Digestive system

Cranial nerves involved

trigeminal, facial, glossopharyngeal, and hypoglossal nerves

Primary focus of esophagus

brings food from top to bottom

LES is the

top sphincter of the stomach

Pyloric is the

lower sphincter of the stomach

Parasympathetic fibers from

vagus

Sympathetic fibers from

celiac ganglia

Chloride is being exchanged by

bicarbonate

PCO2 is maintained by

40mmHg

HCl is released by

active transport

They are both

primary and secondary

HCl secretion

1.acetylodine ( vagus nerve) 2. Histamine (paracrine) 3. Gastrin (paracrine)

Blood from the liver goes through the gastric tissue using the

portal system

Rest converted in intestine to stercobilin, responsible for the

brown color for feces

Pancreas secrete

sodium bicarbonate

Exocrine function of pancreas

aids digestion by producing pancreatic juices containing digestive enzymes and bicarbonate

Pancreatic zymogens:

trypsinogen, chymotrypsinogen, and procarboxypeptidase

Cholecystokinin (CCK):

secreted by mucosa of duodenum in response to arrival of fats in small intestine

Lacteal carry

absorbed fats

Segmentation

movement in which stationary ring-like constrictions appear in several places along the intestine (breaking food down(mechanical))

oligo

more than 2

Ppl are lactose intolerant bc they

don’t produce the enzyme to break down lactose

80% of absorbed sugar is

glucose

Proteases (peptidases)

enzymes that digest proteins

Lipases

fat-digesting enzymes

Fatty acids can’t

be broken down

Vitamins are not digested

but absorbed unchanged

Fat-soluble vitamins:

A, D, E, and K absorbed with other lipids

If ingested without fat-containing food, they are not absorbed at all but are passed in the

feces and waste

Gut microbiome Help in

synthesis of vitamins B and K

Vitamin B6 (pyridoxine)

is a crucial water-soluble nutrient necessary for over 100 enzyme reactions, primarily protein metabolism, nerve function, and hemoglobin formation

floor of mouth

frenulum

Back of mouth

uvula

protases

breaks protein into amino acids

triglyceride

the most common type of fat (lipid) in the body, derived from food (butter, oils) and converted from excess calories, serving as energy storage between meals

lipase

breaks down lipids

ingestion

selective intake of food

digestion

mech and chem breakdown of food

absorption

uptake of nutrients molecules

compaction

absorbing water and consolidating the indigestible into feces

defecation

eliminates of feces

defecation is a

reflex action

mechanical digestion

physical breakdown

chemical

hydrolysis reaction

Example of mechanical digestion

teeth cutting, stomach crumbling

example of chemical digestion

salivary glands, pancreas, small intestine

mucosa

innermost, absorption, epithelium, lamina propria, mucosa, abundant in MALT

submucosa

connective tissue, blood vessels, lots of mast cells

mucularis externa

inner circular, motility, outer longitudinal, smooth muscle, pushes food

serosa

lubricates surfaces

digestive track

GI track, alimentary canal (30ft)

accessory organs

liver, gallbladder, pancreas, salivary glands, and teeth/tongue

submucosal plexus

controls glandular secretions movements

myenteric plexus

controls peristasis and overall motility

oral cavity

cheeks, lips, tongue, palate

how many adult teeth

32

mastication

chewing

Enamel is stronger

than the bone

lower esophageal sphincter (LES)

gatekeeper

peristalsis

pushes food down the tube

oral phase

voluntary

pharyngeal phase

involuntary

esophageal phase

peristalisis

saliva & glands functions

moistens, digests starch/fat, cleanses

composition of saliva

amylase, lipase, mucus, and lysosomes

Amylase

An enzyme breaks down starch into sugars

parotid

in front of earbud

Glands of saliva

parotid, submandibular, sublingual

sublingual

under tongue

rugae

wrinkle within lining

hemorrhoids

swollen veins in your anus

pharynx layers

nasopharynx, oropharynx, laryngopharynx

the stomach produces

chyme

cardiac

upper curve “j”

fundic

top part

pyloric

bottom curve

dysphagia

difficulty swallowing

parietal

secretes HCL & intrinsic

blood supply parasympathetic fibers

from vagus nerve

blood supply drains from

celiac trunk into the hepatic portal

parasympathetic nerve involved

Vagus, CN 10

gastric secretions

HCL, pepsin, gastric lipase, intrinsic factor, chemical messengers

g cells

secretes gastrin

cephalic phase

sight/thoughts

gastric phase

food in stomach (pH 1.5-3.5 very acidic)

intestinal phase

chyme in duodueum

liver

bile production, 2nd largest organ

gallbladder

hydrophobic, stores and concentration bile

bile componets

bilirubin, bile acids/salts

pancreases endocrine function

insulin ang glucacgon

pancreases exocrine function

pancreatic juice =(99% acini)

pancreases enzyme

trypsin, amylase, lipase, ribonuclease

mucos

prevent the stomach from digesting itself

pepsin

digestive enzyme

chyme

paste released into the duodenum

chemical of stomach

pepsin

mechanical of stomach

chyme

duodenum

neutralizes acid (top part)

jejunum

most digestion/absorption (40%)

ileum

Peyer patches (absorb fat-soluble) 60%

surface area enchantments

circular folds, villi, microvilli