Digestive SystemDigestive SystemMouth-- receives food

Tongue

-- striated muscle

-- responsible for smell& taste

-- moves food aroundto form a Bolus

-- also necessaryfor speech

Roof of Mouth(separates nose from mouth)

-- Hard Palate ( made up ofcranial bones)

-- ends in the Uvula

-- Soft Palate(made up of muscle)

Teeth-- allows us to chew food so we can

swallow it

-- get first baby tooth at about6 months of age

(considered a developmental milestone)

-- we have 20 baby (Deciduous )teeth by age 2

-- lose first baby tooth by age 6

Types of Teeth

-- 8 incisors for biting

-- 4 canines for tearing

-- 8 premolars (bicuspids) for grinding

-- baby molars are replaced by these

-- 12 molars (tricuspids) for crushing

-- the last of these are the WisdomTeeth

-- Adult usually have 32 teethbetween ages 17 and 24

Crown

Root

Neck

Enamel

DentinPulp

Nerve BloodVessels

Tooth decay

Cavities

Caries

Inflammation of the gums: GingivitisGum disease that causes loss of bone & teeth: Peridontitis

Tonsils-- play a minor role in protecting us

-- tonsils in back of throat are called:Palatine tonsils

(These are the ones removed duringa tonsillectomy)

-- Pharyngeal tonsils are the Adenoids

(Removal of these is called anAdenoidectomy)

Parotidgland

Sublingualgland

Submandibulargland

Salivary Glands

-- sends saliva to themouth

Salivary-- saliva contains the

Amylase which starts the

of Carbohydrates

enzyme

chemical digestion

(starches)

nasopharynx

oropharynxlaryngopharynx

Epiglottis

LarynxEsophagus

Pharynx

-- has 3 openings

-- as soon as the bolus hits the back ofthe throat, we swallow (reflex action)

-- the larynx is elevated and moves upunder the Epiglottis

-- prevent food from entering the larynx

Esophagus

Heartburn is when the stomach content escapesinto the esophagus

Esophagus

-- pushes food along by: Peristalsis

Cardiacsphincter

-- food enters the stomach through

or Gastroesophagealsphincter

(also called the Lower Esophageal Sphincter)

Vomiting is caused by contraction ofthe diaphragm & abdominal muscles

Stomach

-- lined inside with smooth muscle

-- stores food &starts digestionon Protein

-- food is now a pasty, semisolid liquidcalled: Chyme

-- Gastric gland in the stomach producegastric juices containing:

2. Hydrochloric Acid (HCL)

3. Intrinsic Factor (needed for the absorption of Vit. B 12)

1. Pepsin (an enzyme) -- breaksproteins into Polypeptides

-- These juices are released in response tothe hormone: Gastrin

HCL

-- doesn't digest food, it:1. breaks down the connective

tissue in meat2. kills microorganisms ingested

with the food3. activates the gastric enzyme

(changes Pepsinogen to Pepsin)

Ulcers are caused by HCL penetratingmucous layer of the stomach

Autodigestion

-- once thought due to overproduction of HCL & stress

-- now know it is caused by a bacteriacalled: Helicobacter Pylori(it weakens the gastric mucosal lining)

-- the entire stomach lining is replaced every3 days

PylorusDuodenum

Cardiacsphincter

Rugae

-- allows the stomach to expand forstorage

-- takes stomach 2 to 6 hours to empty

PylorusDuodenum

Cardiacsphincter

-- only two non-nutrient substanceare absorbed here:

Aspirin & Alcohol

the stomach

-- No food or water isabsorbed in

PylorusDuodenum

Cardiacsphincter

Pyloricsphincter

-- empties into the small intestines(Duodenum) through the:

smallintestines

Small Intestines-- approximately

20 feet inlength

Mesentary

-- supported by the Mesentarywhich contains the nerves & bloodthat supply the small intestines

1. Duodenum (frequent area for ulcers)

2. Jejunum 3. Ileum

-- divided into threesections:

Villus

-- like the stomach,the small intestinescontain many glands that producedigestive juices

-- small fingerlike projections

--the villi increasethe surface areafor absorption & secrete certainenzymes for completing the digestion of our food

Villus

Lacteal

-- Amino Acids & Glucose will beabsorbed into the blood stream

-- we digest food to make it smallenough to cross the cellmembrane

-- absorption of food molecules involvesactive transport

-- a small lymphvessel in the center of the villus which absorbs fatty acids & glycerol

So, main functions of the SmallIntestines are:

1. Digest food 2. Absorb nutrients

3. Transport undigested food into the large intestines

Ileocecalvalve

Cecum

AppendixVermiform

Descen

ding

colon

(SigmoidColon)

Transversecolon

Ascendingcolon

Anal canalRectum

Appendix has no digestive function

if inflamed, called:Appendicitis

-- passage through the Large Intestinestakes about 3 to 5 days

AppendixVermiform

Like the esophagus, the large intestinescontain no enzymes

The large intestine's main function is to absorb electrolytes and water

--It also contains bacteriacalled: Escherichia coli

-- they produce Vit. K & someB complex vitamins

-- also gives off an odorcharacteristic of stool

Two Main Functions of the Digestive System:

