09 - NS Automatic Nervous System Flashcards
Structures that regulate ANS reflexes
Hypotalamus
Brainstem
What does the ANS regulate
visceral effectors (internal organs)
- cardiac muscles
- smooth muscles
- glands
How does the ANS receive sensory info
through interoceptors (found w/in the walls of organs)
- monitors blood CO2 levels, stretch of organs, blood vessels (blood pressure)
- not aware of this information unless damage to the viscera
what is the role of the ANS
maintain homeostasis
(blood pressure, breathing rate, digestion)
What are the parts of the central nervous system
sensory (afferent)
motor (efferent) -> somatic & automatic
Automatic -> sympathetic and parasympathetic divisions
Somatic
- one motor nerve
- skeletal muscle
Automatic
- two neurons
- cardiac muscle, smooth muscle, glands
- preganglionic and postganglionic
Sympathetic vs parasympathetic
symp: signals to put on alert
- heart: speed up
- GI tract: reduce activity
parasymp: body relax
- heart: slow down
- GI tract: increase activity
where do the cell bodies of the preganglionic neurons reside
spinal cord
How do the preganglionic neurons differ in the SNS and PNS
SNS = short
PNS = long
where is the ganglia found in the SNS and PNS
SNS = vertebral column
PNS = w/in wall of the organ being innervated
what type of neurotransmitter is used in sympathetic
effector = norepinephrine (adrenaline)
receptors = adrenergic
ganglia = acetylcholine (ACh)
receptors = nicotinic
what type of neurotransmitter is used in parasympathetic
effector = acetylcholine
receptor = muscarinic
ganglia = acetylcholine (ACh)
receptors = nicotinic
another word for sympathetic division
thoracolumbar division
what is the SNS responsible for
fright, flight, fight
what and where is the sympathetic trunk ganglia
aka vertebral chain ganglia or paravertebral ganglia
located near the vertebral column
innervate structures of the head, neck and thorax
What and where is the preventebral ganglia
aka vollateral ganglia
located anterior to the vertebral column on major abdominal arteries
innervate organs below the diaphragm
passes through the chain ganglia as SPLANCHNIC NERVES
what is the adrenal medulla made of/ what is
hosts collections of modified postganglionic neurons called chromaffin cells
What do chromaffin cells do
secrete epinephrine (adreneline) and norepinephrine (noradrenalin) into the bloodstream
What are and what do catecholamines do
hormones that are neurotransmiters made by adrenal medulla: epinephrine and norepinephrine
stimulate all sympathetic effectors through the same receptors activated by sympathetic axons
another word for parasympathetic division
craniosacral division
What is the PNS responsible for
rest, relax, ruminate
salivation, lacrimation, urination, digestion, defecation (SLUDD)
where are the parasympathetic ganglia
(intramural ganglia)
located near or within the wall of the organs innervated
which nerve innervates most of the thoracic and abdominal viscera
vagus nerve
10th cranial nerve (CN X)
t/f = organs receive input from both the sympathetic and parasympathetic NS
true
which organs only receive input from one branch
- visceral/peripheral arterioles (mostly sympathetic)
- iris sphincter - constricts pupil(only parasympathetic inputs)
- radial muscle - dilates pupil (only sympathetic input)
- eccrine sweat glands (sympathetic input)
what is the constriction of the pupil called
miosis
what is the dilation of the pupil called
mydriasis
what do cholinergic neurons do
release the neurotransmitter acetylcholine (ACh) which is quickly degraded by acetylcholinesterase
what do cholinergic neurons include
- sympathetic and parasympathetic preganglionic neurons
- all parasympathetic postganglionic neurons
- sympathetic postganglionic neurons innervating eccrine sweat glands (the only exception!)
what are the types of cholinergic receptors
- muscarinic - found on all parasympathetic target organs (effectors) and most sweat glands
- nicotinic - found on all postganglionic neurons of the ANS as well as skeletal muscle (somatic NS)
what do adrenergic neurons do
release the neurotransmitter norepinephrine (noreadrenaline)
- epinephrine & norepinephrine are also released as endocrine hormones from the adrenal medulla
what neurons are adrenergic
most sympathetic postganglionic
how does noreprinephrine compare to acetylcholine
norepinephrine is broken or removed slowly
- COMPT and MAO (enzymes) help to degrade these neurotransmitters
- the slow removal/breakdown means that SNS responses last longer than cholinergic responses
What are the types of adrenergic receptors
- alpha receptors - bind with epinephrine and norepinephrine
- beta receptors - bind preferentially with epinephrine
Alpha 1
smooth muscle contraction
- found in blood vessels of viscera (except the heart & skeletal muscle), radial muscle of iris, arrector pili muscle and sweat glands of the palms and soles
Alpha 2
pancreas (dec. insulin & digestive enzyme secretion)
- platelets (promotes aggregation)
Beta 1
(you have 1 heart)
cardiac muscle fibers (inc. HR & contracility)
pituitary (inc. ADH secretion)
adipose (inc. lipolysis)
kidney (inc. renin release)
Beta 2
(you have 2 lungs)
relaxes the bronchioles, coronary blood vessels, arterioles of skeletal muscle, uterine smooth muscle
- hepatocytes (promotes glycogenolysis
Beta 3
brown adipose tissue (thermogenesis)
- for cold temps
agonist
substance that stimulates an adrenergic receptor
antaognist
substance that blocks an adrenergic receptor
what is a beta 2 agonist used for
treating symptoms of asthma
what is the beta-1 antagonists used for
treating hypertension
