The Autonomic Nervous System

Front 1

Describe the sensory arm of the ANS, noting the general types of receptors supplying input.

Back 1

Interoceptors
We don't focus on it much, but it's vital for the motor arm
Monitors internal environment

Front 2

Compare and contrast the motor pathways of the somatic nervous system (SNS) and the autonomic nervous system (ANS).

Back 2

SNS - pathway = single neuron/lower motor neuron; motor fibers myelinated; effectors are skeletal muscles; NT at neuroeffector jct or NMJ is ACh
ANS - 1st neuron is preganglionic neuron, w/cell body in autonimic nucleus and axon extending out to a ganglion; synapses in autonomic gangion with a postganglionic neuron (2nd neuron) - has axon from ganglion to effector (smooth, cardiac, glands); preganglionic = myelinated, postganglionic - unmyelinated; NT at synapse in autonomic ganglia = ACh, NT at neuroeffector jct = ACH or NE

Front 3

Cholinergic fiber

Back 3

preganglionic fiber - myelinated, releases ACh

Front 4

Adenergic fiber

Back 4

postganglionic fiber - unmyelinated; relases ACh if it's parasympathetic and NE if it's sympathetic

Front 5

What is a preganglionic neuron? a postganglionic neuron?

Back 5

Pre - 1st in pathway, cell body in autonimic nucleus in CNS, axon extends to ganglion; myelinated; releases ACh always; called cholinergic
Post - axon from ganglion to effectors of ANS; unmyelinated; NT is ACh if it's parasympathetic, and NE if it's sympathetic; called adenergic

Front 6

Between the preganglionic neuron and the postganglionic neuron, which releases NT at a synapse within a ganglion? at the neuro effector synapse?

Back 6

- Preganglionic
- Postganglionic

Front 7

What are the CNS origins of the parasympathetic division?

Back 7

- called the craniosacral division of the ANS
- arises from neuron cell bodies located in brain stem and sacral regions of the spinal cord

Front 8

Where do parasympathetic preganglionic neurons synapse with postganglionic neurons (i.e. general name and location of the ganglia)?

Back 8

- In intramural ganglia - in the wall of the effector
- in terminal ganglia - close to or in the wall of visceral organ
Note: postganglionic are very short and synapse with effector cells in the local area

Front 9

Which body regions and organs are served by parasympathetic preganglionic fibers originating with CNs III, VII, and IX?

Back 9

CNIII - smooth muscle in eye; synapses in ciliary ganglion; lens accomidation; constriction of pupil; important for near visino
CN VII - secretory activity of large glands in head; synapses in pterygopalatine ganglion (nasal mucose, lacrimal glands) and submandibular ganglion (salivary glands)
CN IX - salivary glands (parotid gland/biggest one); otic ganglion

Front 10

Which body regions and organs are served by parasympathetic preganglionic fibers originating with CN X?

Back 10

- 90% of parasympathetic preganglionic fibers; Vagus nerve
- Synapse in intramural ganglia
- branches into plexuses serving heart, lungs, esophagus (cardiac, pulmonary and esophageal plexuses)
- Fibers from R + L vagus intermingle and form anterior and posterior vagal trunks - gastrointestinal organs
- Abdominal cavity - through aortic plexus and branches to abdominal viscera (kidney etc?)

Front 11

Name the nerves that carry parasympathetic preganglionic fibers originating at the S2-S4 level of the spinal cord.

Back 11

- Pelvic (splanchnic) nerves
- see ppt.
innervate genitalia, urinary bladder, inferior hypogastric plexus

Front 12

Intramural ganglion

Back 12

In wall of effector; where the preganglionic and postganglionic fibers of the parasympathetic division of ANS synapse

Front 13

Terminal ganglion

Back 13

Close to or in wall of visceral organ; where the preganglionic and postganglionic fibers of parasympathetic division of the ANS synapse

Front 14

Where specifically does the sympathetic division arise?

Back 14

- the ventral roots of spinal nerves T1-L2
- Cell bodies of the preganglionic neurons are located in the lateral horns of these cord segments

Front 15

Trace the pathway of sympathetic preganglionic fibers from the spinal cord to a paravertebral ganglion.

