chapter 40 Animal metabolism, nutrition, digestion
what are the 7 layers lining the digestive tract (starting from inside to outside)
1.) the lumen 2.) the mucosa 3.) submucosa, 4.) circular muscle 5.) longitudinal muscle 6.) serosa 7.) mesentery
how many essential vitamins are there for humans?
13
how many minerals are required by humans?
19
how many amino acids are humans unable to synthesize on their own
8
pyloric sphincter
A band of muscle at the base of the stomach that opens to allow small amounts of digested food to enter the small intestine.
dietary minerals
A chemical element other than carbon, hydrogen, oxygen, or nitrogen that is required in the diet and must be obtained in food
trypsin
A digestive enzyme produced by the pancreas that breaks down proteins.
epiglottis .
A flap of tissue at the bottom of the pharynx that prevents food from entering the trachea and lungs
bile
A fluid produced by the liver that aids in fat digestion by breaking large clusters of fats into smaller lipid droplets.
energy balance
A form of homeostasis in which the amount of energy calories from food taken in equals the amount of calories used over time to meet metabolic needs.
secretin
A hormone released by cells lining the duodenum in response to the acidic pH of the stomach contents entering the small intestine and that stimulates the pancreas to secrete bicarbonate ions.
mesentery
A membrane in the abdominal cavity through which blood vessels, nerves, and lymph travel to supply the gut.
gastrin
A peptide hormone produced in the stomach that stimulates cells lining the stomach to increase their production of HCl.
pancreas
A secretory gland that has both endocrine function, secreting hormones, including insulin, directly into the blood, and exocrine function, aiding the digestion of proteins, carbohydrates, and fats by secreting digestive enzymes into ducts that connect to the duodenum.
temporomandibular joint
A specialized jaw joint in mammals that allows the teeth of the lower and upper jaws to fit together precisely
submucosa
A tissue layer surrounding the mucosa that contains blood vessels, lymph vessels, and nerves.
lipase .
A type of enzyme produced by the pancreas that breaks apart lipids, thus enabling their more effective digestion
liver
A vertebrate organ that aids in the digestion of proteins, carbohydrates, and fats in the duodenum by producing bile, which breaks down fat.
what are carbohydrates, fats, and proteins used to make?
ATP
essential amino acid
An amino acid that cannot be synthesized by cellular biochemical pathways and instead must be ingested.
ectotherm
An animal that obtains most of its heat from the environment.
endotherm
An animal that produces most of its own heat as by-products of metabolic reactions
recovery metabolism
An animal's elevated consumption of oxygen following activity.
pepsin
An enzyme produced in the stomach that breaks down proteins.
amylase
An enzyme that breaks down starch into smaller subunits
mucosa
An inner tissue layer with secretory and absorptive functions surrounding the lumen of the digestive tract.
vitamin
An organic molecule that is required in very small amounts in the diet.
serosa
An outer layer of cells and connective tissue that covers and protects the gut.
digestive tract (or gut)
Collectively, the passages that connect the mouth, digestive organs, and anus; also known as the digestive tract.
anaerobic metabolism
Energy metabolism in the absence of oxygen
aerobic metabolism
Energy metabolism that uses oxygen gas to oxidize organic compounds, generating ATP; found in Bacteria, Archaea, and the mitochondria of eukaryotic organisms.
The sight, smell, and taste of food send signals to the brain that stimulate a sense of appetite, and to the stomach that stimulate the secretion of _________ and _______________ that break down proteins and lipids.
HCl, digestive enzymes
gizzard
In birds, alligators, crocodiles, and earthworms, a compartment with thick muscular walls in the digestive tract where food mixed with ingested rock or sediment is broken down into smaller pieces
their is a mutual benefit between host animals and the bacteria residing in their gut. what benefits are there between the two?
