Control of the Alimentary System Flashcards
which two factors are involved in the control of the alimentary system
nervous control and hormonal control
which nerves are involved in control of the alimentary system
nerves from both the somatic and autonomic branches of the nervous system
how can the somatic branch of the peripheral nervous system be further divided
sensory and motor
how can the autonomic nervous system be further divided
parasympathetic and sympathetic
which group of hormones control the alimentary system
gastrointestinal tract hormones
what are the gastrointestinal tract hormones
- cholecystokinin
- gastrin
- gastric inhibitory peptide
- secretin
what does secretin do
reduces gastric acid secretion and increases bicarbonate from the pancreas
what is the sympathetic nervous system responsible for
fight or flight; increased heart rate and breathing, reduced gut motility
describe the parasympathetic nervous system
in charge of rest and digest, reducing heart rate and breathing and increasing gut motility
what is cholecystokinin
hormone secreted by the duodenum endocrine cells that helps in digestion of fats and protein
what is CCK
cholecystokinin
describe gastrin
secreted by the G cells of the stomach to stimulate hydrochloric acid by the parietal cells
what is the main role of gastric inhibitory peptide
increase insulin secretion
where in the gastrointestinal tract are the hormones most active
at the level of the stomach
what does the mouth and pharynx function in
secretion of saliva and motility for chewing and swallowing
describe saliva secretory control
some cranial nerves
how does saliva function
both chemically and mechanically
how does saliva function chemically
gustation and olfaction (taste and smell) important to note that smell has a minor effect in human beings
how does saliva function mechanically
functions in chewing and loading the periodontal ligaments
do conditioned reflexes have a large role in humans
no very minor
which cranial nerve is VII
facial nerve
which cranial nerve is IX
glossopharhyngeal
which cranial nerve is V
trigeminal nerve
give a quick description of Ivan Pavlov’s dogs experiment
discovery of classical conditioning whereby the ringing of the bell when presenting the dogs with food stimulated saliva production whenever the bell was rung, even when food was not present
what are the main stimulus that go to the brain to stimulate secretion from the salivary glands
visual
olfactory
mechanical
chemical
what is visual stimulus for saliva secretion
sight of the food
what is olfactory stimulus for saliva secretion
smell of food
what is mechanical stimulus for saliva secretion
chewing
what is chemical stimulus for saliva secretion
taste which is most potent when there is acid content
describe the process of chewing
uses the jaw, facial and tongue muscles
skeletal muscle in type, and is controlled by somatic nerves
voluntary, autonomic control via the central nerves V, VII and XII
describe the process of swallowing
uses the jaw, tongue and pharyngeal muscles
skeletal muscle in type and is controlled by somatic nerves
autonomic and reflex control is via the central nerves V, IX, X, XII and swallowing centre
which cranial nerve controls the oesophagus
X
which cranial nerve is V
trigeminal
which cranial nerve is VII
facial muscles
which cranial nerve is XII
hypoglossal
which cranial nerve is IX
glossopharyngeal
what is secreted in the stomach
gastric juice
what is involved in stomach motility
filling and relaxation
mixing
propulsive movements (peristalsis)
emptying
what are the phases to gastric activity
cephalic phase
gastric phase
intestinal phase
describe the mechanical stimuli of the cephalic phase of gastric activity
the muscles of mastication
describe the chemical stimuli of the cephalic phase of gastric activity
taste and smell
describe the pyschic stimuli of the cephalic phase of gastric activity
visual and emotional
what is involved in head stimuli
mechanical, chemical and psychic stimuli
describe the mechanical stimuli of the gastric phase
distension
describe the chemical stimuli of the gastric phase
food in the stomach
describe the mechanical stimuli of the intestinal phase
distension
describe the chemical stimuli of the intestinal phase
acids and proteins in the duodenum
what is the name of the stimuli for the gastric phase
intragastric stimuli
what is the name of the stimuli for the intestinal phase
intestinal stimuli
what is the name of the stimuli for the cephalic phase
head stimuli
what is the cephalic phase controlled by
long reflex nerves
what is the gastric phase controlled by
long and short reflex nerves and gastrin hormones
what is the intestinal phase controlled by
long and short reflex nerves, gastrointesitnal and secretin hormones and slow gastric emptying
what are long reflex nerves
these carry to the brain
what are short reflex nerves
these are local
what is GIP
gastric inhibitory peptide involved in weak inhibition of stomach acid secretion
stimulates insulin secretion
stops death of pancreatic beta cells
stimulates glucagon and accumulation of fat
what are pancreatic beta cells responsible for producing
insulin
where is secretin produced
the duodenum
what does secretin reduce the secretions from
parietal cells of acid
what does secretin increase the production of
bicarbonate from the pancreas
describe the process of nervous control of the gastrointestinal tract function
there is stimulus picked up by the receptors.
