Digestive System Flashcards
technical term for swallowing
deglutition
necessary to provide them with necessary chemicals for growth, maintenance, and energy production
nutrition
obtained by animals by eating plants or eating animals or both
food
Usually broken down into simpler substances, then absorbed and utilized by tissues and cells
food
function of the digestive system (2)
-to convert complex substances (food) into its simplest forms (nutrients
-to alter the physical and chemical composition of food for absorption and utilization by the body
type of digestion according to location
intracellular
extracellular
digestion that takes place inside the cell
intracellular
digestion that takes place outside the cell
extracellular
type of digestion according to mechanism (2)
physical/mechanical
chemical
digestion that includes processes that alter the physical state of food without changing its molecular structure
physical/mechanical digestion
digestion that is a series of catabolic reactions that break down molecules by the aid of enzymes
chemical digestion
classification of animals based on dietary habits/feeding types
herbivores
omnivores
carnivores
feed on plant material e.g. copepods, goat, cattle, horses
herbivores
feed on herbivores e.g. lion, eagles, sharks
carnivores
feed on both plant and animal materials e.g. pigs, humans
omnivores
type of digestion that is intracellular digestion and consists of only one opening which is both the entrance and exit for food
incomplete digestive tube
exemplified by ciliated protozoa and sponges
incomplete digestive tube
the gut that is a blind closed sac
gastrovascular cavity
in these, ciliary action directs the food into the cytosome “mouth” which enters the cytopharynx where food vacuoles are formed for intracellular digestion and exit the waste from residual vacuoles via cytopyge “anus” for excretion
ciliated protozoans
in these, water with food particles enters the body through pores; the collar cells then trap food particles as their flagella generate currents in the water
sponge
the food trapped in these are then phagocytosed and digested by fusion with lysosomes
colar cells
combination of extracellular and intracellular digestion
incomplete digestive tube
has only one opening to the digestive system that serves as the mouth and anus at the same time
incomplete digestive tube
exemplified by cnidarians and flatworms
incomplete digestive tube
hydria, jellyfish, corals, sea anemones
cnidarians
after ingesting large pieces of food, this begin in the digestive cavity; partially digested particles are completely digested inside cells (intracellular) of the digestive cavity and reabsorbed there; waste are expelled through the same opening
extracellular digestion
extracellular digestion
complete digestive tube
digestive tube with two openings: mouth and anus which permit a one-way flow of ingested food without mixing it with previously ingested food or waste
complete digestive tube
exemplified by roundworms, annelids, mollusks, arthropods, echinoderms, and chordates such as humans
complete digestive tube
food passes in one direction through a series of organs that facilitate digestion of food, absorption of nutrients, and elimination of wastes
complete digestive tube
type of feeding mechanism that makes use of ciliated surfaces to produce water currents to draw drifting food and particles to the mouth
suspension feeding
feeding mechanisms demonstrated by sponges, bivalves, gastropods, and many crustaceans
suspension feeding
makes use of entire body or modified appendages such as tentacle like structures to feed on detritus or organic materials from sediments of soft-bottom habitats such as mud and sands
deposit feeding
feeding mechanism demonstrated by clams, polychaetes, sea cucumbers
deposit feeding
large quantities of sediments are swallowed and the nutrients are digested, and the remains are passed out of this
anus
presence of tearing devices such as beak-like jaws and tooth-like structures for grasping and grinding food
chewing mechanism
requires the capture of live prey
predation
feeding strategies of predators (5)
motile stalkers
lurking predators
sessile opportunists
grazing carnivores
piercing and sucking mechanism
feeding strategies that actively pursue their prey such as octopuses, crabs, gastropods
motile stalkers
feeding strategies that stand still and wait for their pray to come within a distance such as spiders, shrimp, and many vertebrates
lurking predators
feeding strategies that capture prey only when in contact with them such as protozoa, barnacles, and cnidarians
sessile opportunists
feeding strategies that move on substrates picking up small organisms such as snails, worms, sponges, and small crustaceans
grazing carnivores
feeding strategies that are seen in mosquitos, leeches, and intestinal parasites are provided with these mouthparts for feeding on blood and other fluids
piercing and sucking mechanism
