The Muscular System - Davis School · PDF fileSmooth (Visceral) Muscle ... surfaces such as:...
Transcript of The Muscular System - Davis School · PDF fileSmooth (Visceral) Muscle ... surfaces such as:...
![Page 1: The Muscular System - Davis School · PDF fileSmooth (Visceral) Muscle ... surfaces such as: –blood vessels - stomach –urinary bladder - intestines • Non-striated in appearance](https://reader034.fdocuments.us/reader034/viewer/2022051723/5abb51517f8b9ab1118ce06a/html5/thumbnails/1.jpg)
The Muscular System
![Page 2: The Muscular System - Davis School · PDF fileSmooth (Visceral) Muscle ... surfaces such as: –blood vessels - stomach –urinary bladder - intestines • Non-striated in appearance](https://reader034.fdocuments.us/reader034/viewer/2022051723/5abb51517f8b9ab1118ce06a/html5/thumbnails/2.jpg)
Functions of Muscle Tissue
• Movement Facilitation
• Thermogenesis
• Postural Support
• Regulation of Organ Volume
• Protects Internal Organs
• Pumps Blood (HEART)
![Page 3: The Muscular System - Davis School · PDF fileSmooth (Visceral) Muscle ... surfaces such as: –blood vessels - stomach –urinary bladder - intestines • Non-striated in appearance](https://reader034.fdocuments.us/reader034/viewer/2022051723/5abb51517f8b9ab1118ce06a/html5/thumbnails/3.jpg)
Characteristics of Muscle Tissue
• Contractility – able to shorten.
• Extensibility (Flexibility) – able to lengthen.
• Elasticity – able to return to original shape.
• Excitability (Irritability) – able to respond to a stimulus.
![Page 4: The Muscular System - Davis School · PDF fileSmooth (Visceral) Muscle ... surfaces such as: –blood vessels - stomach –urinary bladder - intestines • Non-striated in appearance](https://reader034.fdocuments.us/reader034/viewer/2022051723/5abb51517f8b9ab1118ce06a/html5/thumbnails/4.jpg)
Skeletal Muscle
• Attached to bones
• Striated appearance under a microscope
• Voluntary control (conscious control)
• Multinucleated
• Myofilaments - contractile elements of each muscle fiber
![Page 5: The Muscular System - Davis School · PDF fileSmooth (Visceral) Muscle ... surfaces such as: –blood vessels - stomach –urinary bladder - intestines • Non-striated in appearance](https://reader034.fdocuments.us/reader034/viewer/2022051723/5abb51517f8b9ab1118ce06a/html5/thumbnails/5.jpg)
Cardiac Muscle
• Forms the bulk of heart wall (Myocardium)
• Striated
• Involuntary (typically)
• Fibers are quadrangular and branching
• Cardiac fibers typically have a centrally located nucleus
• Sarcolemmas connected by intercalated discs
– Strengthens cardiac muscle tissue
– Propagates an action potential from cell to cell through specialized structures on the intercalated discs called gap junctions
![Page 6: The Muscular System - Davis School · PDF fileSmooth (Visceral) Muscle ... surfaces such as: –blood vessels - stomach –urinary bladder - intestines • Non-striated in appearance](https://reader034.fdocuments.us/reader034/viewer/2022051723/5abb51517f8b9ab1118ce06a/html5/thumbnails/6.jpg)
Smooth (Visceral) Muscle
• Located in walls of hollow internal surfaces such as:– blood vessels - stomach
– urinary bladder - intestines
• Non-striated in appearance
• Involuntary (typically)
• Can be stretched to great lengths
• Allows for tremendous size variability
![Page 7: The Muscular System - Davis School · PDF fileSmooth (Visceral) Muscle ... surfaces such as: –blood vessels - stomach –urinary bladder - intestines • Non-striated in appearance](https://reader034.fdocuments.us/reader034/viewer/2022051723/5abb51517f8b9ab1118ce06a/html5/thumbnails/7.jpg)
Smooth (Visceral) Muscle
![Page 8: The Muscular System - Davis School · PDF fileSmooth (Visceral) Muscle ... surfaces such as: –blood vessels - stomach –urinary bladder - intestines • Non-striated in appearance](https://reader034.fdocuments.us/reader034/viewer/2022051723/5abb51517f8b9ab1118ce06a/html5/thumbnails/8.jpg)
