Muscular System Notes
Textbook Online

Class Notes

Functions: Movement of the body and all actions. Examples- push blood thru vessels, breath and hold upright. 

Structure: Human body has 640 muscles. 40% of body weight from muscle.

muscle tissue is made of cells that have 10 or more nuclei in each. muscle fibers average 1 inch each, groups of fibers create muscle. 

*Muscles are connected to bones in order to move them. They are connected by tendons (connective tissue).

Voluntary:  muscles one can control. skeletal muscle

Involuntary: muscles that one can not control, automatic. cardiac and smooth muscle.

Types: Three types of muscle:

1. Skeletal: voluntary muscle. can be controlled (nerves)

covering body. striated, long bundles. react quickly and tire quickly. attatched to bone by tendons. 

2. Smooth: involuntary muscle. inside of the body, lines the walls of hollow organs such as the stomach and intestines. made of smooth flat sheets. work automatically for body functions.

3. Cardiac: involuntary muscle. makes the heart beat. built in rythm. combination of smoth and cardiac muscle. uses large amounts of O2 and glucose in the blood, muscle must never tire.

Movement: Muscles contract (shorten) and relax to move parts of the body.  

*Muscles work in pairs: flexor and extensor. One muscle shortens to bend the part and the other brings back the body to the original position or straighten.

* Muscles can also work in complex combinations of many muscles. *Muscles can be working without any body part moving.

*Fuel is needed to have muscles work (glucose). Aerobic respiration takes O2 and glucose to produce ATP with CO2 and H2O as by products. Anaerobic respiration does not use O2 to create ATP.

*Longest muscle: sartorius (inner thigh)

*Biggest muscle: gluteus maximus (bottom)

*Smallest muscle: stapedius (inner ear)

* muscles are shaped many different ways.

Levers: simple machine that works in one movement

Lever- fixed bar Bone

Fulcrum- fixed point  Joint

Effort- force applied Muscle contract/relax

Load- weight on bar or resistance Body part or outside weight

First Class Lever- fulcrum in the middle

Second Class Lever- load in the middle

Third Class Lever- effort in the middle 

*trick- (spangler silly) number of sides of the shapes go in order with the class levels. ie: triangle (3 sides) in the middle is 1st, square (4 sides) in the middle is 2nd.....




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