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Giselle Rojas Muscular System Period 3 - Coggle Diagram
Giselle Rojas Muscular System Period 3
MAJOR FUNCTIONS OF THE MUSCULAR SYSTEM
MAIN FUNCTION: movement
walking
breathing
pumping the heart
moving food through your digestive tract
3 TYPES OF MUSCLES & THEIR FUNCTION
NEUROMUSCULAR JUNCTION
skeletal muscle fibers contract only when stimulated by a MOTOR NEURON (nerve for skeletal tissue)
each skeletal muscle fiber (cell) is functionally (not physically) connected to the axon of a motor neuron, creating a SYNAPSE
the neuron communicates with the muscle fiber by way of chemicals called NEUROTRANSMITTERS which are released at the synapse
NEUROMUSCULAR JUNCTION: a synapse between a motor neuron and a muscle fiber that it regulates
the cytoplasm of the distal end of the motor neuron contains numerous MITOCHONDRIA and SYNAPTIC VESICLES storing neurotransmitters
the muscle fiber membrane in this area contains a specialized region called the MOTOR END PLATE, in which the sarcolemma is tightly folded
the motor end plate contains specific receptors for the new neurotransmitter
when an electrical impulse reaches the end of the axon of a motor neuron, synaptic vesicles release neurotransmitter into the SYNAPTIC CLEFT, the gap between the membranes of the neuron and muscle fiber
3 TYPES: SKELETAL SMOOTH CARDIAC
SKELETAL:
Location: skeletal muscle
Function: movement of bones at joints, maintenance of posture
Striations: present
Nucleus: many nuclei
Features: well-developed transverse tubule system
Mode of control: voluntary
Contraction: contracts and relaxes
Characteristics: rapidly when stimulated by a motor neuron
SMOOTH:
Location: walls of hollow viscera, blood vessels
Function: movement of viscera, peristalsis, vasoconstriction
Striations: absent
Nucleus: single nuclei
Features: lacks transverse tubules
Mode of control: involuntary
Contraction: contracts and relaxes
Characteristics: slowly; single unit type is self-exciting rythmic
CARDIAC
Location: wall of heart
Function: pumping action of the heart
Striations: present
Nucleus: single nucleus
Features: well developed transverse tubule system, intercalated discs separating adjacent cells
Mode of control: involuntary
Contraction: network of cells contracts
Characteristics: as a unit; self-exciting; rhythmic
NAMES OF ALL THE SKELETAL MUSCLES
SLIDING FILAMENT THEORY OF MUSCLE CONTRACTION
DISORDER ASSOCIATED WITH THE MUSCULAR SYSTEM
DISEASE:
Muscular Dystrophy: Muscle weakness and atrophy
CAUSES OR RISK FACTORS:
Genetic
Different types depending on mutation: duchenne, becker, myotonia congenital
SYMPTOMS:
mental retardation
Muscle Weakness
Eye-lid drooping
loss of strength
TREATMENT OPTIONS:
no known cure
physical therapy
Medication
surgery to improve function
physical activity
DISEASE:
Fibromyalgia: Muscle pain
CAUSES OR RISK FACTORS
2 more items...
DISEASE:
Cerebral Palsy: Spastic paralysis causing muscle weakness
CAUSES OR RISK FACTORS:
brain injury or abnormality
hypoxia during
premature birth
brain infections
head injury
SYMPTOMS:
mild to severe
delayed development
muscle tightness
abnormal gait
paralysis
seizures
TREATMENT OPTIONS:
no cure
medication for symptoms
physical therapy
surgical intervention
DISEASE:
2 more items...