Smooth (Visceral) Muscle
![Page 9: The Muscular System - Davis School · PDF fileSmooth (Visceral) Muscle ... surfaces such as: –blood vessels - stomach –urinary bladder - intestines • Non-striated in appearance](https://reader034.fdocuments.us/reader034/viewer/2022051723/5abb51517f8b9ab1118ce06a/html5/thumbnails/9.jpg)
Skeletal Muscle Tissue Structures
![Page 10: The Muscular System - Davis School · PDF fileSmooth (Visceral) Muscle ... surfaces such as: –blood vessels - stomach –urinary bladder - intestines • Non-striated in appearance](https://reader034.fdocuments.us/reader034/viewer/2022051723/5abb51517f8b9ab1118ce06a/html5/thumbnails/10.jpg)
Muscle Tissue Structures
![Page 11: The Muscular System - Davis School · PDF fileSmooth (Visceral) Muscle ... surfaces such as: –blood vessels - stomach –urinary bladder - intestines • Non-striated in appearance](https://reader034.fdocuments.us/reader034/viewer/2022051723/5abb51517f8b9ab1118ce06a/html5/thumbnails/11.jpg)
Sarcomere
![Page 12: The Muscular System - Davis School · PDF fileSmooth (Visceral) Muscle ... surfaces such as: –blood vessels - stomach –urinary bladder - intestines • Non-striated in appearance](https://reader034.fdocuments.us/reader034/viewer/2022051723/5abb51517f8b9ab1118ce06a/html5/thumbnails/12.jpg)
Muscle Tissue Histology
• Myofilaments - structural components of myofibrils
– Myosin - thick myofilaments
– Actin - thin myofilaments
![Page 13: The Muscular System - Davis School · PDF fileSmooth (Visceral) Muscle ... surfaces such as: –blood vessels - stomach –urinary bladder - intestines • Non-striated in appearance](https://reader034.fdocuments.us/reader034/viewer/2022051723/5abb51517f8b9ab1118ce06a/html5/thumbnails/13.jpg)
Regions of a Sarcomere
![Page 14: The Muscular System - Davis School · PDF fileSmooth (Visceral) Muscle ... surfaces such as: –blood vessels - stomach –urinary bladder - intestines • Non-striated in appearance](https://reader034.fdocuments.us/reader034/viewer/2022051723/5abb51517f8b9ab1118ce06a/html5/thumbnails/14.jpg)
Myosin
• Thick myofilaments
• Occupy the A Band of the sarcomere
• Overlap free ends of the actin myofilament
• Shaped like a golf club
– Long, thick protein molecule (tail)
– Globular head at the ends
![Page 15: The Muscular System - Davis School · PDF fileSmooth (Visceral) Muscle ... surfaces such as: –blood vessels - stomach –urinary bladder - intestines • Non-striated in appearance](https://reader034.fdocuments.us/reader034/viewer/2022051723/5abb51517f8b9ab1118ce06a/html5/thumbnails/15.jpg)
Actin
• Thin myofilaments
• Anchored to the Z Line
• Two stranded protein molecule intertwined around each other
• Associated with two regulatory proteins
– Tropomyosin - long stranded protein molecule that follows the contour of actin
– Troponin - protein located at regular interval along the tropomyosin that covers the active sites on actin. Has three subunits
![Page 16: The Muscular System - Davis School · PDF fileSmooth (Visceral) Muscle ... surfaces such as: –blood vessels - stomach –urinary bladder - intestines • Non-striated in appearance](https://reader034.fdocuments.us/reader034/viewer/2022051723/5abb51517f8b9ab1118ce06a/html5/thumbnails/16.jpg)
Myofilaments
![Page 17: The Muscular System - Davis School · PDF fileSmooth (Visceral) Muscle ... surfaces such as: –blood vessels - stomach –urinary bladder - intestines • Non-striated in appearance](https://reader034.fdocuments.us/reader034/viewer/2022051723/5abb51517f8b9ab1118ce06a/html5/thumbnails/17.jpg)
Muscle Action Potential
An electrical impulse that originates at the motor end plate, travels along the length of the sarcolemma, down a transverse tubule, and causes the muscle to contract.
