Please enable JavaScript.
Coggle requires JavaScript to display documents.
The autonomic nervous system - Coggle Diagram
The autonomic nervous system
Involuntary- not under conscious control regulate heart rate, body temperature, glandular function, smooth muscle contractions, secretions
MAJOR FUNCTIONS:
General visceral motor system: most effectors are visceral(organs&tissues) as opposed to somatic (skeletal)
AUTONOMIC VS SOMATIC
Somatic- skeletal muscle. Autonomic- organs, glands, smooth muscle and cardiac muscle
Somatic- one motor neurone from the CNS to skeletal muscle
Autonomic- two motor neurones(preganglionic and postganglionic)
preganglionic- located in the CNS sends its axon to an autonomic nervous system just outside the CNS myelinated, thin axons.
postganglionic-located in the autonomic ganglion unmylelinated very thin axons
ACTIONS OF NEUROTRANSMITTERS-
Somatic- acetylcholine/Ach
Autonomic- postganglionic neurone may release acetylcholine or norepinephrine
COORDINATION OF AUTONOMIC AND SOMATIC SYSTEMS- both send their motor neurones to effectors via the 31 pairs o f spinal nerves. and 12 pairs of cranial nerves. when skeletal is active the autonomic must regulate other body functions such as sufficient blood, oxygen and waste removal.
DIVISION OF THE AUTONOMIC NERVOUS SYSTEM
SYMPATHETIC- fight or flight division reactions include dilated pupils increased heart rate, constriction of blood vessels, increased blood pressure, dilation of bronchioles, burst of energy(glucose), rapid deep breathing patterns
PARASYMPATHETIC- rest and digest, increased digestion, urination and defecation- keeps body calm
acetylcholine is secreted by all preganglionic nerones in the ANS and most preganglionic neurones
Acetylcholine/cholinergic receptors- nicotine receptors Ach receptors that can be activated by nicotine(e.g receptors involved in wave of excitation down Tubules in at primary stage of contraction)
Muscarinic receptors- mushroom receptors which are activated by mushroom toxin, stimulate or inhibit based on target cell. CARDIAC MUSCLE INHIBITORY SMOOTH MUSCLE OF GI TRACT STIMULATORY
Norepinepherine/noradrenaline- released by most postganglionic of the sympathetic nervous systemxceptions: postganglionic sympathetic fibers to some sweat glands of skin, some blood vessels to skeletal
muscle and external genitalia
Norepinephrine- noradrenergic receptors- alpha adrenergic receptors stimulate the effector organ tissue
beta adrenergic receptors - inhibit effector organ/ tissue.
Drug effects on the autonomic nervous system
neostigmine- blocks acetylcholinesterase for accumulation of acetylcholine
beta blockers- blocks binding of norepinepherine to beta-I receptors decreasing heart e.g propanol, nadolol, timolol, pinhole(partial antagonist) metoprolol(most lipid soluble)(atenolol)least lipid soluble
tricyclic antidepressants- prolong binding of norepinepherine to postsynaptic effectors.
anticholinergic drugs- block Act causing increase heart rate, decreased defecation and urination
phentolamine- blocks NE used to treat with high BP
OTHER ROLES OF THE AUTONOMIC NS
SYMPATHETIC
Thermoregulation- vasodilation of capillaries releasing heat from skin
increased metabolic rate
glucose secretions into blood
stimulate medulla to secrete hormones norepinephrine and epinephrine
blood vessels to constrict
arrector pilli
cns REGULATION OF ans
PONS- regulate respiration and the pupils
medulla-can regulate- respiration, heart rate, blood vessel constriction and GI activity
Hypothalamus- csan coordinate the regulation of heart rate blood pressure temperature, water electrolyte balance, pleasure, rage, thirst hunger and sex drive
sympathetic- lateral and posterior hypothalamus parasympathetic medial and anterior hypothalamus
Cerebral cortex and biofeedback- making patient s aware of autonomically controlled functions can allow them to know how to better control them
Abnormalities of Autonomic Control Mechanisms
A. hypertension - increased blood pressure due to overstimulation of sympathetics that results from
stress; NE blockers to treat
B. Raynaud’s disease - abnormal vasoconstriction of vessels in the extremities; surgery to sever
sympathetic fibers used to treat this problem
C. autonomic hyperflexia - massive reflex activation of all autonomics that occurs in response to
spinal injury; can cause death due to loss of control of visceral function
SYMPATHETIC ANTAGONISTS- cocaine inhibits the reuptake of noradrenaline
amphetamine resistant to enzyme breakdown
ephedrine- mild central stimulant