muscle contraction involves several events, that result in the shortening of SARCOMERES, and the pulling of the muscle against its attachments
the pulling force is exerted by the binding of MYOSIN (thick) molecules to ACTIN (thin) molecules
the shortening of a muscle fiber results from an increase in the overlap between actin and myosin filaments, as they slide past each other
shortening of muscle fibers results in shortening of the entire muscle, which then pulls on the attached body part to cause movement
according to the sliding filament model of muscle contraction, during muscle contraction, a myosin head attaches to a binding site on the actin filament, forming a CROSS-BRIDGE
this binding causes the head to bend, pulling on the actin filament, and moving it toward the center of the sarcomere
the head then releases, and attaches to the next binding site on the actin, pulling this site toward the center
as this occurs again and again, the filaments increase their overlap, and the sarcomere shortens from both ends
when many sarcomeres shorten at the same time, the muscle fiber shortens
energy from the conversion of ATP to ADP is provided to the cross-bridges by the enzyme ATPASE; ATP breakdown causes the heads to return to the "cocked" position, ready to bind to another actin binding site
ACTION POTENTIAL IN A MUSCLE FIBER:
ACETYLCHOLINE is the neurotransmitter for skeletal muscle fiber contraction at the neurotransmitter junctions
acetylcholine is produced in the motor neuron, and stored in the synaptic vesicles at the distal end of the neuron
acetylcholine is released into the synaptic cleft in response to an impulse in the motor neuron; it then stimulates the muscle fiber
upon receipt of the muscle impulse, the SARCOPLASMIC RETICULUM releases its stored calcium to the cytosol of the muscle fiber
the HIGH CONCENTRATION OF CALCIUM in the sarcoplasm interacts with the troponin and tropomyosin molecules, which move aside, exposing the myosin binding sites on the actin filaments
cross-bridges now form, and pull on the actin filaments, using the energy of ATP, this causes the sarcomere to shorten
the contraction continues as long as the nerve impulse continues
after the nerve impulse stops, these events lead to RELAXATION of the muscle:
the enzyme ACETYLCHOLINESTERASE, in the motor end plate, rapidly decomposes the acetylcholine
calcium is returned to the sarcoplasmic reticulum, using ATP as an energy source
ATP now binds to the myosin heads, and the linkages between myosin and actin are broken
the actin returns to its original position and the muscle relaxes
SARCOMERE
myofibrils are made up of many units called SARCOMERES (from z-line to z-line is one sarcomere)
a sarcomere extends from one Z-LINE to the next
I BANDS (light bands) are made up pf actin filaments, which are anchored to the z-lines
A BANDS (dark bands) are made up of overlapping thick and thin filaments
in the center of the A band is the H ZONE, which consists of myosin filaments only
the M LINE, in the center of the h zone, consists of proteins that hold the myosin filaments in place
MUSCLE COVERINGS (connective tissue coverings)
fascia blends with the EPIMYSIUM, the layer of connective tissue around each skeletal muscle
the PERIMYSIUM extends inward from the epimysium; it surrounds bundles of skeletal muscle fibers, called FASCICLES, within each muscle
each muscle cell (fiber) is covered by a connective tissue layer called ENDOMYSIUM
FACIAL (front):
Epicranius, frontal belly (frontalis)
Orbicularis Oculi
Zygomaticus
Orbicularis oris
HEAD:
Temporalis
Masseter
NECK:
Sternocleidomastoid
Sternohyoid
SHOULDER:
Deltoid
Trapezius
THORAX:
Intercostals
Pectoralis Major
ARM:
Brachialis
Bicep Brachii
FOREARM:
Brachioradialis
Pronator Teres
Fletor Carpiradialis
Palmaris Longus
ABDOMEN:
Rectus Abdominus
Internal Oblique
PELVIS/THIGH:
3 more items...
NECK (back):
Sternocleidomastoid
Trapezius
Epicranius, occipital belly (occipitals)
SHOULDER:
Infraspinatus
Teres Major
Deltoid
Rhomboid Major
Latissimus dorsi
ARM:
Triceps Brachii
FOREARM:
Brachioradialisis
Extensor Carpi Radialis Longus
Extensor Carpi Ulnaris
Flexor Carpi Ulnaris
HIP:
Gluteus Medius
Gluteus Maximus
THIGH:
Biceps Femoris
Semimembranosus
Adductor Magnus
Gracilis
LEG:
Soleus
Fibularis Longus
Gastrocnemius