1. Describe the types and functions of muscular tissue.

• Skeletal
• Found: on your skeleton
  
• • Functions:
    • movement of the skeleton
    • attatched to the skeleton
    • Stabilizing body positions
    • striated, voluntary movements (voluntary means that it would tire easily Eg: The fist action)
    • Moving substances within body
• Cardiac
• Found: the wall on your heart
  
• • Functions:
    • pumps the heart to send oxygen and blood to the body
    • contracts repeatedly
    • only found in heart
    • involuntary action (pumps all the time and does not tire easily), striated, intercolated discs
    • Moving substances within body
• Smooth
• Found: In your gastrointestinal tract, uterus, bladder, abdominal cavity, male and female reproduction tracts,
  
• • Functions:
    • surrounds hollow tubes in the body (blood vessels, air waves, intestines, pores, etc)
    • non-striated, involuntary
    • Moving substances within body
    • Moves digestive juices (that's why sometimes you get heartburns)
    • Regulates organ volume
      • Sphincters

2. Explain how skeletal muscles contract and relax.
Contract:
1. Myosin heads on thick filaments hydrolyze ATP and become reorientated and energized
2. Myosin heads bind to actin of thin filaments, forming crossbridges
3. Myosin crossbridges rotate toward center of the sacromere (power stroke like rowing a boat) and shifts which causes the contraction. The overlap area increases and it moves only about 20nm.
4. As myosin heads bind ATP, the crossbridges detach from actin

In simpler words:

1. A nerve impulse is sent to the muscle fibers
2. Calcium is released from the sarcoplasmic reticulum and relaxes the filaments
3. Traconin and actin filaments unravel (relax and expands) and myosin head attaches
4. ATP is necessary: releases head from actin and powers the power stroke
5. calcium is taken back into the sarcoplasmic reticulum and the process begins again.

1. 
   

A muscle contraction occurs when a muscle fiber generates tension through the action of actin and myosin, that cross-bridge cycling. While under tension, the muscle might shorten or lengthen. Though contraction may be thought as a shortening process of the muscle fibers, however, the muscular system contraction refers to the general tension by muscle fibers.


3. Describe the sources of ATP and oxygen for muscle contraction.
ATP - supplies the energy and breaks off from the myosin head.
Normally, it would supply 1-3 secs of energy (when in resting motion)
When in high intensity, supplies less than 1 sec of energy
3 Sources:
1) Creatine Phophate
- 7-10 secs of supply; stored in muscle cells; found in red meat
2) Anaerobic Respiration
- No oxygen required; need glucose (glycogen); supplies about 30 secs
3) Aerobic Respiration
- Glucose, oxygen required, uses myoglobin
Mitochondria produces ATP, that is why you will find a surplus of mitochondria in muscle cells.

4. Describe how the frequency of stimulation and motor unit recruitment affect muscle tension.

When looking at muscle tension, the total tension can be produced is caused by the number of muscle fibers that contract in unison. When a muscle fibre contracts when it is not completely relaxed, the tension will be higher than the previous contraction where the muscle was relaxed. The more a muscle fibre is stimulated, the higher the tension.
A motor unit is muscle fibers that are stimulated by a motor neuron, which conducts impulses from the brain to the spinal column and into spinal nerves which stimulate the muscle fibers. Motor unit recruitment is where the number of motor units that are contracting increase. Usually while some motor units are contracting, others relax. This helps the muscle fatigue slowly and move smoothly.

5. Compare the three types of skeletal muscle fibers.
There are two types of muscle tissues that account for an individuals athletic performance. Fast glycolytic (FG) are muscles tissues that usually deals with intense amount of activity over a short period. Slow ative (SO) fibers deal with endurance sports. The total number of skeletal muscle fibers usually does not increase, but the characteristics of the present can change to some extent. Varying from the type of exercise, FG can become FOG (Fast Oxidative-Glycolytic) fibers which show larger diameter, number of mitochondria, blood suply, and strength, if endurance exercises were done. On the other hand, exercise for the great intensity in a short period of time, produces FOG fibers that are larger in size, due to synthesis of thick and thin filaments.

6. Distinguish between isotonic and isometric contractions.
Isotonic Aforce is generated and muscles shorten: muscle fibers shorten to produce the same amount of tension against a constant load. This is the contraction and movement of muscles with a constant load.
Isometric A force is generated but muscles do not shorten: muscle fibers produce tension against a load that prevents shortening. It is like trying to pull up an immovable object.

7. Identify the effects of exercise on skeletal muscle tissue.
Exercise can cause Delayed Onset Muscle Soreness (DOMS) which is believed to be caused as a result of tiny tears in the muscle fibers by eccentric contraction. DOMS can occur from 1-3 days after exercising, and the soreness typically lasts for no longer than 3 days. The soreness can also come from a buildup of lactic acid. Lactic acid froms when the body is using up more oxygen than it can take in, so the muscles respirate anareobically, this process produces lactic acid which can give a burning feeling.

· Endurance type exercises cause the change of FG fibers to fast oxidative fibers. · The transformation causes the increase diameter, blood supply, strength, and the number of mitochondria · Cadusavolar and repertory caused muscles to receive more oxygen and nutrients but does not increase the mass · Exercises that uses a lot of strength causes an increases the size and strength of FG fibers · The increase of size is caused by the synthesis of thin and thick filiments · Muscle hypertrophy is the overall result


8. Describe how skeletal muscles cooperate to produce movement.
Flexion: decrease in the angle of the joint
Extension: increase in the angle of the joint
When one muscle is flexing, another is extending. Ex-when you are flexing your biceps, your triceps are extending.
The contracting muscle is known as the agonist and the relaxing muscle is known as the antagonist.
Abduction : carry an appendage away from midline
Adduction : brings an appendage back to the midline
Elevation : raise a part
Depression : lower a part
Rotation : turns on part around another.



9. Identify and name various skeletal muscles.