chapter 24: digestive system

wall layers of the gi tract?

1. muscosa

2. submucosa

3. muscularis

4. serosa

mucosa is lined by?

lined by specific epithelial tissue

submucosa

with submucosal plexus, the enteric nerve control of the mucosa secretion

which layer of the gi tract that is the enteric nerve control of the mucosa secretion?

submucosa

muscularis

• smooth muscle in circular and longitudinal layers

• myenteric plexus, the enteric nerve control of the smooth muscle motility

which layer of the gi tract has the enteric nerve control of smooth muscle motility?

muscular

serosa is made of?

serous membrane

peritoneum

serous membrane lining in abdominal cavity

peritoneum includes 4 parts?

• greater omentum

• lesser omentum

• mesentery

• mesocolon

greater omentum

around the stomach

lesser omentum

around the stomach

mesentery

around small intestine

mesocolon

around large intestine

teeth types?

• incisor

• canine

• premolar

• molar

incisor

blade-shaped

canine

one cuspid

premolar

bicuspid

molar

four cuspid

dentition pattern for deciduous teeth

2 incisors, 1 canine, 2 molars (=20)

dentition pattern for permanent teeth

2 incisors, 1 canine, 2 premolars, 3 molars (=32)

salivary glands

produce saliva

major pairs secrete into oral cavity

• parotid glands

• sublingual glands

• submandibular gland

exocrine glands produce?

saliva

submandibular gland % in exocrine gland saliva

70%

parotid gland % in exocrine gland saliva

25%

sublingual gland % in exocrine gland saliva

5%

salivary amylase

esophagus layers?

• mucosa

• submucosa

• muscularis

esophagus: mucosa lining tissue?

nonkeratinized stratified squamous epithelium

esophagus: muscularis lining tissue?

smooth muscle in two layers: inner circular and outer longitudinal

deglutition

• swallowing

• food passes through parts of pharynx on it way to esophagus to stomach

• divided into 3 phases

deglutition: oral phase control?

voluntary control

deglutition: pharyngeal phase control?

involuntary control

deglutition: esophageal phase control?

involuntary control

deglutition: oral phase actions?

• tongue up against soft plate → block the exit of the oral cavity → forcing bolus into oropharynx

deglutition: pharyngeal phase actions?

• uvula and soft plate upward and backward → block passage to nasopharynx

• larynx up and epiglottis down → closing air way → forcing bolus to esophagus

deglutition: esophageal phase actions?

• perstalsis push the bolus toward stomach

4 regions of the stomach

• cardia (connects to esophagus)

• fundus

• body

• pylorus - pyloric sphincter (connects to the duodenum)

stomach folds

rugae

where does the pyloric sphincter connect?

stomach → duodenum of small intestine

location of gastric gland?

gastric pits in mucosa layer

gastric gland tissue?

simple columnar epithelium

4 types of cells in the gastric gland?

• mucous cells

• parietal cells

• chief cells

• g cells

gastric gland: mucous cell secretory product

alkaline mucus

gastric gland: parietal cells secretory product

HCl acid and intrinsic factors

gastric gland: chief cell secretory product

pepsinogen (inactive proenzyme) → pepsin (active enzyme) by HCl in gastric lumen

gastric gland: g cell secretory product

gastrin (hormone)

gastric gland: mucuos cell function

form alkaline mucous barrier to protect stomach surface

gastric gland: parietal cell function

HCl:

• kill bacteria

• denature proteins for digestion

• activate pepsinogen

IF:

• cofactor for vitamin B12 absorption

gastric gland: chief cell function

• pepsin → protein (pH= 2.0 as optimal pH) → peptides

• enzymatic breakdown of proteins in stomach

gastric gland: g cell functions

• stimulate secretion of gastric juice

• stimulate gastric motility

controlling mechanism of gastric secretion 3 phases

• cephalic phase

• gastric phase

• intestinal phase

cephalic phase

• stimulation of sensory receptors on head (e.g. sight, hearing, smell, taste)

• anticipating/stimulating effect on gastric secretion

gastric phase

• stimulation on stomach

• continuously stimulating effect on gastric secretion

intestinal phase

• stimulation on small intestine

• negative feedback from small intestine

• inhibiting effect on gastric secretion

gastric secretion controlling mechanisms include?

• parasympathetic nerve (vagus nerve)

• sympathetic nerve

gastric secretion: parasympathetic nerve (vagus nerve)

stimulating effect (via neurotransmitter Acetyl Choline (ACh) on gastric secretions

gastric secretion: sympathetic nerve

inhibiting effect (via adrenergic neurotransmitter Norephinephrine) on gastric secretion

hormones of digestive tract

• gastrin

• secretin

• cholecystokinin

gastric

• by g cells of stomach

• stimulating effect on gastric secretion

secretin

• s cell of small intestine

• inhibiting effect on gastric secretion

cholecysotokinin (CCK)

• by CCK cells of small intestine

• inhibiting effect