The Digestive System

These flashcards cover key vocabulary and critical concepts from the lecture on the digestive system, focusing on anatomy, physiology, and associated processes.

Ingestion

The process of taking in food or drink into the digestive tract.

Mechanical Breakdown

Physically breaking down food into smaller pieces, such as chewing in the mouth.

Digestion

The biochemical process by which food is broken down into simpler components.

Propulsion

The movement of food through the digestive tract, including swallowing and peristalsis.

Defecation

The elimination of indigestible substances from the body as feces.

Mucosa

The innermost layer of the gastrointestinal tract; secretes mucus, digestive enzymes, and hormones.

Lamina Propria

A layer of connective tissue in the mucosa that contains capillaries and lymphoid follicles.

Muscularis Mucosae

A smooth muscle layer that churns and mixes food with gastric juices forming chyme

Submucosa (2)

A layer of areolar connective tissue containing blood and lymphatic vessels.

Supplies blood and nutrients to stomach tissue

Muscularis Externa

The muscle layer responsible for segmentation and peristalsis in the digestive tract.

Serosa

The outermost layer of the digestive tract

Reduces friction with surrounding organs and protects and anchors the stomach

Splanchnic Circulation

Blood supply to the digestive organs via arteries that branch from the aorta.

Stratified Squamous Epithelium

The type of epithelium found in the mouth, designed to resist abrasion.

Uvula

Helps close off the nasal cavity when swallowing, aids speech, and triggers the gag reflex.

Filiform Papillae

The most abundant type of papillae on the tongue, providing texture but no taste.

Lingual Lipase

An enzyme secreted by the tongue that begins fat digestion in the stomach.

Extrinsic Salivary Glands

Glands located outside the oral cavity that produce most saliva.

Intrinsic Salivary Glands

Glands located within the oral cavity that contribute to saliva slightly.

Salivary Amylase

An enzyme in saliva that breaks down starch into sugars.

Gingivae

The gums; the soft tissues that surround the teeth.

Cement

The calcified connective tissue covering the root of a tooth.

Periodontal Ligament

Tissue that anchors the tooth to the jawbone.

Dental Caries

Tooth decay caused by the demineralization of enamel and dentin.

Gingivitis

Inflammation of the gums, often caused by plaque buildup.

Periodontitis

Severe gum disease affecting the supporting structures of teeth.

Esophagus

The muscular tube that connects the throat to the stomach.

Gastroesophageal Sphincter

The muscle that prevents the backflow of stomach contents into the esophagus.

Peristalsis

Waves of muscle contractions that move food through the digestive tract.

Chyme

The semi-fluid mass of partially digested food that moves from the stomach to the small intestine.

Hydrochloric Acid (HCl)

An acid secreted by parietal cells in the stomach, vital for digestion.

Intrinsic Factor

A glycoprotein required for vitamin B12 absorption in the small intestine.

Mucosal Barrier

A protective mechanism in the stomach that prevents damage from acids.

How does bacteria aid in the mucosa barrier

Supports mucus production

Strengthens epithelial cells

Prevents harmful bacteria overgrowth

Gastric Juice

The acidic digestive fluid produced in the stomach.

Cephalic Phase

The phase of gastric secretion triggered by the sight, smell, or thought of food.

Gastric Phase

The phase of gastric secretion when food enters the stomach and activates secretion.

Intestinal Phase

The phase of gastric secretion that begins when chyme enters the small intestine.

Hepatic Portal Circulation

The circulation that drains blood from digestive organs to the liver.

Bile

A digestive fluid produced by the liver that aids in fat digestion.

Cholecystokinin (CCK)

A hormone that stimulates the secretion of pancreatic juices and bile.

Secretin

A hormone that stimulates the secretion of bicarbonate from the pancreas.

Pancreatic Juice

Fluid secreted by the pancreas containing digestive enzymes.

Acini

Clusters of secretory cells in the pancreas that produce digestive enzymes.

Enterohepatic Circulation

The recycling process of bile salts from the intestine back to the liver.

Gallbladder

An organ that stores and concentrates bile from the liver.

Absorption

The process of taking nutrients from the digestive tract into the bloodstream.

Allows nutrients to be used for energy, growth, and repair

Enterocyte

Absorbs nutrients and finishes digestion at the brush border.

Villi

Small, finger-like projections in the small intestine that increase surface area for absorption.

Goblet Cells

Cells in the intestine that secrete mucus to lubricate the intestinal contents.

Paneth Cells

Cells that secrete antimicrobial substances in the intestine.

Nutrient Absorption

The uptake of nutrients from the lumen of the gut into the bloodstream.

Large Intestine (2)

Absorb water and electrolytes

Form feces and stores it until elimination

Bacterial Flora

Microorganisms in the digestive system that assist in digestion and produce vitamins.

Irritable Bowel Syndrome

A chronic condition affecting the large intestine, causing symptoms like cramps and bloating.

Lacteals

Lymphatic capillaries in the villi of the small intestine that absorb fats.

Micelles

Small clusters of fatty acids and bile salts that aid in fat absorption.

Chylomicrons

Lipid transport particles that transport absorbed fats from the intestines.