![Page 18: The Muscular System - Davis School · PDF fileSmooth (Visceral) Muscle ... surfaces such as: –blood vessels - stomach –urinary bladder - intestines • Non-striated in appearance](https://reader034.fdocuments.us/reader034/viewer/2022051723/5abb51517f8b9ab1118ce06a/html5/thumbnails/18.jpg)
Sliding Filament Theory of Muscular Contraction
• Due to an action potential, the actin and myosin myofilaments slide past one another shortening the sarcomere
• No change in length of myofilaments
• H Zone narrows or disappears
• I Band narrows or may disappear
• A Band remains the same length
![Page 19: The Muscular System - Davis School · PDF fileSmooth (Visceral) Muscle ... surfaces such as: –blood vessels - stomach –urinary bladder - intestines • Non-striated in appearance](https://reader034.fdocuments.us/reader034/viewer/2022051723/5abb51517f8b9ab1118ce06a/html5/thumbnails/19.jpg)
Muscle Nerve Interaction
• Neuron - nerve cell
• Axon - long, threadlike process that transmits impulse away from cell body (may be up to 1 meter in length)
• Motor Unit - motor neuron and all the muscle fibers it innervates
• Neuromuscular Junction - junction between axon terminal and muscle fiber
![Page 20: The Muscular System - Davis School · PDF fileSmooth (Visceral) Muscle ... surfaces such as: –blood vessels - stomach –urinary bladder - intestines • Non-striated in appearance](https://reader034.fdocuments.us/reader034/viewer/2022051723/5abb51517f8b9ab1118ce06a/html5/thumbnails/20.jpg)
Neuromuscular Junction
![Page 21: The Muscular System - Davis School · PDF fileSmooth (Visceral) Muscle ... surfaces such as: –blood vessels - stomach –urinary bladder - intestines • Non-striated in appearance](https://reader034.fdocuments.us/reader034/viewer/2022051723/5abb51517f8b9ab1118ce06a/html5/thumbnails/21.jpg)
Neuromuscular Junction
![Page 22: The Muscular System - Davis School · PDF fileSmooth (Visceral) Muscle ... surfaces such as: –blood vessels - stomach –urinary bladder - intestines • Non-striated in appearance](https://reader034.fdocuments.us/reader034/viewer/2022051723/5abb51517f8b9ab1118ce06a/html5/thumbnails/22.jpg)
Neuromuscular Junction
![Page 23: The Muscular System - Davis School · PDF fileSmooth (Visceral) Muscle ... surfaces such as: –blood vessels - stomach –urinary bladder - intestines • Non-striated in appearance](https://reader034.fdocuments.us/reader034/viewer/2022051723/5abb51517f8b9ab1118ce06a/html5/thumbnails/23.jpg)
Muscle Nerve Interaction
• Motor End Plate - location on the muscle fiber at the end of an axon terminal
• Synaptic End Bulb - distal end of axon terminal
• Synaptic Vesicles - membrane enclosed sacs within the synaptic end bulbs that store neurotransmitters
![Page 24: The Muscular System - Davis School · PDF fileSmooth (Visceral) Muscle ... surfaces such as: –blood vessels - stomach –urinary bladder - intestines • Non-striated in appearance](https://reader034.fdocuments.us/reader034/viewer/2022051723/5abb51517f8b9ab1118ce06a/html5/thumbnails/24.jpg)
Muscle Nerve Interaction
• Synaptic Cleft - space between axon terminal and motor end plate
• Subneural Clefts - folds in sarcolemma along the synaptic gutter
• Acetylcholine (Ach) - neurotransmitter released from synaptic vesicles that initiates an action potential in a muscle
![Page 25: The Muscular System - Davis School · PDF fileSmooth (Visceral) Muscle ... surfaces such as: –blood vessels - stomach –urinary bladder - intestines • Non-striated in appearance](https://reader034.fdocuments.us/reader034/viewer/2022051723/5abb51517f8b9ab1118ce06a/html5/thumbnails/25.jpg)
Muscle Response to Nervous Stimuli
• All or None Principle
– Once a threshold stimulus is applied to a motor unit the muscle fibers innervated by that motor unit will contract to their fullest potential
• Threshold Stimulus - the weakest stimulus from a neuron that will initiate a muscular contraction
![Page 26: The Muscular System - Davis School · PDF fileSmooth (Visceral) Muscle ... surfaces such as: –blood vessels - stomach –urinary bladder - intestines • Non-striated in appearance](https://reader034.fdocuments.us/reader034/viewer/2022051723/5abb51517f8b9ab1118ce06a/html5/thumbnails/26.jpg)
Events Leading to Muscular Contraction
• An action potential travels down the motor neuron. When it arrives at the synaptic knob, the membrane of the nerve at the synaptic cleft is depolarized, thereby increasing the Ca++ permeability of the membrane.
