PNB Quiz Prep - Digestive System

What is the first function of the digestive system?

ingestion of nutrients

What is the second function of the digestive system?

secretion

What is the third function of the digestive system?

mechanical and chemical processing

What is the fourth function of the digestive system?

absorption

What is the fifth function of the digestive system?

excretion

What is the ingestion of nutrients?

food and liquids enter the body through the mouth

What begins the digestive process?

ingestion of nutrients

Where does the digestion of food begin?

mouth

What is mechanical processing?

Chewing and muscle contractions break food into smaller pieces; prepares food for easier chemical digestion

What is secretion?

digestive organs release substances into the GI tract

What does secretion include?

enzymes, acids, bile, and mucus

Why is secretion helpful?

breaks down food and protect digestive tissues

What is absorption?

the movement of nutrients from digested food into the blood or lymph

Where does absorption mainly occur?

small intestine

What is the function of absorption?

allows the body to use nutrients for energy, growth, and repair

What is excretion?

undigested material becomes waste

Where does waste move?

large intestine where water is absorbed

What is the mouth?

entry point for food into the digestive tract

What is the purpose of saliva?

begins chemical digestion

What is the esophagus?

muscular tube that connects the mouth to the stomach

Where does peristalsis begin?

esophagus

What is the function of the esophagus?

transports the bolus to the stomach for further digestion

What is the stomach?

muscular organ that stores food temporarily after swallowing

What is the function of the stomach?

churns and mixes food with gastric juices

What begins protein digestion?

acid and enzymes, turn food into chyme

What is the small intestine?

main site for digestion and nutrient absorption

What is the purpose of the small intestine?

enzymes and bile break down food further

Where do nutrients pass in the small intestine?

into blood or lymph for the body to use

What is the main site for mechanical digestion?

stomach

What is the main site for chemical digestion?

small intestine

What is the large intestine?

absorbs water and electrolytes from indigestible food

What does the large intestine form and store?

feces until elimination

What does the large intestine house?

bacteria; aid in breaking down ramaining nutrients

What is the rectum?

stores feces before they are eliminated

What does the rectum signal?

when it’s time to have bowel movement

What ends the digestive tract?

rectum at the anus for excretion

What are the 4 accessory organs?

salivary glands, liver, pancreas, gallbladder

What are accessory organs?

aids digestion but food does not pass through it

What are salivary glands?

produce saliva: water and mucus to lubricate food

What does the salivary gland help form?

bolus for easy swallowing

What do salivary glands support?

oral hygiene; washing away food and bacteria

What is the liver?

produces bile, which emulsifies fats for digestion

What does the liver process?

nutrients from the hepatic portal blood

What organ performs metabolism?

liver

What is the pancreas?

produces digestive enzymes (amylase, lipase, proteases) for the small intestine

What does the pancreas secrete?

bicarbonate to nuetralize stomach acid in the small intestine

What does the pancreas support?

chemical digestion of carbs, proteins, and fats

What is the gallbladder?

stores and concentrate bile produced by the liver

What does the gallbladder release?

bile into the small intestine when fats are present

What is the function of the gallbladder?

emulsifies fats to increase digestion efficiency

What is the first layer of the GI tract (outside-in)?

serosa

What is the second layer of the GI tract (outside-in)?

muscularis

What is the third layer of the GI tract (outside-in)

submucosa

What is the fourth layer of the GI tract (outside-in)?

mucosa

What makes up the serosa?

connective tissue and a layer of epithelial cells

What is the function of the serosa?

outermost layer; protects organs and reduces friction as they move in the abdominal cavity

What is the muscularis made of?

muscle and nervous tissue

What is the function of muscle in the muscularis?

moves and mixes food through peristalsis and segmentation

What is the function of nervous tissue in the muscularis?

coordinates contractions via the myenteric plexus

What is the purpose of the muscularis?

essential for motility and proper digestion

What is the submucosa made up of?

connective, nervous, and lymphatic tissue

What is the function of connective tissue in the submucosa?

supports the mucosa and binds it to the muscularis

What is the purpose of nervous tissue in the submucosa?

regulates secretion and local blood flow

What is the purpose of lymphatic tissue in the submucosa?

helps defend against pathogens in the gut

What is the mucosa made up of?

epithelial, muscle, nervous, and lymphatic tissue

What is the purpose of epithelial tissue is the mucosa?

lines the lumen and absorbs nutrients

What is the purpose of muscle tissue in the mucosa?

creates fold and movement to mix food

What is nervous and lymphatic tissue in mucosa?

coordinate secretion, absorption, and immune defense

Where is the myenteric plexus located?

muscularis externa

What is the myenteric plexus?

major site of nerve control/innervation in the GI tract, mostly parasympathetic

What does the myenteric plexus control?

muscle contractions for peristalsis and segmentation

What is the myenteric plexus essential for?

coordinating motility throughout the digestive tract

What is the muscularis externa?

major site of innervation in GI tract (mostly parasympathetic)

What is the inner circular layer of the muscularis externa?

squeezes the lumen to mix and push food

What is the outer longitudinal layer of the muscularis externa?

shortens the tube to move food along

What does the muscularis externa surround?

lumen; allowing controlled movement based on radius and length

What is the first sub layer of the mucosa (inside-out)

epithelium

What is the second sub layer of the mucosa (inside-out)?

lamina propria (aka gut-associated lymphatic tissue - GALT)

What is the third sublayer of the mucosa (inside-out)?

muscularis mucosae (smooth muscle)

What is the mucosa: epithelium?

top layer of the mucosa, lines the lumen

What is the mucosa:epithelium made up of?

simple/stratified columnar cells

What cells are made in the mucosa:epithelium?

enterocytes, enterendocrine cells, mucin-producing cells

What are enterocytes?

where fat molecules enter through diffusion

What are enteroendocrine cells?

secrete hormones

What are mucin-producing cells?

secrete mucus for protection

What is the lamina propria of the mucosa?

supports small blood vessels and lymph nodes

What is the lamina propria of the mucosa made up of?

connective tissue layer beneath the epithelium

What does the lamina propria of the mucosa provide?

nutrient supply and immune defense

What is the muscularis mucosae of the mucosa?

shapes folds (villi) and microvilli to increase surface area

What is the muscular mucosae of the mucosa made up of?

thin layer of smooth muscle

What does the muscularis mucosae of the mucosa aid in?

movement of mucosa for better absorption and secretion

Where does peristalsis occur?

esophagus, stomach, small intestine, large intestine

What is part of macro motility?

peristalsis and segmentation

What is peristalsis?

wave-like forward contractions of smooth muscle

What is the primary function of peristalsis?

move food forward through the GI tract

What is segmentation?

back-and-forth movements that mix food with digestive juices

Where does segmentation occur?

small intestine

What is the primary function of segmentation?

mixes chyme to enhance digestion and absorption

What is part of micro motility?

phasic and tonic contractions

What are tonic contractions?

sustained, long contractions of smooth muscle