Digestive System part 1 Flashcards
groups of organs that make up GI system
GI tract/gut tube
accessory organs
GI tract/gut tube
extends from mouth to anus and is 5-7m long folded up
includes:
mouth, pharynx, esophagus, stomach, small intestine, and large intestine
accessory organs
most aid in chemical breakdown of food and support GI system
includes:
teeth, tongue, salivary glands, liver, gall bladder, pancreas
processes involved in digestion
ingestion
secretion: release of water, acid, buffers, enzymes
mixing/propulsion
digestion: mechanical and chemical
absorption: products from GI sys into blood and lymph
defecation
layers of GI tract (deep to superficial)
mucosa
submucosa
muscualris
serosa
mucosa
innermost layer, lines lumen
epithelium
lamina propria
muscularis mucosae
histology of mucosa
epithelial layer
- stratified squamous: mouth, pharynx, esophagus, anus
- simple columnar: stomach and intestines, goblet cells
- enteroendocrine cells
enteroendocrine cells
secrete hormones controlling organ function into blood supply from one end of the tube to the other
histology of mucosa
lamina propria
- thin layer of loose areolar CT
- contains blood vessels (capillaries) and lymphatic tissue (MALT)
histology of mucosa
muscularis mucosae
- thin layer of smooth muscle
- causes folds to form in mucosal layer to increase SA
- movements ensure that all absorptive cells are fully exposed to GI system contents
mucosa-associated lymphatic tissue (MALT)
provides immune function if you eat something bad
- acts as a first line of defence
submucosa
consists of loose aerolar CT that contains blood vessels, glands and lymphatic tissue
- also contains submucosal plexus (enteric nervous system)
submucosal plexus
enteric nervous system
- motor portion stimulates mucosal secretions
muscularis
mostly smooth muscle, some skeletal muscle
contains myenteric plexus
- skeletal: in mouth, pharynx, upper/middle esophagus, external anal sphincter
- smooth: throughout the rest of the GI tract; inner circular and outer longitudinal fibers
myenteric plexus
controls motility, stimulates muscle layers to contract
- located between the circular and longitudinal muscle layers
serosa
outermost layer
- serous membrane (visceral peritoneum) reates pathway for blood vessels and nerves
- consistes of aerolar CT covered with simple squamous epithelium
- covers entire GI tract except esophagus
peritoneum
serous membrane in the abdominal cavity
- visceral lauer covers organs, parietal layer lines walls of body cavity
- peritoneal cavity is the space containing serous fluid
peritoneal folds
connections b/w organs or wall and an organ that hold things in place
- contain blood vessels, lymphatic vessels and nerves that supply abdominal organs
major peritoneal folds
greater omentum lesser omentum falciform ligament mesentery mesocolon
retroperitoneal
some rogans are behind the peritoneum and only have serous membrane on one side
include: kidneys, ascending/descending colon and pancreas
greater omentum
runs from stomach in front of abdominal cavity and folds and attaches to transverse colon (4 layers of serous membrane here are known as the fatty apron)
falciform ligament
runs from liver to anterior wall of abdominal cavity
lesser omentum
runs from stomach/duodenum to liver
- carries hepatic portal vein
mesentery
runs from small intestine to posterior wall of abdominal cavity
mesocolon
runs from transverse/sigmoid colon to posterior wall of abdominal cavity
oral cavity proper
area b/w teeth and fauces
hard palate
bone
forms most of the roof of the mouth
soft palate
muscular and forms the rest (posterior) of the roof of the mouth
uvula
prevents swallowed food from entering the nasal cavity
cheek
stratified squamous epithelium protects abrasion
- forms lateral wall of oral cavity
- contains buccinator muscle that help old food and produce speech
oral vestibule
the space b/w cheeks, lips, gums and teeth
superior and inferior lips are called
superior and inferior labia
gingivae
gums
cover sockets of teeth (alveolar processes) and helps anchor teeth
superior labial frenulum
inferior labial frenulum
attaches superior lip to gum
attaches inferior lip to gum
lingual frenulum
- limits movement of tongue posteriorly and stops us from swallowing our tongue
- helps with speech production
- tongue tied: when your lingual frenulum is too short or too long and people can’t properly enunciate their words and interferes with nursing in babies
tongue
forms floor of the mouth, manipulates food for chewing and swallowing, shapes food and senses taste
teeth (starting and ending numbers)
start with 20 baby teeth
end with 32 adult teeth
what types of teeth do we have and how many
incisors: front 4, chisel shaped, cut food
canines: points from cusps (have a single cusp that tears food)
premolars: 2/side, 2 cusps crush and grind food
molars: 3/side, 4 cusps grind food
enamel
made of 95% calcium salts (strongest part of your body) and protects teeth from wear and treat
- makes teeth look white
dentin
calcified CT makes up majority of tooth
- calcified by hydroxyapatite (70% where would be 50% in bone)
- is more yellow
pulp cavity
contains pulp of tooth
CT containing nerves and blood vessels
cementum
bone like substance that attaches the root to the periodontal ligaments and forms gomphosis joint
root canal
an extension of the pulp cavity that contains nerves and blood vessels
periodontal ligaments
helps anchor the tooth to the underlying bone
apical foramen
an opening at the base of a root canal through which blood vessels and nerves enter a tooth
extrinsic muscles of the tongues
hypoglossus
styloglossus
palatoglossus
genioglossus
hypoglossus
- inserts on hyoid and originates on side and bottom of tongue
styloglossus
- runs from side of tongue to styloid process
- elevates tongue and brings back into oral cavity
palatoglossus
- goes from hard/soft palate region and attaches to side of the tongue and brings soft palate and the back of the tongue together when you swallow
genioglossus
goes from mandible and moves tongue anteriorly
- can also depress tongue
types of external salivary glands (pairs)
partoid
submandibular
sublingual
2 main types of salivary glands
- glands within mucous membranes in the oral cavity
and are named for the region where they’re located - glands located outside the mouth that produce saliva in larger amounts and deliver saliva to the oral cavity via ducts
partoid glands
largest, located inferior and anterior to ear
- make very watery saliva and creates salivary amylase
submandibular glands
beneath the base of the tongue
- ducts lead to lingual phrenulum
- has mucous added to saliva, makes it thicker
siblingual glands
located superior to submandibular at the base of the mouth
- has a bunch of tiny ducts with very little amylase in it and has more mucous in it, making saliva thicker
composition of saliva
- 99.5% water
- 0.5% solutes such as ions (Na, Cl, K),
lysozyme (an enzyme that kills bacteria in the mouth) and
IgA (immunoglobulin A that binds up any microbes that get into oral cavity) - salivary amylase: a digestive enzyme that breaks starch down to di- and trisaccharides as you chew food but becomes inactivated by stomach acid
function of saliva
- dissolves food for tasting
- mucous lubricates food
- Cl- activates salivary amylase
- HCO3- buffers acidic foods (binds up H+ ions to buffer pH changes like the bicarbonate system in the blood)