only mammals that feeds on blood
vampire bats
are provided with food vacuoles containing digestive enzymes and the nutrients are absorbed into the cytoplasm
protozoa
in protozoans, waste products are excreted through this
residual vacuole
possess a gut, a blind closed sac known as gastrovascular cavity which has one opening that serves as exit and entry point of food and wastes
cnidarians
digestive tract contains a short esophagus opening into a stomach, midgut, hindgut, and rectum
mollusks
in mollusks, this serves as a site for intracellular digestion
stomach
in mollusks, functions in extracellular digestion and absorption
midgut, hindgut, rectum
possess digestive gut consisting of mouth, esophagus, crop, stomach, intestine, rectum, and anus
insect
in insects, these aid first in breaking up the food which is brough into the mouth, then to the crop via esophagus
mandible and maxillae
insects are provided with these which secrete amylase and gastric glands
salivary glands
secrete lipase, proteases that aid in digestion
gastric glands
where food passes here to the stomach for extracellular digestion
crop
in insects, take place in the intestine and undigested food passes into the rectum for water reabsorption
nutrient absoprtion
in insects, are excreted through anus
solid fecal pellets
accessory structures icludes
lips
tongue
teeth
liver
gallbladder
guard the opening of the mouth
lips
modified as trophic apparatus in them
lips
Modified into beaks in birds and turtles; fleshy in mammals
lips
in invertebrates, this accessory organ is absent among them
tongue
tongue not muscular and bears teeth use for holding prey
fishes
tongue is highly mobile that can project from the mouth to capture insect
amphibians and reptiles
tongue is a thick muscular organ occupying the floor of mouth covered with a mucous membrane which assist in chewing and swallowing
mammals
a fold of mucous membrane connects the tongue to the floor of the mouth cavity in mammals
frenulum
situated in the anterior and lateral sides of the oral cavity
teeth
Situated in the anterior and lateral sides of oral cavity
teeth
Aid in physical breakdown of food
teeth
Present in all vertebrates except in birds and turtles
teeth
kinds of teeth as to mode of development
temporary/primary/deciduous
permanent/secondary/succedareous
kinds of teeth as to shape and function (3)
incisors
molars
cupids or canine
teeth is chisel shaped; for cutting
incisors
teeth are broad crowns with rounder cusps (tips) for grinding
molars
teeth are fanglike; for tearing and piercing
cupids or canine
starts with the mouth and ends with anus; contains food from time it is ingested until it is digested, absorbed, and eventually excreted
alimentary canal
gastro-intestinal tract
digestive tube
parts of complete digestive tube
mouth and buccal/oral cavity
pharynx
esophagus
stomach
small intestine
large intestine
first portion of the digestive tube; initially receives the food
mouth and buccal/oral cavity
also called throat; region between mouth and esophagus
pharynx
common passageway for food, fluid, and air
pharynx
pharynx is divided into (3)
nasopharynx
oropharynx
laryngopharynx
upper part of the pharynx, connected with the nasal cavity above the soft palate
nasopharynx
middle part of the throat, behind the mouth includes the soft palate and side and back walls of the throat, tonsils, and back one third of tongue
oropharynx
most caudal portion of the pharynx, a crucial connection point which food, water, and air pass
laryngopharynx
straight, muscular tube that conducts food (by peristalsis) to stomach
esophagus
Provided with crop or ventral pouch-like outgrowth in the posterior portion of this that that act as temporary storage of food in birds
esophagus
process in the esophagus where mechanical digestion happen
peristalsis
their continued actions in the esophagus chemically ddigest food
salivary amylase and lingual lipase
muscular enlarged sac that acts as temporary storage and for mixing food with digestive juices
stomach
part of stomach
cardiac end
fundus
pylorus
anterior end of the stomach, contains the cardiac sphincter
cardiac end
allow food to enter the stomach and prevent regurgitation back to esophagus
cardiac sphincter
expanded part of the stomach found only in mammals, temporary storage area
fundus (body)
temporary part of stomach – with pyloric sphincter
pylorus
controls the movement of food from the stomach into small intestine
pyloric sphincter
limited absorption of these are done by the stomach
electrolytes, drugs such as aspirin and alcohol
folds in the stomach that brings efficiency in absorption
rugae
in them, the stomach is divided into proventriculus and ventriculus or gizzard
birds
continuous with esophagus that contains gastric glands
proventriculus
muscular sac containing sand or small stones used for crushing and grinding food
ventriculus or gizzard
in them, the stomach is composed of four chambers: rumen, reticulum, omasum, and abomasums
mammals
