Lecture 4 ANS Flashcards
somatic vs autonomic neuron architecture
- somatic: UMN = interneuron in spine and LMN from spine to skeletal muscle - can be very long
- autonomic: preganglionic living in spine synapses with postganglionic in ganglion and innervates organ
varicosities
swellings in postganglionic that release NT along axon
denervation meaning and causes
- cutting of neuron either physically or chemically
denervation hypersensitivity
- autonomic organs often more active if they are denervated
- ex: heart and GI are more active
denervation effect on somatic vs autonomic nervous system
- somatic: no muscle contraction, flaccidity, and muscular atrophy
- autonomic: increased activity (heart rate increases to intrinsic rate)
somatic vs autonomic neurotransmitters onto effectors
- somatic: Ach onto nicotinic receptors and always excitatory
- autonomic Ach or Norepi onto effector organs and excitatory/inhibitory
sympathetic alternate names and reasoning
fight or flight or thoraciccolumbar because comes from T1-T2 and L1-L2 (lumbar0
parasympathetic alternate names and reasoniing
rest and digest or carniosacral division, nerves come from midbrain/brainstem/medulla and lower spine
sympathetic chain of paravertebral ganglia
2 chains of sympathetic ganglia running parallel to spine - pre and postganglionic enter and exit
collateral ganglion
sympathetic ganglion scattered throughout the abdominal and pelvic cavity
mass activation meaning and 3 factors
- sympathetic system activates many organs and effects all at once (master switch) increased heart rate, pupil dilation, increased blood pressure etc
- convergence, divergence, and sympathoadrenal system
divergence
- 1 preganglionic –> many postganglionic –> separate effector organs
- allows for mass activation
convergence
- many preganglionic –> 1 postganglionc
- allows for summation
sympathoadrenal system
- adrenal gland only innervated by sympathetic system
- release epi 85% and norepi 15% into blood stream where it binds to all adrenergic receptors causing mass activation
adrenal medulla and how its like a neuron
- adrenal gland = postganglionic lost axons so just release NT/hormone into blood strem
- explains why adrenal gland only innervated by a preganglionic - it itself is the postganglionic!
adrenal medulla hormones
- epi 85% and norepi 15%
2 locations where sympathetic preganglionics synapse
1) sympathetic chain of paravertebral ganglia
2) collateral ganglia
list 4 parasympathetic cranial nerves, number, and general effector organ
- cranial 3 oculomotor = eyes
- cranial 7 facial
- cranial 9 glossopharyngeal
- cranial 10 vagus nerve, all organs
cranial nerve 3 name, origin, ganglia, effector organ
oculomotor
midbrain –> ciliary ganglion –> circular smooth muscle in eye and ciliary body
cranial nerve 7 name, origin, ganglia, effector organ
Facial nerve: pons –> pterygopalatine and submandibular ganglia –> lacrimal (tear), mucous, and salivary glands
cranial nerve 9 name, origin, ganglia, effector organ
glossopharyngeal nerve: medulla oblongata –> otic ganglion –> parotid gland (salivary)
cranial nerve 10 name, origin, ganglia, effector organ
vagus nerve: medulla oblongata –> terminal ganglia in or near organ –> all organs in abdominal cavity
pelvic spinal nerves origin, ganglia, effector organ
S2-S4 –> terminal ganglia –> lower half of large intestine, rectum, urinary bladder, reproductive tract
2 sets of muscles in pupil and which type of pupil movement
- circular smooth muscle, parasympathetic, contraction = constriction of pupil
- radial smooth muscle, sympathetic, contraction = dilation
circular smooth muscle in pupil - receptor, branch of ANS, stimulation type
muscarinic receptors, parasympathetic, contraction = pupillary constriction
radial smooth muscle - branch of ANS, stimulation type
sympathetic, contraction = pupillary dilation
dual innervation and 2 examples
- most organs are innervated by parasympathetic and sympathetic nerves
- ex: heart, to increase and decrease rate from the intrinsic rate
- ex: GI tract, parasympathetic increases activity and sympathetic decreases activity
