A&P CH23 Digestive System

What is the main function of the digestive system?

To take in food, break it down into nutrient molecules, absorb molecules into the bloodstream, and rid the body of indigestible remains.

What are the two groups of organs in the digestive system?

Alimentary canal and accessory digestive organs.

What does the alimentary canal consist of?

Mouth, pharynx, esophagus, stomach, small intestine, large intestine, anus.

What is the role of accessory digestive organs?

They assist in digestion through the production of secretions.

Name a chemical involved in digestion that creates an acidic environment.

Hydrochloric acid (HCl).

What does pepsin do in the digestive system?

Pepsin is a protease enzyme that breaks down proteins into smaller peptides.

What is bile's function in digestion?

Bile emulsifies fats.

What do amylases break down?

Carbohydrates into simple sugars.

What is the process of ingestion?

The act of eating.

What process moves food through the alimentary canal?

Propulsion.

Define peristalsis.

The alternating waves of contraction and relaxation that propel food through the GI tract.

What is mechanical breakdown?

The process that includes chewing and mixing food with saliva.

What series of steps involves enzymes breaking down complex food molecules?

Digestion.

What is absorption in the digestive system?

The passage of digested fragments from the GI tract into blood or lymph.

What is defecation?

The elimination of indigestible substances via anus.

What is the peritoneum?

Serous membranes of the abdominal cavity.

What are the two types of peritoneum?

Visceral peritoneum and parietal peritoneum.

What is mesentery?

A double layer of peritoneum that holds organs in place and stores fat.

Define intraperitoneal organs.

Organs located within the peritoneum.

What are retroperitoneal organs?

Organs located outside or posterior to the peritoneum.

What are the four basic layers of the alimentary canal?

Mucosa, submucosa, muscularis externa, serosa.

What does the mucosa layer of the alimentary canal do?

Secretes mucus, digestive enzymes, and hormones; absorbs end products of digestion.

What is the function of the submucosa layer?

It helps support the mucosa and transport absorbed nutrients.

What is the role of muscularis externa?

Responsible for segmentation and peristalsis.

What is the function of serosa in the alimentary canal?

Acts as a protective layer lining the outer surface of intestinal organs.

What does splanchnic circulation include?

Arteries that serve digestive organs, such as the hepatic, splenic, and mesenteric arteries.

What is the role of the enteric nervous system?

It regulates glands and smooth muscle in the gut.

Define intrinsic control in digestive activity regulation.

Short reflexes mediated by enteric nervous system.

What is the effect of the parasympathetic system on digestion?

Enhances the digestive process.

What is the sympathetic system's effect on digestion?

Inhibits digestion.

What does the dentition of primary teeth consist of?

20 deciduous teeth that erupt between 6 and 24 months of age.

How many permanent teeth are there?

32 permanent teeth.

What are dental caries?

Tooth decay caused by bacterial infection.

What does mastication refer to?

The process of chewing.

What is the function of salivary glands?

They produce saliva that cleanses the mouth, dissolves food chemicals, and begins digestion of starch.

What enzyme in saliva begins the breakdown of starch?

Amylase.

How is salivation controlled?

By the autonomic nervous system, responding to stimuli such as sight and taste of food.

What is GERD?

Gastroesophageal reflux disease, a condition where stomach contents flow back up into the esophagus.

What are the major functions of the stomach?

Serve as a temporary storage tank and start protein digestion.

What role does hydrochloric acid play in the stomach?

It activates pepsin and denatures proteins.

Define intrinsic factor's function.

It's required for absorption of vitamin B12 in the small intestine.

What does the liver primarily produce, aiding in digestion?

Bile.

What is cholestasis?

Condition where bile cannot flow from the liver to the duodenum.

What are gallstones?

Hard deposits that form in the gallbladder, often due to excess cholesterol.

Identify the major roles of the pancreas in digestion.

Produces pancreatic juice containing enzymes and bicarbonate.

What is the function of bile salts?

Aid in fat emulsification and absorption.

What stimulates bile secretion?

Cholecystokinin (CCK) and secretin.

Where does most digestion and absorption occur?

In the small intestine.

How long is the small intestine?

2–4 meters long.

What is segmentation in the small intestine?

Rhythmic contractions that mix food with digestive juices.

What is the cecum?

The first part of the large intestine.

What occurs in the large intestine?

Absorption of water, vitamins, and minerals; propulsion of feces.

What is defecation reflex?

A reflex initiated by distension of the rectum that leads to fecal elimination.