Digestive System Practice Flashcards

Practice flashcards covering the anatomy, physiology, and pathology of the digestive system based on Chapter 25.

Which organ system processes food, extracts nutrients, and eliminates residue?

Digestive system

What is the first stage of digestion involving the selective intake of food?

Ingestion

Which stage of digestion involves the mechanical and chemical breakdown of food?

Digestion

What is the uptake of nutrient molecules into the epithelial cells of the digestive tract called?

Absorption

In the absorption stage, where do nutrient molecules enter after leaving epithelial cells?

Blood and lymph

What is the consolidation of indigestible residue into feces through water absorption called?

Compaction

Which stage of digestion is the elimination of feces?

Defecation

What is the physical breakdown of food into smaller particles called?

Mechanical digestion

Which structures perform the cutting and grinding action during mechanical digestion?

Teeth

What action in the stomach and small intestines contributes to mechanical digestion?

Churning action

What type of reactions characterize chemical digestion?

Hydrolysis reactions

What does chemical digestion break dietary macromolecules into?

Monomers

Which four structures or organs produce the enzymes for chemical digestion?

Salivary glands, stomach, pancreas, and small intestine

What is the muscular tube extending from the mouth to the anus called?

Digestive tract (alimentary canal)

Which organs are included in the alimentary canal?

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

Which two structures specifically make up the gastrointestinal (GI) tract?

Stomach and intestines

List the accessory organs of the digestive system.

Teeth, tongue, salivary glands, liver, gallbladder, and pancreas

What is the innermost tunic layer that lines the lumen of the digestive tract?

Mucosa

List three things secreted by the mucosa layer.

Mucus, digestive enzymes, hormones

Which tunic layer contains blood vessels, lymphatic vessels, and elastic tissue?

Submucosa

What is the function of the elastic tissue in the submucosa?

Helps organs regain shape after expansion

What are the two layers of the muscularis externa?

Inner circular layer and outer longitudinal layer

Which layer of the muscularis externa can form sphincters?

Inner circular layer

What is the function of sphincters in the digestive tract?

To regulate the passage of material

What is the outermost layer of the digestive tract wall?

Serosa

What type of tissues make up the serosa layer?

Areolar tissue topped by simple squamous

What are two other names for the mouth?

Oral cavity and buccal cavity

What is the term for chewing?

Mastication

What is the primary purpose of mastication regarding enzymes?

To break food into smaller pieces to expose more surface to digestive enzymes

What was identified as the first step of mechanical digestion?

Mastication (chewing)

What percentage of saliva is made of water?

$$99.5\%$$

Besides water, list four components found in saliva.

Mucus, electrolytes, lysozymes, antibodies, and salivary amylase

What is the soft mass of food mixed with saliva called?

Bolus

Which enzyme in saliva begins the chemical breakdown of starches?

Salivary amylase

What are the small salivary glands scattered throughout the oral cavity called?

Intrinsic (minor) salivary glands

At what rate do intrinsic salivary glands secrete saliva?

A constant rate

How many pairs of extrinsic (major) salivary glands are connected to the oral cavity?

Three pairs

What is the daily volume of saliva secreted by extrinsic glands?

$$1 \text{ to } 1.5\,dm^3$$

Name the three pairs of extrinsic salivary glands.

Parotid, submandibular, and sublingual

From the mouth, where does food pass into before entering the esophagus?

Pharynx

How are the glands in the pharynx characterized?

Mucus-producing glands

What muscular tube connects the pharynx to the stomach?

Esophagus

What are the waves of involuntary muscular contractions in the esophagus called?

Peristalsis

During peristalsis, what do the muscles above the bolus do?

Constrict

During peristalsis, what do the muscles below the bolus do?

Relax

What causes heartburn?

Stomach acid regurgitating into the esophagus

Which organ primarily functions as a food storage organ?

Stomach

What is the acidic, soupy mixture of semi-digested food in the stomach called?

Chyme

Which substance secreted by the stomach is essential for vitamin $B12$ absorption?

Intrinsic factor

What is the only function of the stomach essential to life?

