chapter 23

the alimentary canal or gastrointestinal tract does what:

digests and absorbs food

what is the alimentary canal

leads from:

1. mouth

2. pharynx

3. esophagus

4. stomach

5. small intestine

6. large intestine

7. ends at anus

the accessory digestive organs consist of:

• teeth

• tongue

• gallbladder

• salivary glands

• liver

• pancreas

the GI tract is a “disassembly” line meaning:

nutrients become more available to the body in each step

define ingestion

taking food into the digestive tract

define propulsion

swallowing and peristalsis

define peristalsis

waves of contraction and relaxation of muscles in the organ walls

what is chemical digestion

catabolic breakdown of food

what is absorption in the GI tract

movement of nutrients from the GI tract to the blood or lymph

describe the peritoneum

serous membrane of the abdominal cavity

describe the peritoneal cavity

• lubricates digestive organs

• allows them to slide across one another

three major functions of mucosa

• secretion of mucus

• absorption of the end products of digestion

• protection against infectious disease

mucosa consists of what three layers

• a lining epithelium

• lamina propria

• muscularis mucosae

what do mucus secretions do

• protect digestive organs from digesting themselves

• ease food along the tract

stomach and small intestine mucosa contain:

• enzyme secreting cells

• hormone secreting cells

what is lamina propria

• loose areolar and reticular connective tissue

• nourishes the epithelium and absorbs nutrients

• contains lymph nodes important in defense against bacteria

what is muscularis mucosae

smooth muscle cells that produce local movements of mucosa

what is submucosa

dense connective tissue containing elastic fibers, blood and lymphatic vessels, lymph nodes, and nerves

what is muscularis externa

responsible for segmentation and peristalsis

• skeletal muscle- in esophagus

• smooth muscle- circular and longitudinal layers

• sphincters- circular layer thickens to form valve

what is the sublayer “serosa”

the protective visceral peritoneum

• replaced by fibrous adventitia in the esophagus

• retroperitoneal organs have both an adventitia and serosa

what is the submucosal nerve plexus

regulates glands and smooth muscle in the mucosa

what is the myenteric nerve plexus

major nerve supply that controls GI tract mobility

describe the soft palate

mobile fold formed mostly of skeletal muscle

• closes off the nasopharynx during swallowing

superior surface of the tongue bears what three types of papillae

• filiform- give the tongue roughness and provide friction

• fungiform- scattered widely over the tongue and give it a reddish hue

• circumvallate- V shaped row in the back of tongue

salivary glands produce and secrete saliva that:

• cleanses the mouth

• moistens and dissolves food chemicals

• aids in bolus formation

• contains enzymes that break down starch

three pairs of extrinsic glands-

• parotid

• submandibular

• sublingual

describe parotid gland

lies anterior to the ear between the masseter muscle and skin

describe submandibular gland

lies along the medial aspect of the mandibular body

describe sublingual gland

lies anterior to the submandibular gland under the tongue

teeth are classified according to their shape and function:

• incisors- chisel shaped teeth adapted for cutting or nipping

• canines- conical or fanglike teeth that tear or pierce

• premolars and molars- have broad crowns with rounded tips and are best suited for grinding or crushing

tooth structure has what two main regions

crown and root

what is enamel

acellular, brittle material composed of calcium salts and hydroxyapatite crystals is the hardest substance in the body

for tooth structure what is the “neck”

constriction where the crown and root come together

for tooth structure what is “cementum”

calcified connective tissue

what is the periodontal ligament

• anchors the tooth in the alveolus of the jaw

• forms the fibrous joint called a gomaphosis

what is the gingival sulcus

depression where the gingiva borders the tooth

define dentin

bonelike material deep to the enamel cap that forms the bulk of the tooth

define pulp cavity

cavity surrounded by dentin that contains pulp

define pulp in the tooth structure

connective tissue, blood vessels, and nerves