### body part | organ | muscle:

Active muscle
* increases oxygen extraction.
* is responsible for creating spinal stability.
* use a form of stored glucose called glycogen as energy for work.

Agonist
* activate a receptor to achieve their effect
  - while antagonists inhibit the receptor
* are chemical agents which stimulate a certain kind of response
  - chemicals that bind to and stimulate opiate receptors
  - contestants
  - drugs
* produce a response, while antagonists block response to natural epinephrine.

Agonist muscle
* are the prime movers which contract to start the movement.
* produce the primary movement or series of movements through their own contractions.
* shorten with contraction to produce a movement.

### body part | organ | muscle | agonist:

Antihero
* is an agonist
* represent the darker urges of the human ego.

Antagonist muscle
* are the muscle or muscles that can slow down or stop a movement.
* assist in joint stabilization.

### body part | organ | muscle:

Cardiac muscle
* are involuntary and can contract without stimulation from the nervous system
  - part of hearts
* becomes flab and cholesterol levels rise.
* can contract without being stimulated by the nervous system.
* contains a great many mitochondria, which produce energy
* does have several unique features.
* forms the majority of the heart, and pumps blood through the heart chambers
  - mass of the heart
  - walls of the heart
  - themajority of the heart, and pumps blood through the heart chambers
* generates the rhythmic contractions of the heart.
* has a different troponin from skeletal muscle
  - characteristics of both skeletal and smooth muscles
  - more mitochondria than skeletal muscle
* is autorhythmic
  - characterized by a high rate of glucose consumption
  - derived from the anterior splanchnic mesoderm
  - found in the walls of the heart
* is found only in the heart
  - within the heart
  - highly dependent on calcium channel action
  - involuntary and is found exclusively in the heart
  - present in the vena cava and pulmonary veins as they join the heart
  - responsible for the unconscious contraction of the heart
* is striated and found in the heart
  - in appearance and is under involuntary control
* is the muscle found in the penguin heart
* makes up the contractile wall of the heart it is striated and branched
* serves as the pumping tissue of the heart.
* special kind of muscle found in the heart of backboned animals.

Circular muscle
* Some circular muscles change shapes
  - control recta
* surround the worm's body and can make the body shrink or spread out.

Cold muscle
* are more apt to strain and injury than warm ones.
* are more prone to injury
  - tear during lifting
  - vulnerable to injury
* feel tight and are more susceptible to injury, especially pulls and strains.
* take longer to stretch and flex.

Deconditioned muscle
* are inefficient and use more oxygen than muscles that are conditioned.
* use more oxygen than toned muscles.

Different muscle
* get their unique properties from the composition of muscle fiber type.
* seem to correspond to different organs along the lines of the meridians.

Extrinsic muscle
* originate on the axial skeleton and insert on a girdle or limb.
* serve to move the tongue about in the oral cavity.

Eye muscle
* Some eye muscles are part of eyes
  - faces
  - weak at birth
* are specialized to allow acute vision both above and under the water
  - the busiest muscles in the body
* can weaken, giving the person double vision or crossed eyes.
* strain to point the eyes at close distances.

### body part | organ | muscle | eye muscle:

Lateral rectus
* is an eye muscle
* moves the eye vertically.