-- altering the chemical & physicalcomposition of food: Digestio

n-- ridding the body of waste material: Elimination

Digesting -- begins in the mouthends in small intestines

3 Processes Food Undergoes

Absorption -- takes place in thesmall & large intestines

Metabolism -- the use of the nutrients by the cells

-- any disorders of the digestive system will usually

involve problems with 1 or more of these processes

Gallbladder

-- pear shapedmuscular organattached to theventral surface ofthe liver

-- concentrates bile

-- stores the bile produced by the liver

When chyme containing lipids or fatsenter the duodenum, it releases a hormone called: Cholecystokinin

CCK's stimulates the gallbladder to contract-- this pushes bile through the Common Bile

Duct into the duodenum

BILEBILE

-- contains bile pigment

the breakdown of hemoglobin-- mainly bilirubin which comes from

-- breaks large fatmolecules into smaller fat molecules

-- this makes it easier forthe enzyme to act upon the fats

-- also lowers surface tension so fatdroplets are easily distributed in the liquid

-- produce 2 1/4 pints is produced a day

-- contains bile salts whichemulsifies fats

bile

fat

Common bile duct

Hepatic duct

If the Hepatic Duct is obstructed, bilecannot drain out of the liver to the gallbladder

-- bile will be reabsorbed & thebilirubin returned to the blood stream

--skin & sclera will take on a yellowishtinge called: Jaundice

-- since bile gives feces its color, stools would be:gray-white, chalky colored

Common bile duct

Hepatic duct

If Common Bile Duct is obstructed, bile can't get to the duodenum

-- still release CCK, so patient has:severe pain & nausea & vomiting

Hemolytic Jaundice is due to a rapid destruction of RBC's

LIVERLIVER

-- largest gland in the body-- is a exocrine gland-- Functions:

1. Destruction of old RBC

2. Production of bile

3. Storage of glucose as glycogen

4. Production of urea-- a less toxic nitrogen waste made from

Ammonia (byproduct of breakdown of Amino Acids)

6. Detoxification of blood

7. Storage of Fat-soluble vitamins

-- A -- D -- E -- K

5. Production of BloodProteins

Pancreaticduct

PANCREASPANCREAS

-- is an endocrine& an exocrinegland

-- secretes hormonesInsulin & Glucagon

-- it sends pancreatic juices withenzymes via the pancreatic duct tothe duodenum for digesting protein, fats & carbohydrates

Pancreaticduct-- besides enzymes the

pancreatic juices also contain SodiumBicarbonate to neutralize the gastric juices as it enters the intestines

-- the Pancreas releases its enzymesin response to the small intestine hormones: Secretin &

CCK

PERITONEUM

-- it is a serous membrane that linesthe abdominal cavity & covers the organs located in it

-- any organ located behind it, iscalled: Retroperitone

al(pancreas, duodenum, kidneys)

-- Two extension of the peritoneum are:

1. Mesentary

-- found between the parietal& visceral layers

-- encloses most of the smallintestines

-- contains nerves & arteries thatsupplies the small intestines

2. Greater Omentum-- hangs down over the abdomen-- may play a role in fighting

infection

Rectum Anal Canal

--is made up of skeletal muscles &it surrounds the internal sphincter

External Anal Sphincter

--as stool enters

Spinal Cord.

the Rectum, stretchreceptors are stimulatedsending amessage to the Internal Anal

Sphincter

--this causes the urge to

sphincter to relaxdefecate & the internal

--this is why we can voluntarily chooseto defecate

CarbohydrateCarbohydrate DigestionDigestion

Breaks starches into:Maltose -- Malt sugar Sucrose -- Cane sugar Lactose -- Milk sugar

MOUTH

Salivary Amylase (Enzyme) (starts breakdown of starches)

(Enzyme)Pancreatic Amylase & Sodium Bicarbona

te(Neutralizes Gastric Acids)

PANCREAS

(Releases Secretin - Hormone) SMALL INTESTINES

Glucose absorbed through Intestinal Villi into the Blood Stream for use by Cells

(Maltose into Glucose ) (Sucrose into Glucose) (Lactose into Glucose)

Breaks:

SMALL INTESTINES

Intestinal Enzymes:(Maltase)

(Sucrase) (Lactase)

Protein DigestionProtein Digestion

STOMACHReleases Gastrin (Hormone)

HCL -- breaks down connective tissue in meat and activates enzyme

causing the release of:

Activat

es

Pepsin- (Enzyme) breaks proteins into polypeptides

Breaks Peptides into Amino Acids

Peptidase(Enzyme)

SMALL INTESTINES(Releases Secretin --

Hormone)PANCREAS

(Neutralizes Gastric Acids)

Trypsin (Enzyme) & Sodium Breaks polypeptides into peptides

Bicarbonate

Amino Acids absorbed through Intestinal Villi into the Blood Stream

FAT DIGESTIONFAT DIGESTION

Fatty Acids & Glycerol absorbed through the Lacteal into the Lymph for storage & use by cells

Breaks Fat into Fatty Acids& Glycerol

PANCREASSodium Bicarbonate(NeutralizesGastric Acids)

Lipase (Enzyme)

LIVER

GALLBLADDER

Produces Bile

SMALL INTESTINESReleases Hormones -- Secretin & CCK

BileEmulsifies Fats

MECHANICAL DIGESTION

-- includes:

chewing (mastication) swallowingperistalsis defecation

All the chemical reactions that occur in the cell are known as:METABOLISM

1. Catabolism -- releasing stored energy in food

2. Anabolism -- using materials forgrowth & repair