Lab 14 - the digestive system

digestive tract

tube that begins at the mouth and ends at the anus

accessory organs

teeth, tongue, salivary glands, liver, gallbladder, pancreas

gingiva

tissue surrounding the teeth and covering the jaw

hard palate and soft palate

roof of the mouth

adult dental formula

I 2/2, C 1/1, P 2/2, M 3/3

infant dental formula

I 2/2, C 1/1, P 0/0, M 2/2

Incisors

Chisel shaped for cutting

canines (cuspids)

single cusp, high point used for tearing food

premolars (bicuspids)

broad crowns with rounded cusps used to grind or crush

molars (tricuspids)

multiple cusps are well adapted for drinking food into fine pieces

how may teeth are in the adult mouth?

32 (including wisdom)

How many teeth are in the primary dentition?

20

crown

Visible part of the tooth

alveolus

a bony socket in the alveolar ridge that holds a tooth

parotid gland

salivary gland within the cheek, just anterior to the ear

submandibular gland

a salivary gland inside the lower jaw on either side that produces most of the nocturnal saliva

sublingual gland

small, salivary gland under the tongue

purpose of saliva

Moisten, bind, lubricate food

enamel

hard, outermost layer of a tooth

dentin

Dense tissue forming the bulk of a tooth.

pulp cavity

contains blood vessels and nerves

periodontal membrane

membrane surrounding a tooth

cementum

material covering the tooth root

alveolar bone

bone that supports and encases the roots of teeth

root canal

the pulp-filled cavity in the root of a tooth

oropharynx

central portion of the pharynx between the roof of the mouth and the upper edge of the epiglottis

laryngopharynx

the third division of the pharynx, is shared by both the respiratory and digestive systems

Esophagus

A muscular tube that connects the mouth to the stomach.

stomach

large, crescent-shaped organ located in the abdominal cavity; chemical digestion begins in the stomach

small intestine

The part of the digestive system in which most chemical digestion takes place.

parts of the small intestine

duodenum, jejunum, ileum

large intestine

Absorbs water and forms feces

parts of large intestine

cecum, colon, rectum, anal canal

liver

located in the upper right quadrant of the abdominal cavity; produces bile

lobules

functional units of the liver

hepatocytes

cells of the liver, make bile

central vein

drains blood from sinusoids and out of liver

bile

A substance produced by the liver that breaks up fat particles.

bile canaliculi

ducts between hepatocytes that collect bile

portal triad

portal vein, hepatic artery, bile duct

sinusoids

capillaries in the liver located between the hepatocytes

gall bladder

green coloured muscular sac attached to the ventral surface of the liver

stores and concentrates bile

Pancreas

lies between the stomach and duodenum

2 types of glandular tissue in pancreas

Exocrine glands - 98%

endocrine tissue - 2%

peritoneum

membrane that lines the abdominal cavity

visceral peritoneum

covers abdominal organs

parietal peritoneum

lines the body wall

mesenteries

membrane made up of folds of the peritoneum which hold the digestive organs in pace and contain blood vessels, lymphatic vessels and nerves

omentum

a mesentery which hangs free in the abdominal cavity or connects organs to each other

greater omentum

doubled walled peritoneal sac that extends from the inferior border of the stomach over the small and large intestine

spleen

Organ near the stomach that produces, stores, and eliminates blood cells

lesser omentum

attaches stomach to liver

falciform ligament

attaches liver to anterior abdominal wall and diaphragm

mesentery proper

connects different parts of the small intestine together

Mucosa

inner lining of the digestive tract

Submucosa

external to the mucosa; infiltrated with blood vessels and nerves

muscularis (externa)

lies beyond the submucosa and usually consists of 2 layers of smooth muscle arranged in an inner circular layer

serosa

outermost layer, visceral peritoneum

adventitia

layer of fibrous connective tissue, covers external muscle layer and connects the esophagus to surrounding structures

epithelium of esophagus

stratified squamous

epithelium of stomach

simple columnar

gastric pits

shallow depressions that open onto the gastric surface

gastric glands

exocrine glands in the stomach wall that secrete gastric juice into the stomach

rugae

when the stomach is empty, mucosa lies here

oblique layer

smooth muscle

epithelium of small intestine

simple columnar

Microvilli

projections that increase the cell's surface area

goblet cells

produce mucus

intestinal glands/crypts

between the villi; deep indentations

Circular folds (plicae circulares)

deep folds of mucosa and submucosa

major movement of the digestive tract

peristalsis

purpose of vili in small intestine

nutrient absorbtion

digestive enzymes

special proteins that are secreted by various accessory glands; catalyze chemical reactions

salivary amylase

Enzyme in saliva that breaks down starch

Benedicts + starch + saliva

Precipitate - yes; saliva breaks down starch

benedicts + starch

precipitate - no ; no saliva

benedicts + water + saliva

precipitate - no ; no starch

iodine + starch + saliva

colour - clear - saliva broke down starch

iodine + starch

blue - iodine turned starch blue

iodine + water + saliva

clear - no starch

pepsin

protein digesting enzyme

pepsinogen

inactive form of pepsin

hydrochloric acid

substance produced by the stomach; necessary for digestion of food

Has any digestion if the fibrin occurred in test tube A (fibrin + pepsin + HCL)

yes - pepsin denatures the fibrin; only works in acidic environments

Has any digestion of fibrin occurred in test tube B (Fibrin + pepsin + water)

no, pepsin is inactive in water

has any digestion of fibrin occurred in test tube C (Fibrin + HCL + water)

no, there was no pepsin to denature the fibre

what is the chemical nature of fibrin after digestion

amino acids

in what part of the digestive tract is protein digestion occur

stomach

what other enzymes are required for protein digestion

trypsin - chops up proteins

bile salts

compounds in bile that aid in emulsification

pancreatic lipase

digestion of lipids into fatty acids and glycerol

epinephrine effect on intestinal smooth muscle

decrease activity

Acetylcholine effects on intestinal smooth muscle

increase activity