#93 Voluntary and involuntary actions

Knee jerk is an involuntary reflex. 

Two types of action controlled by the human nervous system are: voluntary and involuntary actions. The peripheral nerves transmit both of them.  

Comparison of voluntary and involuntary actions 

Feature	Voluntary action	Involuntary action
Nature	- Conscious thought (make decision about making action). - Free will - Consciously control skeletal muscles	- Does not involve thought - Not under the control of the will - Cannot control the activities.
Examples	If we want to ask question, we raise our hands	Involving - skeletal muscle (e.g. knee jerk) - smooth muscles (e.g. peristalsis) - cardiac muscles (e.g. pumping of the heart)
Role	Respond with the benefit of experience	Respond quickly to avoid danger
Controlled by	Forebrain (Cerebrum): - coordinates incoming information, initiates impulses sent to the effectors. - may spontaneously initiates actions without any sensory stimulation.	- Hind-brain (cranial reflex action)   - Spinal cord (spinal reflex action), e.g. blinking of the eyes
Speed of action	Slow response, as the cerebrum needs time to “think” before an action is carried out.	Rapid response, as the cerebrum is not involved.
Response to the same stimulus	The same stimulus may produce various responses. E.g.  when you are hungry, you may decide to eat or not to eat, or  just need to drink water.	The same stimulus always results in the same response (stereotyped response), e.g. the knee jerk reflex.

Forebrain is responsible for voluntary actions,

hindbrain is responsible for involuntary actions. 

Source: Voluntary and Involuntary Actions