Biology 9: The Digestive System Flashcards
what are the two types of digestion?
intracellular digestion: oxidation glucose and fatty acids for energy
extracellular digestion: obtainment of nutrients from food in the alimentary canal (from mouth to anus)
what is the difference between absorption and digestion?
digestion: the breakdown of food into its constituent organic molecules
absorption: the transport of product for digestion from the digestive tract into the circulatory system for distribution to the body’s tissues and cells
what are the two types of digestion?
mechanical digestion: the physical breakdown of large food particles
chemical digestion: the enzymatic cleavage of chemical bonds
pathway of the digestive tract
oral cavity -> pharnyx -> esophagus -> stomach -> small intestine -> large intestine -> rectum
enteric nervous system
a collection of one hundred million neurons that govern the function of the the gastrointestinal system
present in the walls
trigger peristalsis
can function independent of the brain and spinal cord, but is also regulated by parasympathetic inputs rest and digest
which hormones stimulate feelings of hunger
glucagon and ghrelin
which hormones stimulate feelings of satiety?
leptin and cholecystokinin
which hormones trigger the sensation of thirst?
ADH and aldosterone
salivary amylase
enzyme present in saliva
capable of hydrolyzing starch into smaller sugars
lipase
enzyme present in saliva
catalyzes the hydrolysis of lipids
pharynx
cavity which leads from the mouth and posterior cavity to the esophagus and larynx
the epiglottis covers the larynx during swallowing
what are the three divisions of the pharynx
nasopharynx (behind nasal cavity)
oropharynx (back of mouth)
laryngopharynx (above vocal cords)
esophagus
a muscular tube that connects the pharynx to the stomach
top third skeletal muscle - somatic control
middle third is a mix of skeletal and smooth
bottom third smooth muscle - automatic control
emesis
fancy word for vomiting
upper esophageal sphincter
present in the oropharynx at the back of the mouth
initiates the process of swallowing
lower esophageal sphincter / cardiac sphincter
present at the top of the stomach
relaxes to allow the passage of food into the stomach
stomach
highly muscular organ in upper left quadrant of the abdominal cavity under the diaphragm
uses HCl acid and enzymes to digest food
has thick mucosa to prevent autodigestion
what are the four main divisions of the stomach?
fundus
body
antrum
pylorus
rugae
folds of the internal lining of the stomach
gastric glands
glands in the mucosa of the fundus and body of the stomach
respond to signals from the vagus nerve of parasympathetic (activated by sight, smell, taste of food)
what are the three different cell types of gastric glands?
mucous cells
chief cells
parietal cells
mucous cells
gastric glands which produce the bicarbonate-rich mucous that protects the muscular wall from the acidic and proteolytic environment of the stomach