NASM FNS Chapter 3 – Digestion and Absorption

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Important definitions to memorize for chapter 3 of the NASM FNS

Absorption ~ The movement of nutrients into or across tissues, particularly the passage of nutrients and different substances into the walls of the GI tract and then into the blood

Active Transport ~ The movement of compounds into or out of cells against their respective concentration gradient. This transport needs energy (ATP) and involves carrier (transport) proteins within the plasma membrane

Amylase ~ A secreted salivary catalyst that catalyzes the reaction of amylose, a starch. additionally referred to as ptyalin

Autonomic nervous system ~ The division of the central system that regulates the automated responses of the body; consists of the sympathetic and parasympathetic systems

Bile ~ an alkalescent, yellow-green fluid that is made in the liver and stored long-term within the gallbladder. The first constituents of bile are bile salts, bile acids, phospholipids, cholesterol, and bicarbonate. bile efficiently emulsifies dietary fats, aiding fat digestion and absorption

Bolus ~ A chewed, moistened lump of food that’s able to be swallowed and digested

Catalyze ~ to speed up a chemical process

Cecum ~ The blind pouch at the start of the large intestine into which the small intestine opens from one facet, which is continuous with the colon.

Central nervous system (CNS) ~ The brain and the spinal cord. The central nervous system transmits signals that act to control muscular actions and glandular secretions along the entire GI tract.

Cephalic phase Response ~ The responses of the parasympathetic nervous system to the sight, smell, thought, and sound of food. Additionally, referred to as preabsorptive phase responses.

Cholecystokinin (CCK) ~ A hormone created by cells within the bowel that stimulates the release of digestive enzymes from the pancreas and bile from the gallbladder

Chyme ~ A mass of partly digestible food and digestive juices moving from the stomach into the small intestine

Circular Muscle ~ Layers of smooth muscle that surround organs, together with the stomach and the small intestine

Colon ~ The portion of the large bowel extending from the caecum to the rectum. It comprises four parts- the ascending, transverse, descending, and sigmoid colons. Though usually used interchangeably with the term large intestine, these terms aren’t synonymous.

Concentration Gradients ~ variations between the solute concentrations of 2 substances

Constipation ~ occasional and troublesome bowel movements, followed by a sensation of incomplete evacuation.

Diarrhea ~ Watery stools because of reduced absorption of water

Digestion ~ the process of transforming the foods we ingest into units for absorption

Duodenum ~ The portion of the small bowel closest to the stomach. The small bowel is ten to twelve inches long and wider than the rest of the small intestine

Emulsifiers ~ Agents that mix fatty and watery liquids by promoting the breakup of fat into little particles and stabilizing their suspension in an aqueous solution

Endocytosis ~ The uptake of material by a cell by the indentation and pinching off of its membrane to make a vesicle that carries the material into the cell

Enteric nervous system ~ A network of nerves located within the gastrointestinal wall

Enzymes ~ large proteins within the body that accelerate the speed of chemical reactions but aren’t altered in the chemical process

Esophageal sphincter ~ The gap between the esophagus and the stomach that relaxes and opens to permit the bolus to travel into the stomach and so closes behind it. Additionally acts as a barrier to stop the reflux of stomachal contents. normally known as the cardiac sphincter

Esophagus ~ The food pipe that extends from the pharynx to the stomach, about twenty-five centimeters long

Facilitated Diffusion ~ A method by which carrier (transport) proteins within the cell wall transport substances into or out of cells down a chemical concentration gradient

Flatus ~ Lower intestinal gas that’s expelled through the rectum

Gallbladder ~ A pear-shaped sac that stores and concentrates digestive fluid from the liver

Gastric inhibitory peptide (GIP) ~ A hormone discharged from the walls of the duodenum that slows the discharge of the stomach contents into the small intestine and additionally stimulates the release of insulin from the pancreas

Gastrointestinal (GI) Tract ~ The connected series of organs and structures used for digestion of food and absorption of nutrients; additionally known as the alimentary canal or the digestive tract. The gastrointestinal tract contains the mouth, esophagus, stomach, intestine, bowel (colon), rectum, and anus.

Gastroesophageal Reflux ~ A backflowing of stomach contents into the esophagus, accompanied by a burning pain due to the acidity of the gastric juices

Gastrin ~ A polypeptide hormone discharged from the walls of the stomach mucosa and small intestine that stimulates gastric secretions and motility

Gastric lipase ~ an enzyme within the stomach that hydrolyzes certain triglycerides into fatty acids and glycerol molecules

Hydrochloric Acid ~ an acid of chloride and hydrogen atoms created by the gastric glands and secreted into the stomach. Additionally known as gastric acid

Hydrolysis ~ A reaction that breaks apart a compound through the addition of water

Ileocecal Valve ~ The sphincter at the junction of the small and large intestines

Intrinsic Factor ~ A glycoprotein discharged from parietal cells within the stomach wall that binds to and aids in the absorption of vitamin B12

Irritable Bowel Syndrome (IBS) ~ A riotous state of intestinal motility with no well-known cause. Symptoms include constipation, abdominal pain, and episodic looseness of the bowels.