Back 15

Preganglionic fibers = short, leave cord in ventral roots; exit through intervertebral foramen
Exit - white ramus communicans (plural is white rami communicates)
Enter paravertabral ganglion at the same level of the
These ganglia lie in a vertical row on each side of the vertebral column like a row of pearls form base of skull to coccyx

Front 16

What are three things that can happen to a pregangliionic fiber in a paravertebral ganglion?

Back 16

- Can synapse with postganglionic neuron at same level
- Can ascend/descend the chain and synapse in another chain ganglion at a higher/lower level
- Can pass through the chain ganglion w/o synapsing; synapse in a collateral (prevertebral) ganglion anterior to vertebral column

Front 17

What pathway carries postganglionic fibers from a sympathetic chain ganglion to connect with a spinal nerve?

Back 17

- The gray rami communicates (present only at T1-L4 levels where sympathetic)
- Gray = nonmyelinnated; entrals ventral (or dorsal) ramus of adjoining spinal nerves
- Travel to effectors - errector pilli muscles, blood vessels, etc.

Front 18

Which is more numerous - white rami communicates or gray rami communicates? Explain your answer.

Back 18

Gray is more numerous - present all along the sympathetic chain
White present only T1-L2
Why?

Front 19

What happens in the prevertebral (collateral) ganglia? Where are they located?

Back 19

Part of pathways that pass through the chain ganglia without synapsing
- the preganglionic fibers synapse in them, just anterior to the vertebral column
- the collateral ganglia aren't paired
- they supply tissues in the abdominal cavity

Front 20

Which sympathetic preganglionic fibers synapse in the L + R superior cervical ganglia? in the L+R middle and inferior cervical ganglia? in the collateral (prevertebral) ganglia?

Back 20

- T1-T4 preganglionic fibers synapse in superior cervical ganglia (part of the pathway to the head)
- T1-T6 Preganglionic fibers synapse in middle and inferior cervical ganglia as part of the cardiac and pulmonary plexuses
T5-L2 Preganglionic fibers synapse in collateral ganglia - they form several splanchic nerves

Front 21

Name the nerves that carry preganglionic fibers to the prevertebral ganglia.

Back 21

The splanchnic nerves:
Thoracic splanchnic nerves
Lumbar and sacral splanchnic nerves

Front 22

Name the main collateral ganglia Collectively, these ganglia innervate organs in what body cavity?

Back 22

Abdominal aortic plexus:
most important ganglion of abdominal aortic plexus are the (superior to inferior):
Celiac, superior mesenteric, inferior mesenteric, hypogastric
Postsynaptic neurons in these ganglia supply organs of abdominopelvic cavity: liver, gallbladder, spleen, genitals, intestines, stomach, etc

Front 23

Describe the pathway of the sympathetic preganglionic fibers that synapse with catecholamin-secreting cells in the adrenal medulla.

Back 23

Travel in thoracic splanchnic nerves (most of splanchnic nerves formed bye preganglionic fibers that synapse in Collateral ganglia); but don't synapse
They synapse with chromaffin cells in adrenal medula; causes NE and epinepherine secretion into blood; NT release from postganglionic neurons occurs at varicosities, rather than synaptic knob on teledendria (swellings of NT filled vessicles)
Hormones - long, widespread duration; unmyelinated fiber

Front 24

Explain why the epinephrine and norepinephrine secreting cells of the adrenal medulla are correctly classified as modified sympathetic postganglionic neurons.

Back 24

- unmyelinated fibers, release NT, stimulation of nerve fiber causes release of NT; synapse in ganglion; the postganglionic fiber is longer than the preganglionic fiber???

Front 25

Name and describe the synaptic terminals of sympathetic postganglionic fibers.

Back 25

Occurs at varicosities rather than at synaptic knobs on teledendria; structures filled with NT vesicles; varicosities and receptors scattered
Postganglionic fiber is unmyelinated; no special receptor region (less specific then parasympathetic response);

Front 26

What is a cholinergic fiber? an adrenergic fiber?