• Ca++ diffuses from outside of the synaptic knob to inside the synaptic knob.
![Page 27: The Muscular System - Davis School · PDF fileSmooth (Visceral) Muscle ... surfaces such as: –blood vessels - stomach –urinary bladder - intestines • Non-striated in appearance](https://reader034.fdocuments.us/reader034/viewer/2022051723/5abb51517f8b9ab1118ce06a/html5/thumbnails/27.jpg)
• The influx of Ca++ into the nerve causes the release of Ach.
• Ach is ejected into the synaptic cleft, diffuses across the cleft, and depolarizes the muscle membrane.
• This increases the permeability of the muscle membrane to Na+.
• Na+ rushes into the muscle cell, depolarizing the membrane as it travels away from the motor end plate thus initiating an action potential.
![Page 28: The Muscular System - Davis School · PDF fileSmooth (Visceral) Muscle ... surfaces such as: –blood vessels - stomach –urinary bladder - intestines • Non-striated in appearance](https://reader034.fdocuments.us/reader034/viewer/2022051723/5abb51517f8b9ab1118ce06a/html5/thumbnails/28.jpg)
• Ach is quickly broken down in the cleft by Ach-ase so that each action potential arriving from the nerve initiates only one action potential within the muscle.
• The action potential spreads across the muscle membrane and down the T-tubules deep into the muscle cell.
• The action potential of the T-tubules depolarizes the membrane of the nearby sarcoplasmic reticulum which results in the release of Ca++ into the sarcoplasm.
![Page 29: The Muscular System - Davis School · PDF fileSmooth (Visceral) Muscle ... surfaces such as: –blood vessels - stomach –urinary bladder - intestines • Non-striated in appearance](https://reader034.fdocuments.us/reader034/viewer/2022051723/5abb51517f8b9ab1118ce06a/html5/thumbnails/29.jpg)
• Ca++ is very quickly removed out of the sarcoplasm by the sarcoplasmic reticulum so the effects of one action potential are very short lived and produce a very small contraction.
• Many action potentials are necessary to produce enough force to produce a strong or prolonged muscle contraction.
• The Ca++ released from the sarcoplasmic reticulum binds with troponin and cause troponin to change shape.
![Page 30: The Muscular System - Davis School · PDF fileSmooth (Visceral) Muscle ... surfaces such as: –blood vessels - stomach –urinary bladder - intestines • Non-striated in appearance](https://reader034.fdocuments.us/reader034/viewer/2022051723/5abb51517f8b9ab1118ce06a/html5/thumbnails/30.jpg)
Muscle Contraction Events
![Page 31: The Muscular System - Davis School · PDF fileSmooth (Visceral) Muscle ... surfaces such as: –blood vessels - stomach –urinary bladder - intestines • Non-striated in appearance](https://reader034.fdocuments.us/reader034/viewer/2022051723/5abb51517f8b9ab1118ce06a/html5/thumbnails/31.jpg)
• When troponin changes shape, it physically moves the other regulatory protein, tropomyosin, out of the way exposing the active sites on the actin myofilament.
• Since the heads or cross-bridges of myosin have a very strong affinity for the active sites on actin, they make contact immediately after the active sites have been exposed.
• The acto-myosin complex has ATPase activity and ATP is split into ADP + P and energy is released.
![Page 32: The Muscular System - Davis School · PDF fileSmooth (Visceral) Muscle ... surfaces such as: –blood vessels - stomach –urinary bladder - intestines • Non-striated in appearance](https://reader034.fdocuments.us/reader034/viewer/2022051723/5abb51517f8b9ab1118ce06a/html5/thumbnails/32.jpg)
• The energy released by the splitting of ATP is used to produce movement of the cross-bridges, sliding the actin and myosin filaments past one another which causes the sarcomere to shorten and the muscle to contract and produce force.
