Digestive System

Oral Cavity

This also refers to the mouth and is divided into two regions:
1. the space between the lips or cheeks and the teeth
2. the oral cavity proper, which lies inside the teeth and houses the tongue.

orbicularis oris

Lips are muscular structures, formed mostly by what muscle?

skin

The outer surfaces of the lips are covered by?

keratinized stratified epithelium

What epithelial cell of the skin becomes thin at the margin of the lips.

stratified squamous epithelium

At the internal margin of the lips, the epithelium is continuous with the moist _____________ of the mucosa in the oral cavity.

Cheeks

This forms the lateral walls of the oral cavity.

buccinator

Located within the cheeks are the buccinator muscles.

mastication

The lips and cheeks are important in the process of

mechanical digestion

Mastication begins the process of _________, which breaks down large food particles into smaller ones.

Tongue

This occupies the most of the oral cavity

posterior

Major attachment of the tongue is in the _______ part of the oral cavity.

anterior

The ______ part of tongue is relatively free.

frenulum

This refers to a thin fold of tissue in the anterior attachment to the floor of the mouth.

covered

Anterior ⅔ is _____ by papillae, some of which contain taste buds.

devoid

Posterior ⅓ is _____ of papillae, has only a few scattered taste buds.

lingual tonsil

The posterior portion in the tongue helps form the

32

Normal adult moth contains __ teeth.

[1] One central incisor
[2] One lateral incisor
[3] One canine
[4] 1st and 2nd premolars
[5] 1st , 2nd, and 3rd molars (wisdom teeth)

Each quadrant from the four quadrant in the teeth contains:

permanent teeth or secondary teeth

The teeth of adults are called what?

primary teeth or deciduous teeth

The teeth of adults are replacements for the 20 teeth called?

palate

This refers to the roof of the oral cavity

palate

• This separates the oral cavity from the nasal cavity

• Prevents food from passing into the nasal cavity during chewing and swallowing.

hard palate

One of the palates; anterior part and contains bone

soft palate

One of the palates; posterior part and consists of skeletal muscle and connective tissue.

uvula

This refers to a posterior extension of the soft palate.

tonsils

This is located in the lateral posterior walls of the oral cavity, in the nasopharynx, and in the posterior surface of the tongue

salivary glands

This produces saliva

serous and mucous

Saliva is a mixture of what fluids?

parotid glands

A major pair of salivary gland that produce serous secretions

submandibular glands

A major pair of salivary gland that produce more serous than mucous secretions

sublingual glands

A major pair of salivary gland that produce mucous secretions

salivary amylase

This breaks down starch

Lysozyme

an antibacterial enzyme that prevents bacterial infections in the mouth

pharynx

Also called the throat, which connects the mouth with esophagus

nasopharynx

Part of pharynx in the upper part of the throat located behind the nose.

oropharynx

Part of pharynx located right behind the mouth

laryngopharynx

Th final part of the pharynx located at the posterior part of the larynx.

pharyngeal constrictor muscles

The posterior walls of the oropharynx and laryngopharynx are formed by the superior, middle, and inferior ____________________

esophagus

• A muscular tube, lined with moist stratified squamous epithelium.

• Transports food from the pharynx to the stomach.

25 cm 

esophagus is how long?

skeletal muscle

Upper ⅓ of esophagus has_____ in its wall

skeletal and smooth muscle

The middle third of esophagus has a mixture of _______

smooth muscle

Lower ⅓ of esophagus has______ in its wall

esophageal sphincters

This regulate the movement of food into and out of the esophagus

cardiac sphincter

The lower esophageal sphincter is sometimes called the

stomach

Temporarily storing food, performing mechanical digestion by churning and mixing food with gastric juices, and beginning the chemical digestion of proteins.

chyme

The semi-fluid mass of partially digested food and digestive secretions

cardiac part

The esophagus opens into the _____ of the stomach at the gastro-esophageal opening.

fundus

• Part of the stomach to the left of the cardiac part.