Back 26

Cholinergic - fibers that release ACh
Adrenergic - fibers that release NE at a synapse

Front 27

Which fibers of the ANS are cholinergic? Which are adrenergic?

Back 27

Cholinergic - all preganglionic axons of ANS; all parasmpathetic postganglionic fibers @ synapses w/their effectors
Adrenergic - most sympathetic postganglionic fibers

Front 28

Which division of the ANS is sometimes called the thoracolumbar division? the craniosacral? Explain these designations?

Back 28

Thoracolumbar division - arises from ventral roots of spinal nerves T1-L2; cell bodies of preganglionic neurons located in lateral horns of this part of the spinal cord
Craniosacral - Parasympathetic division - because it arises from neuron cell bodies located in brain stem and sacral regions of the spinal cord

Front 29

Identify the two types of cholinergic receptors. What is the general effect of activation (by ACh binding) of each receptor type?

Back 29

Nicotinic receptors (in both sympathetic and parasympathetic systems); found in NMJ of SNS, all postganglionic neurons, catecholamine-secreting cells of adrenal medula; effect = depolarizes/stimulates/excitation of neuron or effector cell
Muscarinic receptors - effector cells stimulated by postganglionic cholinergic fibers including parasympathetc effectors + a few sympathetic (eccarine sweat glands); effect depends on the type of ion channel that opens/closes; ex k channels in heart hyperpolarize and slow heart; ex2 nonspecific ion channel in bladder and respiratory depolarizes - urinate and airway smaller

Front 30

Identify the classes of adrenergic receptors.

Back 30

Alpha receptors
Beta receptors - act by increasing intracellular cAMP levels, effect varies in cells

Front 31

Identify the subclasses of alpha receptors (a class of adrenergic receptors).

Back 31

Alpha 1 - in blood vessels serving skin, mucosa, abdominal viscera, kidneys salivary glands, all sympathetic except heart; excitatory - more Ca ions makes more contraction, secretion, tone, pupil dilation, vasoconstriction
Alpha 2 - in some vascular smooth muscle, blood platelets, beta cells (secrete insulin), acinar cells (digestive secretions of pancreas); inhibitory - less cAMP - decrease in lipolysis, adipose tissue, platelet agregation, lenin release from kidney

Front 32

Identify the subclasses of beta receptors (a class of adrenergic receptors).

Back 32

Beta 1 - in cardiac muscle, posterior petuitary, adipose tissue, kidney; excitatory - increase in HR, contractility/forcefulness of heart
Beta 2- in smooth muscle in walls of blood vessels, respiratory passages, digestive tract, bladder and ureters; inhibitory - relaxation of smooth muscle
Beta 3 - in adipose tissue; stimulates lipolysis

Front 33

Abdominal aortic plexus

Back 33

Splanchnic nerves contribute
Most important ganglion are:
Celiac, superior mesenteric, interior mesenteric, hypogastric
supply organs of abdominopelvic cavity - liver, gallbladder, spleen, genetals, intestines, stomach etc

Front 34

Explain why sympathetic activation vs. parasympathetic produces effects that are longer lasting and more widespread throughout body.

Back 34

Sympathetic uses hormones (ACh and NE); no special receptor region, less specific than parasympathetic; NT release occurs at scattered varicosities - also scattered receptors; NE's effects last longer than ACh b/c taken up more slowly and adrenal medula releases catecholamines to keep them busy with its reuptake
Paraympathetic synapses with effector cells in local area; NT release is on synaptic knobs of teledendria directly to effector

Front 35

Decscirbe the physiologic effects of sympathetic activation.

Back 35

Fight or flght; usually discharged simultaneously, except with sweat glands
- Constriction of cutaneous blood vessels; increased HR, force of contractipn, blood flow to skeletal musles and away form viscera, lypolysis for energy to muscles; dilation of pupils and respirator passages; increased work of arrector pilli muscles and sweat glands

Front 36

Describe the physiologic effects of parasympathetic activation.

Back 36

SLUDD - Salivation, Lacrimation, Urination, Digestion, Defication
Relaxation, food processing and energy conservation/absorption
Also: decreased HR, bronchoconstriction, pupil constriction

Front 37

What is meant by the term agonist? Antagonist?