region of the stomach where the plant food is fermented by bacteria
rumen
honey-combed compartment where food is molded into small boluses or cuds
reticulum
regurgitated, masticated, and re-chewed into the mouth, re-swallowed and passed to omasum
bolus
part of the stomach that serves as temporary holding site of food
omasum
part of the stomach that is a true glandular stomach; contains simple gastric glands for digestion
abomasums
longest section and most coiled part of the digestive tube
small intestine
Transport remaining residues to the large intestine
small intestine
in them, the small intestine is very long and coiled
herbivores
in them, the small intestine is shorter
carnivores
the small intestine is medium in length
omnivores
part of the small intestine (3)
duodenum
jejunum
ileum
short, anterior portion of the small intestine
duodenum
coiled middle portion of the small intestine
jejunum
longer, posterior portion of the small intestine; remainder and less coiled portion of the small intestine that follow jejunum
ileum
are covered with millions of tiny fingerlike projections called villi which aid in digestion and absorption of nutrients
inner walls of small intestine
additionally bordered with short, delicate processes known as microvilli
villus
form brush border which aid in increasing the internal surface area of the intestine
microvilli
posterior portion of the intestine that is larger in diameter and shorten than the small intestine
large intestine
Reabsorbs water to dry out indigestible food and eliminate them as solid or semi-solid feces through defecation
large intestine
Expanded portion of the digested tube
large intestine
in them it contain bacteria that break down organic waste in feces which produces vitamin K and gases
humans
parts of large intestine (4)
caecum
collon
rectum
anus/cloaca
the junction of small and large intestine
caecum
In some mammals, this is large and contains many microorganisms capable of digesting cellulose
caecum
in humans, this vestigial organ hangs from the caecum
appendix
serves as a special site for digestion of cellulose
appendix
middle portion of the large intestine consisting of the following regions
colon
parts of the colon
ascending
descending
transverse
sigmoid
part of the colon that travels up vertically to the right side of the abdomen
ascending
part of the colon that travels horizontally across the abdomen
transverse
part of the colon that travels vertically down to the left side of the abdomen
descending colon
part of the colon that is s-shaped and connects descending colon to rectum
sigmoid
posterior portion that temporarily stores undigested food
rectum
opening of the rectum to exterior in insects or mammals
anus
opening of the rectum in amphibians, reptiles, and birds
cloaca
posterior opening of a digestive tube
anus or cloaca
common opening for the gametes and wastes; found in amphibians, reptiles, and birds
cloaca
xclusively for the excretion of wastes or feces; found in mammals and bony fishesa
anus
present among insects; absent in amphibians and birds
salivary glands
present on some snakes, present in al mammals
modified salivary glands
function of salivary glands
secrete saliva
produce venom
lubricates food particles as it pass through the digestive tract
saliva
Contains enzyme amylase which begin carbohydrate digestion
saliva
Help cleanse teeth and mouth
saliva
ixture of mucus, water, and digestive enzyme salivary amylase
saliva
breaks down starches which initially happens inside the mouth
salivary amylase
breaks down triglycerides into fatty acids and monoglycerides
lingual lipase
where the salivary glands of snakes produce venom that is injected through this to immobilize prey
fangs
three pairs of salivary glands in mammals
parotid
submandibular or submaxillary
sublingual
salivary glands that lie at the sides of the face immediately below and in front of the ears
parotid
salivary gland that lie beneath the jaw
submandibular/submaxillary
salivary gland that lie beneath the tongue
sublingual
lie at the mucosal lining of stomach
gastric glands
how many gastric glands are present in humans
35 million
produced by gastric glands that contains pepsinogen and hydrochloric acid (HCl)
gastric juice
when mixed with HCl forms pepsin
pepsinogen
digests proteins
pepsin
largest gland, second largest organ
liver
secretes bile
liver
alkaline liquid that is stored in gall bladder
bile
Partially an excretory product and a digestive secretion
bile
how many bile is secreted by the liver
800 to 1000mL
pH of bile
7.6 to 8.6
color of bile due to bile pigments which are by-products of hemoglobin breakdown
yellow green color
where hemoglobin is broken down and is attributed to the yellow green color of bile
wornout RBC
bile is composed of (7)
water
bile salts
bile acids
cholestrol
letchitin
bile pigments
ions
functions of bile (2)
emulsification
neutralizes acidity of food as it leaves the stomach
