Chapter 8- Digestive System

Major Structures of the Digestive system

Oral cavity, pharynx, esophagus, stomach, small intestine, large intestine, rectum, anus

Accessory organs function

aid with digestion but not part of the digestive system

accessory organs are

liver, gallbladder, pancreas

upper GI Tract

mouth, pharynx, esophagus, and stomach

Lower FI Tract

Small intestine, large intestine, rectum and anus

major Structures of the oral cavity

lips, hard palate, soft palate, salivary glands, tongue, teeth, periodontium

Lips function

aid the tongue and cheek in guiding food between the teeth during chewing, aid in speaking, aid in expression of emotions, aid in breathing

Hard Palate

bony anterior portion of the palate, covered in specialized mucous membrane

Soft Palate

flexible posterior portion of the palate, closes off the nasal passage during swallowing

Uvula

hangs from the free edge of the soft palate, important role in snoring, plays a role in some formation of speech sounds

tongue

strong, flexible, and muscular; aids in speech, moves food during chewing and swallowing

papillae

small bumps on the top of the tongue that contain the taste buds

Gingiva “gums”

specialized mucous membranes that surrounds teeth, covers the bone of dental arch, and lines the cheeks

Dental Arches “upper and lower jaw”

maxillary and mandibular arches, firmly hold the teeth in position

Temperomandibular joint “TMJ”

at the back of the mouth where the maxillary arch and the mandibular arch come together

Crown

portion of the tooth that is visible in the mouth, covered with enamel

roots

hold it securely in place within the dental arch

cervix

the neck of the tooth connects the crown to the root

Dentin

makes up the bulk of the tooth, protected by enamel and cementum

Pulp

consists of a rich supply of blood vessels and nerves to provide nutrients to the tooth.

Saliva

colorless liquid that moistens the mouth and begins the digestive process, lubricates food during chewing and swallowing

3 pairs of salivary glands

parotid glands, sublingual glands, submandibular glands

pharynx (throat)

common passage for both food and air

epiglottis

lid-like structure that closes off the entrance to the trachea to prevent food and liquids from moving from the pharynx during swallowing.

esophagus

muscular tube through which ingested food passes from the pharynx to the stomach

lower esophageal sphincter

muscular ring that controls the flow between the esophagus and stomach

mastication

aka “chewing”- breaking down food into smaller pieces, mixes with saliva and prepares it to be swallowed

bolus

a mass of food that has been chewed and ready to be swallowed

during swallowing, food moves…

mouth to the pharynx to the esophagus to the stomach

3 sections of the stomach

fundus, body, and antrum

fundus

upper round part of the stomach

antrum

lower part of the stomach

rugae

folds in the stomach lining- glands within these folds produce gastric juices that aid in digestion and mucus to create a protective coating on the lining of the stomach

pylorus

connects the stomach to the small intestine

gastric juices

contain hydrochloric acid and digestive enzymes to begin the digestive process

the churning action of the stomach works with the gastric juices by converting food into…

chyme

chyme

semi fluid mass of partially digested food; moves from the stomach into the small intestine.

small intestine

extends from the end of the pylorus to the large intestine, coiled up organ up to 20 feet in length, where food is digested and the nutrients are absorbed into the blood

3 sections of the small intestine

duodenum, jejunum, Ileum

Role of the small intestine?

complete the conversion of food into usable nutrients, peristaltic actions move chyme through

duodenum

chyme mixes with pancreatic juices and bile to break down fat globules

jejunum

secretion of large amounts of digestive enzymes to continue digestion

Ileum

primary function is absorption of nutrients

Large intestine

extends from the small intestine to the anus, twice as wide as small intestine but only ¼ long, waste products of digestion are processed in preparation for excretion

4 major parts of the large intestine

cecum, colon, rectum, anus

Role of the Large Intestine

receive the waste products of digestion and stores it until they are eliminated; enters as fluid form, excess water is reabsorbed into the body, remaining waste forms into feces

feces

“stools” solid body wastes expelled through the rectum and out the anus

defecation

“bowel movements” emptying of the Large intesting

flatulence

passing of gas out through the rectum and anus

the liver location

the right upper quadrant of the abdomen

the liver function

removes excess glucose from the blood stream and stores it as glycogen, destroys old erythrocytes, removes toxins from blood, releases bile containing bilirubin which aids in digestion of fats.

the gallbladder

pear shaped organ about the size of an egg located under the liver; it stores and concentrates the bile for later use; bile is used to break apart large fat globules

the pancreas

soft, 6-inch-long gland located behind the stomach; produces and secretes pancreatic juices into the duodenum; aid in digestion and contain sodium bicarbonate to help neutralize stomach acid and digestive enzymes

the process in which complex foods are broken down into nutrients the body can use

digestion

digestive enzymes

chemically break down food into simpler forms of nutrients

nutrient definition

a substance that is necessary for normal functioning of the body

nutrients

carbohydrates, fats, proteins, vitamins, minerals

metabolism

all the processes involved in the body’s use of nutrients

anabolism

building up of body cells and substances from nutrients

catabolism

breaking down of body cells or substances, releasing energy and carbon dioxide

absorption

the process by which completely digested nutrients are transported to the cells throughout the body

villi

cover the lining of the small intestine and absorb nutrients into the bloodstream

lacteals

located in the villi absorb fat and fat soluble vitamins and transport them to the cells of the body via the lymphatic vessels