unit 8 digestive

• known as the GI tract,consists of
• mouth
• pharynx
• esphagus
• stomach
• sm.intestines
• lg.intestines

• teeth
• tongue
• salivary glands
• liver
• gallbladder
• pancreas

food is taken in to the mouth

invovlves swallowing(voluntary),and peristalis(involuntary):

progressive waves ofcontraction that move food along the alimentary canal

chewing(teeth) and churning(stomach)of food.

involves segments of the sm. intestine contracting and relaxing; this mixes food with digestive juices and increases absorption effiency.

breakdown of carbs,proteins, and lipids

transport ofmaterial from the lumen of the alimantary canal to the blood,lymph capillaries.

removal of undigestible material from the body as feces

• 1. covers the digestive organs
• 2.a slit-like potential space
• 3.lines the abdominal wall

double layer of peritoneum;hold organs in place;fat storage

• 1.most meseteries including the greater omentum
• 2.falciform "ligament"(liver) and lesser omentum(liver,stomach and duodenum)

• digestive organs not found in the pelvic or abdominal cavity.but are located just on the outside behind the parietal peritoneum.
• 1.fuse to teh dorsal abd. wall during development
• 2.lose their mesentary

ex: parts of the esophagus,duodenum,colon,and rectum. kidneys

• 1.the innermost layer with 3 sublayers
• 2.absorbs nutrients and secretes mucus
• 3.nourishes the lining epithelium and absorbs digested nutrients. contains lymph.tissue for protection.
• 4. thin layer of smooth muscle

contains major blood vessles, lymph. vessles and nerve fibers

• 1.contains 2 layers of smooth muscle that work 2gether to cause peristalis and segmentation.
• 2.muscle fibers that orient around the circumference of the canal "squeezes" the gut tube
• 3.muscle fibers orient along the length of the canal;shortens the gut tube

composed of the viseral peritoneum

composed of a thick non keratinized stratified squamous epithelium to help deal with friction/"wear and tear" from digested food.

• 1.anterior opening
• 2.between teeth and cheeks (and lips)

• 1.lips;formed from the orbicularis oris muscle
• 2.formed from the buccinator muscle

roof of themouth, hard palate,soft palate,uvula, and palatine tonsils

it is a muscle and contains the lingual tonsils and papillae

"roughen"toungue;provides friction for manipulating food

• fungiform
• circumvallate
• foliate

• saliva(a combo of H20 ions,mucus, and enzymes)
• amylase which begins the digestion of starch in the mouth.

• they keep the mouth moist at all times
• found in the tongue palate lips and cheeks

• they secrete saliva during eating or the antispation of a meal
• they include the parotid,submandibular and sublingual glands

sublingual glands;produce mucus;sublingual glands contain only serous cells

they lie in alveolar sockets of the mandible and maxillary bones

20 include the incisors,canines(cuspids or eyeteeth)and molars

32 include incisors, canines,premolars(bicuspids) molars(including wisdom teeth)

• gums
• above the gums
• below the gums

99% mineralized with hydroxyapatite; hardest substance in the body

like bone but harder and lacking blood vessels;not as hard as enamel.

contains "pulp" and the tooths blood vesels and nerves

connects the cementum of the tooth to the alveolar bone;composed of collagen fibers

• passageway for food, fluids and air
• composed of non keratinized,stratified squamous, epitheluium

it helpsto block the opening to the larynx and assures that food continues down the esophagus.

• muscular tube that propelsfood to the stomach
• lies directly posterior to the trachea
• passes through the diaphragm,turns left and connects to teh stomach at the cardia.

to helpl limit regurgitation of the stomach acid back into the esophagus

• storageof food(for about 4 hours)
• churning of food to turn it into a paste called chyme
• it secretes pepsinogen that converts to pepsin in an acidic envirornment to begin protein digestion
• secretion of hydrochloric acid(HC1)
• very littledigestion occurs in the stomach. mostly in the sm. intestine

linner lining composed of simple columnar epithelium

non permanent fols that allow the stomach to stretch

controls the passage of chyme into the duodenum of the small intestine

• are invaginations that increase the surface area in the stomach
• mucous cells: secrete mucus
• parietal cells:secrete hydrochloric acid
• chief cells: secrets pepsinogen
• enteroendocrine cells: influence digestive system target organs

regualtesstomach secretion and mobility

• simple columnar epithelium
• in the sm.intestine

it greatly increases surface area for digestion and absorption

• duodenum- short c shape first layer
• jejunum-middle section
• ileum-lastand longest section

