Alimentary Control Flashcards
What are the types of somatic nerves in the alimentary system?
motor
sensory
What are the types of autonomic nerves in the alimentary system?
parasympathetic
sympathetic
What hormones are secreted in the GIT?
CCK (cholecystokinin)
Gastrin
Gastric inhibitory peptide (GIP) (increase insulin!!)
Secretin
What is CCK (cholecystokinin)?
secreted by the duodenum endocrine cells
bile sac mover and mainly works by promoting the digestion of fat and protein. It also is an appetite suppressant.
What cells release gastrin?
G cells in the stomach
What is gastric inhibitory peptide?
weak inhibition of stomach acid secretion, but actually stimulates insulin secretion, stops death of pancreatic beta cells (insulin producing cells), stimulates glucagon and also accumulation of fat.
main role is insulin secretion stimulation
What does gastrin do?
stimulate production of HCL by parietal cells
What does secretin do?
active in the duodenum
it reduces gastric acid secretion and increases bicarbonate (HCO3) secretion from the pancreas
Where are hormones most active?
stomach
What regions in the alimentary system are somatic?
mouth
anal canal
What nerves have a role in taste and as a result cause an increase in saliva secretion?
facial nerve (VII) for front 2/3 of tongue
glossopharyngeal nerve (IX) for back 1/3 of tongue
What nerve controls smell?
olfactory (I)
What is the strongest stimuli of saliva?
chemical (taste and smell)
What is the weakest stimuli of saliva?
psychic (visual)
What muscle type controls chewing?
skeletal
What nerve is involved in periodontal ligament loading and results in an increase in saliva secretion?
trigemenal nerve (V)
What nerves control chewing and what muscles do they innervate?
trigeminal (V) nerve - muscles of mastication
facial nerve (VII) - facial muscles
hypoglossal (XII) – tongue muscles
What muscle type controls swallowing?
skeletal
What nerves control swallowing?
trigeminal (V)
vagus (X)
hypoglossal (XII)
glossopharyngeal (IX)
What is inhibited during deglutition?
respiration
Where is the swallowing centre found in the brain?
brainstem
What nerve controls the oesophagus?
vagus (X)
What muscle types are found in the oesophagus?
skeletal and smooth
What is gastric juice and where is it found?
hydrochloric acid (HCl), lipase, and pepsin
stomach
What are the muscle layers of the stomach?
innermost oblique, middle circular, longitudinal outer
What is the process in which substances move in the GIT?
peristalsis
What are the 3 phases that stimulate gastric activity?
Celiac phase
Gastric phase
Intestinal phase
What is the cephalic phase compromised of?
mechanical (chewing- muscles of mastication)
chemical (taste, smell)
psychic (visual, emotional)
What is the gastric phase compromised of?
mechanical (digestion)
chemical (food in stomach)
What is the intestinal phase compromised of?
mechanical (distension)
chemical (acid, protein in the duodenum)
What is a long reflex?
to the brain
What is a short reflex?
locally
What is the control (nervation and hormonal) of the cephalic phase?
long reflex
What is the control (nervation and hormonal) of the gastric phase?
nerves (long and short reflexes)
hormones (gastrin)
What is the control (nervation and hormonal) of the intestinal phase?
nerves (long and short reflexes)
hormones (GIP, CCK secretin)
What are the controls of the small intestine?
mainly short reflexes in response to intra stimuli
What muscle contracts in the small intestine?
smooth muscle
What has the greatest effect on pancreatic bicarbonate secretion?
vagus nerve (cephalic and gastric phase), CCK and VIP all have a weak stimulatory effect on bicarbonate
only secretin has a great one
What is VIP?
Vasoactive intestinal polypeptide
breaks down glycogen
relaxes the smooth muscle of the gall bladder and the stomach.
Is the gallbladder essential?
no
What can the gallbladder sometimes have?
stones made of cholesterol
What has the greatest effect on pancreatic enzyme secretion?
vagus nerve (celiac and gastric) = small effect
gastrin and GIP = small effect
CCK = big effect, stimulates secretion of enzyme rich pancreatic juice
What is the effect of the vagus nerve on the secretion of bile?
relaxation of the sphincter of Oddi
What is the effect of CCK on the secretion of bile?
stimulates contraction of gall bladder
relaxation of the sphincter of Oddi
What is the effect of secretin of the secretion of bile?
stimulates contraction of gall bladder
relaxation of the sphincter of Oddi
(weaker than CCK)
What are the secretions of the large intestine and rectum?
mucus
water and electrolytes
What kind of reflexes control mixing in large bowl?
long
How are long reflexes in the large intestine triggered?
food entering the stomach
What is the gastro-ileal reflex?
gastric activity increased motility in ileum
What is the gastro-colic reflex?
gastric activity increased motility in colon
What is the nerve supply of the colon up to the splenic flexure?
vagus (X)
What is the nerve supply of the descending colon and rectum?
pelvic nerves (S2-4)
What somatic nerve controls the anal canal?
sacral nerve
What ANS branch is the internal anal sphincter controlled by?
parasympathetic
What nerves is the external anal sphincter controlled by?
skeletal muscle that is controlled by somatic nerve supply from the Inferior anal branch of the Pudendal nerve (S2,3,4), which allows conscious control of defecation.
What does the defecation (rectosphincter) reflex result in?
relaxes the internal sphincter. If defecation is not desired, voluntary contraction of the external sphincter can delay it.
series of reflexes take place that lead to:
Contraction of abdominal wall muscles
Relaxation of pelvic wall muscles
Relaxation of external anal sphincter
Peristaltic waves then facilitate the movement of faeces through the anal canal
