ANS and Neural Control of Breathing Flashcards
2 components of peripheral nervous system
- afferent
2. efferenet
3 components of afferent PNS
- somatic sensory
- visceral sensory
- special sensory
2 components of efferent PNS
- somatic motor
2. autonomic motor
3 components of autonomic motor
- sympathetic
- parasympathetic
- enteric
what does ANS stand for
autonomic nervous system
what does the ANS innervate
organs/tissues other than skeletal muscle
examples of what the ANS innervates
smooth muscle, glands, heart, bladder, reproductive organs
primary function of ANS
maintaining homeostasis
enteric nervous system
controls the gut
CNS components of ANS (2)
hypothalamus and specific regions of the medulla
what is still functioning when a person is in a vegatative state
the brain stem
common features between sympathetic and parasympathetic divisions
- dual innervation
2. 2 synapses between CNS and effector
dual innervation
innervated tissues receive inputs from both sympathetic and parasympathetic systems
how many synapses are in between CNS and effector in the somatic system
1
pathway from CNS to effector with sympathetic and parasympathetic systems
preganglionic fiber, ganglion, postganglionic fiber
4 differences between parasympathetic and sympathetic anatomy
- pre- and postganglionic neurons
- transmitters
- postsynaptic receptors
- origin from CNS
difference in pre and postganglionic neurons
sympathetic preganglionic axons are short, postganglionic are long
- parasympathetic is opposite
difference in transmitters
sympathetic = acetylcholine from preganglionic, norepinephrine from postganglionic
parasympathetic = ACh from both
parasympathetic vs sympathetic postsynaptic receptors
both divisions can excite or inhibit the effector
difference in CNS origin
parasympathetic preganglionic fibers originate in brainstem and sacral spinal cord
- sympathetic preganglionic cell bodies are in thoracic and lumbar spinal cords
why is target activation generalized with the sympathetic system
preganglionic axons synapse at ganglions at multiple levels of the spinal cord
- also because adrenal gland releases epinephrine
why is parasympathetic more organ specific
because preganglionic axons only go to one ganglion
when does sympathetic activity increase
during high stress
- the fight-or-flight response
fight-or-flight response
coordinated activation of all systems to support physical exertion
hormonal component of fight-or-flight
adrenal gland releases epinephrine
when does parasympathetic activity increase
during a rest-or-digest state
dysautonomia
diverse array of diseases with neurogenic orthostatic hypotension
another name for orthostatic hypotension
postural hypotension
orthostatic hypotension
upon standing there is a fall in blood pressure as blood moves rapidly to the legs
how do healthy individuals compensate orthostatic hypotension
- drop is detected and sympathetic system releases norepinephrine
- activates alpha 1 norepinephrine receptors on smooth muscle
- smooth muscle contracts
- prevents blood from dropping into lower vessels
what happens to orthostatic hypotension if something goes wrong with norepinephrine or alpha1 NE receptors
no compensatory response
symptoms of no compensatory response
blood pressure falls, dizziness, loss of vision, pass out
syncope
pass out
what else causes compensatory response to fail
dehydration or people taking alpha1 NE blockers for high BP
what do giraffes need to deal with frequent head movements
lots of smooth muscle
neurogenic orthostatic hypotension
loss of NE neurons in brain
where does neurogenic orthostatic hypotensions occur (4 disorders)
- Parkinson’s
- Pure Autonomic Failure
- diabetic neuropathy
- Multiple System Atrophy
2 functions of respiratory networks
- control movement
2. control homeostasis of blood gases, pH, and temperature
2 features of breathing
- robust (reliable)
2. adaptable
3 significant respiratory groups in the brain
- Pontine
- Ventral
- preBotzinger Complex
source of rhythm generation
preBotzinger complex
flow chart of respiratory control
rhythm generator -> pattern generator -> motoneurons -> respiratory muscles -> afferents (mechanical and chemical)
pattern generator
composed of premotor networks and motor neurons
what is the function of the pattern generator
coordinates activity of inspitory and expitory muscles
what is the main respiratory muscle
the diaphragm
do all animals have diaphragms
no, only mammals
how do opiates effect breathing
they depress breathing
clinical problem with opiates
how do we effectively provide painkillers without depressing breathing
when was the preBotzinger Complex discovered to be the rhythm generator
in the 1990s
how was the preBotzinger Complex discovered
scientists observed an in vitro brainstem-spinal cord from a neonatal rat
- sliced it down until they found the section responsible for rhythm
4 advantages of an in vitro approach
- stability
- can apply hi-tech methodologies
- environment control
- no blood-brain barrier
3 hypotheses of rhythm generation
- network hypothesis
- pacemaker hypothesis
- group pacemaker hypothesis
network hypothesis
rhythm arises from network of neurons to produce rhythm via reciprocal inhibition or recurrent excitation
how is the network hypothesis disproven
if you block synaptic inhibition in vitro, rhythm persists
pacemaker hypothesis
neurons spontaneously generate a rhythm like in the heart
- preBotzinger complex contains pacemaker cells
how was the pacemaker hypothesis proven wrong
if pacemakers are blocked rhythm persists
group pacemaker hypothesis
rhythm is generated by recurrent excitation among interconnected pacemakers
in the group pacemaker hypothesis, are pacemakers essential to rhythm
not necessarily, but they are important in neonate
how many muscles are involved in breathing
more than 15
where are peripheral chemoreceptors located
in carotid body
where is the carotid body
where the carotid artery branches into internal and external
what do peripheral chemoreceptors do
monitor CO2, pH, and O2 of arterial blood going to the brain
another example of peripheral chemoreceptors
aortic bodies
initial hypothesis about central chemoreceptors
Rostral and Candal areas monitor CO2 and O2 levels in the brain
most important area in chemosensation
retrotrapezoid nucleus (RTN)
what area might be the RTN
the Rostral area
5 clinical disorder involving the CNS
- chronic congenital hypoventilation syndrome
- apnea of prematurity
- SIDS
- spinal cord injury
- sleep apnea
Ondine’s curse
Chronic Congenital Hypoventilation Syndrome
chronic congenital hypoventilation syndrome
lack of CO2 sensitivity, which results in a lack of desire to breath
why was chronic congenital hypoventilation syndrome difficult to study
babies who had it would die quickly
apnea of prematurity
infants born early do not have mature respiratory networks
SIDS
sudden infant death syndrome
- disease of ommission
disease of ommission
no cause of death found in first year of life, it must be SIDS
spinal cord injury
injury in high cervical region result in inability to drive the diaphragm
what causes sleep apnea
during wakefulness, motoneuron activity increases
- during sleep this decreases
- sleep apnea is caused by reduction in motoneuron activity controlling airways
what is sleep apnea
airway collapse during sleep, leading to snoring and possibly death
