digestive system
variations in bird digestive system
1. A crop, stores food 2. Two stomachs: the proventriculus (enzymes) and the gizzard (grinding). 3. One openings to excrete urine and feces = the cloaca
Steps of Ruminant Digestive System
1. the rumen and the reticulum contain prokaryotes and protists that digest cellulose fiber. 2. Cud regurgitated chewed and swallowed in third stomach, the omasum where water is removed 3. Cud is passed on to the abomasum and broken down by enzymes
Pancreatic cancer is the ___ leading cause of cancer-related death in the US. It has the highest mortality rate of all major cancers.
4th
bolus
A term used to describe food after it has been chewed and mixed with saliva
_______ secrete______, which is converted by acidic gastric juice to ______(a digestive enzyme that hydrolyzes proteins).
Chief cells in gastric glands; pepsinogen; pepsin
Small Intestine
Digestion of food is completed and nutrients are absorbed through its wall; Bile from liver and enzymes from pancreas are released into the duodenum and act on chyme
Parietal cells in gastric glands secrete ____ and _____.
HCl ; intrinsic factor (to absorb vitamin B12)
sponges ingest food via...
Individual collar cells phagocytose food particles; digestion is intracellular within food vacuoles
_____ release chyme in spurts through the ____ of the stomach and into the small intestine
Peristaltic waves; pylorus
Liver
Produces bile, which is stored in gallbladder, Helps maintain glucose concentration in blood by converting excess into glycogen
Esophagus
Takes food to stomach by peristalsis (rhythmical contraction to move contents in tubular organs)
Digestive enzymes are secreted by....
The wall of the digestive tract, and nearby glands
Pharynx
Where digestive & respiratory passages come together; Soft palate closes off nasopharynx; epiglottis covers opening into trachea
complete digestive tract
a digestive tube with two openings, a mouth and an anus.
Large Intestine
absorbs water, salts, and some vitamins, contains opening to anal canal, subdivided into ascending, transverse, descending, and sigmoid colon
salivary glads are...
accessory glands
α-glycosidic bonds are hydrolyzed by_____ that digest polysaccharides to the disaccharide maltose
amylases
Cells that line the pancreatic ducts secrete_________which neutralizes stomach acid in the duodenum and provides the optimal pH for pancreatic enzymes
an alkaline solution rich in bicarbonate ions (pancreatic juice)
Omnivores
animals that eat both plant and animal derived food- and do well eating either.
Carnivores
animals that eat other animals
herbivores
animals whose primary food source is plant-based.
Ruminants
animals with stomach divided into four chambers, this allows them to re-chew food that has been partially digested by symbiotic microorganisms
About 1/3 of the fecal matter is...
bacteria (living and dead), ****ing gross dude
Digestion
breaks down food (mechanical digestion) and degrades complex organic compounds into smaller molecular components (chemical digestion)
___________ play important roles in reducing the peptides to free amino acids.
carboxypeptidase, dipeptidase, and aminopeptidase
4 parts of the large intestine (colon)
cecum, colon, rectum, and anal canal
In rabbits, food passes through the digestive system, collects in the _____, and then it passes as soft feces called _____. The rabbit re-ingests these to further digest them.
cecum; cecotrophes
Food that has been mixed with gastric juices in the stomach before moving to the small intestine is...
chyme
Premolars and molars
crush and grind food
Teeth are composed of...
dentin coated in enamel, with pulp cavity beneath
risk factors for colon cancer
diet, genetic factors, smoking, physical inactivity, heavy use of alcohol, and obesity
incomplete digestive tract
digestive tract with one opening that takes in food and ejects wastes (ex: planarian)
Most chemical digestion takes place in the _______, not in the stomach
duodenum
The gallbladder stores and concentrates bile and releases it into the ______ as needed
duodenum
Facultative carnivores
eat non-animal food addition to animal food - but generally do best eating animals
Cnidarians and flatworms digest food via...
enzyme-containing gastrovascular cavity; Digestion is completed intracellularly within food vacuoles, and undigested food particles are egested through the mouth
Enzymes produced by _______ lining the duodenum catalyze the final steps in digestion of major nutrients
epithelial cells
Pancreas
exocrine gland that produces pancreatic juice and digestive enzymes into the duodenum
Digestion in vertebrates is entirely _____.
