Digestive System Flashcards
Digestive system includes
gastrointestinal tract and accessory organs
Gastrointestinal tract
tube from mouth to anus
Accessory organs
teeth, tongue, salivary glands, pancreas, liver, gall bladder
Digestive system processes
- ingestion
- digestion
- absorption
- defecation
Ingestion
food into oral cavity
Digestion
large molecules broken down into smaller molecules
2 types of digestion
- mechanical
- chemical
Absorption
end products of digestion enter blood or lymph
Defecation
elimination of indigested materials
4 basic layers of gastrointestinal tract
- mucosa
- submucosa
- muscularis externa
- serosa
3 layers of the mucosa
- epithelium with numerous goblet cells
- lamina propria (areolar CT)
- muscularis mucosa
Mucosa epithelium with goblet cells is stratified squamous in what areas?
- mouth
- pharynx
- esophagus
- anal canal
Lamina propr. of mucosa contains
blood, lymph vessels, lymph nodes/tissues
Muscularis mucosa
smooth muscle which allows movement of mucosa
Submucosa tissue subtype
Areolar CT
Submucosa contains
blood, lymphatic vessels, submucosal nerve plexus
Muscularis externa tissue type
smooth muscle, the inner circle layer and outer longitudinal layer
What is between the layers of muscularis externa
myenteric nerve plexus
Contraction of ______ _____ causes
muscular external; motility (mixing and movement)
Cavity =
lumen
Oral cavity includes
- lips
- cheeks
- palate
- tongue
2 palates of the mouth
hard and soft
Hard palate made up of
2 maxillae and 2 palatine bones
Soft palate contains
skeletal muscle and (uvula)
Uvula’s purpose
rises to close the nasopharynx when swallowing
Tongue
attached to hyoid bone, skeletal muscle, and papillae
Papillae
projections of mucosa ( taste buds)
How many salivary glands
3 pairs (6 total)
Pairs of salivary glands
- parotid
- submandibular
- sublingual
Parotid glands
inferior and anterior to ears
Mumps
inflammation of 1 or both parotids
Submandibular glands
floor of mouth, below the mandible
Sublingual glands
below tongue on floor of mouth
Components of saliva
- 99.5% water
- 0.5% solutes (enzyme)
Dentition
(teeth) in maxillae and mandible
Child dentition
primary dentition (deciduous “baby” teeth)
Adult dentition
secondary dentition (permanent teeth)
Total number of child teeth
20
Total number of adult teeth
32
Tooth structure consists of
- crown
- root
- neck
- periodontal ligaments
- root canal
Crown of tooth
above the gum, dentin is majority of tooth, enamel overlay
Root of tooth
dentin and cementum overlay
Dentin, enamel, cementum are..
similar to bone but avascular
Neck of tooth
enamel and cementum boundary
Periodontal ligaments
attach root to bones
Root canal extends to..
pulp cavity
Root canal of tooth
contains CT, blood/lymph vessels and nerves
Oropharynx/Laryngoharynx tissue subtype
Only muscular externa and stratified squamous epithelium
Esophagus
posterior to trachea, passes through diaphragm to the abdominal cavity
Esophagus contains
all 4 histological layers in GI tract from this point on
Exceptions in esophagus
- muscularis externa
- has adventitia
Muscularis externa of esophagus
- upper 1/3 = skeletal muscle
- middle 1/3 = skeletal and smooth muscle
- lower 1/3 = smooth muscle
Adventitia of esophagus
fibrous connective tissue
Stomachs 4 regions
- cardiac region
- fundus
- body
- pyloric region
Fundus
above the esophageal entrance
Pyloric region
(pylorus) has pyloric sphincter
Stomach
converts food into chyme, has greater and lesser curvature
Chyme
food and gastric juice
Stomach mucosa
invagination of epithelium forms gastric glands (exocrine) secrete gastric juice to lumen
Gastric glands contain
- chief cells
- pariental cells
- G cells
- Goblet cells
Chief cells
secrete pepsinogen and gastic lipase
Parietal cells
secrete HCl
G cells
(enteroendocrine cells) secrete gastrin
Rugae
folds of the muscosa and submucosa due to contraction of muscularis mucosa
Rugae allows..
