Medullary Reflexes

Question 1

What 2 centers control respiration?

Answer 1

• Apneustic center

- Pneumotaxic center

Question 2

Where is the pneumotaxic center found?

Answer 2

In the pons

Question 3

Where is the apneustic center found?

Answer 3

In the medulla

Question 4

Which respiratory center sends stimulation to the inspiratory area?

Answer 4

Apneunstic

Question 5

Which respiratory center inhibits the inspiratory area?

Answer 5

Pneumotaxic

Question 6

Which respiratory center causes long deep breaths?

Answer 6

Apneustic

Question 7

Which respiratory center fine tunes respiration?

Answer 7

Pneumotaxic

Question 8

How do the respiratory groups in the medulla reach somatic innervation in the body, how does the body communicate back?

Answer 8

• Reticular spinal tracts go to the cervical cord
• Travel by the phrenic nerve to diaphragm and intercostal muscles
• Afferents from alveoli through CN X go to the solitary nucleus, which triages input

Question 9

What type of reflex is respiration?

Answer 9

Visceral-somatic

Question 10

Describe the pathway of baroreceptor and chemoreceptor reflexes.

Answer 10

• BP changes/ CO2 changes stimulating baro/chemoreceptor
• Baroreceptors travel up CNs IX or X
• Go to solitary nucleus
• Decrease contractility of heart and blood vessels through the vagal nerve (CN X)

Question 11

What type of reflex is the baro/chemoreceptor reflex?

Answer 11

Visceral-visceral

Vagal-Vagal

Question 12

Describe the pathway of a cough reflex.

Answer 12

• GVA info from the trachea, larynx, or pharynx travel to the nucleus solitarius via CN X
• Solitary nucleus projects to upper respiratory centers to activate pneumotaxic center
• Pneumotaxic center causes forced expiration (at diaphragm, intercostals, and abdominals)
• Nucleus ambiguus contracts larynx and pharynx

Question 13

What initiates vomiting? Where is this structure found?

Answer 13

• Area postrema

- Floor of 4th ventricle

Question 14

How does the area postrema cause vomiting?

Answer 14

• Stimulation of AP triggers reflex
• Signal projects to reticular formation
• Travels down vagus nerve to contract contents of stomac (also relaxing gastroesophageal sphincter)
• Travels down cord to abdominal muscles to contract

Question 15

What type of reflex is the vomit reflex?

Answer 15

Visceral-visceral and visceral-somatic

Question 16

What nerve do the afferents causing the vomiting reflex travel?

Answer 16

CN X

Question 17

What type of reflex is the pupillary reflex?

Answer 17

Somatic-visceral

Question 18

How is pupil dilation changed in the pupillary reflex of the medulla?

Answer 18

Touch/ pain receptors of skin in face

Question 19

What nerve supplies the afferent component of the papillary reflex? What structure do the afferents synapse on?

Answer 19

• CN V

- Reticular formation

Question 20

Describe the efferent component of the pupillary reflex.

Answer 20

• Descends down cord from RF
• Stimulates betacell in lateral horn (Sympathetic)
• Enters superior chain ganglion
• Contracts muscle in eye

Question 21

What type of reflex is the carotid-sinus reflex?

Answer 21

Visceral-visceral

Question 22

What nerve carries the afferent fibers of the carotid-sinus reflex? What structure does it synapse on?

Answer 22

• CN IX
• Reticular formation
• Dorsal motor nucleus of CN X
  AND
• Nucleus ambiguus

Question 23

What nerve carries the fibers from the nucleus ambiguus and motor nucleus of CN X to the heart to reduce contractility in the carotid sinus reflex? Where does the nerve synpase?

Answer 23

CN X

• On SA and AV nodes, and atrial muscle

Question 24

What nervous system is used to dilate blood vessels in the carotid-sinus reflex?

Answer 24

Sympathetic