exceptions to dual innervation and 4 main examples
- only innervated by sympathetic or parasymapthetic not both
1) radial and circular smooth muscle of the eye
2) sweat glands - sympathetic
3) arrector pilli of skin - sympathetic
4) blood vessels - sympathetic
5) adrenal gland - sympathetic
vascular smooth muscle of skeletal muscle - explain how this is an exception
- Ach NOT norepi released onto muscarinic vascular smooth muscle of skeletal muscle causing inhibition, vasodilation, and increased blood flow
- epi from adrenal gland binds to B2 receptors and also vasodilates
blood shunting
- vasoconstriction in one area makes more blood available to organs where vasodilation is occurring
adrenergic receptor 1 vs 2
1 = excitatory 2 = inhibitory
alpha adrenergic receptros
- prefer norepi
- Ca2+ secondary messenger
beta adrenergic receptors
- prefer epi
- cAMP secondary messenger
alpha 1 - location and effect
- excitatory
- GI and skin vascular smooth muscle, sphincters, pupil
alpha 2 - location and effect
- inhibitory
- GI tract and brain (negative feedback)
beta 1 - location and effect
- excitatory
- heart ONLY
beta 2 - location and effect
- inhibitory
- bronchioles, vascular smooth muscle of skeletal tissue, GI tract wall, bladder
net effect of sympathetic on blood pressure
- vasodilation of vascular smooth muscle to skeletal muscle
- vasoconstriction everywhere else (especially skin and IG)
- net effect = increased blood pressure
explain how alpha 2 is used in negative feedback
- in brain
- presynaptic to preganglionic –> preganglionic –> postganglionic
- A2 receptors on presynaptic to preganglionic allow inhibition by blood borne epi
- overall inhibition of sympathetic system, makes sure it doesnt go overboard
effect of A2 agonist drugs
- A2 agonist = inhibits symapthetic system - decreases blood pressure and heart rate
antagonistic effect of parasympathetic and sympathetic and 2 examples
- antagonistic = para/sympa effects are often opposite of each other
- ex: heart rate and GI
cooperative effects
- both branches needed for proper functioning
- sympathetic releases sphincters and parasympathetic contracts bladder muscle
- parasympathetic for erection and sympathetic for ejaculation
complementary effects
- effects are similar but not necessary
- ex: parasympathetic activates salivary gladns and sympathetic constricts blood vesses making saliva thicker
atropine and clinical application
- muscarinic antagonist
- M2 on heart inhibits intrinsic rate so atropine increases heart rate
- to increase heart rate: use atropine to decrease parasympathetic first then use a drug that mimics sympathetic
NO effects and example
smooth muscle relaxation, vasodilation
ex: NO causes erection
pupillary dilation - receptor type
- contraction and excitation of radial smooth muscle
- A1 (B1 only in heart)
heart
- increased heart rate, excitatory B1
GI and skin vascular smooth muscle constrict
- constriction = contraction of muscle excitatory
- A1 (B1 only in heart)
skeletal muscle vascular smooth muscle
- dilation = inhibition
- Ach released onto inhibitory muscarinic
- epi/norepi from adrenal gland binds to B2
bronchioles
- dilation to get more air
- inhibitory
- B2 (A2 only for GI secretion and brain negative feedback)
GI tract wall
- relaxation, inhibition
- B2 (A2 for brain and GI secretion)
sphincters
- contraction, excitatory
- A1 (B1 only in the heart)
GI secretion
- inhibitory
- A2 (GI secretion and brain only)
bladder
- inhibitory (recall contraction = peeing)
- B2 (A2 in brain and GI secretion only)
thermoregulatory glands
- excitatory
- EXCEPTION
- Ach onto excitatory muscarinic receptors
A1 agonist drug
- causes constriction
- ex: treatment for nasal congestion, vasoconstriction decreases swelling (but also raises blood pressure)
A2 agonist drug
- recall: brain and GI
- agonist inhibits sympathetic system
B1 agonist drug
- recall: excitatory in heart
- increases heart rate
B1 antagonist drug
- decreases heart rate
B2 agonist drug
- inhibitory to bronchioles
- bronchiole dilation to treat asthma and COPD
