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)