Lecture Quiz 1 Flashcards
What makes up the ailmentary canal?
mouth pharynx esophagus stomach small intestine large intestine
What are the accessory digestive organs?
teeth tongue gallbladder salivary glands liver pancreas
Define ingestion
taking food into the digestive tract
Define propulsion
swallowing
peristalsis
What is peristalsis?
waves of contraction and relaxation in the muscles in organ walls
What is mechanical digestion??
chewing, mixing, and churning food
What is chemical digestion?
catabolic breakdown of food
What is absorption?
movement of nutrients from the GI tract to blood or lymph
What is defecation?
elimination of indigestible solid wastes
What do mechano- and chemoreceptors respond to in the GI tract?
stretch, osmolarity, pH
presence of substrate, end products of digestion
What do the receptors of the GI tract do?
activate or inhibit digestive glands
mix lumen contents and move them along
What are the intrinsic controls of the GI tract?
nerve plexuses near the GI tract initiate short reflexes
short reflexes are medicated by local enteric plexuses
What are the extrinsic controls of the GI tract?
long reflexes arising within or outside GI tract
CNS centers and extrinsic autonomic nerves
What is GI tract ultimately controlled by?
reflex
sympathetic nervous system
Vagus nerve
What is the peritoneum?
serous membrane of the abdominal cavity
has external visceral layer and internal parietal layer
What does the peritoneal cavity do?
lubricates digestive organs and allows them to slide across one another
What is the mesentery?
double layer of the peritoneum
What does the mesentery do?
provides vascular and nerve supplies to the viscera
hold digestive organs in place and store fat
Look up which organs are retroperitoneal and peritoneal
**
What arteries make up the splanchnic circulation?
hepatic
splenic
left gastric
inferior and superior mesenteric
What does the hepatic portal circulation do?
collects nutrient-rich venous blood from the digestive viscera
delivers this blood to the liver for metabolic processing and storage
What is the mucosa?
moist epithelial layer that lines the lumen of the alimentary canal
consists of three layers: lining epithelium, lamina propria, muscularis mucosae
Describe the epithelial lining of the mucosa
simple columnar epithelium and mucus-secreting goblet cells
What does mucus secretion do?
protect digestive organs from digesting themselves
ease food along the tract
What do stomach and small intestine mucosa contain?
enzyme-secreting cells
hormone-secreting cells
these organs are both digestive and endocrine organs
Describe the lamina propria of the mucosa
loose areolar and reticular connective tissue
nourishes the epithelium and absorbs the nutrients
contains lymph nodes - important in defense against bacteria
Describe the muscularis mucosae of the mucosa
smooth muscle cells that produce local movements of mucosa
scant layer
What is the submucosa?
dense connective tissue containing elastic fibers, blood, and lymphatic vessels, lymph nodes, and nerves
What is the muscularis externa?
responsible for segmentation and peristalsis
inner circular and longitudinal layer of smooth muscle
What is the serosa?
protective visceral peritoneum
replaced by fibrous adventitia in the esophagus
retroperitoneal organs have both an adventitia and serosa
What does the submucosal nerve plexus do?
regulates glands and smooth muscle in the mucosa
What does the myenteric nerve plexus do?
major nerve supply that controls GI tract mobility
What controls segmentation and peristalsis?
autonomic NS, local reflex arc, and myenteric nerve plexus
largely automatic
Describe the mouth
lined with stratified squamous epithelium
withstands abrasion
gums, hard palate, dorsum of tongue slightly keratinized
What are the muscles of the lips and cheeks?
orbicularis oris and buccinators
What is the vestibule of the mouth?
bounded by the lips and cheeks externally, and teeth and gums internally
What is the oral cavity proper?
area that lies within the teeth and gums
no absorption happens within the oral cavity
What is the labial frenulum?
median fold that joins the internal aspect of each lip to the gum
What is the hard palate?
underlain by palatine bones and palatine processes of the maxilla
assists in chewing
slightly corrugated on either side of the midline ridge
What is the soft palate?
mobile fold formed mostly of skeletal muscle
closes off the nasopharynx during swallowing
uvula projects down from its free edge
What are the functions of the tongue?
gripping and repositioning food
mixing food with saliva and forming the bolus
initiation of swallowing and speech
What do the intrinsic muscles of the tongue do?
change the shape of the tongue
make the tongue thicker, thinner, longer
What do the extrinsic muscles of the tongue do?
alter the tongues position
protrude, extract, side to side
What are the three types of papillae?
filiform - give tongue roughness and provide friction
fungiform - give tongue reddish color
circumvallate - V shaped row in back of tongue
What is the sulcus terminalis of the tongue?
groove that separates tongue into two areas
anterior 2/3 in oral cavity
posterior third in oropharynx
What is the role of saliva?
