ANS physiology Flashcards
2 parts of the ANS
parasympathetic and sympathetic
exceptions to divide of para and sympathetic
○ Salivary glands have both sympathetic and parasympathetic innervation, but both stimulate saliva secretion
organs that don’t receive dual innervation
○ Sweat glands receive only sympathetic neurons
○ Blood vessels (arterioles and veins) receive only sympathetic nerve fibres, except penis and clitoris
sympathetic tone
§ A baseline firing frequency
§ Vasomotor tone provides partial constriction
The ANS is activated mainly by
centres in the spinal cord, brain stem, hypothalamus and portions of the cerebral cortex
Hypothalamus
□ Nuclei for primitive functions - hunger, thirst
§ Midbrain, pons, and medulla
□ Nuclei for cardiac and vasomotor control, salivation, swallowing, sweating, bladder control, and pupillary changes
§ Spinal cord reflexes
□ Defecation and micturition reflexes integrated in cord
□ Brain can inhibit these responses consciously
parasympathetic nerves
pre and post ganglionic nerve
ganglion in the effector organ
sympathetic nerves
pre and post ganglionic nerve
ganglion in the spinal cord
OR
pre ganglionic goes to adrenal gland and blood stream acts and post ganglionic nerve
where do parasympathetic nerves leave the spinal cord
cranio sacral
top and bottom
where do sympathetic nerves leave the spinal cord
thoraco lumbar
middle
neuromessenger used by parasympathetic
○ Both pre and post ganglionic nerves produce and secrete acetyl choline
neuromessenger used by sympathetic
uses acetyl choline but also uses noradrenaline at the post ganglionic nerves
exceptions to neuromessenger used by sympathetic
§ Sweat glands
□ Sympathetic nerve but only uses acetyl choline
§ Also neuroendocrine
□ Releases adrenaline into blood stream
□ Blood stream acts as post ganglionic supply
