Ch. 14 - The Digestive System

What are the two groups of the digestive system?

Organs of the alimentary canal (GI tract) and accessory digestive organs.

What is the alimentary canal and what is another name for it?

The hollow muscular tube from mouth to anus, also called the gastrointestinal (GI) tract.

List the organs included in the alimentary canal.

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

List the accessory digestive organs.

teeth, salivary glands, liver, gallbladder, and pancreas

What is the body’s largest serous membrane?

Peritoneum

What is the inner and outer layer of the peritoneum called?

Visceral peritoneum (inner) and parietal peritoneum (outer)

What does retroperitoneal mean?

behind the peritoneum

What organs are retroperitoneal?

pancreas, duodenum, kidneys

What forms the roof of the mouth?

The hard palate (anterior) and soft palate (posterior).

What is the lingual frenulum and its function?

A fold of mucous membrane that holds the tongue to the floor of the mouth.

What is another name for the mouth?

oral cavity

What do the 3 salivary glands secrete?

saliva

What is in saliva?

H2O, Lysozymes, & salivary amylase

What is the function of salivary amylase?

Breaks starch (amylose) into oligosaccharides like maltose which causes the sweet taste when chewing rice

What are the parts of a tooth (in order)?

Crown, Neck, Root

What are the layers of a tooth (in order)?

Enamel, Dentin, Pulp, root canal

What is gingiva?

Gum

What connects the pharynx and stomach?

The esophagus.

Which part(s) of the pharynx plays a role in breathing and swallowing food?

oropharynx and laryngopharynx

What are the regions of the stomach?

Cardia, fundus, body, pyloric antrum, and pyloric sphincter (valve)

What are the 3 main types of cells in the stomach?

Parietal cells, chief cells, enteroendocrine cells (G cells)

What do parietal cells synthesize?

Hcl (H+ + Cl-) and Gastric lipase

What do chief cells synthesize?

pepsinogen and intrinsic factor

What does Hcl help pepsinogen break down into, and what is its function?

Pepsin helps break down protein

What do entereroendocrine cells (G cells) synthesize?

gastrin

What is gastrin and its function?

Hormone that activates parietal & chief cells

What are the three sections of the small intestine?

Duodenum, jejunum, and ileum.

What are the folding structures of the small intestine and their function?

circular folds (plicae circulares), villi, and microvilli all help increase surface area to aid in digestion and absorption

What is another name for the circular folds in the small intestine?

Plicae circulares

What is lacteal?

Inside each villus; modified lymphatic capillary where oils travel through & assists with nutrient absorption

What is the function of villi in the small intestine?

They increase the surface area for nutrient absorption.

What is the first part of the large intestine?

Cecum.

What are the two valves in the anal canal?

External anal sphincter (voluntary) and internal anal sphincter (involuntary).

What is the crown of a tooth?

The exposed part of the tooth covered with enamel.

What is the function of bile?

To emulsify fats.

What does bile flow through?

Bile duct (common bile duct)

What does pancreatic juice flow through?

Pancreatic duct

What are the 2 types of cells in the pancreas and what are their functions?

Exocrine cells make digestive enzymes. Endocrine cells make hormones such as insulin and glucagon

What can cause jaundice?

Bile leaking into the blood, hepatitis, or cirrhosis.

What is the role of the pancreas in digestion?

It produces enzymes that digest all classes of nutrients.

What is pancreatic juice made of?

Water, HCO3- (bicarbonate), & pancreatic enzymes to digest

What is included in the pancreatic enzymes to digest?

Carbohydrates, lipids, proteins, DNA & RNA

What is included in bile?

H2O, cholesterol, phospholipids, bile salts, and bile pigments

What are bile pigments?

Bilirubin made by the Heme from old RBCs

What happens if gallstones are blocking the pathway?

Causes agonizing pain when gallbladder contracts.

Can prevent bile from entering small intestine. Bile backs up into liver and bile salts & pigments enter bloodstream. (1 cause of jaundice)

What is the role of the appendix?

It hangs off the cecum and can become obstructed, leading to appendicitis.

What are the major components of gastric juice?

Hydrochloric acid, pepsinogen, and mucus.

What is the function of the gallbladder?

To store bile.

What happens when too much water is removed from bile?

Gallstones can occur.

What are the main functions of the digestive tract?

Digestion and absorption

What is ingestion?

The act of taking food into the mouth

What is propulsion in the GI tract?

Movement of foods through the GI tract, accomplished by peristalsis

What is mechanical breakdown?

The physical grinding of foods into smaller pieces to increase surface area

What is segmentation?

The alternating contraction and relaxation of circular muscles in the GI tract that mixes food

What is digestion?

The chemical breakdown of food by enzymes

What are the monomers of carbohydrates?

Monosaccharides, such as glucose, fructose, and galactose

What are the monomers of proteins?

Amino acids

What are the monomers of lipids?

Fatty acids and glycerol

What are the monomers of nucleic acids?

Nucleotides

What is absorption in the digestive process?

Transporting digested products into the blood or lymph

What is defecation?

The elimination of wastes as feces

Which part of the nervous system controls digestive activities?

The parasympathetic branch of the autonomic nervous system

What occurs in the mouth during digestion?

Food is mechanically broken down and mixed with saliva; no absorption occurs

What initiates carbohydrate digestion in the mouth?

Salivary amylase

What is deglutition?

The act of swallowing food

What are the two phases of swallowing?

Buccal phase (voluntary) and pharyngeal-esophageal phase (involuntary)

What stimulates the release of gastrin in the stomach?

The presence of food and rising pH

What is pepsinogen activated to in the stomach?

Pepsin, in the presence of hydrochloric acid

What is the primary energy value of food measured in?

Kilocalories (kcal), also called Calories

What are major nutrients?

Proteins, carbohydrates, and lipids

What is MyPlate?

A food guide issued by the USDA showing food categories and healthy portion sizes

What are triglycerides?

The main form of lipids in the diet, or neutral fats

What is metabolism?

All chemical reactions in the body

What is catabolism?

The breakdown of substances into smaller, simpler ones

What is anabolism?

The buildup of substances into larger, more complex ones

What is the central role of the liver in metabolism?

The liver makes bile, detoxifies substances, and regulates blood glucose levels

What are low-density lipoproteins (LDLs)?

Cholesterol carriers that transport cholesterol to body cells

What is the basal metabolic rate (BMR)?

The amount of energy the body uses at rest to carry out essential life activities

What is heat stroke?

A condition where heat loss mechanisms have stopped working, leading to dangerously high body temperature