Digestive System Lecture Notes Flashcards

A comprehensive set of vocabulary flashcards covering the anatomy, histology, and physiological processes of the human digestive system as described in the Chapter 23 lecture.

Digestion

The process of breaking down larger organic molecules (carbohydrates, lipids, proteins, and nucleic acids) into their smallest components for absorption.

Alimentary canal

The continuous muscular tube or passageway that food travels through from the mouth to the anus, including the mouth, pharynx, esophagus, stomach, small intestine, and large intestine.

Accessory organs

Organs that aid in digestion but are not part of the canal itself, including the teeth, tongue, salivary glands, pancreas, gallbladder, and liver.

Duodenum

The beginning section of the small intestine where chyme is mixed with pancreatic juices and bile.

Jejunum

The middle section of the small intestine.

Ileum

The end section of the small intestine that joins the large intestine at the ileocecal junction.

Cecum

The very beginning of the large intestine where it meets the ileum.

Ingestion

The voluntary process of putting food into the mouth.

Propulsion

The movement of food through the alimentary canal via swallowing and peristalsis.

Peristalsis

An involuntary muscle movement in one direction that pushes food through the digestive tract.

Mechanical digestion

Physical manipulation of food such as chewing (mastication), churning in the stomach, and segmentation.

Segmentation

A back and forth muscle movement in the alimentary canal that mixes separate substances together.

Chemical digestion

The process of using enzymes, water, and specific $pH$ levels to break down chemical bonds in food.

Absorption

The transport of small digested molecules across the epithelial tissue of the alimentary canal and into the bloodstream.

Defecation

The voluntary release of indigestible leftovers (feces) from the large intestine.

Peritoneum

The serous membrane of the digestive system consisting of a visceral layer lining organs and a parietal layer lining the cavity wall.

Mesentery

A double layered membrane that connects the visceral and parietal peritoneum and provides a pathway for blood vessels, nerves, and lymphatic vessels.

Retroperitoneal

Organs located behind the parietal peritoneum, such as the kidneys, pancreas, and parts of the large intestine.

Mucosa

The innermost region of the alimentary canal wall made of epithelium, lamina propria, and muscularis mucosae.

MALT (Mucosa Associated Lymphoid Tissue)

Immune tissue embedded within the lamina propria that protects against invaders like viruses and bacteria.

Submucosa

A connective tissue layer beneath the mucosa containing blood vessels, nerves, lymphatic vessels, and deep glands.

Muscularis externa

The muscle layer responsible for peristalsis and segmentation, typically consisting of longitudinal and circular layers.

Serosa

The outermost layer of the alimentary canal wall that secretes lubricating serous fluid.

Amylase

An enzyme found in saliva specifically used for breaking down carbohydrates.

Bolus

A ball of food that has been chewed and is ready for swallowing.

Rugae

Wrinkles or folds inside the stomach that allow it to shrink when empty.

Pyloric sphincter

The valve that opens and closes to allow food to leave the stomach and enter the small intestine.

Chyme

The substance formed when a bolus mixes with acidic gastric juices in the stomach.

Pepsin

An enzyme in the stomach that initiates the breakdown of proteins, active only in low $pH$ environments.

Parietal cells

Stomach cells that secrete $HCl$ (hydrochloric acid) to maintain a $pH$ of $2$.

Chief cells

Stomach cells that secrete pepsinogen, the inactive precursor to pepsin.

Villi

Finger-like projections in the small intestine that increase surface area for secretion and absorption.

Microvilli

Tiny projections on the surface of epithelial cells known as the brush border that contain enzymes for digesting carbs, proteins, and nucleic acids.

Bile

An emulsifier produced by the liver and stored in the gallbladder that breaks large lipid droplets into smaller ones.

Hostrum

The bulging, pouch-like areas found along the length of the large intestine.

Hostile contractions

The term used for segmentation (back and forth muscle movement) in the large intestine.