A&P II - Ch. 23 Study Guide

What is digestion?

food breakdown processes in the mouth, stomach, small intestine, and large intestine

Where does food become a bolus?

mouth

Where does food become chyme?

stomach

Where does food become feces?

large intestine

Where does ingestion occur?

mouth only

Where does mechanical breakdown occur?

mouth, stomach, and small intestine

Where does propulsion occur?

mouth and remaining GI tract

Where does digestion occur?

mouth, stomach, small intestine, large intestine

Where does absorption occur?

stomach, small intestine, and large intestine

Where does defecation occur?

large intestine only

What is mechanical breakdown?

physical breakdown of large food particles into smaller particles without altering their chemical composition

What is chemical digestion?

enzyme-driven breakdown of large food particles into smaller particles that can be absorbed into the bloodstream

What are some examples of mechanical breakdown?

mastication (chewing), churning, segmentation

What are some examples of chemical digestion?

salivary amylase, pepsin and hydrochloric acid, pancreatic lipase

What is peristalsis?

adjacent segments of the GI tract that alternately contract and relax

What is segmentation?

non-adjacent segments of the GI tract that alternately contract and relax

Which layer of the alimentary canal responsible for peristalsis?

muscularis externa

What are sphincters?

ring-like muscular valves that contract and relax to regulate food, liquid, and waste passage

What is the peritoneum?

serous membrane that surrounds most abdominopelvic organs

Which layer of the peritoneum lines the external surface of organs?

visceral peritoneum

Which layer of the peritoneum lines the body wall?

parietal peritoneum

What is peritonitis?

inflammation of the peritoneum

What can peritonitis be caused by?

burst appendix

What are mesenteries?

fold in the peritoneum that extends form the dorsal and ventral body walls to most abdominopelvic organs

What is the main function of mesenteries?

suspends intestines from the abdominal wall, keeping them in place to prevent them from twisting ot collapsing

What is the hepatic portal circulation?

system that drains nutrient-rich blood from the digestive organs

How does the hepatic portal circulation drain blood?

from the digestive organs to the liver

What is special about blood from the hepatic portal circulation?

blood is nutrient-rich

What is the mucosa of the alimentary canal?

epithelium, lamina propria, and muscularis mucosa secretes mucous, digestive enzymes, and hormones while absorbing digestive end products

What is the submucosa of the alimentary canal?

areolar connective tissue containing blood / lymphatic vessels, lymphoid follicles, nerves, and glands that provides flexibility and support

What is the muscularis externa of the alimentary canal?

smooth muscle layer containing a circular layer and longitudinal layer that is responsible for peristalsis

What is the serosa of the alimentary canal?

simple squamous epithelium and areolar connective tissue that contains mesenteries

Which is the best description for the esophagus?

stratified squamous epithelium, thick and productive, protection

Which is the best description for the stomach?

simple columnar epithelium, glands and three muscle lasyers, digestion and mixing

Which is the best description for the small intestine?

simple columnar epithelium and microvilli, villi and folds, absorption

Which is the best description for the large intestine?

simple columnar epithelium and goblet cells, no villi and mucous, water absorption

Which are examples of mechanical stimuli?

stretch that activates mechanoreceptors

Which are examples of chemical stimuli?

pH, nutrients, and solutes that activate chemoreceptors

Which is NOT a hormone that regulates GI tract acitivty?

oxytocin

Where does gastrin secreted from and where does it act upon?

released by the stomach, stimulates acid production in the stomach and defecation

Where do CCK and secretin secrete from and where do they act upon?

released by the duodenum, inhibit stomach secretions and stimulate liver / pancreas secretions

Which branch of the ANS inhibits stomach functions?

symphathetic fibers

Which branch of the ANS stimulates stomach functions?

parasympathetic fibers

What are short reflexes?

intrinsic stimuli that act within the GI wall

What are long reflexes?

