objective 6 pt 1 Flashcards
what are the main functions of the digestive system?
- Take in food
- Break it down into nutrient molecules
- Absorb molecules into the bloodstream
- Rid body of any indigestible remains
continuous muscular tube that runs from the mouth to the anus
absorbs fragments through lining into blood
Alimentary Canal
breaks down into smaller fragments
digests food
what are the organs of the alimentary canal?
mouth, pharynx, esophagus, stomach, small intestine, large intestine, anus
what are the accessory digestive organs?
teeth, tongue, gallbladder, digestive glands (salivary glands, liver, pancreas)
produce secretions that help break down foodstuffs
digestive glands
what are the 6 essential activities that the processing of food involves?
ingestion
propulsion
mechanical breakdown
digestion
absorption
defacation
eating
ingestion
movements of food through the tract
propulsion
major means of propulsion of food that involves alternating waves of contraction and relaxation
peristalsis
processes that physically mix and break foods down into smaller fragments
mechanical breakdown
local constriction of intestine that mixes food with digestive juices; makes absorption more efficient by repeatedly moving different parts of food mass over the intestinal wall
segmentation
catabolic process that involves enzymes that break down food molecules into their chemical building blocks
digestion
passage of digested end products from intestinal mucosa into blood or lymph
absorption
elimination of undigested substances via anus in form if feces
defecation
serous membranes of abdominal cavity that consists of…
peritoneum
what are the 2 parts of peritoneum?
visceral peritoneum
parietal peritoneum
membrane on external surface of most digestive organs
visceral peritoneum
membrane that lines body wall
parietal peritoneum
fluid-filled space between two peritoneum’s
serous fluid lubricates and allows mobile digestive organs to glide easily across one another and along body wall to carry out their activities
peritoneal cavity
double layer of peritoneum; layers are fused back to back
extends from body wall to digestive organs
provides routes for BV, lymphatics, and nerves
holds organs in place and also stores fat
mesentery
what are the 4 basic layers of all digestive organs?
mucosa
submucosa
muscularis externa
serosa
innermost tunic layer that lines lumen
mucosa
what are the functions of the mucosa?
vary depending on region of the GI system
* Secretes mucus, digestive enzymes, and hormones
* Absorbs end products of digestion
* Protects against infectious disease
contains blood and lymphatic vessels, lymphoid follicles, and nerve fibers that supply surrounding GI tract tissues
has abundant amount of elastic tissues that help organs to regain shape after storing large meal
submucosa
muscle layer responsible for segmentation and peristalsis
contains inner circular muscle layer and outer longitudinal layers
muscularis externa
thickens in some areas to form sphincters that act as valves to control food passage from one organ to the next and prevent backflow
circular layer
outermost layer which is made up of the visceral peritoneum
serosa
where food is chewed and mixed with enzyme-containing saliva that begins process of digestion, and swallowing process is initiated
mouth
what are the organs associated with the mouth?
tongue
salivary glands
teeth
bounded by lips, cheeks, palate, and tongue
lined with stratified squamous epithelium
oral cavity
anterior opening
oral orifice
made of orbicularis oris muscle
lips (labia)
made of buccinators muscle
cheeks
area within teeth and gums
oral cavity proper
area between lips/cheek and gum/teeth
oral vestibule
forms the roof of the mouth and has two distinct parts
palate
formed by palatine bones and palatine
hard palate
slightly corrugated to help create friction against tongue
mucosa
fold formed mostly of skeletal muscle
closes off nasopharynx during swallowing
palatine tonsils located here
soft palate
fingerlike projection that faces downward from free edge of soft palate
uvula
occupies floor of mouth
composed of interlacing bundles of skeletal muscle
contains taste buds
tongue
what are the functions of the tongue?
gripping, repositioning, and mixing of food during chewing
formation of bolus, mixture of food and salvia
initiation of swallowing, speech, and taste
attachment to flood of mouth; limits posterior movement of tongue
lingual frenulum
what are the functions of salvia?
cleanses mouth
dissolves food chemicals for taste
moistens food; compacts into bolus
begins breakdown of starch with enzyme amylase
what are the major salivary glands?
parotid
submandibular
sublingual
anterior to ear
opens next to second upper molar
parotid
medial to body of mandible
ducts opens at base of lingual frenulum
submandibular
anterior to submandibular gland under tongue
opens via 10-12 ducts into floor of mouth
sublingual
composed of two types of secretory cells
salivary glands
produce watery secretion, enzymes, ions, bit of mucin
serous cells
produce mucus
mucous cells
97-99.5% water
ph 6.75-7.0
salvia
what do solutes include?
- Electrolytes
- Enzymes (lipase, amylase)
- Proteins (mucin, lysozyme, IgA)
- Metabolic wastes (urea, uric acid)
when are major salivary glands activated by parasympathetic nervous system?
- Ingested food stimulates chemoreceptors and
mechanoreceptors in mouth and send signals to the
salivatory nuclei in the brain. Increase serous saliva. - Strong sympathetic stimulation inhibits salivation
and results in dry mouth (xerostomia)
lie in sockets in gum-covered margins of mandible and maxilla
teeth
process of chewing that tears and grinds food into smaller fragments
mastication
consists of 20 deciduous teeth or baby teeth, that erupt between 6 to 24 months of age
primary dentition
32 deep-lying ______ enlarge and develop while roots of milk teeth are reabsorbed from below, causing them to loosen and fall out
permanent teeth
chisel shaped for cutting
incisors
fanglike teeth that tear or pierce
canines
broad crowns with rounded cusps used to grind or crush
premolars
broad crowns, rounded cusps; best grinders
molars
what are the major regions of teeth?
crown
root
cement
periodontal ligament
gingival sulcus
dentin
exposed part of above gingiva
covered by enamel, the hardest substance in body
heavily mineralized with calcium salts and hydroxyapatite crystals ‘
enamel-producing cells degenerate when tooth erupts, so no healing if tooth decays or cracks
crown
portion embedded in jawbone
connected to crown by neck
root
calcified connective tissue
covers root; attaches it to periodontal ligament
cement
forms fibrous joint called gomphosis
anchors tooth in bony socket
periodontal ligament
groove where gingiva borders tooth
gingival sulcus
bonelike material under enamel
maintained by odontoblasts of pulp cavity
dentin
