4.2 HBS

Flashcards related to the digestive system.

Gastrointestinal (GI) tract

A network of organs that work together to break down food into nutrients that your body can absorb and use for energy, growth, and repair.

Oral Cavity

The location where teeth mechanically break down food, the tongue helps food travel, and salivary glands chemically break down food by producing enzymes.

Pharynx

A muscular tube (throat) where food and liquids move through.

Esophagus

The tube where muscles contract to transport food and liquids towards the stomach.

Stomach

A muscular sac that mechanically and chemically breaks down food; muscles churn and squeeze food, mixing it with digestive juices (gastric acid, enzymes) to create chyme.

Small intestine

Chyme enters here from the stomach, consisting of the duodenum, jejunum, and ileum.

Duodenum

The first and shortest part of the small intestine; receives food from the stomach and mixes it with digestive juices from the pancreas and liver; 12 finger widths long.

Jejunum

The middle section of the small intestine; most of nutrient absorption happens here.

Ileum

The last and longest part of the small intestine; any remaining nutrients are absorbed here.

Large intestine

Also known as the colon; the last part of the digestive system; a long, muscular tube that absorbs water from waste material and eliminates it from the body as stool.

Cecum

A pouch-like structure that marks the beginning of the large intestine; stores and absorbs water from digested material from the small intestine; houses beneficial bacteria for digestion.

Colon

Known as the large intestine; absorbs water, stores stool until bowel movement, muscles in the colon contract to move stool towards the rectum.

Ascending Colon

The first part of the large intestine; receives partially digested food and starts the process of absorbing water and nutrients from waste material.

Transverse Colon

The longest and most mobile part of the large intestine; absorbs water from waste material and helps move material along to the next part.

Descending Colon

Stores and absorbs water from waste material; makes stool more solid so it can be eliminated.

Sigmoid Colon

Stores stool until the body has a bowel movement; muscles in the sigmoid colon contract and relax to move stool towards the rectum.

Rectum

A short, muscle tube that stores stool until a bowel movement; muscles in the rectum wall contract and push stool towards the anus; when enough stool fills the rectum, it triggers the urge to defecate.

Anus

A muscular ring that controls the passage of stool; muscles relax to allow stool to pass through; lined with special tissue that protects it from irritation, has nerves that signal to the brain when it’s time for a bowel movement.

Salivary glands

Exocrine glands that produce saliva; saliva contains enzymes, mucus, and electrolytes which break down carbohydrates, moisten food, lubricate the mouth, lets you taste by dissolving taste bud stimulants and contains substances that help kill bacteria in the mouth.

Tongue

A muscular organ involved in tasting, swallowing, speaking, and moving food around the mouth during chewing; covered in papillae (tiny bumps) which contain taste buds.

Teeth

Breaks down food into smaller pieces so that it can be easily swallowed and absorbed by body (mechanical digestion); incisors (sharp edges to cut food), canines (pointed teeth to tear food), premolars (flat surface to crush/grind food), molars (broad, flat surface to grind food).

Soft palate

A muscular structure at the back of the roof of your mouth; plays a role in speech, swallowing, and breathing; made of muscles and connective tissue, covered by mucous membrane (same type of tissue that lines the inside of your mouth).

Hard palate

A bony front part of the mouth; separates the nasal cavity from the mouth cavity; rough and bumpy; helps with speech and chewing.

Uvula

A teardrop-shaped piece of soft tissue that hangs in the back roof of the mouth; part of the soft palate; plays a role in speech, swallowing (prevents from going into the nose) and reflexes (triggers gag reflex if touched).

Liver

The largest and most complex organ; produces bile (fluid that breaks down fats in the small intestine), processes nutrients absorbed by the small intestine, produces proteins essential for blood clotting, filters toxins and waste products from the body and produces immune system factors to remove bacteria from the bloodstream.

Pancreas

A gland located behind the stomach; produces digestive enzymes that break down carbohydrates, proteins, and fats in the small intestine; produces hormones that regulate blood sugar levels (insulin - lowers blood sugar, glucagon - raises blood sugar).

Appendix

A pouch attached to the large intestine; believed to play a role in the immune system by storing and repopulating good gut bacteria after illness or taking antibiotics.

Gallbladder

Stores, concentrates, and controls the release of bile produced by the liver; when you eat something high in fat, the gallbladder contracts and releases bile into the small intestine.

Upper esophageal sphincters (UES)

Also known as the pharyngoesophageal sphincter; a muscular valve located at the top of the esophagus; regulates what passes between the pharynx (throat) and esophagus; prevents heartburn by preventing stomach acid from flowing back up, aiding swallowing by relaxing to allow foods to pass and prevents aspiration.

Lower esophageal sphincters (LES)

Also known as the gastroesophageal or cardiac sphincter; a muscular valve located where the esophagus meets the stomach; a one-way valve that allows food and liquids to pass into the stomach but prevents stomach contents from flowing back.

Pyloric sphincter

Located at the lower end of the stomach where it meets the intestine; controls the flow of partially digested food (chyme) from the stomach to the small intestine and prevents backflow of stomach acid and undigested food.

Mechanical digestion

Physically breaks down food into smaller pieces; happens through chewing in the mouth or churning in the stomach; smaller pieces of food have a larger surface area, making it easier to chemically digest.

