Digestive System {Chapter 23]

What are other names for the digestive system

gastrointestinal tract, alimentary canal, gut

What are the major processes of the DI

Ingestion, Propulsion, Mechanical breakdown, Digestion, Absorption, Defecation

What is peristalsis?

wave-like muscle contractions

What is segmentation?

a type of mechanical breakdown; mixing in the small intestine

What is the visceral peritoneum?

covers the organs external surface

What is the parietal peritoneum

lines inside of abdominal cavity

Where is the peritoneal cavity

between visceral and parietal peritoneum

What is serosa

The thin, double-layered membrane that covers the walls of the ventral body cavity and the outer surfaces of the organs it contains.

What are the four layers of the alimentary canal

mucosa, submucosa, muscularis externa, serosa

What layer is the mucosa

the innermost layer

What does the mucosa do

secrets enzymes and mucus
absorption of nutrients
protects from infections

What are the layers of mucosa

epithelium - lines lumen
lamina propria - supplies blood, nerves, MALT
muscularis mucosa - helps digestion/absorption

What layer is the submucosa

the second layer

What is the histology of the submucosal layer

areolar C.T; contains blood, nerves, lymph

What layer is the muscularis externa

second most outer layer; Histology is Smooth muscle

What layer is the serosa

outermost layer; protects and supplies with blood

Mucosa (Picture)

B

Submucosa (Picture)

C

Muscularis externa (Picture)

D

Serosa (Picture)

E

What is splanchnic circulation?

includes arteries that branch off the abdominal aorta to serve digestive organs and the hepatic portal circulation

How much of cardiac output does splanchnic circulation receive

25%, and more after eating

What is the nervous supply for the digestive system

Enteric nervous system

What is the function of lips and cheeks

keep food between teeth

What is the gross anatomy of the mouth

Oral cavity, Lips, Cheeks, Hard/Soft palate, Tongue
Parotid/Sublingual/Submandibular salivary glands
Teeth, Pharynx, Esophagus

Which palate is hard

The anterior

Which palate is soft

The posterior

What is the function of the palates

create a barrier to keep food from entering the nasal cavity/ nasopharynx

What is a bolus

ball of food

Parotid salivary gland (Picture)

Sublingual salivary gland (Picture)

Submandibular salivary gland (Picture)

What is the function of saliva

Dissolves food for tasting, moistens food, contains amylase/lipase/lysozyme

How much saliva is produced per day?

1.5 liters

What is Amylase

Amylase is an enzyme that catalyses the breakdown of starch into sugar

what is lipase

enzyme that breaks down lipids

What is lysozyme

enzyme that kills bacteria

what promotes salivation

Chemoreceptors and mechanoreceptors

How many deciduous teeth are there?

20

How many permanent teeth are there?

32

Incisors (Picture)

A, used for cutting

canines (Picture)

B, used for piercing/tearing

premolars [bicuspids] (Picture)

C, grinding

Molars (Picture)

D, grinding

What is the inner histology of the esophagus

Stratified Squamous epithelium

Cardiac sphincter (Picture)

C

pyloric sphincter (Picture)

A

What are the function of the stomach

Storage, mechanical breakdown, initial digestion

How much does the stomach hold

50 ml empty
4 L full

What do mucous neck cells secrete?

acidic mucus

What do parietal cells secrete?

HCl and intrinsic factor

What does intrinsic factor do?

absorbs vitamin B12

What does HCl do in the stomach?

Kills microbes

What type of gland cells are in the stomach

Mucous Neck cells
Parietal Cells
Chief cells
Enteroendocrine cells
goblet

What do chief cells secrete?

Pepsinogen and Lipases

What does pepsinogen do?

becomes pepsin in acid

What does pepsin do?

breaks down proteins

What do enteroendocrine cells secrete?

hormones/molecules to help digestion

What is the mucosal barrier?

The physical defense of the stomach lining that prevent self-digestion. Bicarbonate rich mucus and tight junctions between epithelial cells

How do ulcers form?

when Helicobacter pylori destroys mucus

How much gastric juice is produced per day?

3 L

What is the cephalic phase?

Smell, sight, and though of food triggers gastric secretions

What is the gastric phase?

When food reaches stomach, dramatically increases secretions

What is the intestinal phase?

As food enters duodenum

What is the alkaline tide?

Blood pH increases leaving stomach due to H_ ions entering stomach causing HCO3- ions to enter the blood
Blood becomes basic

What is chyme

a mixture of partially digested food, water, and gastric juices

How does food enter the duodenum

The pyloric sphincter squirts 3 ml of chyme

What supplies the liver with blood

The Hepatic Artery=Ox blood from Aorta
Hepatic Portal Vein=Nutrient rich blood from GI

Where does bile leave the liver from

common hepatic duct

What forms the bile duct?

common hepatic duct and cystic duct

What WBC cleans blood within the liver

Hepatic Macrophages

What cells are arranged in lobules in the liver

Hepatocytes

What are hepatocytes

functional cells of the liver

What do hepatocytes do?

Produce bile, detoxify blood, store vitamins, and process nutrients

What is bile

fat emulsifier, made of bile salts and phospholipids
alkaline

What is Hepatitis

inflammation of the liver

What is cirrhosis?

a chronic disease of the liver marked by degeneration of cells, inflammation, and fibrous thickening of tissue. It is typically a result of alcoholism or hepatitis.

Hepatic duct (Picture)

common bile duct (Picture)

What is the common bile duct

duct where exocrine secretions from the liver, pancreas and gall bladder enter the small intestine

Portal triad (Picture)

Portal triad (Slide Picture)

Hepatic vein (Picture)

Liver lobules (SLide Picture)

Lobule central vein (Slide Picture)

Gall bladder (Picture)

D

What is the function of the gallbladder

bile storage and release

What causes gallstones?

too much cholesterol or too few bile salts

How much pancreatic juice is produced per day?

1.5 L

What enzymes makes up pancreatic juice

Proteases [Tripsin, Carboxypeptidase, Chymotrypsin]
Amylase
Lipase
Nucleases

What converts trypsinogen to trypsin?

enteropeptidase from duodenum

What does trypsin activate?

chymotrypsin and carboxypeptidase

What does trypsinogen activate into

Trypsion

What is the order of sections in the small intestine

Duodenum (25 cm)
Jejunum (2.5 m)
Ileum (3.6 m)

What is the function of villi and microvilli

increase surface area for absorption

What are intestinal crypts

They are pits between intestinal villa that contain cells that make intestinal juice

What are the secreationatory cells within the small intestine

Goblet cells
Enteroendocrine cells
Paneth cells
Duodenal Glands

What are enterocytes?

basic epithelium cells, intestinal absorptive cells

What are enteroendocrine cells?

hormones and paracrine messengers that aid in digestion activity

What are paneth cells?

They are located at the base of the crypts and produce antibiotic peptides and proteins.