• Superior to the cardiac opening.

body

• Largest part of the stomach

• Turns to the right, creating a greater curvature and a lesser curvature.

pyloric part

• Funnel-shaped as the body narrows

• Opens into the small intestine and is surrounded by the pyloric sphincter.

small intestine

Functions as the absorber of nutrients

1st and 2nd portions

Most of the absorption in the small intestine occurs where?

6 m long

The small intestine is how long?

duodenum

• about bout 25 cm long

• Receives chyme from the stomach, bile from the liver, and pancreatic juice from the pancreas.

• Nearly completes a 180-degree arc.

jejunum

• About 2.5 m long

• Makes up 2/5 of the total length of the small intestine.

• Main site for nutrient absorption.

ileum

• About 3.5 m long

• Makes up 3/5 of the small intestine

peptidases

An enzyme that digest proteins. It break peptide bonds in proteins to form amino acids

disaccharides

an enzyme that digest small sugars

Peristaltic contractions

This cause the chyme to move along the intestine

Segmental contractions

This mix intestinal contents

large intestine

• Portion of the digestive tract extending from the ileocecal junction to the anus.

18-24 

How many hours are required for material to pass through large intestine?

3-5

How many hours is required for chyme to move through small intestine?

feces

While in the colon, chyme is converted into?

1500

How many mL of chyme enter the cecum each day? 

90%

How much volume is reabsorbed in the cecum?

80-150 mL

How much feces are normally eliminated by defecation?

cecum

• Proximal end of the large intestine, located in the right lower quadrant of the abdomen.

• A sac that extends inferiorly about 6 centimeters.

• Absorbs leftover water and salts

appendix

a tube that is attached to the cecum about 9 centimeters long.

ascending colon

The colon that extends superiorly from the cecum, near the liver.

transverse colon 

This colon goes across the belly from right to left, near the spleen

descending colon

This colon goes down the left side of abdomen

sigmoid colon

This colon forms forms an S-shaped tube that extend medially and then inferiorly and ends at the rectum.

rectum

• A straight, muscular tube that begins at the termination of the sigmoid colon and ends at the anal canal.

• Thicker in muscle, enabling it to hold and store feces.

anal canal

• The last 2 to 3 centimeters of the digestive tract.

• Begins at the inferior end of the rectum and ends at the anus.

internal anal sphincter

The smooth muscle layer of the anal canal is even thicker than that of the rectum which forms the

external anal sphincter

This is at the anal canal that is formed by skeletal muscle.

liver

• The largest internal organ and weighs about 1.36kg or 3 pounds.

• Located at the right upper quadrant of the abdomen.

• The posterior surface of the liver is in contact with right ribs 5-12.

right, left, caudate, quadrate

The liver consists of four lobes

falciform ligament

This separate the right and left lobes in the liver

Porta

A gate through which blood vessels, ducts, and nerves enter or exit the liver

Hepatic artery

Blood vessel that delivers oxygenated blood to the liver

Hepatic portal vein

Blood vessel that carries nutrient-rich blood from the digestive tract to the liver.

hepatic veins

This is where blood exits the liver and empties into the inferior vena cava.

hepatic lobules

These are hexagonal-shaped regions defined by a portal triad and a central vein.

the hepatic portal vein, the hepatic artery, and the hepatic duct

Portal triads have 3 structures:

hepatic cord

This refers to strings of cells that radiate out from the central vein like the spokes of a wheel. It is composed of hepatocytes, the functional cells of the liver.

Hepatic sinusoids

This are blood channels in the spaces between the hepatic cords.

Bile canaliculus

a cleft-like lumen that lies between the cells within each cord.

gall bladder

A small, hollow, pouch-like organ about 8 cm long and 4 cm wide, located beneath the liver.

fundus

First part of gall bladder to fill with bile

body

The main storage area of gall bladder for bile

neck

A part of gall bladder that connects to cystic duct

40-70

How much mL of bile is stored in the gall bladder?

pancreas

This is composed of both endocrine and exocrine tissues that is located behind the stomach and is retroperitoneal 

head

A part of pancreas nestled within the curvature of the duodenum

body and tail

A part of pancreas extending to spleen

pancreatic islets

The endocrine part of pancreas consists of?

islets of Langerhans

The pancreatic islets of the pancreas are also called?