Hydrolysis

The chemical process of breaking down compounds by reaction with water.

Amylases

Enzymes that catalyze the breakdown of starches into sugars.

Proteases

Enzymes that break down proteins into peptides and amino acids.

Lipases

Enzymes that catalyze the hydrolysis of fats.

What are the major digestive organs in the alimentary canal (9)

Oral cavity

Pharynx

Esophagus

Ribs

Diaphragm

Stomach

Large intestine

Small intestine

Pelvis

What are the accessory digestive organs (9)

Teeth

Tongue

Salivary glands

Trachea

Aorta

Liver

Spleen

Gallbladder

Pancreas

What are the 6 essential activities for the GI tract

Ingestion

Mechanical breakdown

Propulsion

Digestion

Absorption

Defecation

What is the function of peritoneum

Protects, supports, and lubricates abdominal organs

Visceral peritoneum (2)

Covers surface of abdominal organs

Protects and supports organs directly

Parietal peritoneum (2)

Lines the abdominal cavity wall

Anchors organs and provides structural support

Peritoneal cavity (2)

Space between visceral and parietal peritoneum

Contain serous fluid that reduces friction as organs move

Intraperitoneal organs (2)

Completely surrounded by visceral peritoneum and suspended by mesenteries

EX= stomach, liver, and spleen

Retroperitoneal organs (2)

Organs behind the peritoneum

EX= kidneys, adrenal glands, pancreas, duodenum,

Mouth (2)

mechanical digestion, chemical digestion, speech

Tongue (4)

Formation of bolus

Initiation of swallowing, speech, and taste

Uses intrinsic and extrinsic muscles

Hard palate (2)

Separates the mouth from nasal cavity so you can chew and breathe at the same time

Soft palate (2)

Fold formed mostly of skeletal muscle

Closes off nasopharynx during swallowing

Lingual frenulum

anchors the tongue, prevents excessive movement, and helps with speech and swallowing.

Salivary glands (2)

Exocrine glands that secrete saliva and contain serous cells

Function= moistens food to form Bolus, cleanses mouth, and contains lysozyme to inhibit bacteria growth

Serous cells

Secrete watery, enzyme-rich fluid that begins carbohydrate digestion

helps lubricate and protect oral tissues.

Teeth (2)

Hard structures

Function= cut, tear, and grind food for swallowing and assist speech by shaping sounds

What are the 3 tooth and gum diseases

Dental caries

Gingivitis

Periodonitis

Pharynx

Allows passage of food, fluids, and air

What are the esophagus layers (4)

Mucosa: stratified squamous epithelium

Submucosa: has mucus glands

Muscularis externa: upper=skeletal muscle, middle=skeletal&smooth muscle, lower=smooth muscle

Adventitia: connects esophagus to surrounding structures

What is the digestive process through the mouth (5)

Ingestion

Mechanical digestion

Propulsion

Deglutition

Chemical digestion

What are the 4 layers of the stomach

Mucosa

Submucosa

Muscularis externa= has an extra oblique muscle layer to churn and mix food more powerfully.

Serosa

What is the function of parietal cells

Secrete HCI for digestion and intrinsic factor for V B12 absorption

What is the function of chief cells

Secrete pepsinogen for protein digestion and gastric lipase for fat digestion

What is the function of enteroendocrine cells

Secrete Gastrin to stimulate HCI release and increase stomach motility

What is the importance of gastric juices? (4)

digest proteins and fats

Protect the stomach

Help absorb V B12

Kill pathogens

What is the digestive process in the stomach

Food is churned into chyme

Proteins are digested by HCI and pepsin

Fats start digestion by gastric lipase

Mucus protects the lining

Gastrin regulates acid and motility

What is the life crucial component of the stomach and why?

intrinsic factor because it enables vitamin B12 absorption which is essential for RBC and nervous system health

How is gastric juice regulated (3)

Cephalic phase

Gastric phase

Intestinal phase

What is the digestive function of the liver

Produces bile to break down fat droplets and aid fat-soluble vitamin absorption

What is the digestive function of the gallbladder

Stores and releases bile into duodenum when needed

What is the digestive function of the pancreas

Secretes enzymes and bicarbonate to digest carbs, fats, proteins, and neutralize chyme

How do the liver, gallbladder, and pancreas work together to create intestinal secretions

Together they digest nutrients and neutralize stomach acid in the small intestine

What are the 3 subdivisions of the small intestines

Duodenum=produce alkaline mucus

Jejunum=chemical digestion and absorption

Lleum=prevent bacteria coming from LI

What is the main function of the small intestine

To complete digestion and absorb nearly all nutrients into the bloodstream and lymphatic system.

Does digestion occur in the small intestine ?

Yes occurs mostly in the duodenum

What are the layers of the wall for the small intestines (4)

Mucosa= villi,microville, and intestinal glands

Submucosa= has Peter’s patch and brunner’s gland (mucus gland)

Muscularis externa=segmentation+peristalsis

Serosa

What are the cells found in the villi and intestinal crypts (6)

Enterocytes

Goblet cells

Enteroendocrine cells

Paneth cells

Stem cells

Intraepithelial lymphocytes

Stem cells

Stem cells divide to produce crypt cells