BI232 Chapt 15

Give a brief description of what "autonomic tone" is.

When there is usually some effect of both divisions at the same time

For each of the following sympathetic pathways, describe step by step what structures the various fibers pass through on their way to the target. Make sure to include any other pertinent information from your lecture presentation regarding these specific pathways

a. Spinal nerve pathway - Preganglionic fiber enters spinal nerve, then enters sympathetic ganglion (via white communicating ramus) where it synapses Preganglionic fiber may synapse in chain ganglion at the same segment, an inferior segment, or a superior segment Postganglionic fiber leaves chain ganglion (via gray communicating ramus) and re-enters spinal nerve Postganglionic fiber then continues along either ventral or dorsal ramus to target b. Splanchnic nerve pathway - Preganglionic fiber enters chain ganglion via white communicating ramus, but does not synapse Leaves chain ganglion through nerve known as a splanchnic nerve Fiber arrives at collateral ganglion, where it synapses Postganglionic fiber goes on to target c. Adrenal medullae pathway - Same as splanchnic nerve pathway, however, the preganglionic fiber does not synapse in collateral ganglion Passes through collateral ganglion and synapses in adrenal medulla

List three processes that the sympathetic division decreases (inhibits).

digestive secretion and motility, along with urine formation

List five processes that the sympathetic division of the ANS excites (enhances).

mental alertness, metabolic rate (catabolism and oxygen consumption), respiration rate, diameter of respiratory tree, heart rate, heart contractility, blood pressure, body temperature, and sweat production

List three processes that the parasympathetic division decreases (inhibits).

metabolic rate, heart rate & contractility, blood pressure, respiratory tree diameter & pupil diameter

Name the neurotransmitter released by all preganglionic sympathetic neurons. What is the effect (excitatory, inhibitory, or varied) of this neurotransmitter on the postganglionic neurons it binds to? Define the term cholinergic. What specific type of neurotransmitter receptor is located on the dendrites and cell bodies of the postganglionic sympathetic neurons, and how did these receptors get their name?

All preganglionic neurons release ACh, the effect is always excitatory. Cholinergic is relating to or denoting nerve cells in which ACh acts as the neurotransmitter The type of neurotransmitter receptor located on dendrites & cell bodies of the postganglionic sympathetic neurons is nicotinic receptors; they get their name because nicotine also binds to these receptors and has the same effect as ACh.

Various sympathetic targets have different adrenergic receptors. What are the various types of adrenergic receptors discussed in the lecture notes, and what effect does the intended neurotransmitter have on the target cell when it binds to these various receptors? What is the typical mechanism of action that brings about a change in the target cell when this particular neurotransmitter binds to its receptor?

Alpha-adrenergic receptors are usually excitatory Beta-adrenergic receptors are usually inhibitory

Give an example of an autonomic reflex initiated by stimulation of somatic receptors. Next, give an example of an autonomic reflex initiated by stimulation of visceral receptors

An example of an autonomic reflex initiated by stimulation of somatic receptors is crossed-extensor reflex or stretch reflex. An example of an autonomic reflex initiated by stimulation of visceral receptors is knee jerk reflex or blinking.

Where specifically are the cell bodies of the preganglionic sympathetic neurons located?

Cell bodies of preganglionic neurons housed in lateral gray horns (T1 - L2)

What is the function of the autonomic nervous system (ANS)? What effectors does the ANS control?

Functions of the ANS -Self-governed motor function of visceral effectors (cardiac and smooth muscle, and glands) -Thus, involuntary control of cardiovascular, respiratory, digestive, and urinary systems -Ultimately maintains homeostasis Regulates activity of visceral effectors

Norepinephrine is a common neurotransmitter of the ANS. Why is norepinephrine released from the adrenal medullae considered to be a hormone?

Ganglionic neurons release the neurotransmitters epinephrine and norepinephrine which function as hormones because they are released into blood

List the names of three specific collateral ganglia.

Inferior mesenteric, superior mesenteric & celiac ganglia

Describe two reasons why the sympathetic division of the ANS has a more widespread effect on visceral effectors of the body than the parasympathetic division does.

It has more widespread effect due to neural divergence (one preganglionic fiber might synapse with 10 - 20 postganglionic neurons) and release of adrenal medullary hormones

Are all visceral effectors innervated by only one division of the ANS, both divisions of the ANS, or does it vary?

It varies

Where specifically are the cell bodies of the preganglionic parasympathetic neurons located?

Located in the brainstem & the sacral spine (S2-S4)

List four differences between the somatic nervous system and the autonomic nervous system.

