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