Jejunum ~ the middle section (about four feet) of the small bowel, lying between the duodenum and small intestine

Lacteal ~ a small lymph vessel within the interior of each enteric villus that picks up chylomicrons and fat-soluble vitamins from intestinal cells

Large Intestine ~ The tube (about five feet) extends from the gut of the small intestine to the anus. the large bowel includes an appendix, cecum, colon, rectum, and anal canal

Lingual lipase ~ A fat-splitting catalyst secreted by cells at the bottom of the tongue

Liver ~ the biggest gland-containing organ within the body, it produces and secretes digestive juice, detoxifies harmful substances, and helps metabolize carbohydrates, lipids, proteins, and micronutrients

Longitudinal Muscle ~ Muscle fibers aligned lengthwise

Lumen ~ Cavity or hollow channel in any organ or structure of the body

Lymph ~ Fluid that travels through the human lymphatic system, made from fluid drained from between cells and huge fat particles

Lymph Nodes ~ Rounded mounds of lymphoid tissue that are encircled by a capsule of dense connective tissue. Human lymphatic nodes filter yellow lymph (lymphatic fluid) and store lymphocytes (white blood cells). They’re situated on lymphoid vessels. additionally known as lymphoid glands

Lymphatic System ~ A system of smallish vessels, ducts, valves, and other organized tissues (e.g., lymphoid nodes) through which humor moves from its origin within the tissues toward the heart via the action of muscles

Microvilli ~ Minute, capillary-like projections that reach from the surface of absorbent cells facing the enteric lumen. Singular is microvillus

Mucosa ~ The innermost layer of a cavity. The alimentary tract’s inner layer is also known as the intestinal wall. it’s composed of human epithelial cells and glands

Pancreas ~ an organ that secretes enzymes that affect the digestion and absorption of nutrients and that releases hormones, like insulin, that regulate metabolism also as the disposition of the end product of food in the body

Passive Diffusion ~ The movement of chemical compounds into or out of cells without energy expenditure or the involvement of transport proteins in the plasma membrane. additionally known as simple diffusion

Pepsin ~ A protein-digesting catalyst made by the stomach in the GI tract

Pepsinogen ~ The inactive kind of the catalyst pepsin

Peristalsis ~ The wavy, rhythmical muscular contractions of the gastrointestinal tract that propel its contents down the tract

pH ~ A measure of a solution’s proton concentration or acidity. it’s equal to the negative log of the proton (H+) concentration expressed in moles per liter

Phagocytosis ~ is how cells engulf massive particles and little microorganisms. Receptors on the surface of cells bind these particles and organisms to bring them into massive vesicles inside the cytosol. From phago, “eating,” and cyto, “cell.”

Pinocytosis ~ is the method by which cells internalize fluids and macromolecules. To do so, the plasma membrane invaginates and forms a pocket around the substance. From pino, “drinking,” and cyto, “cell.”

Pyloric Sphincter ~ A circular muscle that forms the gap between the stomach and the small intestine. It regulates the passage of food into the small bowel.

Rectum ~ The muscular final section of the bowel, extending from the sigmoid flexure to the anal orifice

Salivary Glands ~ Glands within the mouth that unleash spit

Secretin ~ an enteric hormone discharged throughout digestion that stimulates the pancreas to unleash water and bicarbonate

Segmentation ~ Periodic muscle contractions at intervals along the gastrointestinal tract that alternate forward and backward movement of the contents, thereby breaking apart chunks of the food mass and combining in acidic digestive juices

Serosa ~ A smooth membrane comprising a mesothelial layer and loose connective tissue. The intestines are coated in a serous membrane

Small Intestine ~ The tube (approximately ten feet long) where peptide, fat, and sugar digestion is completed and where the bulk of nutrients are absorbed. the small bowel is split into 3 parts: the duodenum, the jejunum, and the ileum

Sphincters ~ Circular bands of muscle fibers that surround the entrance or exit of a hollow anatomical structure (e.g., the stomach) and act as valves to manage the flow of material

Stomach ~ The enlarged, muscular, pouchlike portion of the gastrointestinal tract between the esophagus and the intestine, with a capacity of about one quart

Submucosa ~ The layer of loose, fibrous connective tissue beneath the mucosa

Ulcer ~ A craterlike lesion that happens within the lining of the abdomen or duodenum; additionally known as a peptic ulcer to distinguish it from a skin ulcer

Vascular System ~ A network of veins and arteries through which the blood carries nutrients. additionally known as the cardiovascular system

Villi ~ little, digitate projections that blanket the folds within the lining of the small bowel. Singular is villus