Chapter 4 - Human Digestion & Absorption Flashcards
Tissue
Collection of cells adapted to perform at specific function
What are the four major types of tissue?
Epithelial, connective, muscle, nervous
Epithelial Tissue
Composed of cells that cover surfaces outside and inside the body (ex: skin)
Epithelial cells absorb nutrients, secret important substances, excrete waste, and protect underlying tissues.
Connective Tissue
Supports and protects the body by holding structures (ex: cells, cell parts) together, stores fat, and produces blood cells (ex: tendons, cartilage, parts of bone, arteries, and veins)
Muscle Tissue
Can contract and relax and permits movement
Nervous Tissue
Transmits nerve impulses from one part of the body to another. Found in the brain and spinal cord.
Organ
A structure consisting of cells and tissues that perform a specific function in an organism
Organ System
Groups of organs classified as a unit because they work together to perform a function or set of functions
Digestion
The process of breaking down foods into a form the body can use.
Absorption
The uptake of nutrients from the GI tract into either the blood or the lymph
What are the nine major parts of the digestive system?
- the mouth/salivary glands
- the esophagus
- the stomach
- the liver
- the gallbladder
- the pancreas
- the small intestine
- the large intestine
- the rectum
What does the mouth/salivary glands do?
Chew food, perceive taste, moisten food with saliva, lubricate food with mucus, release starch-digesting (amylase) enzyme, initiate swallowing reflex.
What does the esophagus do?
Lubricate with mucus, move food to stomach by perialistic waves (swallowing)
What does the stomach do?
Store, mix, dissolved and continue digestion of food, dissolve food particles with secretions, kill micro organisms with acid, release protein-digesting (pepsin) enzyme, lubricate and protect stomach surface with mucus, regulate emptying of dissolved food into small intestine, produce intrinsic factor for vitamin B-12 absorption
What does the liver do?
Produce bile to aid fat digestion and absorption
What does the gallbladder do?
Store, concentrate, and later release bile into the small intestine
What does the pancreas do?
Secrete sodium bicarbonate and enzymes for digesting carbohydrate, fat, and protein
What does the small intestine do?
Mix and propel contents, lubricate with mucus, digest and absorb most substances using enzymes made by the pancreas and small intestine
What does the large intestine do?
Mix and propel contents, absorb sodium, potassium, and waters house bacteria, lubricate with mucus, synthesize some vitamins and short-chain fatty acids, form feces
What does the rectum do?
Hold feces and expel via the anus, the opening to the outside of the body
Alimentary Canal
Tubular portion of the digesting tract that extends from the mouth to the anus. Also known as the GI tract.
What does alimentary mean?
“Relating to nourishment or nutrition”
Nutrients must pass through the walls of what to be absorbed into the body?
the alimentary canal
What are the four layers of alimentary canal wall?
(in order) mucosa, submucosa, muscle, serosa
Mucosa
Innermost layer of the alimentary canal wall.
Lined with epithelial cells and glands.
Not smooth, has lumen (finger-like projections) which increase the surface area of the mucosa.
Submucosa
2nd layer of the alimentary canal wall.
Loose connective tissue, glands, blood vessels, and nerves.
Vessels carry substances to and from the GI tract.
Muscle
3rd layer of the alimentary canal wall.
Double layered with inner circular smooth muscle and outer longitudinal muscle fibers.
Move food forward through the GI tract.
(Stomach has 3rd layer of muscle fiber).
Serosa
Outermost layer of the alimentary canal wall.
Protects the GI tract, secretes fluid that cushions the GI tract and reduces friction during movement.
Sphincter
Muscular valve that controls the flow of foodstuffs in the alimentary canal.
What are the 5 types of sphincters?
Lower esophageal (cardiac) sphincter, pyloric sphincter, sphincter of Oddi (hepatopancreatic), ileocecal valve, anal sphincter
Lower Esophageal (Cardiac) Sphincter
Prevents the back flow (reflux) of stomach contents into the esophagus
Pyloric Sphincter
Controls the flow of stomach contents into the small intestine
Sphincter of Oddi (Hepatopancreatic)
Controls the flow of bile from the common bile duct into the small intestine
Ileocecal Valve
Prevents the contents of the large intestines from rendering the small intestine
Anal Sphincter
Prevents defecation until the person desires to do so
Peristalsis
Coordinated wave of contraction and relaxation that moves the bonus ahead of the wave through the GI tract.
Segmentation
Back and forth action in the small intestine that breaks apart the bolts and mixes them with digestive juices
Where do you find saliva and what is its digestive purpose?
Found in the mouth.
Contributes to starch digestion, lubrication, and swallowing.
Where do you find mucus and what is its digestive purpose?
Found in the mouth, stomach, and intestines.
Protects the GI tract cells, lubricates digesting food.
Where do you find digestive enzymes (amylases, lipases, proteases) and what are their digestive purposes?
Found in the mouth, stomach, small intestine, and pancreas.
They break down carbs, fats, and protein into forms small enough for absorption
Hydrolysis Reaction
Chemical reaction that breaks down a compound by adding water. One product receives a hydrogen ion (H+) and the other recipes a hydroxyl ion (OH-).
Hydrolytic enzymes break down compounds using water in this manner.
Where do you find hydrochloric acid (HCl) and what is its digestive purpose?
Found in the stomach, from the parietal cell.
Promotes digestion of protein, destroys microorganisms, increases solubility of minerals.
Where do you find bile and what is its digestive purpose?
Made in the liver, stored in the gallbladder.
Aids in fat digestion (emulsifies fat)
Where do you find bicarbonate and what is its digestive purpose?
Found in the pancreas and small intestine.
Neutralizes stomach acid when it reaches the small intestine.