the receptors can then either travel to the nerve plexus or go to the cns before going to the nerve plexus.
the plexus goes to the smooth muscle or glands
response is initiated
describe the process of hormonal control of the gastrointestinal tract function
stimulus
receptors
endocrine cells
circulation
smooth muscle and glands
response
what are the secretions of the small intestine
intestinal juice
describe the motility functions of the small intestine
mixing, villus movements, segmentation contractions and peristalsis
how is the small intestine mainly controlled
local nerves known as short reflexes in response to intra luminal stimuli
which muscle type contracts in the small intestine
smooth muscle
what is found in pancreatic juice
bicarbonate
what is secretin released as in response to
acid
what does CCK move
the bile sac
how does CCK mainly work
by promoting the digestion of fat and protein - also an appetite suppressant
how does VIP function in the gut
breaks down glycogen and relaxes the smooth muscle of the gall bladder and the stomach
how is secretion of bile released
it is controlled by the vagus nerve which stimulates the relaxation of the sphincter of oddi
what is CCK released from the duodenum in response to
fat and protein
what stimulates the contraction of the gall bladder
CCK
what are the secretions of the large intestine and rectum
mucous and some water and electrolytes
what are the motility functions of the large intestine and rectum
mixing
mass movements
defaecation
what is super peristalsis
mass movements
what are the mixing and segmentation movements controlled by in the large intestine
local reflexes
what are long reflexes triggered by
food entering the stomach, which increases the motility in intestines
what does the gastro ileal reflex allow
increase in gastric activity on the ileum
what does the gastro colic reflex mean for the colon
increased motility on the colon - could be related to mass movements
describe the control of the large intestine and rectum
mainly neural. controlled by autonomic nervous system
which cranial nerve supplies the splenic flexure
vagus
what supplies the descending colon and rectum
the pelvic nerves
describe the control of the anal canal
autonomic control and voluntary
autonomic controls the internal sphincter
voluntary control of the external sphincter
sacral somatic nerves are also involved
describe the control of the internal anal sphincter
parasympathetic fibres which relax involuntarily
describe the control of the external anal sphincter
skeletal muscle that is controlled by somatic nerve supply from the inferior anal branch of the pudental nerve which allows conscious control of defecation
describe the rectosphincteric reflex
initiated when the rectum is distended and it relaxes the internal sphincter
what is responsible for relaxing the internal sphincter
the rectosphincteric reflex
what can delay defecation
voluntary contraction of the external sphincter
what are the series of reflexes that take place to lead to defaecation
- relaxation of the external sphincter
- contraction of abdominal wall muscles
- relaxation of pelvic wall muscles
- peristaltic waves then facilitate the movement of faeces through the anal canal
what produces gastrin
g cells
what is the gastric inhibitory peptide
a weak inhibitor
where in the alimentary is the somatic nervous system more active
at the top and bottom, as you can choose to eat and shit
where is the autonomic nervous system more active in the alimentary system
the middle
where in the alimentary system are hormones most dominant
in the area of the stomach and upper part of the small intestine
what is motility in the mouth and pharynx
the activity of chewing and swallowing
what influences production of saliva
chemical and mechanical influence
which two hormones are involved in gastric activity
GIP and secretin
what does distension mean
swelling
what do prestaltic waves facilitate
movement of faeces through the anal canal
what facilitates the movement of faeces through the anal canal
peristaltic waves