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Nervous system: 2. Comparing response-control systems: endocrine - hormones and nerve cells - nervous system

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Sub-index of biology notes on the nervous system


(2) Comparing two control systems

(endocrine-hormone systems and nerve cells-nervous system)

The nervous system and endocrine hormone system are two quite different mechanisms of control in the body, BUT, in principle they function in similar ways AND interact with each other too.

The endocrine system uses chemical molecule messengers (hormones) to communicate information.

See Homeostasis - introduction to how it functions (negative feedback systems explained) 

and Hormone system - Introduction to the endocrine system - role of thyroxine 

The nervous system uses electrical impulse messages to communicate information.

Endocrine hormone system Receptor detects changes in the environment Chemical messenger - hormone molecule signal

Slower, but acts for much longer - carried in blood to all organs, but only affects target organ

Coordination centre

A gland e.g. pancreas

Receives signal and processes information

Chemical messenger - hormone molecule signal

Slower, but acts for much longer - carried in blood to all organs, but only affects target organ

Effector

A gland that secretes a hormone to restore an optimum level or trigger some other chemical response

Nervous system Receptor detects changes in the environment Electrical signal - nerve impulse

Rapid and short duration - carried in nerve fibres to specific locations like muscles

Coordination centre

Brain or spinal cord

Receives signal and processes information

Electrical signal - nerve impulse

Rapid and short duration - carried in nerve fibres to specific locations like muscles

Effector

Muscles that respond to the signal

Comparing nerve and hormone functions

Hormones effectively act as 'chemical messages' to trigger particular biochemical reactions and their effects are ..

more general around the body, but tend to affect particular cells in particular organs,

and relatively long-lasting compared to e.g. the fast but short-term nervous impulses and responses of a reflex arc.

Compared to the hormone system of response and control in the body, nerve signals are electrical (not chemical, except at synapses), the nerves act very fast - a short burst of a nervous impulse for a short time, acting from one precise area to another in the body.


Keywords, phrases and learning objectives for this part on comparing the endocrine and nerve control systems

Be able to compare the endocrine-hormone systems and the nerve cells-nervous systems control systems and understand how they operate in completely different ways.


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