extrinsic stimuli that act through the CNS

Which two subdivisions of the nervous ssytem from inputs for long reflexes?

peripheral nervous system (PNS) and autonomic nervous system (ANS)

Which digestive processes occur in the mouth?

ingestion, mechanical breakdown, propulsion, and digestion

What is the lingual frenulum?

fold of mucous membrane that anchors the tongue to the oral cavity floor

Which epithelial tissue type lines the mouth?

stratified squamous epithelium

What are the 3 salivary glands?

parotid, submandibular, and sublingual

What are the functions of saliva?

dissolves food chemicals for taste, moistens / compacts food into bolus, and begins breakdown of starch

What is the pH of saliva?

slightly acidic

How many deciduous (baby) teeth are there?

20

How many permanent (adult) teeth are there?

32

Which classification of teeth are specialized to cut?

incisors

Which classification of teeth are specialized to tear and pierce?

canines

Which classification of teeth are specialized to grind and crush?

premolars

Which classification of teeth are the best grinders?

molars

What are the wisdom teeth?

third molars

When does heartburn occur?

when the stomach acid regurgitates into the esophagus

Which epithelial tissue type lines the pharynx and esophagus?

stratified squamous epithelium

What is chyme?

acidic slurry of ingested food formed in the stomach

What is the pyloric valve?

valve that controls stomach emptying

Which digestive processes occur in the stomach?

mechanical breakdown, propulsion, digestion, absorption

What can be absorbed in the stomach?

only alcohol and aspirin

What is the pH of gastric juice?

highly acidic

Which 4 cells are found in gastric pits?

mucous cells, parietal cells, chief cells, enteroendocrine cells

What do mucous cells in gastric pits secrete?

cloudy, alkaline mucus

What do parietal cells in gastric pits secrete?

hydrochloric acid (HCl) and intrinsic factor

What do chief cells in gastric pits secrete?

pepsinogen and lipases

What do enteroendocrine cells in gastric pits secrete?

paracrines, hormones, and gastrin

What is the function of gastrin?

stimulates the stomach to secrete hydrochloric acid (HCl)

Which type of cells secrete gastrin?

G-cells

Where are G-cells located?

pyloric antrum of the stomach (smaller amounts in duodenum)

What are the 3 phases of gastric activity?

cephalic phase, gastric phase, and intestinal phase

What is the source of control for the cephalic phase of gastric activity?

central nervous system (CNS) control

What is the source of control for the gastric phase of gastric activity?

intrinsic control

What is the source of control for the intestinal phase of gastric activity?

intestinal control

What is the falciform ligament?

strip of mesentery that attaches the liver to the ventral body wall

What is hepatitis?

general inflammation of the liver

What is cirrhosis?

progressive, chronic liver inflammation

What are common causes of hepatitis?

viral infection, drug toxicity, and wild mushroom poisoning

What are common causes of cirrhosis?

chronic hepatitis and alcoholism

What is bile?

fat emulsifier secreted by the liver into the duodenum through ducts

What type of molecule is broken down by bile?

large fat droplets into smaller droplets

What are acini?

clusters of acinar cells that secrete pancreatic juice

What is the pH of pancreatic juice?

8

What does the gallbladder do?

stores and concentrates bile

What are gallstones?

crystalized cholesterol

Which duct does bile exit the liver?

common hepatic duct

Which duct does bile exit the gallbladder?

cystic duct

Which segment of the intestines do the hepatic and pancreatic ducts connect?

duodenum

Where are proteases activated?

duodenum

How do inactive proteases protect the pancreas?

prevent enzymes from destroying pancreatic tissue

What are the 3 segments of the small intestine?

duodenum, jejunum, and ileum

What are vili?

folds that increase surface are

What are microvilli?

finger-like projections that increase surface area

What do intestinal crypts do?

make intestinal juices and contain enteroendocrine cells

Where are intestinal crypts located?

between the villi

What are lacteals?

lymphatic capillaries that absorb and drain fats