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

Response local in specific effectors only Nervous Response local in specific effectors only Effectors are muscles or glands Response is contraction or secretion Hormones Response more widely spread Effectors are target cells with specific receptors in membranes 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