Digestive System + ACTUAL FLASHCARD SET

Function of the Digestive System

To break down food and absorb nutrients to facilitate constant self-repair and growth (e.g., during development or pregnancy).

Glucose

The preferred source for generating ATP in the body.

Nutrients

Substances that serve as building blocks for tissues and fuel molecules for energy production.

Alimentary Canal

A long tube extending from the mouth to the anus, developing as a single continuous tube in the embryo.

Doughnut Analogy

An analogy relating the digestive tract to a doughnut, where the 'cake' is body tissue and the 'hole' is the lumen, part of the outside universe.

Lumen

The inside space of the digestive tube, connected to the outside world at both ends.

Mechanical Digestion

The physical process of mashing food into a 'goo' or 'slurry'.

Mastication

The act of chewing food.

Churning

The stomach's action of twisting and mashing content to form a goo.

Segmentation

Contractions in the small intestine that mix food with digestive enzymes.

Chemical Digestion

The enzymatic breakdown of food into microscopic building blocks for absorption.

Propulsion

The movement of food through the digestive tube.

Deglutition

The scientific term for swallowing.

Peristalsis

The major mechanism for propulsion, involving coordinated muscle contractions to push food along the tube.

Ingestion

The act of taking food into the mouth.

Defecation

The process of eliminating waste from the body.

Daily Saliva Secretion

1 to 2 liters of saliva produced per day.

Gastric Juice Secretion

At least 2 liters of gastric juice produced per day.

Intestinal Juice Secretion

At least 2 liters of intestinal juice produced per day.

Reabsorption

The process by which excessive digestive fluids are reabsorbed to prevent dehydration.

Cholera

A disease that prevents fluid reabsorption, potentially leading to dehydration and death.

Accessory Organs

Structures such as teeth, tongue, salivary glands, gallbladder, liver, and pancreas that assist in digestion.

Mucosa

The innermost layer of the alimentary canal containing epithelium, glands, and lymphatic tissue.

Submucosa

A layer containing additional glands and a nerve network (submucosal plexus).

Muscularis Externa

additional innermost oblique smooth muscle layer for churning mechanical digestion and mix food

Serosa

The outermost layer of the alimentary canal, made of connective tissue and serous epithelium.

Peritoneum

A slippery serous membrane lining the abdominal cavity.

Clinical Concern of Peritonitis

Injury or infection of the peritoneum leading to scarring and adhesions.

Mesentery

A double layer of peritoneum providing pathways for blood vessels and nerves to the intestine.

Celiac Trunk

An artery supplying blood to the stomach, liver, and spleen.

Superior Mesenteric Artery

An artery supplying the small intestine and two-thirds of the large intestine.

Inferior Mesenteric Artery

An artery supplying the final third of the large intestine, rectum, and anus.

Vagus Nerve

Cranial Nerve X, controlling the parasympathetic nervous system in the digestive tract.

Parasympathetic Control

Involves 'rest and digest' functions, stimulating digestion.

Sympathetic Control

Under stress, the body prioritizes survival over digestion.

Mucosa in Oral Cavity

Stratified squamous mucosa, a tougher tissue suitable for abrasive foods.

Salivary Amylase

An enzyme that begins carbohydrate digestion in the mouth.

Lipase

An enzyme that breaks down lipids/fats.

Peptidase

An enzyme that breaks down proteins.

Papillae Types

Different types of projections on the tongue: filiform (no taste buds), fungiform, and circumvallate (contain taste buds).

Taste Buds

Sensory structures located in the valleys of papillae that detect taste.

Regions of the Tooth

Includes crown, neck, and root; parts of the tooth structure.

Dental Enamel

The hardest substance in the body, protecting teeth from bacteria.

Dentin

Bone-like material underneath enamel.

Pulp Cavity

The living center of the tooth containing blood vessels and nerves.

Major Salivary Glands

Include parotid, sublingual, and submandibular glands

Clinical Note (Mumps)

An infection that affects the parotid glands.

Pharynx Anatomy

Includes nasopharynx, oropharynx, and laryngopharynx.

Voluntary Phase of Swallowing

The phase where the tongue pushes the bolus back to the pharynx.

Involuntary Phase of Deglutition

Controlled by the glossopharyngeal nerve, involving smooth muscle movement.

