Chapter 15 Flashcards
ANS contributes to homeostasis by ? (2)
1) responding to subconscious visceral sensations
2) exciting/inhibiting smooth/cardiac muscle & many glands
Biggest difference between ANS & SNS
involvement of conscious control
in SNS, feedback via sensations are consciously percieved & skeletal muscle = main tool used for reflexive & voluntary movement
ANS usually operates without conscious control (though centers in hypothalamus & brain stem regulate ANS reflexes)
Interoceptors (sensory) receptors in BV, visceral organs, muscles & NS monitor internal conditions
- chemoreceptors → monitor blood CO2
- mechanoreceptors → detect stretch in organ walls & BVs
Autonomic motor neurons regulate…
visceral activies by either increasing or decreasing ongoing activities in their effector tissues
Why are some autonomic responses the basis for polygraphs?
because some autonomic responses can NOT be consciously altered
Anatomy of all autonomic pathways can best be understood by picturing..
double-barrelled neuronal construct consisting of preganglionic neuron leading to intermediate ganglion (contains cell bodies of post-ganglionic neurons that innervate effector)
Sensory Input
a) SNS
b) ANS
a) from somatic senses & special senses
b) mostly from interoceptors, some from ^
control of motor output
a) SNS
b) ANS
a) voluntary control
b) involuntary
motor neuron pathway
a) SNS
b) ANS
a) one-neuron pathway → somatic motor neurons from CNS synapse directly with effector
b) two-neuron pathway
neurotransmitters & hormones
a) SNS
b) ANS
a) All somatic motor neurons release ACh
b) all sympathetic & parasympathetic preganglionic neurons release ACh
most sympathetic postganglionic neurons release NE , to sweat glands - release ACh
parasympathetic post-ganglionic neurons → ACh
(2) divisions of ANS
parasympathetic
sympathetic
Most body organs have __ __
dual innervation → recieve impulses from both sympathetic & parasympathetic neurons
Sympathetic Division
- neuronal arrangement
single sympathetic preganglionic fibers synapses with many postganglionic branches (20 or more) to create diverging circuit
postganglionic axons terminate in several dif visceral effectors → making effects of sympathetic stimulation a widespread massive response
Parasympathetic Division
- neuronal arrangement
- more controlled response
presynaptic parasympathetic neurons synapse with only 4-5 postsynaptic neurons → supply single visceral effector
→ leads to narrow, focused action on specific organs
ANS Neurotransmitters
- how many used in entire NS?
over 100
Chemicals used to transmit chemical messages in ANS (2)
acetylcholine (ACh)
norepinephrine (NE)
Cholinergic
synapses at which ACh is used
Adrenergic
synapses at which norepinephrine & epinephrine are used
Cholinergic receptors
receptors that respond to ACh release by these cholinergic neurons
- integral membrane proteins in postsynaptic PM
(2) subtypes of cholinergic receptors
1) nicotinic receptors
2) muscarinic receptors
1) nicotinic receptors
found in?
found in ganglia, chromaffin cells of adrenal medulla & motor end plate of NMJ
2) muscarinic receptors
- found?
found in synapses with effector organs
Cholinergic neurons rekease ACh
- include?
1) all sympathetic & parasympathetic PREganglionic neurons
2) sympathetic POSTganglionic neurons that innervate most sweat glands
3) all parasympathetic POSTganglionic neurons
Norepinephrine (NE) & Epinepinephrine (E) can be released as? by?
1) as neurotransmitter by sympathetic postganglionic neurons (NE)
2) as hormone into blood by chromaffin cells of adrenal medullae (NE & E)
(2) main types of adrenergic receptors
1) alpha receptors
2) beta receptors
- found on visceral effectors innervated by most sympathetic postganglionic axons
alpha & beta receptors are further broken down into…based on?
alpha-1
beta-1
- (excitation)
alpha-2
beta-2
- (inhibition)
- based on specific responses elicited & by their selective binding of drugs that activate/block them*
Norepinephrine favors which adrenergic receptors?
alpha-1 & alpha-2
Epinephrine works on both receptors equally well
Sympathetic Stimulation leads to? (7)
1) secretion of NE by adrenal glands
2) increase in rate/strength of heartbeat
3) constriction of BV on non-essential organs
4) dilation of essential organs’ vessels
5) increase of breathing rate/depth
6) conversion of glycogen → glucose
7) decrease in GI activity
Responses of Parasympathetic NS
- (6) increases
- (3) decreases
Increased: (SLUDD)
- salivation
- lacrimation
- urination
- digestion
- defecation
Decreased:
- rate/force of heartbeat (atrial)
- airway size & rate of breathing
- pupil size
