alimentary control Flashcards
what are the nerve divisions involved in alimentary control?
somatic (voluntary)
- sensory
- motor
autonomic (involuntary)
- sympathetic
- parasympathetic
what are the hormones in the GIT?
- cholecystokinin (CCK)
- gastrin
- gastric inhibitory peptide (GIP)
- secretin
where is CCK secreted from and what is its function?
the duodenum endocrine cells
- functions to help digest fats and proteins
where is gastrin secreted from and what is its function?
G cells in the stomach
- functions to stimulate HCL by parietal cells
what is the function of GIP?
increases insulin secretion
what is the function of secretin?
increase HC03 (bicarbonate) from the pancreas
where are hormones most active?
at the level of the stomach
what is secretory control done by?
entirely neural via some cranial nerves
what are the cranial nerves involved with chemical taste and smell secretion control?
taste- 7 and 9
smell- 1
what cranial nerve is involved with mechanical chewing secretion control?
loading periodontal ligaments CN 5
what are the stimuli involved with salivatory secretion?
- vision
- olfactory (smell)
- mechanical (chewing)
- chemical (taste)
what muscles are involved in chewing?
jaw, facial and tongue muscles
which cranial nerves are involved in chewing?
5, 7, 12
what muscles are involved in swallowing?
jaw, tongue and pharyngeal muscles
what cranial nerves are involved with swallowing?
5, 9, 10 and 12
what muscles are involved in the oesophagus?
mix of skeletal and smooth muscle
what cranial nerve is involved with the oesophagus?
10- vagus
what are the functions of the stomach?
- secretion (gastric juice)
- motility (filling, relaxation, mixing, peristalsis, emptying)
what are the stimuli of gastric activity?
cephalic phase
- mechanical chewing (muscles of mastication)
- chemical (taste, smell)
- psychic (visual, emotional)
gastric phase- stimulates secretion
- mechanical (distension)
- chemical (food in stomach)
intestinal phase
- mechanical (distension)
- chemical (acid, protein in duodenum)
what is distension?
knowing you’re full
what are the controls of gastric activity?
cephalic phase
- nerves (long reflex)
gastric phase
- nerves (long & short reflexes)
- hormones (gastrin)
intestinal phase
- nerves (long & short reflexes)
- hormones (GIP and secretin)
- tends to slow gastric emptying
short vs long nerve reflexes
long- to brain
short- locally at that site
what are the functions of the small intestine?
- absorption
- secretions (intestinal juice)
- motility (mixing, villus movements, segmentation contractions, peristalsis)
what are the controls of the small intestine?
mainly by local nerves/short reflexes in response to intra-luminal stimuli