Ch. 44 Animal Nutrition Flashcards
heterotroph
an organism that obtains energy and nutrients from other organisms rather than making their own food
(ie) animals
processes necessary for an animal to obtain energy from its food
1) ingestion
2) digestion
3) absorption
4) elimination
ingestion
taking in food
digestion
breakdown of food into smaller pieces
(ie) carbs become monosaccharides
absorption
uptake of nutrients
elimination
disposal of wastes
nutrient
substances an organism needs to remain alive
food
any material that contains nutrients
Recommended Dietary Allowance (RDA)
specify the amount of each essential nutrient that an individual must ingest to meed the needs of most healthy people
essential nutrients
nutrients that cannot be synthesized and must be obtained in the diet
- required for normal growth, reproduction, and maintenance
essential amino acid
any amino acids that cannot be synthesized by humans
- must be obtained from food
- 8 essential amino acids
types of essential amino acids
1) isoleucine
2) leucine
3) lysine
4) methionine
5) phenylalanine
6) threonine
7) tryptopha
8) valine
vitamin
organic compounds that are vital for health
- required only in minute amounts
- several function as coenzymes in critical reactions
electrolyte
inorganic ions that influence osmotic balance
- required for normal membrane function
inorganic substance
substance that fulfills a variety of functions not preformed by electrolytes
- important components of cofactors or structural materials
suspension feeder
organisms that filter small organisms or bits of organic debris from water, by means of cilia, mucous-lined “nets” or other structures
(ie) anenome
food-getting techniques
1) suspension feeders
2) deposit feeders
3) fluid feeders
4) mass feeders
deposit feeder
organism that swallows organic-rich sediments and other types of deposited material
(ie) whales
fluid feeder
organism that sucks or laps up fluids
(ie) lampreys
mass feeder
organism that seizes and manipulates chunks of foods by using jaws, teeth, beaks, or special toxin-injecting organs
- majority of animals
(ie) lions
adaptive radiation
rapid evolutionary diversification within one lineage, producing many descendant species with a wide range of adaptive forms
- each of which lives in a different habitat or employs a distinct feeding method
(ie) cichlid fishes
endemic species
a species that lives in one geographic area and nowhere else
(ie) cichlids
pharyngeal jaw
jaws located behind normal oral jaws
- have toothlike protuberances whose shape corresponds to the type of food they eat
(ie) snakes’ jaws are located near back of throat
reason why snakes do not choke on their food
the trachea is separate from the esophagus
digestive tract
(alimentary canal or gastrointestinal (GI) tract)
the long tube that begins at the mouth and ends at the anus
types of digestive tracts
1) incomplete digestive tracts
2) complete digestive tracts
incomplete digestive tract
a digestive tract that has just 1 opening
- ingestion & elimination through 1 hole
- mouth openings into gastrovascular cavity where digestion takes place
0 not very efficient
_ expensive: must filter water
- no actual feces
(ie) anenome
complete digestive tract
a digestive tract with 2 openings (mouth & anus)
- interior of this tube communicates directly w/ the external environment via openings
advantages of complete digestive tracts
1) animals can feed on large pieces of food
2) chemical & physical processes can be separated w/in the canal, so they occur independently of each other and in a prescribed sequence
3) material can be ingested and digested continuously
how to digest faster
1) ↑ chew
2) ↑ saliva
3) ↑ amylase
types of macromolecules
1) carbs
2) lipids
3) proteins
carbohydrate digestion
1) mouth: salivary amylase breaks down carbs
2) esophagus: pass
3) stomach: pass
4) lumen of small intestine: pancreatic α-amylase monosaccharides (simple sugars) & disaccharides trisaccharides
5) cell membrane of epithelial cell:
6) epithelium of small intestine: facilitated diffusion
7) bloodstream: enters
lipid digestion
1) mouth: lingual lipase breaks down lipids
2) esophagus: pass
3) stomach: pass
4) lumen of small intestine: bile salts & pancreatic lipase - monoglycerides fatty acids (facilitated diffusion)
5) cell membrane of epithelial cell:
6) epithelium of small intestine: monoglycerides fatty acids -> triglycerides -> chlymicrons (protein-coated globules) -> exocytosis
7) bloodstream: enter by way of lymph vessels
protein digestion
1) mouth: enter
2) esophagus: pass
3) stomach: pepsin breaks down proteins into polypeptides
4) lumen of small intestine: trypsin, chymotrypsin, elastase & carboxypeptidase - short peptides & amino acids
5) cell membrane of epithelial cell:
6) epithelium of small intestine: facilitated diffusion & cotransport
7) bloodstream: enters
salivary amylase
any enzyme that can break down starch by catalyzing hydrolysis of the glycosidic linkages between the glycose residues
- most important catalyst in the breakdown of carbohydrates
where does break down of carbohydrates start?
in the mouth via amylase
where does break down of lipids start?