breaks down fat globules and aids in absorption of fatty acids, cholesterol, and fat-soluble vitamins
emulsification
other functions of liver (7)
-maintenance of normal glucose concentration
-lipid metabolism
-protein metabolism
-storage area
-destroying damaged RBC and foreign substance
-altering composition of toxic substances
- blood reservoir
produces pancreatic juice and sends it to duodenum by way of pancreatic duct
pancreas
contains important enzymes for digestion such as proteases, lipase, amylase, nucleases, and carboxypeptidase
pancreatic juice
digests proteins (ex. trypsin and chymotrypsin)
proteases
example of proteases
trypsin
chymotrypsin
digests fats
lipase
digest starch
amylase
digest DNA and RNA to form nucleotides
nucleases
digests peptides and amino acids
carboxypeptidase
secrete intestinal fluids with brush border enzymes
intestinal glands
converts trypsinogen to trypsin
enterokinase
converse lactose to glucose and galactose
lactase
converts maltose to glucose
maltase
converts sucrose to glucose and fructose
sucrase
converts α-dextrins to glucose
a-dextrinase
converts peptides to amino acids
peptidase
converts nucleotides to bases, pentoses, and phosphates
nucleosidase and phosphatase
converts polysaccharides to maltose, maltotriose, and alphadextrins
salivary amlyase
converts trigylcerides and other fats to fatty acids and monoglycerides
lingual lipase
converts proteins to peptides
pepsin
gastric juice that converts fats and oils in butterfat in milk to fatty acids and monoglycerides
gastric lipase
converts polysaccharides to maltose, maltotriose, alpha-dextrins
amlyase
pancreatic juice that converts proteins to peptides
elastase
pancreatic juice that converts triglycerides emulsified by bile salts to fatty acids and monoglycerides
lipase
converts RNA and DNA to nucleotides
nucleases
pancreatic juice that converts protein to peptides (2)
tyrpsin
chymotrpysin
pancreatic juice that converts peptides to peptides and amino acids
carboxypeptidase
converts alpha-dextrins to glucose
alpha-dextrinase
converts maltose to glucose
maltase
converts tyrpsinogen to trypsin
enterokinase
converts nucleotides to nitrogenous base, pentoses, and phosphatases
nucleosidases and phosphatases
taking in of food through the mouth
ingestion
process of digestion in the buccal/oral cavity
chewing or mastication
two types of digestion
physical digestion
chemical digestion
initially digested to become tri- and dissacharides by amylase
carbohydrates
initially digested to fatty acids and triglycerides by lipase
fats
ground mass of food with saliva
bolus
involves upward and backward movement of the tongue which brings bolus posterior to the mouth
swallowing or deglutition
– located in the pharynx are stimulated causing muscular contractions
swallowing receptors
involves movement of food in the esophagus by peristalsis to the stomach
propulsion and storage
in them, food is temporarily stored in the crop
birds
as food reaches the stomach, churning or mixing waves pass over it every 15 to 25 seconds, and the stomach secretes gastric juices containing enzymes for digestion
digestion
movement in the stomach
churning
responsible for the digestion of fats and oils in butterfat in milk
gastric lipase
three phases of gastric secretion (3)
cephalic or “head” phase
gastric or “belly”
intestinal phase
phase of gastric secretion when food is smelled, tasted or seen, vagus nerves from the brain are stimulated causing secretion of small amount of juice in the stomach
cephalic or head phase
phase of gastric secretion that occurs when food reaches stomach
gastric or belly
phase of gastric secretion occurs when partially digested food enters the opening section of small intestine
intestinal phase
the food is in this nutrient-rich, semi-liquid mass after gastric churning
chyme
takes place in the small intestine
final digestion and absoprtion
mechanical digestion through the following movements (2)
peristalsis
segmentation
longitudinal waves of contraction that move along the intestine, followed by waves of relaxation
peristalsis
movement that produces local constrictions in the small intestine and brings food particles into contact with the absorptive wall by moving it back and forth
segmentation
is a movement that occurs slowly and in segmenting manner. it ensures that the chyme is mixed facilitating absorption of water, mineral salts and vitamins.
Haustral churning
weak compared to peristalsis of stomach and esophagus so that chyme remains from 3-5 hours inside the small intestine to enhance digestion and absorption
segmentation
chemical digestion or
complete digestion of particles are through the action of different substances/enzymes secreted by them
liver
gallbladder
pancreas
intestine
dry out indigestible food and eliminate them as solid or semi-solid feces through defecation
water re-absorption
in them, reabsorption of water takes place through specialized rectal glands
insects
in them feces is excreted through the cloaca
reptiles and birds