• The myosin cross-bridge has a low affinity for ADP but a very high affinity for ATP.
• It discards the ADP and becomes recharged with a new ATP.
![Page 33: The Muscular System - Davis School · PDF fileSmooth (Visceral) Muscle ... surfaces such as: –blood vessels - stomach –urinary bladder - intestines • Non-striated in appearance](https://reader034.fdocuments.us/reader034/viewer/2022051723/5abb51517f8b9ab1118ce06a/html5/thumbnails/33.jpg)
Muscle Contraction Events
![Page 34: The Muscular System - Davis School · PDF fileSmooth (Visceral) Muscle ... surfaces such as: –blood vessels - stomach –urinary bladder - intestines • Non-striated in appearance](https://reader034.fdocuments.us/reader034/viewer/2022051723/5abb51517f8b9ab1118ce06a/html5/thumbnails/34.jpg)
• The myosin then releases its hold on the active sites on actin, swivels back to its original position, and is ready to respond to another action potential.
• When another action potential comes along the entire process is repeated.
• It takes many action potentials to produce enough shortening of the sarcomeres to generate enough force to produce movement of a body segment.
![Page 35: The Muscular System - Davis School · PDF fileSmooth (Visceral) Muscle ... surfaces such as: –blood vessels - stomach –urinary bladder - intestines • Non-striated in appearance](https://reader034.fdocuments.us/reader034/viewer/2022051723/5abb51517f8b9ab1118ce06a/html5/thumbnails/35.jpg)
Muscle Contraction Events
![Page 36: The Muscular System - Davis School · PDF fileSmooth (Visceral) Muscle ... surfaces such as: –blood vessels - stomach –urinary bladder - intestines • Non-striated in appearance](https://reader034.fdocuments.us/reader034/viewer/2022051723/5abb51517f8b9ab1118ce06a/html5/thumbnails/36.jpg)
Muscle Origin and Insertion
• Origin
– Body segment with most mass
– Usually more proximally located
– Usually larger surface area of attachment
• Insertion
– Body segment with least mass
– Usually more distally located
– Usually smaller surface area of attachment
• Gaster (Belly)
– Fleshy portion of the muscle between the tendons of the origin and insertion
![Page 37: The Muscular System - Davis School · PDF fileSmooth (Visceral) Muscle ... surfaces such as: –blood vessels - stomach –urinary bladder - intestines • Non-striated in appearance](https://reader034.fdocuments.us/reader034/viewer/2022051723/5abb51517f8b9ab1118ce06a/html5/thumbnails/37.jpg)
Roles of Skeletal Muscles
• Agonist (Prime Mover)– Muscle responsible for the majority of force
• Antagonist– Performs the opposite movement
• Synergist– Muscle that assists the agonist
• provides additional force
• redirects the force of the agonist
• Fixator (Stabilizer)– Stabilizes a body segment so the prime
mover can act more effectively
![Page 38: The Muscular System - Davis School · PDF fileSmooth (Visceral) Muscle ... surfaces such as: –blood vessels - stomach –urinary bladder - intestines • Non-striated in appearance](https://reader034.fdocuments.us/reader034/viewer/2022051723/5abb51517f8b9ab1118ce06a/html5/thumbnails/38.jpg)
Selected Superficial Skeletal Muscles (Anterior View)
• Pectoralis major
• Deltoid
• Biceps brachii
• Sternocleidomastoid
• Diaphragm
• Quadriceps– rectus femoris
– vastus medialis
– vastus lateralis
![Page 39: The Muscular System - Davis School · PDF fileSmooth (Visceral) Muscle ... surfaces such as: –blood vessels - stomach –urinary bladder - intestines • Non-striated in appearance](https://reader034.fdocuments.us/reader034/viewer/2022051723/5abb51517f8b9ab1118ce06a/html5/thumbnails/39.jpg)
Anterior Skeletal Muscles
![Page 40: The Muscular System - Davis School · PDF fileSmooth (Visceral) Muscle ... surfaces such as: –blood vessels - stomach –urinary bladder - intestines • Non-striated in appearance](https://reader034.fdocuments.us/reader034/viewer/2022051723/5abb51517f8b9ab1118ce06a/html5/thumbnails/40.jpg)