Somatic NS -voluntary control -one division -effectors: skeletal muscles -CNS motor neuron directly synapses with effector Autonomic NS -involuntary control -two divisions -effectors: visceral muscles/glands -CNS motor neuron first synapses with autonomic ganglion

What is the primary neurotransmitter released from postganglionic sympathetic neurons, onto target cells? What is the effect (excitatory, inhibitory, or varied) of this neurotransmitter on target cells? Define the term adrenergic.

Most postganglionic neurons release norepinephrine, the effect varies based on the type of receptor that is on the target cells. Adrenergic is relating to or denoting nerve cells in which epinephrine, norepinephrine or a similar substance acts as a neurotransmitter

Name the four cranial nerve pairs that carry some parasympathetic fibers. For each, list one target served by these parasympathetic fibers.

Oculomotor (III) - regulation of intrinsic eye muscles for pupil constriction and lens rounding Facial (VII) - submandibular and sublingual salivary glands; lacrimal and nasal glands Glossopharyngeal (IX) - parotid salivary glands Vagus (X) - most important; provides 90% parasympathetic motor output. Innervate structures of neck, thoracic cavity, and most of abdominopelvic cavity

For each of the following, give a brief description of what the structure is, and where it is located

Preganglionic neuron -Cell bodies housed in brainstem or gray matter of spine Preganaglionic fiber -Myelinated axons of preganglionic neurons that issue from CNS via cranial or spinal nerves -Synapse with cell bodies of autonomic ganglia Postganglionic neuron -Cell bodies housed in autonomic ganglia Postganglionic fiber -Unmyelinated axons of postganglionic neurons -Synapse with visceral effectors

How many types of sympathetic ganglia are there? Name each type and give a brief description of each.

Sympathetic Chain -are found in two chains that lie lateral to vertebral column -typically 23 ganglia on each side Collateral -(accessory or prevertebral) ganglia are three ganglia anterior to vertebral bodies Adrenal Medullae -each contain one modified ganglion -Deep inside each of the two adrenal glands

How many types of parasympathetic ganglia are there? Name each type and give a brief description of each.

Terminal ganglion: located near the target organ Intramural ganglion: located in the wall (tissue) of the target organ

Are the autonomic ganglia of the sympathetic division of the ANS located close to the spine, or relatively far away from the spine (close to the target)? Are the preganglionic fibers in this division relatively short or long? What about the postganglionic fibers?

The autonomic ganglia are relatively close to the spine. The preganglionic fibers in this division are short & myelinated. The postganglionic fibers are long & unmyelinated.

Are the autonomic ganglia of the parasympathetic division of the ANS located close to the spine, or relatively far away from the spine (close to the target)? Are the preganglionic fibers in this division relatively short or long? What about the postganglionic fibers?

The autonomic ganglia of the parasympathetic division of the ANS are located close to the target organs. The preganglionic fibers are long & myelinated. The postganglionic fibers are short & unmyelinated.

Name the neurotransmitter released by all preganglionic parasympathetic neurons. What is the effect (excitatory, inhibitory, or varied) of this neurotransmitter on the postganglionic neurons it binds to? What specific type of neurotransmitter receptor is located on the dendrites and cell bodies of the postganglionic parasympathetic neurons?

The neurotransmitter released by all preganglionic parasympathetic neurons is ACh. The effect is always excitatory The specific type of neurotransmitter receptor located on the dendrites and cell bodies of postganglionic parasympathetic neurons is nicotinic receptors.

What is the neurotransmitter released from postganglionic parasympathetic neurons, onto target cells? What is the effect (excitatory, inhibitory, or varied) of this neurotransmitter on target cells?

The neurotransmitter released from postganglionic parasympathetic neurons onto target cells ACh The effect of this neurotransmitter on target cells is excitatory or inhibitory based on the type of muscarinic receptors are present.

Which division of the ANS is considered to be the "rest and digest" division? Why is it called this?

The parasympathetic chain is considered rest and digest. It is called this because primarily inhibitory.

Which ANS division is primarily excitatory? Which is primarily inhibitory? Give an example of a situation where the primarily excitatory division inhibits a process.

The parasympathetic chain is primarily inhibitory & the sympathetic chain is primarily excitatory.

Which division is called the "craniosacral" division? Why is this?

The parasympathetic division is the craniosacral division because preganglionic fibers contained in nerves issuing from brainstem and sacral spine (S2 - S4)

Which division is commonly referred to as the "fight or flight" division? Why is this?

The sympathetic chain is considered fight or flight. It is called this because it is primarily excitatory.

Which ANS division is referred to as the "thoracolumbar" division? What does this mean?

The sympathetic division is the thoracolumbar division because preganglionic fibers travel through spinal nerves of thoracic and lumbar segments

List five processes that the parasympathetic division of the ANS excites (enhances).

serous salivary secretions, stomach & intestinal gland secretion, blood flow to digestive tract, gut motility, urination, defecation & anabolism