extracellular
bile salts break up fat into _____ via emulsification
fat droplets
Constipation
feces are hardened because of excess water removal in the colon
series of steps by which animals meet nutritional needs
feeding -> injection -> digestion -> absorption -> egestion
many omnivores are...
filter feeders
canines
found in carnivores, used to pierce prey and tear food
Incisors
front teeth found in herbavores for clipping
Alkaline mucus secreted by the _______ helps protect the stomach from gastric juices
gastric mucosa
Epithelial lining of the stomach has millions of _____, which drain ______.
gastric pits; gastric glands
Lipase secreted by the pancreas into the duodenum digests fat droplets to...
glycerol and fatty acids
stomach
has a lining of protective mucus; sphincter allows food to enter where it is degraded into a thick liquid (chyme); has deep folds that disappear as the stomach fills to an approximate volume of one liter
_____ must eat large quantities of food to obtain the nourishment they need
herbivores
All animals are...
heterotrophs
Undigested material and unabsorbed chyme enter large intestine via ________ and exit through the ______.
ileocecal valve; colon
Feeding
is the selection, acquisition, and ingestion of food
bile does not enzymatically digest food because...
it contains no digestive enzymes
compared to the small intestine, the large intestine is...
larger in diameter, but shorter in length
Pancreatic amylase secreted by the pancreas into the duodenum digests starch to...
maltose
_____ is more easily digested than _____.
meat; plants
Enzymes produced by cells lining the small intestine break down disaccharides to _________.
monosaccharides
path of vertebrate digestion
mouth → pharynx (throat) → esophagus → stomach → small intestine → large intestine → anus
absorption
moves nutrients through lining of the digestive tract and into the blood, which transports the nutrients to all the cells of the body
Digestive tract wall has four layers, from inside to out:
mucosa, submucosa, muscle layer, and visceral peritoneum
Diarrhea
not enough water is removed from the feces
Three Major Pairs of Salivary Glands
parotid, submandibular, and sublingual glands
Trypsin secreted by the pancreas into the duodenum digests protein to...
peptides
Pepsin produced by the stomach degrades protein to _______
polypeptides
Egestion
process of discharging food that is not digested/absorbed from the body
Obligate carnivores
rely entirely on animal flesh to obtain their nutrients
Rugae
ridges on the hard palate and the wall of the stomach; allow the stomach to expand to hold up to a liter of food
Saliva contains _______ which initiates starch digestion
salivary amylase
Omnivores often have ______ that help them distinguish among a wide range of smells and tastes and thereby select a variety of foods
sensory adaptations
Peristaltic waves
sequence of rhythmic contraction of smooth muscles of a hollow organ to force material forward and prevent backflow
The amino acids are absorbed into the bloodstream through the ________.
small intestines
Starch in the stomach is degraded to _______ and ______ until salivary amylase is inactivated by stomach acids
small polysaccharides; maltose
Ribonuclease and deoxyribonuclease in the pancreas...
split the nucleic acids RNA and DNA to free nucleotides
A large part of protein digestion takes place in the ______.
stomach
Tongue is composed of...
striated muscle
Adaptations for capturing and killing prey
tentacles, claws, fangs, poison glands, and teeth
Animals cannot digest ____________; and many have a symbiotic relationship with bacteria, fungi, and other microorganisms which can digest it for them.
the cellulose of plant cell walls
Three regions of the small intestine
the duodenum, jejunum, and ileum
ingestion
the process of taking food into the digestive cavity (eating)
Incisors
used by carnivores for biting and cutting meat
First part of the large intestine forms a cecum; the _______ projects from the cecum
vermiform appendix
Millions of tiny intestinal ___ increase the surface area of the small intestine for digestion and absorption of nutrients
villi (or microvilli same diff)
Bacteria in the large intestine produce ______ and _____ - which large intestine absorbs with water and sodium, forming feces
vitamin K; vitamin B
bile contains...
water, bile salts, bile pigments, cholesterol, salts, and lecithin (a phospholipid)