Ans

Question 1

The autonomic nervous system is activated by centres located in the?

Answer 1

Spinal cord brain stern hypothalamus

Question 2

Post ganglion neurons are

Answer 2

Unmyelinated

Question 3

Give the organisation of autonomic nervous system

Answer 3

1. Paravertebral sympathetic chain of ganglia 2. Prevertebral ganglia 3. Nerves extending from ganglia to viscera

Question 4

Name the pre vertebral ganglia

Answer 4

1. Celiac 2 superior mesentric 3 aorticorenal 4 inferior mesentric 5.hypogastric

Question 6

What is the autonomic nervous system responsible for?

Answer 6

It controls most visceral functions of the body, such as arterial pressure, gastrointestinal motility, and sweating.

The autonomic nervous system operates both entirely and partially in controlling these functions.

Question 7

How quickly can the autonomic nervous system change visceral functions?

Answer 7

It can increase heart rate to twice normal within 3 to 5 seconds and double arterial pressure within 10 to 15 seconds.

It can also decrease arterial pressure low enough to cause fainting within the same time frame.

Question 8

What are the main centers that activate the autonomic nervous system?

Answer 8

Centers located in the spinal cord, brain stem, and hypothalamus.

Portions of the cerebral cortex, especially the limbic cortex, can also influence autonomic control.

Question 9

What role do visceral reflexes play in the autonomic nervous system?

Answer 9

They allow subconscious sensory signals from visceral organs to control their activities through reflex responses.

This involves the autonomic ganglia, brain stem, or hypothalamus.

Question 10

What are the two major subdivisions of the autonomic nervous system?

Answer 10

The sympathetic nervous system and the parasympathetic nervous system.

Each has distinct characteristics and functions.

Question 11

Where do sympathetic nerve fibers originate?

Answer 11

In the spinal cord between segments T1 and L2.

These fibers pass into the sympathetic chain and then to the tissues and organs.

Question 12

What is the structure of the sympathetic pathway?

Answer 12

It is composed of two neurons: a preganglionic neuron and a postganglionic neuron.

This contrasts with the single neuron in the skeletal motor pathway.

Question 13

What happens to preganglionic sympathetic fibers after they leave the spinal nerve?

Answer 13

They pass through a white ramus into a sympathetic chain ganglion.

They can synapse in the ganglion, pass upward or downward, or travel to a peripheral sympathetic ganglion.

Question 14

What types of fibers are sympathetic nerve fibers that extend back into spinal nerves?

Answer 14

They are small type C fibers.

These fibers control blood vessels, sweat glands, and piloerector muscles of the hairs.

Question 15

What percentage of fibers in the average skeletal nerve are sympathetic fibers?

Answer 15

About 8%.

This indicates the importance of sympathetic fibers in controlling various bodily functions.

Question 16

Give pathway for sympathetic nerve fibers

Answer 16

IML to ventral rami to spinal nerve to sympathetic chain to white ramus to post ganglion nerve to spinal nerve

Question 19

What is the segmental distribution of sympathetic nerve fibers?

Answer 19

The sympathetic pathways from different spinal cord segments are not distributed to the same body parts as somatic spinal nerve fibers from those segments.

Question 20

Where do sympathetic fibers from cord segment Il generally terminate?

Answer 20

Sympathetic fibers from cord segment T1 generally pass: (1) up the sympathetic chain to terminate in the head; (2) from T2 to terminate in the neck.

Question 21

What is the termination pattern for sympathetic fibers from T3 to T6?

Answer 21

Sympathetic fibers from T3, T4, T5, and T6 terminate in the thorax.

Question 22

Where do sympathetic fibers from T7 to T11 terminate?

Answer 22

Sympathetic fibers from T7, T8, T9, T10, and T11 terminate in the abdomen.

Question 23

What determines the distribution of sympathetic nerves to each organ?

Answer 23

The distribution is determined partly by the locus in the embryo from which the organ originated.

Question 24

From where does the heart receive sympathetic nerve fibers?

Answer 24

The heart receives many sympathetic nerve fibers from the neck portion of the sympathetic chain.

Question 25

Why do abdominal organs receive sympathetic innervation from the lower thoracic spinal cord?

Answer 25

Because most of the primitive gut originated in this area.

Question 26

What is the pathway of preganglionic sympathetic nerve fibers to the adrenal medullae?

Answer 26

Preganglionic sympathetic nerve fibers pass from the intermediolateral horn cells of the spinal cord, through the sympathetic chains, then through the splanchnic nerves, and finally into the two adrenal medullae.

Question 27

What do the modified neuronal cells in the adrenal medullae secrete?

Answer 27

They secrete epinephrine and norepinephrine into the bloodstream.

Question 28

What type of cells are the secretory cells in the adrenal medullae derived from?

Answer 28

They are embryologically derived from nervous tissue and are actually postganglionic neurons.

Question 29

What cranial nerves do parasympathetic fibers leave the central nervous system through?

Answer 29

Parasympathetic fibers leave through cranial nerves III, VII, IX, and X.

Question 30

Where do additional parasympathetic fibers leave the spinal cord?

Answer 30

They leave through the second and third sacral spinal nerves and occasionally the first and fourth sacral nerves.

Question 31

What percentage of all parasympathetic nerve fibers are in the vagus nerves?

Answer 31

About 75% of all parasympathetic nerve fibers are in the vagus nerves (cranial nerve X).

Question 32

What regions of the body do the vagus nerves supply parasympathetic nerves to?

Answer 32

The entire thoracic and abdominal regions of the body.

