Digestive System Flashcards
Alimentary Canal
Continuous muscular tube
Open on both ends
Begins in the oral cavity and ends at the anus
Composed of the mouth (oral cavity), pharynx, esophagus, stomach, small intestine, large intestine, anus
Accessory Digestive Organs
tongue, teeth, salivary glands, liver, pancreas, gallbladder
Four layers found in the alimentary canal
Mucosa (Innermost layer)- secretes mucus into the interior of the small and large intestine.
Submucosa (second inner layer) -contains blood and lymph vessels, lymph nodes, nerves, and mucus glands
Muscularis externa (third layer) -made of two layers longitudinal fibers and circumfrential fibers that help contract and move food.
serosa (outermost layer) -made of cells that make serous fluid
Lingual frenulum
vertical mucus membrane by which the body of the tongue is attached to the floor of the mouth.
Mouth is made up of what structures:
Lips- form the opening
Tongue -form the floor
Cheeks- form the walls
Hard and soft palete- form the roof
Uvula- form the posterior border
Uvula
hangs inferiorly from the soft palete
Tongue attachments
The mandible, hyoid bone, and lingual frenulum
Mastication
Mechanically food is chewed by the teeth in the mouth
Amylase
the salivary glands release this enzyme to chemically begin breaking down starches.
Salivary glands
Secrete saliva and amylase to moisten food and to begin breaking down starches
Maxilla
upper arch of teeth are located in the maxilla
Mandible
lower arch of teeth contained in the mandible
How many teeth and what kind?
32 teeth total
4 types of teeth that accommodate a meat and vegetable diet.
One half of each jaw has:
2 incisors for biting
1 canine for tearing
2 premolars for grinding
three molars for crushing
Three parts of the tooth
The crown, neck, and root
Root of tooth
The largest part of the tooth located within the alveolar process of the jaw bone
Neck of tooth
located within the upper portion of the gums
Crown of tooth
located above the gum (the part you can see
Pulp Cavity
At the center of every tooth there is a pulp cavity that has blood vessels and nerves (that allow for sensations of heat, cold, and pain
Dentin
bone like substance composing most of each tooth
Enamel
Hardest substace in the body- made of connective tissue, that protects the crown of the tooth
Tongue
grips and repositions the food in between the teeth to form a bolus (mass of compact food)
papillae
raised bumps on tongue
3 types: fungiform, circumvallate, and filiform
Taste buds are on fungiform and circumvallate papillae
Pharynx
nasopharynx, oropharynx, laryngopharynx
Two layers of muscle (circumferential outer layer and inner longitudinal layer) – contract alternatively causing peristalsis to squeeze food into the esophagus
Stomach anatomy
c-shaped organ
concave lesser curvature and convex greater curvature
Peritoneum
stomach is covered by serous membrane called greater omentum and lesser omentum
Lesser omentum
peritoneum that attaches the lesser curvature of the stomach to the liver
Greater omentum
hangs down like an apron and attaches the greater curvature of the stomach to the posterior wall of the abdomen, covering the transverse colon, and the anterior surface of the small intestine
Rugae
folds within the stomach that allow it to expand and hold more food (2-4 liters)
Stomach has two purposes –
hold food and to mechanically mix food with gastric juices by vigorously contracting when food is present
the stomach has three muscular layers - longitudinal layer, circular layer, and a special oblique layer that help breakdown the food into smaller pieces for later stages of absorption (chyme- soupy consistency of the stomach contents)
Ulcer
a sore caused by disintegration of tissues (can be caused by h.pylori - which leads to duodenal ulcers by eating away at the mucosal lining
Three parts of the small intestine and the valve that allows chyme to enter from the stomach
The pyloric sphincter is the valve that controls the opening of the small intestine - only allowing a small amount of chyme to enter at time
Duodenum, jejunum, ileum (slightly longer than the jejunum)
ileocecal valve
The valve that controls entrance into the large intestine from the small intestine.
pyloric sphincter
controls the entrance of the small intestine.
The duodenum
This is the shortest part of the small intestine, and the point of entry for the pancreatic and liver enzymes (bile) enter the small intestine.