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86 terms

Chapter 41: Animal Nutrition

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nutrition
food being taken in, taken apart, and taken up
herbivores
animals that eat mainly plants or algae, such as cattle, parrotfish, and termites
carnivores
animals that eat mostly other animals, such as sharks, hawks, and spiders
omnivores
animals that regularly consume animals as well as plants or algae, such as humans, cockroaches, and crows
essential nutrients
materials that an animal's cells require but cannot synthesize; include minerals and preassembled organic molecules--amino acids, fatty acids, vitamins, minerals
8
number of essential amino acids
complete
proteins in animal products are _________ amino acids, meaning they provide all essentials in proper proportions
incomplete
proteins in plants are ___________ amino acids, meaning they are missing one or more essentials
essential fatty acids
_______________ are unsaturated and often found in seeds, grains, and vegetables
vitamins
organic molecules with diverse functions that are required in small amounts; can be water soluble or fat soluble
13
number of essential vitamins for humans
water soluble
B complex and vitamin C are what classification of vitamins?
fat soluble
Vitamins A, K, and D are what classification of vitamins?
minerals
inorganic nutrients, such as zinc and potassium, which are needed in small amounts from 1 mg to 2500 mg per day
undernourishment
the result of a diet that consistently supplies less chemical energy than the body requires
malnourishment
the long term absence from the diet of one or more essential nutrients
epidemiology
the study of human health and disease that has been helpful in giving insight to human nutrition
ingestion
the act of eating
suspension feeders
animals that sift small food particles from water (whales)
substrate feeders
animals that live in or on their food source (maggots)
fluid feeders
animals that suck nutrient rich fluid from a living host (mosquitoes)
bulk feeders
animals that eat relatively large pieces of food (snakes, humans)
digestion
when food is broken down into molecules small enough for the body to absorb
enzymatic hydrolysis
the splitting process that catalyzes digestion
mechanical digestion
the process that breaks food into smaller pieces, increasing surface area to make it available for chemical processes
absorption
this occurs when an animal's cells take up small molecules, such as amino acids and sugars
elimination
this occurs when undigested material passes out of the digestive system
intracellular digestion
the hydrolysis of food inside vacuoles that begins after a cell engulfs food
extracellular digestion
the breakdown of food in compartments that are continuous with the outside of the animal's body
gastrovacular cavity
this functions in digestion as well as in the distribution of nutrients throughout the body; found in animals with a simple body plan
alimentary canal
a digestive tube with two openings, a mouth and an anus, both of which are further compartmentalized
peristalsis
alternating waves of contraction and relaxation in the smooth muscles lining the alimentary canal that move food along; enables digestion while lying down
sphincters
ringlike valves formed by muscular layers at junctions between specialized compartments that regulate the passage of material
oral cavity
the mouth; where ingestion and the initial steps of digestion occur; presence of food stimulates a nervous reflex that causes salivary glands to deliver saliva
salivary glands
stimulated by presence of food to deliver saliva through ducts to the oral cavity; initiate chemical digestion and protect oral cavity
amylase
an enzyme in saliva that hydrolyzes starch and glycogen into smaller polysaccharides and the disaccharide maltose
bolus
a ball of partly digested food selected by the tongue that moves from the back of the mouth to the pharynx for further digestion
pharynx
the throat region that opens to two passageways: 1) esophagus, 2) trachea
esophagus
this connects the pharynx to the stomach; contains striated muscle at the top and smooth muscle further down to help peristalsis
stomach
the organ that is located just below the diaphragm in the upper abdominal cavity; primarily stores food and continues digestion, though it does absorb a few nutrients into the bloodstream; can stretch to accommodate 2L of food and liquid; secretes gastric juices
gastric juice
a digestive fluid that is churned with food
chyme
a mixture of gastric juices and partly digested food; its HCl denatures proteins
protease
a gastric juice that contains pepsin
pepsin
a protein-digesting enzyme that breaks proteins into polypeptides
parietal cells
the cells that release gastric juices by secreting H+ and Cl- ions at high concentrations
chief cells
the cells that release pepsin in its inactive form in the stomach lumen
pepsinogen
the inactive form of pepsin which is converted by HCl into active pepsin by clipping off a portion of it to expose the active site
mucus
