Tag: nervous system of man

• Involuntary actions in response to external or internal stimuli are termed as reflex actions. Peripheral nervous system and the spinal cord are involved in controlling the reflex actions. Here, the brain is not involved.
• The reflex action was discovered by Marshall. He proposed the theory explaining the body's reflex, or involuntary, actions.
  
• So, the correct answer is 'Marshall'.

• A stimulus is anything that can be perceived by a given organism including sight, sound, touch, smell, taste, etc.
•  A response is generally characterized as the behaviour proximal to the stimulus. So if a bell rings and a person jumps the stimulus is the bell and the response is the jump. 
• The ability of an organism or organ to respond to external stimuli is called sensitivity. When a stimulus is applied to a sensory receptor, it normally influences by a simple reflex. Hence, Simple reflex is best to characterize the simple response to simple stimuli. 

The reflex action is defined as the sudden and involuntary movements that are controlled directly by the spinal cord. These actions do not require memory generation most of the time, like blinking of the eyes when something comes close to them. These are called the unconditional reflexes. Some reflex actions may involve learning and these are call the conditional reflexes. For example release of saliva at the sight of the food. Obeying the orders is the voluntary set of actions performed under the command of the somatic nervous system. It involves memory generation so as to remember the tasks and voices.