The Digestive System Flashcards
Define metabolism
the biochemical reactions that allow a cell or organism to extract energy from its surroundings and use that energy for homeostais
Define organic
molecule based on carbon
What are the four important classes of macromolecules
carbohydrates, lipids, proteins, nucleic acids
Carbohydrates consist of …
monosaccharides, dissarcharides, and polysaccharides
What is the difference between saturated and unsaturated fats?
unstaturated; double bonds, bend in fatty acid chain; liguid at room temp(can’t stack easily)
-saturated; no double bonds, no bend, solid at room temp
What is Antherosclerosis and what could it lead to?
Lipid containing deposits(plaque ) build up in the walls of blood vessels
-plaques reduce blood flow which could lead to heart attack or stroke
What are substances animals are required to have in their diet that they can not make for themselves?
essential amino acids, fatty acids, minerals, vitamins
What does the stomach do in digestion
stores food and continues digestion
What does the small intestine do in digestion
completes digestion and begins the absorption of nutrients
What does the large intestine do in digestion
primarily absorbs water and mineral ions from digestive residues
What are sphincters
rings of smooth muscle form valves between major regions of digestive tract
What are common structures in the mammalian digestive system
mouth, pharynx, esophagus, stomach, intestines, anus
What layer is the mucosa in the vertebrate gut
Most inner layer, lines inside of gut, has epithelial cells that absorb nutrients, seal of digestive contents form body fluids
-has glandular cells: secrete enzymes, mucus, pH regulation
What is the submucosa in the vertebrate gut
Second most inner layer; elastic connective tissue, neuron network, blood, and lymph vessels
-neural network: local control of digestive activity
What is the muscularis in the vertebrate gut
Third most inner layer;formed by circular layer (constricts gut diameter) and longitudinal layer (shortens and widens gut): push contents through the gut (peristalsis)
-oblique layer (stomach only)
What is the serosa layer in the gut
outermost gut layer, made of connective tissue that is continuous with mesentery (tissue that suspends digestive organs in the abdomen)
-secretes a lubricating fluid to reduce friction between digestive organs and other organs
Define peristalsis
coordinated contractions of circular and smooth muscles produce perstaltic waves that move digestive contents from mouth to anus
Describe the digestive process all the way to the swallowing reflex
-Digestion begins in the mouth; teeth breaks down food into smaller bits
-Salivary glands in the mouth secret saliva; salivary amylase digests starch
-Food mass (bolus) is swallowed; through the pharynx and esophagus to stomach
-epiglottis blocks trachea
Describe the swallowing reflex
elevation of soft palate prevent food bolus from entering nasal passages
-pressure of tongue seals back of mouth and prevents bolus from backing up
-layrnx moves upward, pushing glottis against epiglottis to prevent bolus from entering airway
Describe the digestion process in the stomach
-stomach secretes gastric juices (HCl and pepsin), mucus
-stomach churns acid contents into chyme
Chief cells secrete:
pepsinogen: the precursor for pepsin
Parietal cells secrete..
-H+ and Cl-
When food enters the stomach..
-stretch receptors in stomach wall are activated; stimulate the release of pepsinogen, HCl, mucus
Define Gastrin
-major hormone that regulates acid secretion in the stomach
Fat is digested in..
small intestines and is digested more slowly than other nutrients, so further emptying of the stomach is prevented until fat is processed
Proteins are broken down by
endopeptidases, exopeptidases
Polysaccharides hydrolyzed by
-amylase, then disaccharidases
Triglycerides hydrolyzed
-by lipase
Nucleic acids hydrolyzed
-by nucleases (DNase, RNase)
Absorption of nutrients begins in the
-small intestine
Villi and microvilli greatly increase the …. Of intestine
surface area
What are intestinal villi
-folds of lining of small intestine