CHAPTER 10 TEST REVIEW Flashcards
what is the functions of skeletal muscles
Move the body
Maintain of posture
Protect and support
Regulate elimination of materials
Produce heat
characteristics of skeletal muscles
Excitability
Conductivity
Contractility
Extensibility
Elasticity
fascicle
Muscle fibers bundled
3 concentric layers of wrapping (skeletal muscles)
Epimysium- Dense irregular connective tissue wrapping whole muscle
Perimysium- Dense irregular connective tissue wrapping fascicle
Endomysium- Areolar connective tissue wrapping individual fiber
parts of a muscle cell
Sarcoplasm (cytoplasm)
Multiple nuclei (individual cells are multinucleated)
Sarcolemma (plasma membrane)
Myofibrils (hundreds to thousands per cell)
Sarcoplasmic reticulum
Clinical View: Muscular Dystrophy
Collective term for hereditary diseases where skeletal muscles
degenerate
Duchenne muscular dystrophy (DMD) is most common type
* Defective or insufficient dystrophin
* Sarcolemma damaged during muscle contraction
* Calcium enters cells, damages proteins
* Problems begin in early childhood
* Walking difficulties, muscle atrophy, postural issues
* Incurable; patients rarely live beyond age 30
Clinical View: Myasthenia Gravis
Autoimmune disease, primarily in women
* Antibodies bind to ACh receptors in neuromuscular
junctions
* Receptors removed from muscle fiber by endocytosis
* Results in decreased muscle stimulation
* Rapid fatigue and muscle weakness
* Eye and facial muscles often involved first
* May be followed by swallowing problems, limb weakness
Clinical View: Muscular Paralysis and Neurotoxins
Tetanus
* Spastic paralysis caused by toxin from Clostridium tetani
* Blocks release of inhibitory neurotransmitter in spinal cord,
resulting in overstimulation of muscles
* Vaccination prevents this life-threatening condition
Botulism
* Muscular paralysis caused by toxin from Clostridium
botulinum
* Prevents release of ACh at synaptic knobs
* Although toxin ingestion can be life-threatening, careful
injections of it can treat spasticity (for example, due to
cerebral palsy) or can be used for cosmetic purposes
(diminishing wrinkles)
Clinical View: Anabolic Steroids as Performance-
Enhancing Compounds
Anabolic steroids
* Synthetic substances that mimic testosterone
* Require prescription for legal use
* Stimulate manufacture of muscle proteins
* Popular performance enhancers
* Side effects include
* Increased risk of heart disease and stroke
* Kidney damage and liver tumors
* Testicular atrophy, breast development in males
* Acne, high blood pressure, aggressive behavior
* Growth of facial hair and menstrual irregularities in wome
excitation of a skeletal muscle fiber (3)
calcium entry at synaptic knob
release ach from synaptic knob
Binding of ACh at the motor end plate
oxygen debt
Amount of additional oxygen needed after exercise to
restore pre-exercise conditions
3 parts to a muscle twitch
Latent period
Contraction period
Relaxation period
muscle tone (definition)
Resting tension in a muscle
muscle fatigue (definition)
reduced ability to produce muscle tension
effects of aging on muscles
Loss of muscle mass with age
Decreased size, power, and endurance of skeletal muscle
* Loss in fiber number and diameter (decrease in myofibrils)
* Decreased oxygen storage capacity
* Decreased circulatory supply to muscles with exercise
Reduced capacity to recover from injury
* Decreased number of satellite cells
* Decreased flexibility
