Digestive Flashcards
digestive tract path
mouth
pharynx: oropharynx, hypopharynx
trachea
asophagus
stomach
large intestine
accessory digestive organs
liver
gall bladder
pancreas
food processing parts
- motility/propulsion
- chemical/mechanical digestion
- absorption
- defecation
motility is due to
muscular contractions and mixing food with digestive juices
1. swallowing: oropharynx
2. peristalsis: esophagus, stomach, small intestine large intestine
parts that do mechanical digestion
- chewing: mouth
- Churning: stomach
- segmentation: small intestine
parts that do Absorption
- small intestines: nutrients, water to blood/lymph vessels
- Large intestine: water to blood vessels
digestive tunics
lumen
1. epithelium (mucosa layer)
2. lamina propria (mucosa layer) areolar CT can have lymphatic patch and blood vessels to provide nutrients and remove waste from epithelium
3. muscularis mucosa (mucosa layer):thin layer of smooth muscle can cause epithelium to fold to increase contact with food being digested
4. submucosa/nervous plexus: normally areolar CT may have glands and nervous tissue
5. muscularis 2 layers: inner circular outer longitudinal smooth muscle
6. serosa or adventitia depending on where in digestive tract. serosa for movement, adventitia melds with surrouding CT
peritoneum
largest serous membrane in the body found in the abdominal cavity and associated with digestive tract
Parts of peritoneum
- lesser omentum
- mesocolon
- mesentary
- greater omentum/fatty apron
lesser omentum characteristics
liver to the stomach
mesocolon characteristics
the transverse colon to posterior abdomen wall
greater omentum characteristics
hangs down in front of the small and large intestines. folds over itself and makes 2 layers of double membrane
mesentary characteristics
surrounds the small intestine connects the posterior ab wall. is like a fan around the small intestine
falciform ligament characteristics
connects liver to the anterior of the ab wall. looks like its dividing the liver
serous membrane
2.5 layers
1. visceral: against the organs
1.5 paritoneal cavity has paritoneal fluid between membranes for blood vessels nervs and lymph vessels to access organs
2. parietal: lines the wall of the cavity
salivary glands
- parotid gland: carries saliva and amylase through the parotid duct to the upper cheeck by second molar. largest, between the ear and masseter.
- submandibular gland: carries amylase and mucus. 2nd largest. along the mandible
- sublingual gland: only saliva/mucus. about 10-12 small ducts to release saliva
How much saliva per day
1.5 L. parasympathetic (relax and digest) stimulates flow
which nervous system is for digestion
parasympathetic. sympathetic inhibits it and gives dry mouth
saliva composition
- 99% water: dissolves food for taste, provide H2O for hydrolysis
- IGA immunoglobulin: antibacterial
- Phosphate ions/salts
- HCO3- : buffers pH
- Cl- : activates saliva amylase
- Amylase: digests amylose part of starch/carbs
- lysoszomes: damage bacteria cell walls
- mucus: lubricates food for easier swallowing
Saliva function
- moisten mouth, aid in swallowing
- Start digestion of starches with amylase
- clean/get things away from teeth
- inhibit bacteria growth
- dissolves food molecules which stimulates taste buds
extrinsic tongue muscle
Cranial nerve 12 controls, moves tongue fwd, back, side-side
FIlliform papillae
smallest of taste papillae, no taste buds only texture
esophagus locatin
6th cervical-11th thoracic, posterior to trachea, peirces diaphram through esophageal hilus meets stomach at cardiac orifice
esophagus characteristics
same basic tunics as digestive system
mucosa is nonkaratinized stratified ssquamous due to friction of food.
upper esophageal sphincter: upper part has skeletal muscle (you control swallowing)
lower esophageal sphincter: lower part smooth muscle (automatic)
swallowing phases
- voluntary: tongue pushes bolus to the oropharynx
- pharyngeal phase: involuntary. food goes down esophagus
- esophageal phase: bolus to stomach through peristalsis. circular muscle closes behind, longitundinal contracts to be smaller the circular muscle contracts and pushes the bolus down
stomach holds how much food and for how long
2-4L
2-4hrs
stomach functions
- digestion
- storage
pyloris
stomach area next to the exit to the small intestine: exit controled by pyloric sphincter
Chyme
name for contents in stomach
where is a gastric gland located
bottom of the gastric pit that extends to the lamina propria
how often is epithelium in stomach replaced
3-6 days
stomach muscularis layers
- longitudinal (outside)
- circular (mid)
- oblique (deepest)
how often does the stomach mix food
15-20s
cells that line gastric pits
- chief cells: secrete pepsinogen precurser to pepsin
- parietal cells: make HCL and intrinsic factor
- mucous cells: protect epithelium
- G-cells: secrete hormone gastrine (enteroendocrine)
Pepsin
cuts C terminal of carboxyl end of: phenylalaine, leucine and glutamic acid. activated by HCL and activated pepsin
pensinogen secreted by cheif cells
Intrinsic factor
secreted by parieta cells
need intrinsic factor to absorb B12 which is needed to make mature RBC
only necessary for life function stomach does
Gastric juice properties
pH 2
2-3L/day is made