N24- Swallowing + (look at oral bio swallowing ) -

Question 1

what is the anatomical definition of a sphincter?

Answer 1

circular muscle closing an opening (visible post-mortem)

Question 2

what is the physiological definition of a sphincter?

Answer 2

muscle which binds an opening tightly( may not be visible post Mortem)

Question 3

Name the upper and lower oesophageal sphincters and what type of sphincter are they?

Answer 3

• Upper- Cricopharyngeus
• Lower - slight thickening of wall
• physiological but not anatomical sphincters

Question 4

what are the two types of swallowing muscles?

Answer 4

• obligate

- facultative

Question 5

Describe obligate swallowing muscles.

Answer 5

• same action every time
• “all-or none” action
• Example: mylohyoid, palatopharyngeus, pharyngeal constrictors , oesophageal muscles

Question 6

Describe facultative swallowing muscles.

Answer 6

• roles variable from one swallow to another
• roles variable from one individual to another
• Example: lip muscles, facial muscles , jaw closing muscle, extrinsic tongue muscles

Question 7

Describe the neural control of swallowing.

Answer 7

• In the swallowing centre in the CNS
• beginning in the dorsal centre (pattern generator )
• to ventral centre for relay
• to swallowing muscle motor neurones and autonomic nerves
• to swallowing muscles

Question 8

What nervous system controls reflex swallowing?

Answer 8

peripheral

Question 9

Describe the peripheral nervous system in reflex swallowing.

Answer 9

• mechanoreceptive nerves
• receptors at back. of the mouth and pharynx esp anterior tonsillar pillars
• water sensitive nerves around epiglottis
• chemoreceptors in mouth
• synpases mainly in nucleus of solitary tract (dorsal swallowing centre)

Question 10

what nervous system control voluntary swallowing?

Answer 10

central nervous system

Question 11

Describe the central nervous system in voluntary swallowing.

Answer 11

• cerebral cortex

- related to sensory perception of bolus:food particles small enough, bolus cohesive , enough taste extracted

Question 12

what are the roles of the swallowing centre?

Answer 12

• idenitfy initiating signal as correct one for swallowing (and not gagging)
• generate and send out appropriate signals to motor neurones to produce “all-or-nothing” swallowing

Question 13

where is the swallowing centre located?

Answer 13

• in brainstem(medulla)
• dorsal part: nucleus of the solitary tract
• ventral part- medial reticular formation

Question 14

what is the stimuli for gag reflex?

Answer 14

• mechanical at back of mouth/oropharynx e.g. soft palate, tonsillar pillars, base of tongue
• rarely food
• often dental procedures

Question 15

what sensory fibres of what cranial nerves are involved in gag reflex?

Answer 15

• IX
• X
• V

Question 16

what does the CNS determine?

Answer 16

swallowing or gagging and to suppress the other