Esophagus

A transport tube that moves food from the mouth to the stomach.

Gastric Acid

Hydrochloric acid with a pH of 1 to 2, protecting the stomach lining.

GERD

Gastroesophageal Reflux Disease, characterized by chronic acid reflux.

Chyme

The liquid mass of food created in the stomach.

Projectile Vomiting

Teniae coli

three bands of longitudinal layer of muscularis externa that bunch up colon into haustra

Haustra/Haustrum

wrinkled pouches, “sluggish segmentation”

Epiploic appendages

fat filled sacs of visceral peritoneum, function unknown

Hepatic artery

delivers oxygenated blood from heart ot liver

Hepatic portal vein

delivers partially deoxygenated, nutrient dense blood from small intestine to liver

Hepatic vein

drains blood from liver to inferior vena cava

Hepatocytes

80% of liver’s volume; variety of functions

Bile Canaliculi

accommodate bile produced by hepatocytes

Hepatic sinusoids

open blood space from fenestrated capillaries from hepatic portal vein

Central vein

carries blood from sinusoids to hepatic vein

Kupffer cells (Reticuloendothelial cells)

phagocytes to remove dead RBCs, WBCs. bacteria, and other foreign materials

Portal Triad

arrangement of bile duct, hepatic artery and hepatic portal vein branches

gastric glands

secrete gastric juice

Gastro-endocrine/ G cells

Secretes gastrin, protects stomach from pepsin and HCL

Parietal cells

Secretes HCl acid + intrinsic

Chief Cell

secretes pepsinogen and lipase

Mucus Neck Cell

Secretes mucus

Function of Mucus Neck Cell

protects stomach from pepsin and HCl

Functions of Parietal Cell

HCL converts pepsinogen to pepsin and kills microbes, Intrinsic factor is absorption of Vitamin B12

Functions of Chief Cell

Pepsinogen converted to pepsin for protein digestion, Lipase converts lipids into glycerol and fatty acids

Functions of Gastro-endocrine (G cell)

Gastrin, on arrival of food to stomach, it stimulates gastric glands to secrete more HCL and pepsinogen, increases intestinal motility

Intestinal glands

between villi in crypts produce intestinal juice containing water and mucus

Duodenal glands (Brunners glands)

produce bicarbonate-rich, buffering mucus secretions, only found in duodenum.

Bile

mixture of water, *bile salt *, phospholipids, pigments, electrolytes, cholesterol, and triglycerides secreted by the liver

Emulsification

large lipid globules broken down into smaller lipid globules; increases surface area for digestion

Pancreas Endocrine functions

islet cells secrete hormones

Pancreas Exocrine functions

acini secrete pancreatic juice into duodenum

duct cells secrete bicarbonate into duodenum

Large intestine regions

cecum (appendix attached), colon (ascending, transverse, descending, sigmoid), rectum, anus

Ileocecal valve

leads from small intestine into large

circular folds (plica circulare)

deep ridge in mucosa and submucosa, from proximal duodenum to mid-ileum; causes chyme to spiral and slow for absorption

Villi

Within circular folds; covered with absorptive cells and house an arteriole and venule and a lateal

Microvilli (brush border)

extensions of epithelial plasma membrane; contain digestive enzymes for CHO and proteins

Internal sphincter

smooth muscle; involuntary

External sphincter

skeletal muscle; voluntary

Ingestion, mastication (chewing), deglutition (swallowing), propulsion (peristalsis), mechanical digestion, chemical digestion, absorption, and defecation.

What are all the types of digestive processes?

Pepsin

breaks down proteins (gastric glands)

Pyloric Stenosis

Overdevelopment of pyloric sphincter in infants leading to projectile vomiting.

Pyloric Sphincter

sphincter that controls stomach emptying

rugae of mucosa

folds or ridges in the mucosal and submucosal layers of hollow organs that allow expansion, increase surface area, and enhance organ function.

Goblet cells

protection from acids

Brush border cells

Digestion of sugars and proteins

Entero-endocrine cells (secretin hormone)

stimulates pancreas to secrete bicarbonate and liver to secrete bile into gallbladder

Entero-endocrine cells (CCK)

causes contraction of gall bladder to release bile, and pancreas to release pancreatic juice into duodenum

Paneth cells

Phagocytosis / Immune

Secrection of Goblet cells

Mucus