NUR 406 GI Exam 3 - 3. tast buds chemoreceptors that detect, - salt...

NUR 406 GI Exam 3

• GI tract AKA

alimentary canal

• mouth

reservoir for chewing and mixing of food with saliva

• tast buds

chemoreceptors that detect,

• salty
• sour
• bitter
• sweet

• olfactory nerve CN1

taste and smell

• how many permanent teeth do we have

32

• esophagus

• upper 1/3 striated (motor neuron innervations)

• middle 1/3 mixed striated and smooth
• lower 1/3 smooth (vagus nerve, involved in relaxation)

• upper esophagus sphincter role 1 / 4

keeps air from entering the esophagus

• lower esophagus sphincter role

gastroesophageal, allows for the passage of food into the stomach, tightens to prevent reflux.(hiatus, where the diaphragm is and esophagus passes through into the stomach)

• phases of swallowing

• oral phase

• pharyngeal phase
• esophageal phase

• steps of swallowing

• the bolus enters the pharynx and the soft palate closes the nasal cavity

• the larynx rises up to meet the epiglottis. the bolus presses on the epiglottis and bends it

downward, closing the opening to the windpipe

• the bolus enters the esophagus

• oral phase

voluntary, food bolus to back of mouth

• where is the swallowing center located

medulla oblongata in the brain stem

• pharyngeal phase

involuntary, food bolus stimulates this phase by contact 2 / 4

• esophageal phase

involuntary, peristalsis is triggered, the lower esophageal sphincter opens (relaxes) via CNX (vagus) innervation

• primary peristalsis

occurs after swallowing

• secondary peristalsis

if bolus of food becomes lodged, the increase in pres- sure stimulates contraction to move food towards stomach

• layers of the GI tract

• Mucosa

thick layer that secretes enzymes

• Submucosa

holds glands

• Muscularis

layers with peristalsis

• Serosa

protective, holds everything together

• local controls of enteric nervous system 3 / 4

• outer

myenteric plexus -> intesti- nal movements and peristalsis

• inner

submucosal plexus -> intestinal secretions and local blood flow

• autonomic NS control of enteric nervous system

• parasympathetic

• sympathetic

• parasympathetic control of GI

though vagus nerve it increases secretions, motility, and controls intestinal reflexes (relaxation of cardiac sphincter)

• sympathetic control of GI

• vasoconstriction

• inhibits motility and secretions

• intestinal smooth muscle

has its own slow wave frequency for contraction

• cardiac orfice

entrance of the esophagus to the stomach

• / 4