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Esther Ramirez Period #5 Muscular System - Coggle Diagram
Esther Ramirez
Period #5
Muscular System
Major Functions
Movement: responsible for all locomotion and manipulation.
Ex: walking, digesting, pumping blood, aerobatic and aerobic exercises
Maintains body posture and body position
Stabilize joints
Generate heat as they contract
3 Types of Muscles & Their Functions
3 Types of Muscles:
1) Skeletal Tissue: Voluntary movement; locomotion; manipulation of the environment; facial expression; voluntary control
2) Smooth Tissue: Propels substance or objects (food stuffs, urine, a baby) along internal passageways; involuntary contol.
3) Cardiac Tissue: As it contracts, it propels blood into the circulation; involuntary control. Has intercalated discs
Muscle Functions:
1) Antagonist: Opposes or reserves particular movement. Prime mover and antagonist are located on opposite sides of joints across which they act
2) Synergist: Helps prime movers. Adds extra force to same movement. Reduces undesirable or unnecessary movement
3) Fixators: Type of synergist that immobilizes bone or muscles origin rather than enhancing movement of prime movers.
Gives prime mover stable bade on which to act
Names of All Skeletal Muscles
● Bicep brachii
● Brachialis
● Brachioradialis
● Deltoid
● External obliques
● Flexor carpi radialis
● Flexor carpi ulnaris
● Frontalis (Epicranius frontal belly)
● Iliopsoas
● Masseter
● Orbicularis oris
● Orbicularis oculi
● Palmaris longus
● Pectinus
● Pectoralis major
● Pronator teres
● Rectus abdominis
● Serratus anterior
● Sternocleidomastoid
● Sternohyoid
● Temporalis
● Tensor fasciae latae
● Trapezius
● Tricep brachii
● Zygomaticus
● Adductor longus
● Fibularis longus
● Extensor digitorum longus
● Gastrocnemius
● Gracilis
● Iliotibial tract
● Rectus femoris
● Sartorius
● Soleus
● Tibialis anterior
● Vastus lateralis
● Vastus medialis
● Brachioradialis
● Deltoid
● Extensor carpi radialis
● Extensor carpi ulnaris
● Flexor carpi ulnaris
● Gluteus maximus
● Gluteus medius
● Infraspinatus
● Latissimus dorsi
● Occipitalis (Epicranius occipital belly)
● Rhomboid major
● Sternocleidomastoid
● Teres major
● Trapezius
● Tricep brachii
● Bicep femoris
● Adductor magnus
● Gastrocnemius
● Gracilis
● Soleus
● Fibularis longus
● Semitendinosus
● Semimembranosus
● Bicep femoris
● Adductor magnus
● Gastrocnemius
● Gracilis
● Soleus
● Fibularis longus
● Semitendinosus
● Semimembranosus
Neuromuscular Junction
1) AP arrives at axon terminal
2) Voltage-gated calcium channels open, calcium enters motor neuron
3) Calcium entry causes release of ACh neurotransmitter into synaptic cleft
4) ACh diffuses across to ACh receptros (Na+ chemical gates) on sarcolemma
5) ACh binding to receptors, open gates, allowing Na+ to enter resulting in end plate potential
6) Acetylcholin esterase degrades ACh
Sliding Filament Theory of Muscle Contraction
2) Relative size of fibers: the bulkier the muscle, the more tension it can develop
Muscle cells can increase in size (hypertrophy) with regular exercise
3) Frequency of stimulation: the higher the frequency, the greater the force
Stimuli are added together
1) # of muscle fibers stimulated (recruitment) the more motor units recruited, the greater the force.
Force of contraction depends on # of cross-bridge attached by 4 factors shown below:
4) Degree of muscle stretch: muscle fibers with sarcomeres that are 80-120% their normal resting length generate more force
If sarcomere is less than 80% resting length, filaments overlap too much, and force decreases
If sarcomere is greater than 120% of resting length, filaments do not overlap enough, so force decreases
Action Potential in a Muscle Fiber
Single Muscle Fibers: Striations, Sarcomeres, Myofilaments, and Molecular composition of myofilaments
Striations: strips formed from repeating series of dark light bands along the length of each myofibril.
A bands: dark regions
H zone: line of protein (myosin) that dissects H Zone vertically
I bands: lighter regions
Z discs (line): coin-shaped sheet of proteins on mid-line pf light I band
Sarcomere: small contractile unit (functional unit) of muscle fiber. Contains A band w/ 1/2 of I band at each end
Consists of area between Z discs
Involved sarcomeres aligned end along myofibril, like boxcars of train
Myofilaments: Orderly arrangement of actin and myofilaments within sarcomere. Actin myofilaments are thin filaments
Extend across I band and pathway in A band
Anchored to Z discs
Myosin myofilaments: thick filaments
Extend length of A band
Connected at M line
Sarcomere: cross section shows hexagonal arrangement of one thick filament surrounded by six (6) thing filaments
Molecular Composition of Myofilaments: thick filaments composed of a protein myosin that contains two (2) heavy and four (4) light polypeptide chains.
Heavy chains: intertwine to form myosin tail
Light chains: form myosin globular head
During contraction, heads link thick and thin filaments together forming cross bridges
Myosins are off set from each other resulting in staggered array of heads at different points along thick filament
Thin Filaments: composed of fibrous protein actin
Actin: is polypeptide made-up of kidney shaped G actin
(globular) subunits
G actin sub units bears active sights myosin head attachment during contraction
Muscle Coverings (Connective Tissue)
Skeletal Tissue: Voluntary movement; locomotion; manipulation of the environment; facial expression; voluntary control
Cardiac Tissue: As it contracts, it propels blood into the circulation; involuntary control. Has intercalated discs
Smooth Tissue: Propels substance or objects (food stuffs, urine, a baby) along internal passageways; involuntary contol.
Excitability (responsiveness): ability to receive and respond to stimuli
Contractility: ability to shorten forcibly when stimulated
Extensibility: ability to be stretched
Elasticity: ability to recoil to resting length
Connective Tissue Sheaths: Each skeletal muscle, as well as each muscle fiber, is covered in connective tissue. Supports cells and reinforces whole muscle. Sheaths from external to internal:
Epimysium: surrounding entire muscle; may blend w/ fascia
Perimysium: fibrous connective tissue surrounding fascicles (groups of muscle fibers)
Endomysium: fine areolar connective tissue surrounding each muscle fiber
Disorders
Rigor Mortis: 3-4 hours after death, muscles begin to stiffen
Peak rigidity occurs about 12 hours post mortem
Intracellular Ca+ levels cannot be pumped back into SR
Results in cross-bridge formaion
ATP also needed for cross-bridge detachment
Results in myosin head staying bound to actin, causing constant state of contraction.
Muscles stay contraction until muscle proteins break down, causing myosin to release.
Toxins, drugs, and diseases interfere with events at the neuromuscular junction
Ex: myasthenis gravis: disease characterized by drooping upper eyelids, difficulty swallowing, talking, and generalized muscle weakness.
Involves shortage of ACh receptors because person's ACh receptors are attacked by own anti-biotics.
Suggests this is an autoimmune disease.
Ducheme muscular dystrophy (DMD) is most common and serious form of muscular dystrophies, muscular-destroying diseases, soalmist exclusively in makes