Chemical digestion

Uses enzymes to break down food into sugars, amino acids, and fatty acids; smaller molecules can be absorbed by the body and used for energy, growth, and repair; enzymes are produced in the mouth (saliva), stomach (stomach acid and enzymes), small intestine (enzymes and bile) and large intestine.

Bolus

A mass of food that forms in the mouth during chewing; a mixture of food particles and saliva; saliva moistens and breaks down food as you chew, making it easier to swallow.

Chyme

A mixture created during digestion; consists of partially digested food, digestive enzymes, and stomach acid; forms in the stomach as muscles churn and break down food.

Rugae

Ridges/folds in the lining of a hollow organ; most commonly referred to as gastric rugae (folds in the lining of the stomach); increases surface area for efficient absorption of nutrients; aids in mixing and movement of food.

Villi

Finger-like projections that line the inside of your small intestine; act like sponges, increasing the surface area of your small intestine, allowing more nutrients to be absorbed from food into your bloodstream.

Bile

A greenish-yellow fluid that helps with digestion; produced by the liver and stored in your gallbladder; when you eat fatty foods, your gallbladders squeezes bile into your small intestine.

Upper endoscopy

Esophagogastroduodenoscopy (EGD) is an invasive procedure used to look inside the upper digestive tract; insertion of an endoscope (long, thin, flexible tube with a light and small video camera) through your mouth, down your throat, esophagus, stomach, and duodenum; if abnormal tissue is spotted, a biopsy is performed by biopsy forceps (tweezers) passed through the endoscope.

Colonoscopy

A type of endoscopy; an invasive procedure used to look inside the large intestine; insertion of a colonoscope (4ft long, thin, flexible tube with light and camera) inserted through the anus, rectum, and sigmoid, descending, transverse and ascending segments of the colon; most commonly used to screen for colorectal cancer and other digestive problems; a biopsy is performed to remove an abnormal piece of tissue (polyps - growths on the inner lining of intestines).

Biopsy

A procedure to remove a piece of tissue or sample of cells from a person’s body so that it can be tested and examined in a laboratory for disease; some biopsies remove small tissue with a needle, some surgically remove a suspicious nodule/lump through endoscopy and some create an incision in your skin to access cells (skin punch biopsy); after a sample is taken, it’s sent to a pathology lab for testing.

Colon Polyps

Abnormal growths that form on the inner lining of the large intestine; very common as people age; most polyps are not cancerous but sometimes they can turn into colon cancer over time.

Celiac disease

A serious condition that affects the small intestine; triggered by gluten which is a protein found in wheat, barley and rye; when gluten is ingested, the immune system attacks the small intestine, damaging it and making it hard to absorb nutrients from food.

GERD

Gastroesophageal reflux disease; a common condition that happens when stomach acid flows back up into the food pipe (esophagus); caused by a weakened LES (valve between esophagus and stomach) or hiatal hernia (part of the stomach pushed through the diaphragm).

Peptic Ulcers

Sore spots that develop on lining of stomach or small intestine; most commonly caused by infection with bacteria called helicobacter pylori (H.pylori) and long term use of pain relievers (aspirin, ibuprofen).

Crohn’s Disease

Inflammatory bowel disease (IBD) that causes inflammation in digestive tract.

Whipple’s Disease

Rare bacterial infection that affects the digestive system; caused by a bacterium (Tropheryma whipplei).

Irritable Bowel Syndrome

(IBS); common condition that affects the large intestine

Dysbiosis

A microbial imbalance that results when “bad” bacteria in the GI tract overgrows and inhibits the growth of “good” bacteria, leading to an imbalance between the two groups.

Fecal transplant

Also known as fecal microbiota transplant (FMT), is a medical procedure that transfers stool from a healthy person into the intestines of someone who is sick; the stool contains bacteria that can help restore balance of good and bad bacteria in the gut, which is important for digestion and overall health.

Taste bud

Tiny sensory organs located on the tongue that allow you to perceive taste; contains taste receptor cells that detect different chemicals in your food (chemicals dissolve in saliva and come into contact with taste receptors; taste receptors send signals to the brain and interprets them as flavors).

Columnar epithelium

Acts as barrier to protect underlying tissue in colon; contains cells that absorb water from digested material passing through colon; made of tall, column-shaped cells with projections that increase surface area for absorption

Proteins

Building blocks of your body

Carbs

Body’s main source of energy

Fats

Essential for body function

Salivary amylase (ptyalin)

Found in saliva and begins breakdown of carbohydrates before food reaches stomach; breaks down complex carbohydrates like starches into smaller sugar molecules

Pepsin

Enzyme produced in stomach; helps break down proteins into smaller chains of amino acids

Bile

Substance produced by liver and stored in gallbladder; helps break down fats into smaller particles, allowing pancreatic lipase to work more efficiently

Lactase

Enzyme that’s found in small intestine; breaks down lactase, a complex sugar into glucose and galactose, simple sugars

Gastric bypass

A surgeon creates a small pouch in the upper part of the stomach. The pouch is connected directly to the lower part of the small intestine, bypassing the rest of the stomach and the first part of the small intestine. This means less food can fit in the stomach and nutrients from food are absorbed directly, resulting in weight loss.

Lock and key

Substrate fits perfectly into the enzyme; they have complementary shapes

Induced fit

enzyme molds to the shape of the substrate but is unchanged at the end