cleanses the mouth
moistens and dissolves food chemicals
aids in bolus formation
contains enzymes that break down starch
Describe the parotid gland
extrinsic salivary glands
lies anterior to the ear between the masseter muscle and skin
duct opens into the vestibule next to second upper molar
Describe the submandibular gland
extrinsic salivary gland
lies along the medial aspect of the mandibular body
ducts open at the base of the lingual frenulum
Describe the sublingual glands
extrinsic salivary gland
lies anterior to the submandibular gland under the tongue
opens via 10-12 ducts into the floor of the mouth
Where is saliva secreted from?
serous and mucous cells of salivary glands
What does saliva consist of?
electrolytes - sodium, potassium, chloride, phosphate, HCO3
digestive enzyme salivary amylase
proteins - mucin, lysozyme, defensins, IgA
metabolic wastes - urea and uric acid
What do intrinsic glands do in salivation?
minor glands
keep the mouth moist
What do extrinsic salivary glands do?
secrete serous, enzyme-rich saliva in response to ingested food and the thought of food
What does the sympathetic system do to salivary glands?
inhibits salivation
dry mouth
When are permanent teeth in the mouth?
21 years
Describe the primary set of teeth
20 deciduous teeth that erupt between 6 and 24 months
Describe permanent teeth takeover
enlarge and develop, causing the root of the deciduous teeth to be resorbed and fall out between 6 and 12 years
all but the third molars have erupted by the end of adolescence
usually 32 permanent teeth
What are incisors?
chisel-shaped teeth for cutting or nipping
What are the canines?
fanglike teeth that tear or pierce
What are the premolars and molars?
broad crowns with rounded tips
best suited for grinding or crushing
during chewing, upper and lower molars lock together, generating crushing force
What is the shorthand for ratio of upper to lower teeth in primary teeth?
2I, 1C, 2M
What is the shorthand for ratio of upper to lower teeth in permanent teeth?
2I, 1C, 2PM, 3M
What is the crown of the tooth?
exposed part of the tooth above the gingiva
What is enamel?
acellular, brittle material composed of calcium salts and hydroxyapatite crystals
hardest substance in the body
encapsules crown
What is the root?
portion of the tooth embedded in the jaw bone
What is cementum?
calcified connective tissue
covers the root
attaches it to the periodontal ligament
What is the periodontal ligament?
anchors the tooth in the alveolus of the jaw
forms the fibrous joint called a gomphosis - only place where this is found
What is the neck of the tooth?
constriction where the crown and root come together
What is the gingival sulcus?
depression where the gingiva borders the tooth
What is the dentin?
bonelike material deep to the enamel cap that forms the bulk of the tooth
What is the pulp cavity?
cavity surrounded by dentin that contains pulps
What is the pulp of the tooth?
connective tissue, blood vessels, nerves
responsible for tooth sensation
What is the root canal?
portion of the pulp cavity that extends into the root
What is the apical foramen?
proximal opening to the root canal
What are odontoblasts?
secrete and maintain dentin throughout life
What are dental caries?
gradual demineralization of enamel and dentin by bacterial action
How does dental carries pan out?
dental plaque, sugar, bacteria, mouth debris adheres to teeth
acid produced by bacteria dissolve calcium salts
organic matter is digested by proteolytic enzymes
What is gingivitis?
plaque accumulates, calcifies and forms calculus or tartar
this disrupts seal between gingivae and teeth
puts gums at risk for infection
What is periodontitis?
serious gum disease resulting from an immune response
immune system attacks intruders as well as body tissues
carves pockets around the teeth and dissolves bone
Describe the pharynx
lines with stratified squamous epithelium and mucus glands
has two skeletal muscle layers - inner longitudinal and outer pharyngeal constrictors
What does the pharynx allow?
oro- and laryngopharynx allow passage of food and fluids to the esophagus
air to the trachea
Describe the esophagus
muscular tube going from the laryngopharynx to the stomach
travels through the mediastinum and pierces the diaphragm
joins stomach at the cardiac orifice
What is the esophageal mucosa?
nonkeratinized stratified squamous epithelium
Describe how the esophagus transports food
empty esophagus is folded longitudinally and flattened
glands secrete mucus as bolus moves through
muscularis changes from skeletal (superior) to smooth muscle (inferior)
What are the digestive processes in the mouth?
food is ingested
mechanical digestion begins (chewing)
propulsion is initiated by swallowing
salivary amylase begins chemical breakdown of starch
pharynx and esophagus serve as conduits to the stomach
What does swallowing incorporate?
coordinated activity of tongue, soft palate, parhynx, esophagus, and 22 separate muscle groups
What is the buccal phase?
bolus is forced into the oropharynx
this is voluntary
What happens during the pharyngeal-esophageal phase?
controlled by medulla and lower pons
all routes except into digestive tract are sealed off
this is involuntary
