Intro to autonomic neurvous system

Question 1

What criterion is used to organize the nervous system into the SNS and the ANS?

Answer 1

The somatic nervous system involves processes that are perceived or controlled consciously.

The autonomic nervous system includes processes regulated below the conscious level.

Question 2

What kind of motor neurons are Part of autonomic nervous system?

Answer 2

The ANS consists of motor neurons that:
* Innervate smooth and cardiac muscle and glands
* Make adjustments to ensure optimal support for body activities
* Operate via subconscious control

Question 3

What are the anatomic features that distinguish the motor neurons in the SNS and the ANS?

Answer 3

The somatic nervous system has a single lower motor neuron extending from the CNS. It has large, myelinated axons and always releases ACh.

The autonomic nervous system has a chain of two lower motor neurons extending from the CNS. The first neuron synapses in a ganglion, has small myelinated axons, and always releases ACh. The second has small unmyelinated axons and releases ACh or NE.

Question 4

Effectors in Somatic nervous system vs Autonomic nervous system

Answer 4

Somatic nervous system
* Skeletal muscles
ANS
* Cardiac muscle
* Smooth muscle
* Glands

Question 5

Somatic nervous system efferent pathways and neurotransmitter effects.

Answer 5

Efferent Pathways
* A, thick, heavily myelinated somatic motor fiber makes up each pathway from the CNS to the muscle
Neurotransmitter Effects
* All somatic motor neurons release acetylcholine (ACh)
* Effects are always stimulatory

Question 6

Somatic nervous system Efferent Pathways

Answer 6

• ANS pathway is a two-neuron chain
  1. Preganglionic neuron (in CNS) has a thin, lightly myelinated preganglionic axon
  2. Ganglionic neuron in autonomic ganglion has an unmyelinated postganglionic axon that extends to the effector organ

Question 7

Somatic nervous system Neurotransmitter Effects steps

Answer 7

• Preganglionic fibers release ACh
• Postganglionic fibers release norepinephrine or ACh at effectors
• Effect is either stimulatory or inhibitory, depending on type of receptors

Question 8

What are the divisions of Autonomic nervous system?

Answer 8

1. Sympathetic division
2. Parasympathetic division

Question 9

What is role of Parasympathetic Division?

Answer 9

Rest and digest

• Promotes maintenance activities and conserves body energy
• Its activity is illustrated in a person who relaxes, reading, after a meal
• Blood pressure, heart rate, and respiratory rates are low
• Gastrointestinal tract activity is high
• Pupils are constricted and lenses are accommodated for close vision

Question 10

Role of the Sympathetic Division

Answer 10

Mobilizes the body during activity; is the “fight-or-flight” system
* Promotes adjustments during exercise, or when threatened
* Blood flow is shunted to skeletal muscles and heart
* Bronchioles dilate
* Liver releases glucose

Question 11

Compare the parasympathetic and sympathetic divisions, in terms of types of axons and locations of ganglia.

Answer 11

The parasympathetic division has short axons with relatively few branches and ganglia located close to or within the wall of the organ.

The sympathetic division has long axons with many branches and ganglia located in the sympathetic trunk or prevertebral ganglia.

Question 12

Which four cranial nerves have a
parasympathetic component? What organs are innervated by each?

Answer 12

The oculomotor nerve innervates the ciliary and constrictor muscles of the eye.

The facial nerve innervates the lacrimal, submandibular, and sublingual glands.

The glossopharnygeal nerve innervates the parotid salivary gland.

The vagus nerve innervates the thoracic organs, most of the abdominal organs, and the gonads.

Question 13

Sympathetic Trunks Pathways steps

Answer 13

1. Synapse with a ganglionic neuron within the same ganglion
2. Ascend or descend the sympathetic trunk to synapse in another trunk ganglion
   3.Pass through the trunk ganglion and emerge without synapsing

Question 14

How does Postganglionic axons enter the ventral rami?

Answer 14

Postganglionic axons enter the ventral rami via the gray rami communicantes

Question 15

What are the pathways to the head?

Answer 15

• Fibers emerge from T, - T4 and synapse in the
  superior cervical ganglion
• These fibers
• Innervate skin and blood vessels of the head
• Stimulate dilator muscles of the iris
• Inhibit nasal and salivary glands

Question 16

What are Pathways to the Thorax

Answer 16

Preganglionic fibers emerge from
T, - T6 and synapse in the cervical trunk ganglia
Postganglionic fibers emerge from the middle and inferior cervical ganglia and enter nerves
C4-Cs
These fibers innervate:
* Heart via the cardiac plexus
* Thyroid gland and the skin
* Lungs and esophagus

Question 17

Pathways with Synapses in Collateral Ganglia

Answer 17

• Most fibers from T5 - L2 synapse in collateral ganglia
• They form thoracic, lumbar, and sacral splanchnic nerves
• Their ganglia include the celiac and the superior and inferior mesenteric

Question 18

Pathways to the Abdomen

Answer 18

• Preganglionic fibers from
  T5 - L2 travel through the thoracic splanchnic nerves
• Synapses occur in the celiac and superior mesenteric ganglia
• Postganglionic fibers serve the stomach, intestines, liver, spleen, and kidneys

Question 19

Pathways to the Pelvis

Answer 19

• Preganglionic fibers from T,0
• La travel via the lumbar and sacral splanchnic nerves
• Synapses occur in the inferior mesenteric and
  hypogastric ganglia
• Postganglionic fibers serve the distal half of the large intestine, the urinary bladder, and the reproductive organs

Question 20

Pathways with Synapses in the Adrenal Medulla

Answer 20

• Some preganglionic fibers pass directly to the adrenal medulla without synapsing
• Upon stimulation, medullary cells secrete norepinephrine and epinephrine into the blood
  Sympathetic Trunk