Secretion of intrinsic factor

What is the general shape of the stomach?

J-shaped

What are the four regions of the stomach?

Cardiac part, fundus, body, and pyloric part

Which part of the stomach connects to the esophagus?

Cardiac part

Name the ring of smooth muscle between the esophagus and the stomach.

Cardiac sphincter

What is the superior dome-shaped region of the stomach?

Fundus

What is the name of the stomach's midportion?

Body

What is the narrower pouch at the inferior end of the stomach?

Pyloric part

Which sphincter regulates the passage of chyme into the duodenum?

Pyloric sphincter

What are the invaginations in the gastric mucosa called?

Gastric pits

What structures in the stomach produce gastric juice?

Tubular (gastric) glands

Which stomach cells secrete mucus?

Mucous cells

Where are regenerative (stem) cells located in the stomach?

In the base of the pit

What three substances are secreted by parietal cells?

Hydrochloric acid (HCl), intrinsic factor, and ghrelin

Which hormone secreted by parietal cells is known as the hunger hormone?

Ghrelin

What two substances are secreted by chief cells?

Gastric lipase and pepsinogen

What do enteroendocrine (G) cells secrete?

Gastrin

What is the daily volume of gastric juice produced?

$$2 \text{ to } 3\,dm^3$$

What are the three main components of gastric juice?

Water, hydrochloric acid, and pepsin

What is the pH range of hydrochloric acid ($HCl$) in the stomach?

$$1.5–3.5$$

List four functions of hydrochloric acid ($HCl$) in the stomach.

Denatures protein, activates pepsin, breaks down plant cell walls, and kills bacteria

How is pepsinogen converted into pepsin?

By hydrochloric acid ($HCl$)

What is the function of pepsin?

Digests proteins

What percentage of fats are digested in the stomach by gastric lipases?

$$10\% - 15\%$$

Where does the majority of fat digestion occur?

Small intestine

In HCl formation, what enters parietal cells to combine with water?

$$CO_2$$

When $CO_2$ and water combine in parietal cells, what two ions are formed?

Bicarbonate and hydrogen ions ($H^+$)

As bicarbonate ($HCO_3^-$) leaves the parietal cell, what ion enters?

Chloride ($Cl^-$)

What specific layer of the mucosal barrier protects the stomach from acid?

Thick layer of alkaline mucus

What structures between epithelial cells prevent gastric juice from seeping into tissue?

Tight junctions

How often are the surface cells of the stomach replaced?

Every $3–6$ days

What term refers to inflammation of the stomach lining?

Gastritis

What bacterium causes most peptic ulcers?

Helicobacter pylori

Besides bacteria, what type of drugs can cause peptic ulcers?

Non-steroidal anti-inflammatory drugs (e.g., aspirin)

Which two systems regulate gastric secretion and motility?

Nervous and endocrine systems

Name the three phases of gastric activity.

Cephalic phase, gastric phase, and intestinal phase

Which phase involves the stomach being controlled by the brain?

Cephalic phase

What triggers the cephalic phase?

Sight, smell, taste, or thought of food

What percentage of stomach acid secretion occurs during the cephalic phase?

$$40\%$$

Which nerve fibers stimulate gastric secretion during the cephalic phase?

Parasympathetic nerve fibers

How long does the gastric phase typically last?

$$3–4 \text{ hours}$$

What fraction of gastric juice is released during the gastric phase?

Two-thirds

What two physical or chemical changes trigger the gastric phase?

Stretching of the stomach and increasing pH

Which hormone triggers the release of gastric juice during the gastric phase?

Gastrin

Which organ responds to arriving chyme during the intestinal phase?

Duodenum

What hormone does the duodenum release to initially stimulate the stomach?

Intestinal gastrin

Name the two hormones released by the duodenum that inhibit gastric secretions.

Secretin and cholecystokinin (CCK)

What is the liver's primary digestive function?

Production of bile

What is the chief function of the gallbladder?

Storage of bile

Which organ supplies most of the enzymes needed to digest chyme?

Pancreas

What substance does the pancreas secrete to neutralize stomach acid?

Bicarbonate