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Muscle contraction - Coggle Diagram
Muscle contraction
Cardiac muscle
it is located only in the heart
It consists of self-exciting tissue
Rhythmic contractions
Involuntary
It pumps blood
LUNGS
and the body
The action potential spreads out to the cells across the surface of the sarcolema
Calcium defuses into intracelular fluid from the extracelular fluid
The free calcium activates the calcium channels of the sarcoplasmic reticulum
The calcium defuses the myoplasm
Process
Signal from Center Nervous System (CNS)
The signal is brought by the motor neuron
That signal generates an action potential
This action causes the release of calcium ions from the sarcoplasmic reticulum
Calcium ions binds to troponin on action, thus exposing the binding sites for myosin
The myosin heads bind to the actin, forming a cross-bridge that pulls the actin filaments causing them to slide over the myosin filaments. Thus, causing contraction
Once the motor neuron stops sending signals, calcium ions are returned back to the sarcoplasmic reticulum. This inactives the actin; cross-bridges are broken and the muscle relax
They are connected to the muscle fibers
Their connection is called motor unit
Smooth muscle tissue
They are found in the walls of hollow organs
Blood vessel, organs of digestive tract, etc
Lacks of striations as actin and myosin are not arranged in a sarcomere pattern
It is regulated by a neural innervation of the autonomic nervous system
It is affected by hormones, paracrines
They rely on cross-bridge cycling
However cross-bridge cycling cannot occur until myosin heads are activated
Begins by a rise of cytosolic calcium levels
Action potential travels along the sarcolemma of a smooth microfiber, calcium channels open
The calcium are also released from the sarcoplasmic reticulum
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