food being taken in, broken down and absorbed
eat mainly plants and algae
eat mainly other animals
eat both animals and plants/algae
an animals diet must satisfy what 3 nutritional needs?
organic building blocks
materials that an animals cells require but cannot synthesize
4 classes of essential nutrients
organic molecules that have diverse functions and are required in very small amounts by the body
inorganic nutrients such as iron and sulfur that are usually required in very small amounts.
condition that results from a diet that lacks one or more essential nutrients
insufficient intake of essential nutrients can cause
diet that fails to provide adequate sources of chemical energy
study of human health and disease
3 main stages of food processing
ingestion-act of feeding or eating
elimination-excretion of unused material
the take up of small molecules by an animals cells
cellular organelles that contain hydrolytic enzymes that break down food
digestive compartment with just a single opening that functions to both digest and distribute nutrients throughout the body
4 main feeding mechanisms in animals
suspension/filter feeders (oysters/humpback whale)
substrate feeders (leaf miner)
fluid feeders (mosquito)
bulk feeders (humans)
alternating waves of contraction and relaxation that move food through the alimentary canal
ring-like valves at some junctions between compartments of the digestive system
mouth or initial location of food intake
produce fluid/saliva that helps food move along the digestive system
enzyme found in saliva that hydrolyzes starch
a viscous mixture of water, salts, cells, and glycoproteins called mucins
ball of chewed food
pharynx/throat cavity opens what 2 passages?
connects the throat to the stomach
flap of cartilage that covers the trachea when food passes by enroute to the stomach
upper part of the respiratory tract
located just below the diaphragm, stores food and begins digestion of proteins
digestive fluid of the stomach that consists of hydrochloric acid and pepsin
mixture of ingested food and digestive juice
protein digesting enzyme
protease of gastric juice
inactive form of pepsin
how does HCl convert pepsinogen to active pepsin?
by clipping off a small portion of the molecule and exposing its active site
first 25 centimeters of the small intestine where chime mixes with digestive juices from the pancreas, liver, gall bladder, and intestinal gland cells
important organ that excretes digestive juices and insulin
mixture of substances made by the liver that digest fats and other lipids in the small intestine
organ where bile is concentrated and stored
jejunum and ileum
food continues to get broken down and stored
finger like projections of the small intestine
microscopic projections on villi
transport across the epithelial cells of the small intestine can be
hepatic portal vein
blood vessel that leads directly to the liver
water soluble globules coated with phospholipids, cholesterol, and proteins that circulate in the blood
vessel at the core of each villus
1.5 meter long portion of one arm of the T shape which leads to the rectum and anus. major function is to recover water from the lumen if additional water is needed by the body somewhere
other arm of the long intestine that is important for fermenting ingested materials
wastes of the digestive system
animals assortment of teeth
herbivorous bird with an esophageal pouch that houses microorganisms that break down cellulose
deer, sheep, cattle, that have highly evolved mutualistic adaptations with multiple microorganisms
branch of the nervous system dedicated to the digestive organs which regulates events as well as peristalsis in the small and large intestine
endocrine system plays critical role in digestion by doing what?
secreting the right proteins/enzymes at the right place and time
consumption of more calories than the body needs often resulting in obesity
obesity contributes to health problems including:
key hormone in the appetite signaling pathway
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