11. ANS Flashcards
(44 cards)
1
Q
Fiber connections of autonomic pathway involved in limbic system
A
- hypothalamus (centrally)
- via the fornix
- to temporal lobe
2
Q
key functions of hypothalamus related to autonomic fibers
A
- via fornix to temporal lobe (limbic system)
- receive inputs from frontal lobe
- pituitary regulation (endocrine function)
- descending autonomics (via brainstem and spinal cord)
3
Q
purpose of hypothalamus connecting descending pathway
A
Hypothalamus HAS to anatomically connect w/ the preganglionic neurons (sympathetic and parasympathetic system) in brainstem and spinal cord (via descending pathway (aka descending autonomics)
4
Q
differences between somatic and autonomic efferents?
A
-
somatic efferent:
- CNS is lower (alpha) motor neuron
- single synapse
- voluntary muscle
-
autonomic efferent:
- CNS is preganglionic neuron
- two-synapse
- involuntary muscle and glands
5
Q
autonomic nervous system: definition
A
network of neurons that regulates target organs in response to perturbation of homeostasis
6
Q
ANS responses: key characteristics
A
- automatic
- involuntary
- unconscious
7
Q
2 divisions of ANS, and the differences
A
-
sympathetic
- short-term mobilization during crisis
- short preganglionic, long postganglionic fiber
- ACh is key PREganglionic NT; Norepi is key POSTganglionic NT
-
parasympathetic
- long-term maintenance of body health
- long preganglionic, short postganlgionic fiber
- ACh is key pre- and post-ganglionics
8
Q
although sympathetic division NT is usually ACh (preganglionic), and Norepi (postganglionic); what is a pathway that is an exception?
A
ACh can act on adrenal medulla, sending Epi (or NE, DA, peptides) via bloodstream –> to effector organ
9
Q
IRIS:
Sympathetics/ parasympathetics?
A
- SNS: dilation of pupil
- Preganglionic: C8-T3
- Postganglionic: superior cervical ganglion
- PNS: constriction of pupil
- Preganglionic: Edinger-Westphal nucleus
- Postganglionic: ciliary ganglion (pupil constrictor)
10
Q
Parotid gland:
Sympathetics/ parasympathetics?
A
- SNS: secretion is reduced and viscid
- preganglionic: T1-T3
- post-gang: superior cervical ganglion
- PNS: secretion increased and watery
- pre-gang: inferior salivatory nucleus
- post-gang: otic ganglion
11
Q
heart & coronary vessels:
SNS & PNS
A
- SNS: increased HR; dilation or constriction of vessels
- pregang: T1-T5
- postgang: cervical and upper thoracic ganglia
- PNS: decreased HR; constriction of vessels
- pregang: dorsal vagal nucleus
- postgang: intracardiac ganglia
12
Q
bronchi:
SNS and PNS
A
- SNS: dilation
- pregang: T2-T5
- postgang: upper thoracic ganglia
- PNS: constriction
- pregang: dorsal vagal nucleus
- postgang: pulmonary ganglia
13
Q
stomach:
SNS and PNS
A
- SNS: inhibition of peristalisis & secretion
- pregang: T6-T10
- postgang: celiac ganglion
- PNS: inc. peristalsis & secretion
- pregang: dorsal vagal
- postgang: myenteric & submucosal ganglia
14
Q
which sympathetic preganglionic fibers involve:
T1-T5?
A
heart and coronary vessels
15
Q
which sympathetic POSTganglionic fibers involve:
superior cervical ganglion?
A
iris &
parotid gland
16
Q
which sympathetic POSTganglionic fibers involve:
cervical and upper thoracic ganglia
A
heart and coronary vessels
17
Q
which parasympathetic PREganglionic fibers involve:
dorsal vagal nucleus?
A
- heart
- coronary vessels
- bronchi
- stomach
18
Q
portions of spinal cord associated wih parasympathetics?
A
cranial and sacral
19
Q
portions of spinal cord associated wih SYMPATHETICS?
and pathway
A
- thoracic and lumbar (~T1-L2) –> preganglionics emerge
- pregang synapse in SYMPATHETIC TRUNK –>
- postganglionics travel –>
- to target organs & syanpse there
20
Q
which ganglia/targets do the VAGUS nerve synapse with?
A
- cardiac ganglion –> heart
- bronchial ganglion –> lungs
- pulmonary ganglion –> lungs
- enteric ganglion –> stomach
21
Q
sympathetic flow from CNS to target organ
A
- from lateral horn of spinal cord –>
- via visceral efferent fibers –>
- peripheral nerve –>
- white communicating ramus –>
- to sympathetic trunk –> a few possible paths
- @ spinal cord level: via gray communicating ramus to blood vessels/skin
- @ spinal cord level: to prevertebral ganglion –> viscera
- ascending thru sympathetic trunk
- descending thru sympathetic trunk
22
Q
preganglionic spinal outflow to parasympathetic ganglia:
for ocular constrictor, glands, and vagus
A
- Edinger-westphal nucleus –> oculomotor nerve (CN III) –> pupil constrictor
- salivatory nuclei –> facial nerve (VII) and glossopharyngeal (IX) –> innervates glands
- doesal motor nucleus of vagus (X) & nucleus ambiguous –> vagus nerve –> outputs of vagus
23
Q
sympathetic division effects, via descending autonomics
A
- ascends sympathetic chain –> stellate ganglion –> superior cervical ganglion –>
- eye –> dilates pupils
- lacrimal & salivary glands –> decreases salivation
- sympathetic chain –> heart & lungs –> inc respiratory & heart rate, & constricts BVs
- sympathetic chain –> celiac ganglion –> stomach –> inhibits digestive processes
24
Q
parasympathetic division effects, via descending autonomics
A
from descending autonomics –>
- oculomotor nerve (CN 3) –> eye –> constricts pupil
- facial nerve (CN 7) & glossopharyngeal (9) –> parotid gland –> increases salivation
- vagus nerve (CN 10) –> lung –> decreases respiratory rate
- vagus nerve (CN 10) –> heart –> decreases HR
- vagus nerve (CN 10) –> stomach –> stimulates digestive processes
25
which parasympathetic nerve originates in :
MIDBRAIN
OCULOMOTOR (CN III) --\> eye --\> pupil constriction
26
which parasympathetic nerve(s) originates in :
## Footnote
**PONS**
1. **facial nerve (CN 7)** --\> parotid gland --\> inc. salivation
2. **glossopharyngeal nerve (CN 9)** --\> parotid gland --\> inc. salivation
27
which parasympathetic nerve originates in :
## Footnote
**MEDULLA**
**vagus nerve -**-\> dec. HR & resp rate, vasoDILATION, stimulates digestive processes
* cardiac g.