Back 37

Main muscle for a movement; main function
Antagonist - opposing movement or function

Front 38

Explain why blood vessels are said to exhibit sympathetic(vasomotor) tone.

Back 38

Dual innervation, with one division having predominant control
- Sympathetic (vasomotor) control b/c vessels are always partially constricted - sympathetic system is dominant here

Front 39

Explain why the heart at rest is said to exhibit parasympathetic (vagal) tone.

Back 39

- HR is slowed when we're at rest
- in fight or flight the sympathetic overpowers for a short period of time
Dual innervation occurs here

Front 40

What part of the CNS performs overall integration of ANS activity?

Back 40

The hypothalamus - directly and indirectly (through reticular formation)
Input from limbic system responses - emotional input, physiologic response

Front 41

Describe the control of ANS function exhibited by the reticular formation and the limbic system.

Back 41

Limbic system - sends emotional input to thalamus and produces a physiologic response
Reticular formation - the hypothalamus relays commands through reticular formation; it mediates between the different areas

Front 42

Ramus communicans (white and gray)

Back 42

White - from ventral roots of spinal cord to paravertebral ganglion at same level
Gray from paravertebral ganglion to ventral roots of spinal cord

Front 43

Ramus communicantes

Back 43

Plural of Ramus communicans

Front 44

Paravertebral ganglion

Back 44

Sympathetic chain ganglion
String of pearls alongside the spinal cord
Where the preganglionic fiber goes
From base of skull to coccyx

Front 45

Prevertebral ganglia

Back 45

Collateral ganglion
not paired; supply tissues in abdominal cavity
just anterior to vertebral column
some preganglionic fibers pass through chain/paravertabral ganglion and synapse here - they make up the splanchnic nerves
fibers from T5-L2 synapse here

Front 46

Collateral ganglia

Back 46

Prevertebral ganglion
not paired; supply tissues in abdominal cavity
just anterior to vertebral column
some preganglionic fibers pass through chain/paravertabral ganglion and synapse here - they make up the splanchnic nerves
fibers from T5-L2 synapse here

Front 47

Sympathetic chain ganglion

Back 47

Paravertevral ganglion
String of pearls alongside the spinal cord
Where the preganglionic fiber goes
From base of skull to coccyx

Front 48

Nicotinic receptor

Back 48

Binds ACh - one of two types of cholinergic receptors
Always a stimulatory effect

Front 49

Muscarinic receptor

Back 49

Binds ACh - one of two types of cholinergic receptors
Effect depends on type of ion channel that closes/opens

Front 50

Monoamine oxidase (MAO)

Back 50

Inactivates NE - slower than ACh breakdown, however
Found in low levels in tissues - causes "enzymatic inactivation"

Front 51

Catechol-O-Methyltransferase (COMT)

Back 51

One of several enzymes that degrade catecholamines like norepinepherine and epinepherine
The sympathetic division (adrenal medulla) releases other catecholamines to help keep the enzymes busy

Front 52

Contrast the sympathetic and parasympathetic motor pathways, noting differences in origin, length of preganglionic and postganglionic fibers, location of ganglia and NT profiles.

Back 52

Sympathetic - Origin:ventral roots of spinal nerves T1-L2; in the lateral horns; Fiber length: Preganglionic fibers short, post-longer; Ganglia location: paravertebral next to spinal cord, prevertebral/collateral ganglia right next to it(anterior to vertebral column); NT profiles:Preganglionic fibers release ACh and post- release NE
Parasympathetic: Origins: neural cell bodies in brain stem and sacral regions of spinal cord; Fiber Length: preganglionic are very long, postganglionic are very short, synapse with effectof cells in local area; Ganglia location: interamural or terminal ganglia in wall of effectors of wall of visc. organ; NT profiles: always releases ACh

Front 53

Which body regions and organs are served by sacral parasympathetic outflow?

Back 53

Intramural ganglia in walls of effector organs
Pelvic splanchnic nerves; inferior nypogastric plexus; urinary bladder, genitalia, etc. see ppt.