• chyme from the stomach
• bile from the liver and gallbladder via the hepatopancreatic ampulla
• digestive enzymes from the pancreas via the hepatopancreatic ampulla

• connects to the large intestine
• prevents feces from entering the small intesine

• largest gland in the body
• performs over 500 functions including metabolic functions
• converts glucose into glycogen
• detoxifies many poisons and drugs like alcohol
• has hepatocytes(liver cells) that produce bile 2 aide in digestion

• right lobe
• leftlobe
• caudate lobe
• quadrate lobe

• remnant of fetal circulation; in fetusserved as a liver bypass
• remnant of fetal umbilical vein
• a mesentary

carries blood from the digestive tract to theliver

its made in the liver and stored in the gallbladder

• hepatocytes
• central vein

• portal arteriole
• portal venule
• a bile duct

destroy bacteria and other foreign particles

• bile flows from right and left hepatic ducts of the liver into the common hepatic duct
• then into the common bileduct
• out through the hepatopancreatic ampulla
• and finally into the duodenum where it is needed.

bile backs up into the common bile duct and cystic duct and finally the gallbladder where it is stored

• controls whether bile is secreted or stored
• closed when no digestion is occurring

• both and endocrine gland (enzymes) and exocrine gland(hormones)
• makes stores and secretes enzymes fro digestion
• produces the hormones glucagon and insulin to regulate blood glucose

• has a head and tail: head touches tthe duodenum and tail connects to the spleen
• contains the main panreatic duct and accessory pancreatic duct
• hepatopancreatic ampulla and sphincter control relase of pancreatic secretions

• small amount of digestion by bacteria
• absorption of water and electrolytes to form feces

• first portion of the large intestine;connects to the ileum at the ileocecal valve
• worm shaped; has some lymphatic function

• ascending,transverse, descending,sigmoid
• locaterd in the pelvic region

• internal:smooth muscle involuntary control
• external: skeletal muscle voluntary control

maintain constant muscle tone to constrict the large intestine and form pouches called haustrae

• composed of simple columnar epithelium
• no because there is no need digestion and absorption take place elsewhere

• moving food from mouth to anus
• mechanically mixing food to break it down into smaller pieces to increase surface area for exposure to digestive organs
• hormones and paracrines can alter it
• parasymphathetic input from the vagus nerve increases it.

spontaneously depolarize to cause contraction of the smooth muscle in the wall of the GI tract

segements of the sm intestine contract to churn the contents bakc and forth

• 9 liters
• adults
• reabsorbed

• 2.0
• food
• 7.0
• digestive secretions

• 7.5 L
• small intestine
• 1.4L
• large
• 0.1

a viscous secretion it forms a protectice coating over the mucosa of the GI tract, and helps lubricate the contents of the gut.

part of the simple columnar epithelium of the intestine. secretes mucus in the sm. and lg. intestine

mechanical and chemical

surcose (table sugar)

• milk and sugar
• maltose

simple sugars like glucose and fructose

• glycogen
• cellulose (fiber)

no because we lack the neccessary enzymes

animal protein is the least. animal protein is the most digestable.

egg protein is the best with 85-90%digested and absorbed.

endopeptidases and exopeptidases.

• endopeptidases attack peptide bonds in the anterior of the amino acid chain
• whereas exopeptidases chop off single amino acid from the ends of the chain.

• about 90%
• becasue they are the primary form found in both plants and animals.

abnormal relaxation or weakness of esophageal stomach junction. exposure can lead to a esophageal ulcer

heartburn regurgition belching

a crater like erosion of the mucosa of any part od the GI tract that is exposed to acid. usually i the pyloric region of th stomach or duedenum

either 2 much cholestrol or 2 little bile salts can lead to crystalization of cholesterol in the gallbladder producing gallstones; thye can block the cystic duct which require surgery to remove the gallbladder.

a progressive inflammation of the liver that usually results from chronic alcohol; resulting scar tissue can impede the floewo f blood through the liver

pathalogical state in which the intestinal secretion of fluid is not balanced by absorption, resulting inwatery stools. in extreme cases can cause severe dehydration and even death if not treated

caused by consciously ignoring the defacation reflex or through increased motility; continued water absorptin creates hard dry feces that are difficult to expel

forceful expulsion of gastric and duodenal contents from the mouth; protective reflex designed to remove toxic material from the GI tract before it can be absorbed