a viscous and slippery material containing glycoproteins, cells, salts, and water that lines the stomach that protects against self-digestion;
small intestine
the primary station of enzymatic hydrolysis of macromolecules; 6 meters long
duodenum
the first 25 centimeters of the small intestine that serves as a major crossroad in digestion; chyme from stomach mixes with digestive juices of pancreas, liver, and gallbladder; controls digestive secretions into alimentary canal
pancreas
an organ that aids chemical digestion by producing an alkaline solution rich in bicarbonate and the enzymes trypsin and chymotripsyn
bile
a mixture of substances that act as detergents that aid in the absorption of lipids; stored and concentrated in gallbladder, but made in liver
liver
this organ breaks down toxins, balances nutrients, breaks down dysfunctional red blood cells, and makes bile
gallbladder
an organ that stores bile
chylomicrons
water-soluble globules that are made by the recombination of fats into triglycerides within the epithelial cells of the small intestine, and then coated with phospholipids, cholesterol, and proteins; too large to pass through membranes of capillaries to be absorbed,
lacteal
a vessel at the core of each villus that is a part of the vertebrate lymphatic system, which is a network of vessels filled with clear fluid called lymph; chylomicrons are sent here after their formation
hepatic portal vein
the convergence of veins that carry blood away from the villi and to the liver, heart, and other organs; allows the liver to regulate distribution of nutrients
large intestine
the organ at the end of the alimentary canal; includes the colon, cecum, and rectum; joins the small intestine with a T-junction sphincter
colon
an organ in the large intestine that leads to the rectum and anus; recovers water that entered the alimentary canal through osmosis
cecum
a pouch connected to the large intestine that is important for fermenting ingested material such as cellulose
appendix
a fingerlike projection of the cecum that has a minor and dispensable role in immunity
feces
wastes of the digestive system that become increasingly solid as they are moved along the colon by peristalsis; it takes 12-24 hours for material to travel the length of the colon
rectum
the terminal portion of the large intestine in which feces are stored until they can be eliminated; consists of two sphincters: one voluntary and one involuntary
carnivores
these animals generally have pointed incisors and canines that can be used to kill prey and rip or cut away pieces of flesh; jagged molars crush and shred food
herbivores
these animals usually have teeth with broad, ridged surfaces that grind tough plant material; incisors and canines are modified for biting off pieces of vegetation
omnivores
these animals have unspecialized teeth--there are combinations of traits found in both carnivorous and herbivorous dentition
overnourishment
the consumption of more calories than the body needs for normal metabolism; can cause obesity, the excessive accumulation of fat that contributes to type 2 diabetes, some types of cancer, and cardiovascular disease
oral cavity, esophagus, pharynx
polysaccharides, sucrose, and lactose are digested here by salivary amylase (in order of system)
stomach
proteins are digested here into polypeptides by pepsin
lumen of small intestine
digested here: polysaccharides, maltose, polypeptides, amino acids, DNA, RNA, nucleotides, fat globules, fat droplets, glyercol, fatty acids, monoglycerides
epithelium of small intestine
digested here: monosaccharides, small peptides, amino acids, nucleosides, nitrogenous bases, sugars, phosphates
amylase
primary enzyme for the digestion of carbohydrates
pepsin
enzyme for digestion of proteins in stomach
carboxypeptidease, chymotrypsin, trypsin
enzymes (in alphabetical order) for digestion of proteins in lumen of small intestine
nuclease, phosphatease
enzymes generally used in the digestion of nucleic acids
bile salt, lipase
enzymes generally used in the digestion of fats
interior surface
this part of the stomach is highly folded and dotted with pits leading to the tubular gastric glands
gastric gland
this part of the stomach includes different components of gastric juices, including mucus cells, chief cells, and parietal cells
mucus cells
these cells secrete a lubricating material that coats the stomach
rumen
the first chamber of ruminant digestive systems; boluses enter this area when food is ingested
reticulum
the second chamber of ruminant digestive systems; mutualistic prokaryotes and protists go to work here, then secrete fatty acids; periodical regurgitation occurs in order to further break down fiber
omasum
the third chamber of ruminant digestive systems; water is removed from the cud
absomasum
the fourth chamber of ruminant digestive systems; the cud, which contains microorganisms, passes through for digestion by enzymes
PYY
an appetite-regulating hormone that suppresses appetite and acts as a counter to ghrelin
ghrelin
an appetite-regulating hormone that triggers the sensation of hunger
insulin
an appetite-regulating hormone that is secreted after a rise in blood sugar