Uses ELECTROCHEMICAL impulses to muscles and glands instead of using hormones.
Response in MILLISECONDS
What does humoral mean?
Things chemically in the blood.
Control of the Endocrine System
Humoral stimuli (in fluids) → hormone
Medulla (nervous system) → hormone
Hypo → pituitary → other glands → hormone (tropic system)
Structure and Function
Structure: loosely related cells/tissues/organs; widely scattered; highly vascularized Function: control body activities and maintain homeostasis (w/ negative feedback by use of hormones)
Characteristics of Hormones
Affect metabolic activity
Change in plasma membrane permeability or potential
Synthesize proteins in the cell
Enzyme activation or deactivation
Secreted through DUCTLESS glands into ECF Has specific target cell Amino acid or steroid
Activity of Steroid Hormones
Hormone (estrogen.. etc) is secreted from gland. Travels to target area Diffuses into TARGET cell and combines with nuclear receptors to turn on a gene RESPONSE is PROPORTIONAL to how many hormone-receptor complexes are formed
Activity of Amino Acids
Hormone is secreted=first message Travels to target of hormone receptor on cell membrane; does not enter cell G-protein acts as signal transducer to next molecule, an effector enzyme called adenylate cyclase.
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