in the mouth via lingual lipase
where does break down of proteins start?
in the stomach via pepsin
lingual lipase
an enzyme produced by glands in the tongue
- breaks down fat molecules in fatty acids & monoglycerrides
- breakdown of lipids
salivary gland
a type of gland that secretes saliva (water + glycoproteins + mucus) into the mouth
saliva
a mixture of water, mucus-forming glycoproteins, and digestive enzymes
mucus
a slimy mixture of glycoproteins (mucins) and water
- secreted in many animal organs for lubrication
- serves as a barrier to protect surfaces from infection
mucin
glycoprotein
esophagus
a muscular tube connecting the mouth and stomach
- food travels down esophagus via peristalsis
peristalsis
rhythmic waves of muscular contraction
- pushes food along
- involuntary movement (reflex)
- stimulated by swallowing
reflex
automatic reaction to simulus
crop
(a modified esophagus)
a storage organ in the digestive system of certain vertebrates, such as birds
- allows individuals to eat a large amount in a short time then retreat to a safe location while digestion occurs
- may also be used for processing
stomach
a tough, muscular pouch bracketed on both ends by valves (sphincters)
- very acidic (will corrode anything)
- muscular contractions in stomach = churning, which mixes and breaks down food mechanically
the predominant acid in the stomach
hydrochloric acid (HCl)
why do we get diarrhea?
there is not enough water absorption
- water passes through digestive system
- results in dehydration
sphincter
a muscular valve that can close off a tube, as in blood vessel or a part of the digestive tract
- seals off stomach from esophagus & stomach from intestine
gastric juice
a mix of hydrochloric acid (HCl) and pepsin (enzyme) that begins the digestion of proteins
pepsin
a protein-digesting enzyme present in the stomach
chief cell
specialized stomach cells that contain a pepsin precursor (pepsinogen) which converts to active pepsin depending on stomach environment
pepsinogen
pepsin precursor that is converted to active pepsin by contact with the acidic environment of the stomach
- inactive enzyme
parietal cell
a cell in the stomach lining that secretes hydrochloric acid
-source of HCl in gastric juice
mucous cell
a type of cell found in the epithelial
carbonic anhydrase
an enzyme that catalyzes the formation of carbonic acid (H2CO3) from carbon dioxide and water
- high concentration in parietal cells
ulcer
a hole in an epithelium that damages the underlying basement membrane and tissues
- mucus layer is not present
- ulcers in stomach/small intestine may result in intense abdominal pain
- caused by bacterium “Helicohacter pylori”
- untreated ulcer may lead to perforation (leaks)
Helicobacter pylori
bacterium that eats away mucus layer
- causes ulcers
ruminant
member of a group of hoofed mammals that have a complex, four-chambered stomach specialized for digesting cellulose rather than protein
(ie) cattle, sheep & deer
cud
a mixture of partially digested food and cellulose-digesting bacteria
rumen
largest chamber in ruminant stomach
- food here may be regurgitated for further chewing (cud)
- serves as fermentation vat
- packed w/ symbiotic bacteria & protists (which can break down cellulose)
ruminant stomachs
1) rumen
2) reticulum
3) omasum
4) abomasum
ruminant stomach characteristics
- able to harvest energy from cellulose
- can regurgitate cud from the largest chamber (rumen) for further chewing
- folded in complex ways
- big acid bag
reticulum
2nd chamber in ruminant stomach that is adjacent to rumen
- packed w/ symbiotic bacteria & protists (which can break down cellulose)
omasum
third chamber in ruminant stomach
- responsible for removing water
abomasum
final chamber in ruminant stomach
- contains ruminant’s own digestive enzymes
- corresponds to a true stomach
modified stomachs
1) ruminant
2) avian gizzard
meant to ingest food quickly & digest later
avian gizzard
modified stomach
- very strong muscle
- grinds food
- necessary since birds do not have teeth
small intestine
the portion of the digestive tract between the stomach & large intestine
- site for final stages of digestion
- site for most of nutrient absorption
- 6 meter long tube
- large surface area for absorption
when is digestion complete?
