increase skeletal muscle size  Effects of Exercise on Muscle Results of increased muscle use from anaerobic exercise – aka strength/resistance training Individual muscle cells make more contractile filaments & connective tissue increases – Increase in muscle size – Increase in muscle strength  Examples Aerobic Exercise Anaerobic Exercise Note: most major sports are a mix of both aerobic and anaerobic exercises  Effects of Exercise on Muscle Stretching results in increased flexibility – Muscles should be stretched to counteract the constant shortening that occurs daily. Muscle fibers are lengthened slowly to make the body more limber. – This helps the muscles avoid injury when contracted and also increases range of motion.  General Rules for Exercise 5 days / week 30 minutes / day – At least 10-minute increments Mix of aerobic and anaerobic exercises 10,000 steps each day? ≈ 5 miles Average US adult walks 6,000 steps each day. CDC recommends 150 minutes of moderate activity per week ≈ 7,500 steps each day  Aging Amount of Muscle tissue decreases Connective Tissue increases Muscles become sinewy (stringier) Body weight declines due to loss of muscle mass By age 80, muscle strength usually decrease by 50% without weight training exercises  Complications Muscle cramps – Painful, uncontrollable muscle contractions – Caused by dehydration and ion imbalance (heavy exercise) – Stretching/Massaging can alleviate cramps Pulled muscles (“torn muscles”) – Muscles are stretched too far, resulting in tearing of fibers – Results in internal bleeding, swelling, and pain  Diseases & Disorders Atrophy – Muscle Wasting Away Protein in muscle starts to disintegrate – This will happen due to decreased movement or use of any specific muscle groups Commonly seen in people who were confined to a hospital bed for an extended period of time. Tetanus – Bacterial infection from puncture wound that overstimulates the nerves for muscle activity – Results in maximal (“tetanic”) muscle contraction – Usually affects neck and jaws (“lockjaw”) Diseases and disorders of the muscular system (text 6.5)