expansion without tearing
Function of muscularis external of stomach
churning
3 layers of muscularis external of stomach
- inne oblique
- middle circular
- outer longitudinal
Small intestine goes from ___ ____ to ____ ____
pyloric sphincter; ileocaecal valve
3 segments of small intestine
- duodenum
- jejunum
- ileum
Duodenum
first fold (short), extra glands here secrete alkaline mucosa to protect against stomach acid
Jejunum
middle section
Ileum
has groups of lymph nodules (peyer’s patches)
Peyer’s patches
prevent infection of small intestine and bacteria from entering blood
Segments specialized to increase absorption surface area
- plicae circulares
- villi
- microvilli
Plicae circulares
submucosa thrown into folds
Villi
projections of mucosa into lumen, contains blood capillaries and lacteals
Lacteals
lymph capillaries that absorb blood
Microvilli
brush border on enterocytes, extend into lumen
Within epithelium separate enteroendocrine cells in stomach secrete hormones
- secretin
- cholecystokinin
Small intestine accessory organs
- pancreas
- liver
- gall bladder
Pancreas parts
- head
- body
- tail
Pancreas contain
- exocrine glands
- endocrine glands
2 types of exocrine glands
- acinar cells/acini
- duct cells
Acinar cells/acini
secrete digestive enzymes into ducts
Duct cells
secrete alkaline fluid to neutralize stomach acid
Pancreatic juice =
digestive enzymes and alkaline fluid
Endocrine glands =
Islets of langerhans (amid acini)
Endocrine glands secrete
hormones such as insulin and glucagon to regulate blood sugar
4 lobes of the liver
- right
- left
- quadrate
- caudate
Cells of the liver
hepatocytes
Functions of liver
filters material from GI tract before going to rest of body, produces bile for fat digestion
Gall bladder
muscular sac on surface of liver
Gall bladder has ____ not submucosa
rugae
Function of gall bladder
stores and concentrates bile between meals
Gall bladder, liver, and pancreas enter..
duodenum via series of ducts
Large intestine goes from ___ ____ to ____
ileocaecal valce; anus
Large intestine has no
villi or folds
Large intestine consist of
- caecum
- appendix
- colon
- rectum
- anus
Parts of the colon
- ascending
- hepatic flexure
- transverse
- splenic flexure
- descending
- sigmoid
In colon muscularis externa longitudinal layer is..
incomplete which = taenjae coli
Contraction in colon forms pouches called
haustra
Epiploic appendages
fat filled pouches with unknown function
Rectum has
no taenjae coli
Anal canal
last 3 cm of rectum
Anus has 2 anal sphincters
internal (smooth) and external (skeletal w/ voluntary control)
Immune function of intestines
lymph nodules in mucosa throughout small and large intestine and peyers patches
Digestive function of intestines
lymph vessels most absorbed fats from small intestines enters lacteals
Portal system
blood vessels between 2 capillary beds (no blood passes through though)
Peritoneum is
serous membrane
Visceral peritoneum against
organ wall
Parietal peritoneum against
abdominal wall
Peritoneal cavity filled with..
serous fluid
Serosa between organs =
sheet of 2 fused visceral peritoneum layers that contains blood vessels and nerves
Peritoneum forms
folds in some areas (omenta)
Greater omentum
(fatty apron) covers tranverse colon and small intestine, has fat fro protection, insulation and NRG reserve
Lesser omentum
lower to stomach
Mesentery
Suspends small intestine from cavity wall, double layer of parietal peritoneum
Retroperitoneal
behind the peritoneum, peritoneum lines only one side
Peritonitis
inflammation of peritoneum
