Download Comparison of coordination by hormones and the nervous system

Comparison of coordination by
hormones and the nervous
system
Control and coordination
A system which matches specific
responses to particular stimuli to
ensure “the right thing happens in the
right place at the right time to the
right degree
Achieved by:
The endocrine system.
Hormones secreted by endocrine glands carried in the bloodstream
to particular target organs whose cells have hormone-specific
receptors in their membranes e.g.
• adrenal glands/adrenaline,
• pancreas/insulin
• thyroid gland/thyroxine
• pituitary gland/ADH
• kidney/EPO
Hormones are chemicals affect chemical processes in the target
cells e.g.
• insulin: glucose  glycogen
• testosterone  protein synthesis
Most of these responses are
• long term
• permanent
The nervous system
• Coordination and control is achieved by the transmission of
electrical signals -nerve impulses - along specialised cells –neurones.
Nerve impulses cause a response in effectors e.g.
• contraction in muscles
• secretion by glands
Responses are
• short duration
• not permanent
Nervous system
• Signal = nerve
impulses (electrical)
• +chemicals at
synapses
• Nerve impulses
transmitted by
neurones (=cells)
Hormones
(endocrine system)
• Signal = hormones
(chemicals)
• Hormones
transmitted by blood
stream
Nervous system
• Signals transmitted
very rapidly
• Responses are rapid
• Reponses short
term; only while
impulses arrive
Hormones
• Signals transmitted
slower
• Responses are
generally slower
• Responses normally
more long term, until
hormone broken
down
Nervous
• Response local in
specific effectors only
Hormones
• Response more widely
spread
• Effectors are muscles
or glands
• Effectors are target
cells with specific
receptors in membranes
• Response is contraction
or secretion
• Response is a chemical
change e.g.
glucose  glycogen,
protein synthesis
Nervous
• Response is not
permanent
• Controls specific rapid
responses to rapid
changes in the
environment
Hormones
• Response often a
permanent change
• Controls more longer
duration responses to
changes in the
environment e.g.
insulin/blood sugar,
ADH/water and long
term changes
associated with growth
and development