The Muscular System Flashcards
What is myology?
The study of muscles
How many muscles are in the human body?
Over 600
How much of the total body weight is muscle tissue?
40-50%
What is skeletal muscle?
Attach to bones of skeleton
Striated: striped, alternating light and dark bands
Voluntary
What is smooth muscle?
Lining of some hollow organs
Stomach, lungs, large and small intestine, bladder, arteries, blood vessels
Non-striated (smooth looking)
Involuntary
What is cardiac muscle?
Found in walls of heart
Striated
Involuntary
What are the functions of muscle?
- ) Movement-integration of bones, muscles, tendons, joints, and ligaments which allows movement
- ) Movement of Muscles through Body-blood through circulatory system, oxygen through respiratory system, food through digestive system, urine through urinary system, and sex cells through reproductive system
- ) Regulate Organ Volume-contraction of muscle can prevent outflow of contents, urine by bladder and feces by anal sphincter
- ) Stabilize Body Positions-skeletal muscle can maintain body positions
- ) Heat Production- by product of muscle contraction is heat
Of all the energy it takes to move a muscle, how much is heat and how much is actually used to move the muscle?
60%–>heat
40%–>muscle
What is a myofiber?
Muscle cell-makes up muscles
Cylindrical in shape
Many nuclei
Contains sarcoplasm (cytoplasm of a muscle)
What is a myofibril?
Smaller cylindrical structure that makes up a myofiber
For a muscle to move, what must it be stimulated by?
A nerve
What proteins make up a myofibril?
Actin and myosin
What is the area where the muscle and nerve meet?
Myoneural Junction
What two neurotransmitters are released at the myoneural junction?
Acetylcholine (a-ch): chemical released at MJ that causes a muscle to contract
Cholinesterase: chemical released at MJ that causes a muscle to relax
What is myasthenia gravis?
Disease of muscular weakness
Too little A-ch or too much cholinesterase
Who cured myasthenia gravis and how?
Mary B. Walker while studying natives who used a poison, curare, to relax muscles and Neostigmine, drug that cured my. Gravis, to reverse it by increasing production of A-ch or suppressing amount of cholinesterase.
Who discovered the physiology of a muscle contraction and in what year?
2 men named Huxley (Germany) in 1957
What is a sarcomere?
Set pattern of striations in a muscle
What proteins are in the A-band?
Both actin and myosin
What proteins are in the H-band?
Only myosin
What proteins are in the I-band?
Only actin
What proteins are in the Z-band?
None
Describe the sliding filament mechanism of a muscle contraction.
A-ch released at M.J.–>actin and myosin filaments to slide over one another–>sarcomere to contract–>myofibril to contract–>muscle to contract
What does skeletal muscle consist of?
75% water
20% proteins
5% various minerals (Ca, Mg, and P) and organic molecules (glucose, ATP’s, creatine, creatine phosphate)