when food reaches the end of the small intestin
function of small intestion
1) final digestion
2) absorption
lacteal
a small lymphatic vessel extending into the center of a villus in teh small intestine
- receives chylamcirons containing fat absorbed from food
protease
an enzyme that can break up proteins by cleaving the peptide bonds between amino acid residents
- digest polypeptides into monomers
- many types of proteases, each specific for a different kind of polypeptide
- synthesized in inactive form by pancreas
protein processing by pancreatic enzymes
1) synthesized in inactive form by pancreas
2) transferred through pancreatic duct to the small intestine
3) activated in small intestine
pancreas
a large gland in vertebrates that has both exocrine & endocrine functions
- secretes digestive enzymes into a duct connected to the intestine
- secretes several hormones (notably, insulin & glucagen) into the bloodstream
pancreatic duct
a duct joining the pancreas to the common bile duct to supply pancreatic juices which aid in digestion provided by the exocrine pancreas
trypsinogen
a pancreatic enzyme
- activated by enterokinase into trypsin
- inactive enzyme
trypsin
a protein-digesting enzyme present in the small intestine that activates several other protein-digesting enzymes
- active enzyme
- activates other enzymes synthesized by pancreas
hormone
any of many different signaling molecules that circulate throughout the plant or animal body
- can trigger characteristic responses in distant target cells at very low concentrations
secretin
1st hormone produced in the small intestine in response to the arrival of food from the stomach
- FCN: induce a flow of bicarbonate ions from the pancreas to the small intestine
digestion is under both _______ and _______ control
neural; hormonal
bicarbonate function in digestion
neutralizes acid arriving from stomach
secretin function
1) food present, DIGEST
2) neutralize acid to base
digestion occurs in a _____ environment
basic
cholecystokinin
2nd hormone produced in the small intestine
- stimulates secretion of digestive enzymes from pancreas
- stimulates secretion of molecules from liver that are involved in lipid digestion
gastrin
a hormone produced by cells in the stomach lining in response to the arrival of food or to a neural signal from the brain
- stimulates other stomach cells to release hydrochloric acid
nuclease
any enzyme that digests RNA or DNA molecules
- produced in pancreas
pancreatic amylase
an enzyme that digests glucose chains by catalyzing hydrolysis of the glycosidic linkages between the glucose residues
- produced by the pancreas
nutrient absorption characteristics
1) highly selective - plasma membrane of microvilli are responsible for bringing specific nutrients into the cell
2) active - requires ATP to bring nutrients into epithelium against a concentration gradient
which molecules can enter the bloodstream?
proteins & carbohydrates
why can’t lipids enter the bloodstream?
because lipids are hydrophobic
pancreatic lipase
an enzyme that breaks certain bonds in complex fats
- results in release of fatty acids & small lipids
- produced in pancreas
hydrophobic fats
tend to enter the small intestine in large globules
- must be broken up (emulsified) before digestion can begin
emulsification
the dispersion of fat into an aqueous solution
- usually requires the aid of amphipathic substance (detergent or bile salts), which can break large fat globules into microscopic fat droplets
bile salt
small lipid that breaks
- steroid derivative of bile
- synthesized in the liver
- secreted in complex solution (bile)
- responsible for emulsification of fats during digestion
bile
a complex solution
- produced by liver
- stored in the gallbladder
- secreted into intestine
- contains bile salts
fatty-acid binding protein
a group of molecules that coordinate lipid responses in cells
- strongly linked to metabolic & inflammatory pathways
- attaches to monoglycerides & fatty acids to enter the epithelial cells
chylomicron
protein-coated globules that can diffuse into lacteals
how is water absorbed in small intestine?
when solutes from digested material are brought into the epithelium of the small intestine via active transport, water follows passively by osmosis
cecum
an outpocketing of the digestive tract located at the start of the large intestine
- break down cellulose
- equivalent to reticulum in ruminants
- larger size in leaf-eating primates (rabbits)
- smaller in humans
why is a leaf-eating primate’s cecum larger?
they need a larger cecume to use it as a fermentation chamber for processing cellulose
why is the human cecum (appendix) smaller?
functions in defense against invading bacteria & invading bacteria/viruses
large intestine
the distal (away) portion of the digestive tract
- consisting of the cecum, colon & rectum
- FCN: compact wastes that remain & absorb enough water to form feces
- covered in aquaporins
- water rescued
parts of the large intestine
1) cecum (appendix)
2) colon
3) rectum
rectum
the last portion of the digestive tract
- feces held here until expelled
colon
the portion of the large intestine where feces are formed by compaction of wastes & reabsorption of water
- main section of section of large intestine
cloaca function
1) reproduction
2) waste excretion
cloaca
a body cavity opening to the outside
- enlarged portion of the large intestine
- used by both excretory & reproductive systems
- present in some mammals & many nonmammalian vertebrates
(ie) chicken butt
diabetes mellitus
a disease of abnormally high levels of glucose
- type 1 or 2
insulin
hormone produced in pancreas when blood glucose levels are high
- causes cells to increase glucose uptake/processing
- result: decrease in blood glucose levels
glucagon
hormone produced in pancreas when blood glucose levels fall too much
- causes liver to catabolize glycogen and produce glucose via gluconoeogenesis
- w/draw stored glycogen (stored fats)
gluconeogenesis
synthesis of glucose from non-carbohydrate compounds
- causes rise in blood glucose levels
type 1 diabetes
disease where insulin is not synthesized
- sugar not stored
treated w/ insulin injections & careful attention to diet
type 2 diabetes
disease with defective versions of insulin
- too much sugar intake, not enough storage/insulin
- correlated w/ obesity
treated by prescribed diets, monitoring blood glucose levels & drugs that increase cellular responsiveness to insulin
