Muscular System Flashcards
What are the functions of muscles
movement stability control of body openings and passages heat production glycemic control
movement
move from place to place; move body contents
stability
maintain posture
control of body openings and passages
mouth; internal sphincters
heat production
85% of body heat produced by skeletal muscles
glycemic control
regulation of blood glucose concentration within its normal range; skeletal muscles absorb, store, and use a large share of
one’s glucose, and play a highly significant role in stabilizing it’s blood concentration
what are the characteristics of muscles
responsiveness (excitability) conductivity contractility extensibility elasticity
responsiveness (excitability)
when stimulated by chemical signals, stretch, and other stimuli, muscle cells respond with electrical changes across the cell membrane
conductivity
stimulation of a muscle cell produces more than a local effect; the local electrical change triggers a wave of excitation that travels rapidly all the cell and initiates processes leading to contraction
contractility
muscle cells are unique in their ability to shorten substantially When stimulated; enables them to create movement
extensibility
ability to stretch again between contractions
elasticity
ability to stretch, release, and recoil to a shorter length
Epimysium
covers entire muscle; attachment to tendon
perimysium
surrounds fascicle or bundle of skeletal muscle
endomysium
surrounds individual skeletal muscle cell
parallel
fibers run parallel and can be arranged with or without body/gaster (biceps brachii – with body/gaster); (rectus abdominis – without body/gaster)
convergent
fibers meet at a common attachment site (mylohyoid)
pennate
fibers arranged at an angle;
unipennate
fibers on one side of tendon (extensor digitorum longus)
bipennate
fibers on both sides of tendon (rectus femoris)
multipennate
fibers branch within tendon (deltoid)
circular
fibers arranged in circular pattern (orbicularis oris or oculi); sphincters
tetanus (lock jaw)
caused by bacterium Clostridium tetani; toxins released cause the involuntary contraction of skeletal muscle; jaw muscles affected first
caused by a deep dirty wound
botulism (food poisoning)
caused by bacterium Clostridium botulinum; toxins released prevent the release of Ach (acetylcholine); causes paralysis of respiratory muscles
treated with oxygen, acetylcholine and pump the stomach
hernias
due to weakness in a muscle; organ can protrude through the muscle
inguinal hernia
most common; groin region; small intestine pushes through groin muscles, and can twist and strangulate
clostridium
doesn’t require oxygen
hiatal hernia
most painful; weakness in diaphragm; stomach and liver push up into thoracic cavity; difficulty in breathing
Muscular Dystrophy (MD)
group of genetic diseases characterized by progressive weakness and degeneration of the skeletal muscles. Some forms of muscular dystrophy are seen in infancy, or childhood, while other forms may not appear until middle age or later.
Duchenne’s Muscular Dystrophy
sex linked disease
females can be carriers
*is the most common form of MD
it primarily affects boys, since the recessive mutation in the p21 gene on the X chromosome; since males have one X they usually have the disease, whereas, females are carriers of the disease
the p21 gene codes for the protein dystrophin, which is involved with maintaining the integrity of the muscle; therefore, dystrophin is absent in people with Duchenne’s MD
onset is between 3 and 5 years, and progresses rapidly; most boys are unable to walk by age 12
**symptoms include: progressive difficulty walking; frequent falls; fatigue; and muscle deformities
diagnosis; a CPK test is performed to measure creatine phosphokinase to determine if the muscles are damaged; in Duchenne’s MD, CPK leaks out of the muscle cell and into the blood, so a higher level of CPK would confirm that the muscle is damaged
some boys die in infancy, while others have a pro-longed life span into adulthood; depending on the rate of progression of the disease
NO CURE
Becker Muscular Dystrophy
**is a less severe form of Duchenne’s MD
have faulty or not enough dystrophin
onset is at about age 12 years; most men are unable to walk by age 25 to 30 years
***symptoms include: progressive muscle weakness of legs and pelvis; muscle weakness also occurs in arms, neck, and other areas of the body, but not as severely as in the lower half of the body; fatigue
diagnosis; CPK test
Facioscapulohumeral Muscular Dystrophy:
**usually begins in the teenage years
**progressive weakness in muscles of the face, arms, legs, and around the shoulders and chest
it progresses slowly, and can vary in symptoms from mild to disabling
Myotonic Muscular Dystrophy:
**most common adult form MD
**symptoms include; prolonged muscle spasms; cataracts; cardiac disturbances; and endocrine disturbances
individuals with Myotonic MD have long, thin faces, drooping eyelids, and a swan-like neck
Myasthenia Gravis:
“ grave muscle weakness “; progressive muscle weakness
**chronic, autoimmune neuromuscular disease
is caused by a defect in the transmission of nerve impulses to muscles
**antibodies block, alter, or destroy the receptors for acetylcholine at the neuromuscular junction; prevents muscle contraction from occurring
usually affects any skeletal muscles, and muscles that control eye and eyelid movement, facial expression, and swallowing
**occurs in both genders; most commonly affects young adult women (under 40 years), and older men (over 60 years), but can occur at any age
diagnosis with a blood test to measure presence of acetylcholine receptor antibodies
can use medications to help reduce and improve muscle weakness; acetylcholinesterase agents such as neostigmine, which help improve neuromuscular transmission, and increase muscle strength
patients can periodically go into remission and no symptoms occur