Selected Superficial Skeletal Muscles (Posterior View)
• Trapezius
• Triceps brachii
• Gastrocnemius
• Latissimus dorsi
• Hamstring Group
– semimembranosus
– biceps femoris
– semitendinosus
• Gluteus maximus
![Page 41: The Muscular System - Davis School · PDF fileSmooth (Visceral) Muscle ... surfaces such as: –blood vessels - stomach –urinary bladder - intestines • Non-striated in appearance](https://reader034.fdocuments.us/reader034/viewer/2022051723/5abb51517f8b9ab1118ce06a/html5/thumbnails/41.jpg)
Posterior Skeletal Muscles
![Page 42: The Muscular System - Davis School · PDF fileSmooth (Visceral) Muscle ... surfaces such as: –blood vessels - stomach –urinary bladder - intestines • Non-striated in appearance](https://reader034.fdocuments.us/reader034/viewer/2022051723/5abb51517f8b9ab1118ce06a/html5/thumbnails/42.jpg)
Muscle Diseases and Disorders
![Page 43: The Muscular System - Davis School · PDF fileSmooth (Visceral) Muscle ... surfaces such as: –blood vessels - stomach –urinary bladder - intestines • Non-striated in appearance](https://reader034.fdocuments.us/reader034/viewer/2022051723/5abb51517f8b9ab1118ce06a/html5/thumbnails/43.jpg)
Myalgia (Fibromyalgia)
• Painful disorders of muscles, tendons, and surrounding soft tissue
![Page 44: The Muscular System - Davis School · PDF fileSmooth (Visceral) Muscle ... surfaces such as: –blood vessels - stomach –urinary bladder - intestines • Non-striated in appearance](https://reader034.fdocuments.us/reader034/viewer/2022051723/5abb51517f8b9ab1118ce06a/html5/thumbnails/44.jpg)
Muscular Dystrophies
• Muscle destroying diseases characterized by the degeneration of individual muscle fibers
• Leads to progressive atrophy of skeletal muscles
• Due to a genetic defect
![Page 45: The Muscular System - Davis School · PDF fileSmooth (Visceral) Muscle ... surfaces such as: –blood vessels - stomach –urinary bladder - intestines • Non-striated in appearance](https://reader034.fdocuments.us/reader034/viewer/2022051723/5abb51517f8b9ab1118ce06a/html5/thumbnails/45.jpg)
Shin Splints
• Pain in the lower leg
• Tendonitis of the tibialis posterior muscle
• Inflammation of the periosteum
• Stress fracture of the tibia
• Exaggerated enlargement of muscles within the epimysium
• Pulling away of the periosteum from the underlying bone
• Treatment:– RICE
– strengthen tibialis anterior muscle
![Page 46: The Muscular System - Davis School · PDF fileSmooth (Visceral) Muscle ... surfaces such as: –blood vessels - stomach –urinary bladder - intestines • Non-striated in appearance](https://reader034.fdocuments.us/reader034/viewer/2022051723/5abb51517f8b9ab1118ce06a/html5/thumbnails/46.jpg)
Sprains• the forcible wrenching or twisting of a
joint with partial or complete rupture or injury to joint attachments without dislocation
• 1st Degree Sprain = stretching of ligaments
• 2nd Degree Sprain = partial tearing of ligaments
• 3rd Degree Sprain = complete tear of ligaments
![Page 47: The Muscular System - Davis School · PDF fileSmooth (Visceral) Muscle ... surfaces such as: –blood vessels - stomach –urinary bladder - intestines • Non-striated in appearance](https://reader034.fdocuments.us/reader034/viewer/2022051723/5abb51517f8b9ab1118ce06a/html5/thumbnails/47.jpg)
Strains
• pulling or overstretching a muscle
• soft tissue (Muscle) injury
![Page 48: The Muscular System - Davis School · PDF fileSmooth (Visceral) Muscle ... surfaces such as: –blood vessels - stomach –urinary bladder - intestines • Non-striated in appearance](https://reader034.fdocuments.us/reader034/viewer/2022051723/5abb51517f8b9ab1118ce06a/html5/thumbnails/48.jpg)