Human Anatomy & Physiology II: Digestive System

This set of vocabulary flashcards covers both the upper and lower digestive systems, including organs of the alimentary canal, accessory organs, specific cellular functions, and the structural features of the intestines.

Alimentary Canal

A continuous tube that food and drink travel through, starting at the mouth and ending at the anus; it includes the oral cavity, pharynx, esophagus, stomach, small intestine, and large intestine.

Accessory Digestive Organs

Organs connected with the alimentary canal that assist with the breakdown of food, such as the teeth, tongue, salivary glands, liver, gall bladder, and pancreas.

Starch

A complex carbohydrate that must be converted into a simple carbohydrate, such as glucose (a monosaccharide), to be used by cells.

Cellulose

A major component of plants that is not digestible by humans and passes through the digestive system unchanged to be removed in the feces.

Salivary Glands

Three pairs of accessory organs (Parotid, Sublingual, and Submandibular) that secrete saliva containing enzymes for chemical breakdown in the oral cavity.

Hard Palate

The structure at the top of the mouth against which the tongue presses food to assist with mechanical breakdown.

Pharynx

The throat, which is divided into three regions: the nasopharynx (upper), oropharynx (middle), and laryngopharynx (final).

Epiglottis

A valve present in the laryngopharynx that directs swallowed food away from the respiratory tract and toward the esophagus.

Chyme

A semifluid mass into which ingested food is converted through chemical and mechanical digestion within the stomach.

Stomach Muscle Layers

Three layers—oblique, circular, and longitudinal—whose contractions cause the stomach to churn and mix food with liquids.

Chief Cells

Cells in the stomach that secrete the enzymes pepsin (for protein breakdown) and lipase (for fat breakdown).

Stomach Acidity

The internal environment of the stomach which maintains a $pH=1.5-2$ to help break down food.

Small Intestine

A long tube connecting the stomach to the large intestine that performs chemical digestion and absorbs almost all nutrients into the blood.

Duodenum

The first segment of the small intestine specialized in chemical digestion using secretions from the liver, gall bladder, and pancreas.

Pyloric Sphincter

A valve that periodically opens to allow chyme from the stomach to enter the duodenum.

Bile

A fluid produced by the liver that serves to emulsify fats, breaking large droplets into smaller, more easily absorbed droplets.

Hepatocytes

Cells in the liver organized into hexagonal stacks called liver lobules that produce bile.

Portal Triads

A set of three tubes located at the corner of each liver lobule, composed of a vein, an artery, and a bile duct.

Gall Bladder

An accessory organ that stores bile produced in the liver.

Cystic Duct

The tube that connects the gall bladder to the shared pathway for bile transport.

Common Bile Duct

The tube through which bile released from the gall bladder enters the duodenum.

Exocrine Pancreas

The portion of the pancreas consisting of acinar cells that secrete digestive enzymes (amylases, lipases, proteases, and nucleases) into the duodenum.

Endocrine Pancreas

The portion of the pancreas consisting of islets that release hormones like insulin into the blood.

Jejunum

The middle segment of the small intestine specialized in nutrient absorption by maximizing surface area.

Villi

Finger-like projections covering the circular folds of the jejunum that increase surface area and contain blood vessels for nutrient transport.

Microvilli

Also known as a brush border, these are tiny finger-like projections on the surface of villi that further increase surface area for absorption.

Ileocecal Valve

The valve at the end of the ileum that connects with the large intestine and controls the entry of materials.

Large Intestine Functions

Absorption of some water, electrolytes ($Na^+$, $Cl^-$), and vitamins; holding the gut microbiome; and moving indigestible materials to be removed as feces.

Cecum

A dead-end tube in the large intestine near the connection with the ileum that contains the appendix.

Colon Sections

The four parts of the colon: Ascending (upward), Transverse (across), Descending (downward), and Sigmoid (S-shaped).

Haustra

Segments of the colon formed by rings of smooth muscle that contract like drawstrings to push materials through the tract.

Anal Sphincter

Muscular structure at the end of the rectum that controls the removal of feces through the anus.

Describe three structural features in the JEJUNUM that increase surface area?

The jejunum has circular folds (plicae circulares), villi, and microvilli that all increase its surface area for nutrient absorption.

Be able to identify small intestine tissue in a microscope image (hint: think about what distinguishing feature to look for)

Presence of villi (finger-like projections)

Where in the body is the ILEOCECAL VALVE and what is its function?

Between the ileum (small intestine) and cecum (large intestine). Controls movement of material into the large intestine

What are the three main components of the LARGE INTESTINE?

Cecum, colon, rectum

Be able to identify the APPENDIX from an image of the large intestine. In what part of the large intestine is the appendix found?

Small tube-like projection off the cecum, attached to the cecum

Be able to identify the four sections of the COLON in the large intestine.

The four sections of the colon are the ascending colon, transverse colon, descending colon, and sigmoid colon.

Be able to identify HAUSTRA in an image of the large intestine. What is the function of haustra smooth muscle?

Segmented pouches of the large intestine Contracts to move material through the colon

Be able to identify the LIVER, PANCREAS, GALL BLADDER, STOMACH, SMALL INTESTINE, and LARGE INTESTINE from an image of the digestive system.

• Liver – upper right abdomen

• Gallbladder – under liver

• Pancreas – behind stomach

• Stomach – upper left abdomen

• Small intestine – center of abdomen

• Large intestine – surrounds small intestine

List the order of structures food passes through in both the small intestine and large intestine (try to include as many structures as possible)

Food passes through the duodenum, jejunum, ileum in the small intestine, followed by the cecum, ascending colon, transverse colon, descending colon, sigmoid colon, and finally the rectum in the large intestine.

Full path from small → large intestine?

Duodenum → Jejunum → Ileum → Ileocecal valve → Cecum → Ascending → Transverse → Descending → Sigmoid → Rectum → Anus

What is this?

LIVER: HEPATOCYTES ARE ORGANIZED INTO HEZAGONAL STACK CALLED LIVER LOBULES

LABEL

LABEL