U4 Lecture 32 Flashcards
the ANS operates via??
reflex arcs
is the ANS voluntary or involuntary
involuntary
what is the ANS controlled by
centers in the hypothalamus and brain stem
what is the output from the autonomic system
2 efferent neurons exit the CNS
what is the output of the somatic system
1 efferent neuron exits the CNS
what is the effector of the autonomic system
cardiac muscle, smooth muscle and glands
what is the effectors of the somatic system
skeletal muscle
where does the neuron that stimulates the skeletal muscle exit the spinal cord in the somatic nervous system
the anterior horn
what happens in the autonomic nervous system
one efferent neuron exits spinal cord at the lateral horn and synapses with another efferent neuron in a ganglion (cell bodies in the PNS)
what is the first efferent neuron called that exits the spinal cord in the ANS
preganglionic neuron
what is the second efferent neuron called that synapses with the first neuron in the ANS
postganglionic neuron
what does the sympathetic division of the ANS do
fight or flight
prepares body for stress
what does the parasympathetic division of the ANS do
rest and digest
promotes digestion and storage of nutrients
where are most ganglia located
near the spinal cord
what is thoracolumbar
preganglionic neurons begin in the thoracic and lumbar regions of the spinal cord
what is the sympathetic trunk (chain) and what does it do
paired ganglia near spinal cord, postganglionic neuron innervates visceral organs in the thoracic cavity
what is the prevertebral ganglia (collateral) and what does it do
anterior to vertebral bodies, postganglioic neurons innervate abdominopelvic organs
what is the adrenal medulla and what does it do
acts as a modified sympathetic ganglion , postganglionic neurons are short and release norepinephrine (20%) and epinephrine (80%) into the blood stream
what are NE and epinephrine called
catecholamines
what is the sympathetic trunk made of
3 cervical
11 thoracic
4 lumbar
4 sacral
what are the prevertebral ganglia made of
celiac
superior mesenteric
inferior mesenteric
what do the preganglionic neurons do in the SNS
preganglionic neurons release acetylcholine which binds to nicotinic cholinergic receptors on postganglionic cell body
what do the postganglionic neurons do in the SNS
release norepinephrine which binds to adrenergic receptors on effector cell
what do preganglionic neurons do in sweat glands
they release ACh
what do postganglionic neurons do in sweat glands
release ACh instead of NE at the effector tissue; ACh binds to muscarinic cholinergic receptors at sweat gland
what do the preganglionic neurons do in the adrenal medulla
release ACh
what do chromatin cells do in the adrenal medulla
act as postganglionic neurons and the adrenal medulla acts as a modified ganglion
what do chromatin cells release into the blood
epinephrine and norepinephrine
when is NE a neurotransmitter
when it is released from sympathetic nerve endings directly at target tissues (short lived effects )
when is NE a hormone
when it is released form the adrenal gland into the blood stream (long lasting effects)
why is epinephrine a hormone
it is released from the adrenal gland into the blood
what do adrenergic receptors do
bind epinephrine (adrenaline) and norepinephrine (noradrenaline) at effector tissues
where are alpha adrenergic receptors found and what do they do
found in smooth muscle of arterioles, bladder; result in constriction when activated
where are beta adrenergic receptors found and what do they do
they are found in heart, bronchioles, liver; cause an increase in metabolism
what is the goal of the SNS
fight or flight
to increase mental alertness increase energy availability (glucose) and body ability to handle a stressor
what are the specific responses to SNS
- mobilize fuels
- redistribution of blood flow
- decrease urinary output and digestive functions
- increae heart rate and blood pressure
- increase activity of sweat glands
- increase diameter of bronchioles
- dilation of pupils