* bronchial g.
* pulmonary g.
* enteric g.
28
vasoDILATION / dilation of coronary vessels is a
(SNS or PNS) process
vasodilation is PARASYMPATHETIC; to decrease HR
(acts via vagus nerve)
29
hypothalamic input & output
* **visceral sensory information** from the body --\> indicating perturbation in homeostasis
* issues a command (**visceral motor command**) thru descending autonomics to restore homeostasis
30
central and peripheral components of descending autonomics?
3 neurons in pathway from hypothalamus
* **central** = **1st order neuron** of the descending autonomic pathway (hypothalamus, brainstem, spinal cord)
* **peripheral = pre- and postganglionic** autonomic neurons (2nd and 3rd order neurons)
31
CC: horner's syndrome
cause and sxs
1. lesion in descending SYMPATHETIC pathway --\> dominance of parasympathetic
2. sxs: loss of sympathetic tone to IPSILATERAL side
* pupil dilator: miosis (**constricted pupil**)
* tarsal: pstosis (**drooping eyelid**)
* sweat gland: anhidrois (**lack of sweating**)
32
CC: central horner's VS preganglionic horner's
* central horners: **anhidrosis on ipsilateral body**
* preganglionic horners: **anhidrosis on ipsilateral face**
33
visceral motor component(s) of the vagus nerve
1. motor components - **located in reticular formation; dorsal position in brainstem**
* dorsal motor nucleus of vagus nerve
* nucleus ambiguous
34
actions of visceral motor component of vagus nerve
very important pathway -- induces rest & digest in the following structures:
* innervate vessels to lung and heart
* cardiac muscle
* bronchial muscles
* smooth muscle of GI tract
* gastric secretions
35
autonomic reflex arcs:
define and key characteristics
* elicited by perturbations to fxn of ANS targets --\>
* SNS and PNS are reciprocally engaged **to restore homeostasis**
* automatic and unconscious
36
list the autonomic reflex arcs
* ocular
* cardiovascular
* glandular
* GI system
* urogenital
37
pupillary light reflex pathway:
AFFerent limb
* afferent limb - sensory inputs
1. retina, where light input is received
2. optic nerve
3. optic chiasm
4. optic tract
5. synapses in pretectal region of midbrain
38
pupillary light reflex pathway:
EFFERENT LIMB
efferent limb - motor inputs
1. syanpse in **pretectal nucleus of midbrain** --\> projects to
2. **Edinger-westphal** component (PNS) of CN3/ oculomotor nuclear complex
3. **oculomotor nerve** (CN 3)
4. **ciliary ganglion**
5. contriction of pupil
39
autonomic centers **_cardiac:_**
location, output, function
1. medullary reticular formation --\> sympathetic nucleus in spinal cord
* vasomotor cardioaccelerator and pressor
2. medullary reticular formation --\> neurons in dorsal vagal nucleus and reticular formation of medulla
* depressor and cardiodecelerator
40
principal autonomic centers: **respiration**
location, output, function
Autonomic centers in both medulla and pons:
* **medullary reticular formation** --\> phrenic, intercostal & abdominal motor neurons
* fxn: inspiration and expiration
* **pontine reticular formation** --\> medullary respiratory centers
* fxn: **apneusis** (prolonged inspiration) and **pneumotaxis** (control of expiration)
41
principal autonomic centers: **emesis (vomiting)**
location, output, fxn
* medullary centers --\> emetic center, vagal & parasympathetic preganglionic neurons
* fxn: vomiting
42
possible triggers of the vomiting reflex
Reticular formation of medulla (vomiting center):
1. **blood borne toxins, etc** --\> acting on chemoreceptor trigger zone
2. **higher cerebral cortex** (sensory input or memory/fear/anticipation) --\> vomition center
3. **stomach and other viscera vagal and sympathetic afferents** --\> vomition center
43
principal autonomic centers: **micturition**
location, output, fxn
Controlled by pons --\> fxn is **micturition**
* pontine reticular formation --\> sacral parasympathetic neurons for detrusor contraction and inhibition of somatic motor efferent neurons and supplying sphincter
44
micturition reflex
1. visceral afferents from stretch receptors (bladder) --\> to spinal cord --\>
2. ascending tracts of spinal cord --\> **pontine micturition center (PMC)**
3. integration in PMC --\> initiates micturition response --\>
4. descending pathways carry impulses to motor neurons of spinal cord
5. MOTOR
* \*PNS efferents stim contraction of detrusor muscle/ open urethral sphincter
* \*sympathetic EFFERENTS to bladder are inhibited
6. somatic motor efferents to external urethral sphincter are inhibited; sphincter muscle relaxes --\>
7. urine passes thru urethra adn bladder is emptied
