Chapter 3: Digestion and Absorption Flashcards
Absorption
The movement nutrients into or across tissues; particularly, the passage of nutrients and different substances into the walls of the GI tract 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
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
blind pouch at the start of the large intestine into which the small intestine opens from one facet and that 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’s made up of 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
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 stabilising their suspension in an aqueous solution
Endocytosis
The uptake of material by a cell be the indentation and pinching off of its membrane to make a vesicle that carries 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 dischargeof the stomach contents into the smallintestine and additionally stimulates 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 alimentary canalor 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 hyrolyzes 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 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
small lymph vessel within the interior of each enteric vilius that picks up chylomicrons and fat-soluble vitamins from intestinal cells
Large Intestine
The tube (about five feet) extending from the gut of the small intestine to the anus. the large bowel includes 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 metabolise carbohydrates, lipids, proteins, and micronutrients
Longitudinal Muscle
Muscle fibers aligned lengthwise
Lumen
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), as well as 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 thetissues 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 inner layer of the alimentary tract, additionally known as the intestinal wall. it’s composed of human epithelial cells and glands
Pancreas
an organ that secretes enzymes that have an effect on 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 chemical compounds into or out of cells without the expenditure of energy 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
Pepsinogen
Peristalsis
The wavy, rhythmical muscular contractions of the gastrointestinal tract that propel its contents down the tract
pH
A measure of the proton concentration, or acidity, of a solution. it’s equal to the negative log of the proton (H+) concentration expressed in moles per litre
Phagocytosis
the method by which 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
the method by which cells internalise fluids and macromolecules. To do so, the plasma membrane invaginates and forms a pocket round 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 thee 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 bicaronate
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 composed of a mesothelial layer and loose connective tissue. The intestines are coated in serous membrane
Small Intestine
The tube (approximately ten feet long) where the digestion of peptide, fat, and sugar is completed, and where the bulk of nutrients are absorbed. the smallbowel is split into 3 parts: the duodenum, the jejunum, and the ileum
Sphincters
Circular bands of muscule 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 oesophagus 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 pepticulcer to distinguish it from a skin ulcer
Vascular System
A network of veins and arteries through that 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