Question 33

Which organs are supplied by the vagus nerves?

Answer 33

The heart, lungs, esophagus, stomach, entire small intestine, proximal half of the colon, liver, gallbladder, pancreas, kidneys, and upper portions of the ureters.

Question 34

What do the parasympathetic fibers in the third cranial nerve supply?

Answer 34

The pupillary sphincter and ciliary muscle of the eye.

Question 35

Which glands are supplied by the seventh cranial nerve?

Answer 35

The lacrimal, nasal, and submandibular glands.

Question 36

What gland is supplied by the ninth cranial nerve?

Answer 36

The parotid gland.

Question 37

Where are the sacral parasympathetic fibers located?

Answer 37

In the pelvic nerves, which pass through the spinal nerve sacral plexus at the S2 and S3 levels.

Question 38

What do the sacral parasympathetic fibers distribute to?

Answer 38

The descending colon, rectum, and urinary system, lours portions of ureter and also cause erection

Question 39

How is ganglia arrangement different in sympathetic and parasympathetic?

Answer 39

Only cranial nerves have A ganglia outside the target organ spinal nerves have it in the organ.

Question 40

What are the two main synaptic transmitter substances secreted by the sympathetic and parasympathetic nerve fibers?

Answer 40

The two main synaptic transmitter substances are acetylcholine and norepinephrine.

Question 41

What term is used for fibers that secrete acetylcholine?

Answer 41

Fibers that secrete acetylcholine are said to be cholinergic.

Question 42

What term is used for fibers that secrete norepinephrine?

Answer 42

Fibers that secrete norepinephrine are said to be adrenergic.

Question 43

What is the origin of the term 'adrenergic'?

Answer 43

The term 'adrenergic' is derived from adrenalin, which is an alternate name for epinephrine.

Question 44

What type of neurons are all preganglionic neurons in both the sympathetic and parasympathetic nervous systems?

Answer 44

All preganglionic neurons are cholinergic.

Question 45

What effect does acetylcholine have when applied to ganglia?

Answer 45

Acetylcholine or acetylcholine-like substances will excite both sympathetic and parasympathetic post-ganglionic neurons.

Question 46

What type of neurons are almost all postganglionic neurons of the parasympathetic system?

Answer 46

Almost all of the postganglionic neurons of the parasympathetic system are cholinergic.

Question 47

What type of neurons are most postganglionic sympathetic neurons?

Answer 47

Most of the postganglionic sympathetic neurons are adrenergic.

Question 48

Which postganglionic sympathetic nerve fibers are cholinergic?

Answer 48

The postganglionic sympathetic nerve fibers to the sweat glands and perhaps to a very few blood vessels are cholinergic.

Question 49

What do the terminal nerve endings of the parasympathetic system secrete?

Answer 49

The terminal nerve endings of the parasympathetic system all or virtually all secrete acetylcholine.

Question 50

What do almost all sympathetic nerve endings secrete?

Answer 50

Almost all of the sympathetic nerve endings secrete norepinephrine, but a few secrete acetylcholine.

Question 51

What are acetylcholine and norepinephrine called in terms of their function?

Answer 51

Acetylcholine is called a parasympathetic transmitter and norepinephrine is called a sympathetic transmitter.

Question 52

What are the postganglionic autonomic nerve endings similar to?

Answer 52

They are similar to but much smaller than those of the skeletal neuromuscular junction.

Question 53

How do many parasympathetic and sympathetic nerve fibers interact with effector cells?

Answer 53

They merely touch the effector cells or terminate in connective tissue adjacent to the cells.

Question 54

What are bulbous enlargements on nerve fibers called?

Answer 54

They are called varicosities.

Question 55

What is synthesized and stored in the varicosities?

Answer 55

Transmitter vesicles of acetylcholine or norepinephrine.

Question 56

What do varicosities contain that is essential for transmitter synthesis?

Answer 56

Large numbers of mitochondria that supply adenosine triphosphate.

Question 57

What triggers the secretion of neurotransmitters from nerve terminals?

Answer 57

The influx of calcium ions due to depolarization of the fiber membrane.

Question 58

What happens when calcium ions diffuse into nerve terminals?

Answer 58

They cause the terminals or varicosities to empty their contents to the exterior.

Question 59

What is Acetylcholine synthesized from?

Answer 59

Acetylcholine is synthesized from Acetyl-CoA and Choline by the enzyme choline acetyltransferase.

Question 60

Where is Acetylcholine stored before release?

Answer 60

Acetylcholine is stored in vesicles in the terminal endings and varicosities of cholinergic nerve fibers.

Question 61

What happens to Acetylcholine after it is secreted?

Answer 61

After secretion, Acetylcholine persists in the tissue for a few seconds before being split into acetate ion and choline by acetylcholinesterase.

Question 62

What is the role of acetylcholinesterase?

Answer 62

Acetylcholinesterase catalyzes the breakdown of Acetylcholine into acetate ion and choline.

Question 63

How is choline reused in the synthesis of Acetylcholine?

Answer 63

The choline formed after the breakdown of Acetylcholine is transported back into the terminal nerve ending for the synthesis of new Acetylcholine.

Question 64

Where does the synthesis of Norepinephrine begin?

Answer 64

The synthesis of Norepinephrine begins in the axoplasm of the terminal nerve endings of adrenergic nerve fibers.

Question 65

What are the basic steps in the synthesis of Norepinephrine?

Answer 65

1. Tyrosine is hydroxylated to form Dopa. 2. Dopa is decarboxylated to form Dopamine. 3. Dopamine is transported into the vesicles.