In the process of nourishing themselves by aiding in the digestion of the host's gut contents, the bacteria provide nutrients and certain vitamins, such as biotin and vitamin K, that the animal cannot produce itself
Large aquatic animals apprehend prey by:
Large aquatic animals apprehend prey by suction feeding and active swimming.
canine
One of the teeth in carnivores specialized for piercing the body of prey.
molar
One of the teeth in the back of the mouth of mammals specialized for crushing and shredding tough foods such as meat and fibrous plant material
incisor
One of the teeth in the front of the mouth, used for biting.
premolar
One of the teeth of mammals between the canines and molars that are specialized for shearing tough foods.
esophagus
Part of the foregut; the passage from the mouth to the stomach.
large intestine
Part of the hindgut and the site of reabsorption of water and minerals; also known as the colon.
colon
Part of the hindgut and the site of reabsorption of water and minerals; also known as the large intestine.
small intestine
Part of the midgut; the site of the last part of digestion and most nutrient absorption.
circular muscle
Smooth muscle that encircles the body or an organ; in the digestive tract, a circular muscle layer contracts to reduce the size of the lumen.
longitudinal muscle
Smooth muscle that runs lengthwise along a body or organ; in the digestive tract, a longitudinal muscle layer contracts to shorten small sections of the gut
absorption
The direct uptake of molecules by organisms, commonly to obtain food. In vertebrate digestion, it is the process by which breakdown products are taken up into the bloodstream.
foregut
The first part of an animal's digestive tract, including the mouth, esophagus, and stomach.
mouth
The first part of the foregut, which receives food
hindgut
The last part of an animal's digestive tract, including the large intestine and rectum.
stomach
The last part of the foregut, which serves as a storage and digestive chamber; also known as the crop.
midgut
The middle part of an animal's digestive tract, including the small intestine.
adenosine triphosphate (ATP)
The molecule that provides energy in a form that all cells can readily use to perform the work of the cell. ATP is the universal energy currency for all cells.
suspension filter feeding
The most common form of food capture by animals, in which water with food suspended in it passes through a sievelike structure.
The most reliable source of all eight essential amino acids is _______
The most reliable source of all eight essential amino acids is meat
rectum
The part of the hindgut where feces are stored until elimination.
extracellular digestion
The process in most animals in which food is isolated and broken down outside a cell, in a body compartment.
intracellular digestion
The process in single-celled protists in which food is broken down within cells.
pharynx
The region of the throat that connects the nasal and mouth cavities
catabolic
The set of chemical reactions that break down molecules into smaller units and, in the process, produces ATP to meet the energy needs of the cell.
anabolic
The set of chemical reactions that build molecules from smaller units utilizing an input of energy, usually in the form of ATP. Anabolic reactions result in net energy storage within cells and the organism.
electron transport chain
The system that transfers electrons along a series of membrane-associated proteins to a final electron acceptor, using the energy released as electrons move down the chain to produce ATP.
citric acid cycle
The third stage of cellular respiration, in which acetyl-CoA is broken down and more carbon dioxide is released.
the acid produced by the stomach is neutralized to create an environment for the intestinal enzymes to act. how does this occur?
These functions are carried out by the small intestine with the help of two other organs, the pancreas and liver
peristalsis
Waves of muscular contraction that move food toward the base of the stomach.
Following digestion, the breakdown products are taken up into the bloodstream in a process called _____________.
absorption
metabolic rate is affected by
activity level, body size, body temperature
Food entering the mouth is mixed with salivary secretions that contain________, an enzyme that breaks down carbohydrates, and secretions from the tongue that contain _______, an enzyme that breaks down lipids
amylase, lipase
metabolic rate
an animal's overall rate of energy use
Animals rely on ___________________ for short bursts of intensive activity
anaerobic glycolysis
The pancreas also secretes ________________ ions, which neutralize the acid produced by the stomach
bicarbonate
The liver participates in digestion by producing
bile
how do humans obtain the amino acids that they
by the food they eat
the enzyme amylase breaks down
carbohydrates
the three main classes of molecules for sources of energy are
carbohydrates, fats, and proteins.
ectotherms regulate their body temperature by
changing their behavior, moving into shade or sitting on a rock in the sun
Excess water absorption can cause___________, whereas too little water absorption results in _________
constipation, diarrhea.
what do the muscles lining the digestive tract do?
contract alternately to mix gut contents, producing a traveling wave during peristalsis that moves the contents along the digestive tract from compartment to compartment
which have more active lifestyles, endotherms or ectoderms?
endotherms
In the _______________, peristalsis moves the food toward the stomach.
