Chapter 14 - The Digestive System

What is the gastrointestinal tract (GI)?

What is the gastrointestinal tract (GI)?

It is a long, continuous tube of the digestive system.

What are some accessory digestive organs?

salivary glands, liver, pancreas, gall bladder.

What is the job of the digestive system?

To take in food, release water, acid, buffers, pushing food through the GI tract, absorb nutrients.

What is the peritoneum?

The membrane that covers the abdominal organs and lines the abdominal cavity.

What are the four layers of the GI tract from the INSIDE to the OUTSIDE.

Mucosa, submucosa, muscularis, serosa.

What does the enteric nervous system (ENS) do?

It coordinates the GI tracts blood supply movement for absorbing nutrients.

What is peristalsis?

The process of moving food (bolus) down the esophagus though muscle contractions.

What are the three stages in deglutition?

Voluntary stage (getting ready to swallow), pharyngeal stage (process of swallowing), and esophageal stage (muscles contract to move the food into the stomach).

What is GERD? (Gastro-esophageal reflux disease)

When the lower esophageal sphincter fails to close and acid of the stomach goes up

After the bolus (food) enters the stomach and touches the gastric pits, what happens next?

gastric juices composed of enzymes, HCl, and other fluids are released.

The process of the stomach emptying its contents into the small intestine is called ________

gastric emptying

What are the main functions of the stomach…?

It mixes saliva, food and gastric juices to form chyme before moving that to the small intestine.

Secretes HCl, pepsin, intrinsic factors, and gastric lipase.

Secretes gastrin into blood.

Digestion in the small intestine begins where?

At the duodenum

After chyme enters the small intestine what happens?

It stimulates S cells to secrete secretin, which stimulates the pancreas to secrete pancreatic bicarbonate into the duodenum.

What type of cells make bile?

Liver cells called hepatocytes

What do bile salts do?

They break down large lipid globules into small ones through emulsification.

What does the gallbladder do?

It stores bile and releases it into the duodenum of the small intestine.

What does pancreatic amylase do?

It breaks down starches.

What does trypsin, chymotrypsin, and carboxypeptidase do?

They break proteins into amino acids.

What does pancreatic lipase do?

It breaks triglycerides into fatty acids.

What does ribonuclease and deoxyribonuclease do?

They break down nucleic acids.

What are the functions of the large intestine?

Peristalsis drives the contents of the colon into the rectum, bacteria convert proteins to amino acids, it absorbs water, forms feces.

What are the physical processes in digestion?

chewing, mixing, and peristalsis.

What are the chemical processes in digestion?

Secretions of fluids like salvia, gastric juices. W

What happens in anabolic reactions?

Simple organic molecules are combined to make more complex ones by using ATP and splitting it into ADP.

What happens in a catabolic reaction?

Complex organic molecules are broken down into simpler ones.

How can glucose be made in the body?

By breaking down glycogen (called glycogenolysis) stored in the liver and skeletal muscle.

What is gluconeogenesis?

A process of making glucose from pyruvic acid, G3P, and certain amino acids.

What is lipogenesis?

Process of breaking down triglycerides.

What is lipolysis?

Process of splitting triglycerides/phospholipids.

What stimulates lipid formation?

Insulin

What stimulates lipid breakdown?

norepinephrine and epinephrine.

What are lipoproteins?

Water-soluble packages that transport lipids.

What do very-low density lipoproteins do?

They transport triglycerides from liver cells to adipose cells for storage.

What do high density lipoproteins do?

They carry excess cholesterol from body cells to liver cells for disposal.

What is Glucose-6-phosphate?

It is a cell that traps glucose inside and can be metabolized to form ATP.

What is pyruvic acid?

It is the end product of glycolysis and can be metabolized to create ATP.

What are the factors in heat production?

Gender, age, nervous system, hormones, activity, eating.

What are the factors in heat loss?

evaporation, radiation, conduction, convection.

Where are the thermoreceptors in the body that detect temperature?

Located in the skin and hypothalamus.

How is a fever created?

It is created when phagocytes release chemicals called pyrogens that reset the thermostat to a higher temperature through secretion of prostaglandins.