esophagus
If an animal eats more food than it requires, energy stores such as ___ deposits grow over time
fat
the enzyme lipase breaks down
fat
what kind of organisms are ectotherms
fish, amphibians, reptiles, and invertebrates
what are the three main parts of the digestive tract
foregut, midgut, hindgut
Bile produced by the liver is stored in the ______________ . When fats enter the duodenum, cells lining the duodenum release a peptide hormone called ____________, which causes the ____________ to contract, thus releasing the bile into the duodenum
gallbladder, cholecystokinin (CCK), gallbladder
When food arrives in the stomach and digestion there begins, cells lining the stomach secrete a peptide hormone called _______
gastrin
Birds, alligators, crocodiles, and earthworms break down food into smaller pieces farther along their digestive tracts in the
gizzard
stomach has several mechanisms to protect itself from the acidic environment and presence of digestive enzymes:
glands in the lining of the stomach secrete mucus to protect the stomach wall. cells in the stomach secrete some digestive enzymes in an inactive form; otherwise, the cells themselves would be digested
Glucose can be partially broken down in the absence of oxygen by
glycolysis
Endotherms have a _________ metabolic rate than ectotherms
higher
endotherms usually, but not always, maintain a constant body temperature that is ______ than that of their environment
higher
what kind of organisms are endotherms?
humans and birds
The stomach is maintained at a low pH through the secretion of __________________ by specific cells lining the stomach
hydrochloric acid (HCl)
The process in single-celled protists, which obtain food particles by phagocytosis, is _________________________
intracellular digestion
why do stomachs serve as storage
it may take a long time for digestion
Some digestive enzymes are produced by the small intestine. For example, cells of the small intestine produce _________, an enzyme that breaks down the sugar lactose into glucose and galactose
lactase
After the absorption of nutrients in the small intestine, water and inorganic ions are absorbed in the_______________ of the hindgut
large intestine, or colon,
hindgut includes
large intestine, rectum, and anus
average rate at which each gram of body tissue consumes energy is _______ in larger animals compared to smaller ones
less
the different arrangement of specialized teeth mammals show differences in
lifestyle
If the pH of the stomach becomes too ______, gastrin secretion is inhibited, an example of a negative feedback loop
low
what does the tongue do?
manipulates food and transports it within the mouth cavity. it moves the food into position within the mouth for effective cutting and maceration into smaller pieces by the teeth. When food has been chewed and is ready to be swallowed, the tongue moves it to the rear of the mouth cavity
At rest, larger animals consume ______ energy and have ______ metabolic rates than smaller ones
more, higher
what kind of animals use filter feeding?
mostly aquatic, many worms, bivalve mollusks, such as scallops, clams, and oysters
chemical digestion, in most mammals begins in the
mouth
The foregut includes the
mouth, esophagus, and stomach or crop, which serves as an initial storage and digestive chamber.
Animals that cannot acquire enough food are in _________ energy balance and become undernourished
negative
Metabolic rate can be measured by the animal's rate of ______________
oxygen consumption
Many of the digestive enzymes that act in the small intestine are not produced by the small intestine, but instead by the ___________
pancreas
The primary digestive enzyme produced in the stomach is
pepsin
Food and its breakdown products move through the gastrointestinal tract by _______________, waves of smooth muscle contraction and relaxation
peristalsis
During swallowing, food is pushed through the ____________, over the ___________, a flap of tissue that protects food from entering the trachea and lungs, and into the ____________, a tube that connects the pharynx to the stomach
pharynx, epiglottis, esophagus
the enzyme trypsin breaks down
proteins
When an animal shifts from rest to activity, its metabolic rate and oxygen consumption ______ to meet its increased demand for ATP
rise
The pancreas is stimulated to secrete bicarbonate ions by the hormone ________
secretin
Final digestion and nutrient absorption take place in the ____________
small intestine.
Absorption of glucose into the cells of the small intestine is driven by the movement of the ______________ down a concentration gradient.
sodium ions
energy intake
sources of energy
The ____________ is one of the main sites of protein and lipid breakdown
stomach
many nutrients necessary for life cannot be synthesized by an animal's metabolism and therefore must be acquired from
the food they eat
what is the difference between pepsin and trypsin if they both break down proteins
the location at which they are found, pepsin is found in the stomach while trypsin is produced by the pancreas
the midgut includes
the small intestine
energy use
the ways in which energy is expended
Cells that line the small intestine are connected by ________ junctions
tight
The small intestine has highly folded inner surfaces, called ______, which themselves have highly folded surfaces, called __________
villi, microvilli
By the time the gut contents reach the large intestine, the nutrients have been absorbed into the body, but ______ and ____________ remain
water, inorganic ions
