Digestion Flashcards
What is digestion in its most basic form?
The breakdown of food into smaller components that can be more easily absorbed and assimilated by the body.
What is catabolism?
It is a set of metabolic pathways that break down molecules into smaller units to release energy.
True/False: Digestion is a form of catabolism.
True.
What are the two forms of digestion?
Chemical and mechanical digestion.
What is mechanical digestion?
The physical breakdown of large pieces of food that can then be accessed by digestive enzymes.
What is chemical digestion?
Enzymes break down the food into molecules the body can use.
In humans and many other species of animal, what action starts digestion?
Mastication.
Is mastication mechanical or chemical digestion?
Mechanical.
What is the role of saliva in human digestion?
It softens the food and begins to process the starch right away.
Where does food go after mastication?
It goes down the esophagus and into the stomach.
Gastric juice is what digests proteins in the human stomach. What is gastric juice made of?
Hydrochloric acid and pepsin.
What mixture lines the stomach wall and keeps the gastric juices from burning our stomach?
Mucus.
What is peristalsis?
It is a series of contractions along the stomach wall that helps to mix the food with the enzymes.
What is the liquid that results from the stomach’s digestion called?
Chyme.
Where does 95% of absorption of nutrients occur?
In the small intestine.
Where are water and minerals absorbed into the blood stream?
The large intestine (colon).
What organisms primarily use external digestion?
Fungi.
How does external digestion work?
The organism secretes enzymes and break down organic material, then the products diffuse back into the organism.
Why is internal digestion more efficient?
Because more of the products can be captured and the internal environment can be more efficiently controlled.
How do spiders digest things?
They expel digestive enzymes from their mouth and then swallow the soupy mixture.
What is the gastrovascular cavity?
It is the “mouth” of the Venus flytrap and other carnivorous plants.
What is a ruminant?
A mammal that can acquire nutrients from plant-based food by fermenting it in a specialized stomach prior to digestion.
What is cud?
Plants that ruminants have already fermented and are chewing again to further break down the plant matter.
What are some examples of ruminants?
Cattle, goats, antelope, sheep, giraffes, yaks, deer, camels, llamas, and some macropods.
What is the difference between the mouths of herbivores and the mouths of carnivores?
Carnivores have large mouths and strong jaw muscles. Herbivores have smaller jaws and strong tongues.
Why is the digestive tract of an herbivore so long?
It takes longer to absorb nutrients from plant matter.
What are a herbivore’s teeth like?
They are flat and good for grinding and crushing rather than tearing.
What is the difference between the saliva of a carnivore and the saliva of an herbivore?
Herbivore saliva contains digestive enzymes.
Do carnivores or herbivores have much larger stomachs?
Carnivores.
Does the human digestive tract more resemble that of a carnivore or a herbivore?
Carnivore.
What are some characteristics that show humans are part carnivore?
Canine teeth, tendency to spend a long time between meals, up and down chewing motion of the jaws, length of digestive tract, function of the stomach, no systems that break down or utilize cellulose.
How many compartments does the stomach of a ruminant have?
Four.
What are the four compartments or a ruminant’s stomach called?
Rumen, reticulum, omasum, and the abomasum.
What happens in the rumen and the reticulum?
Food is mixed with saliva and the solid matter forms cud. Fiber is then broken down. The cud is then regurgitated and chewed to completely mix it with saliva.
True or False, the rumen and reticulum do not share the same function.
False. They share the same function, as chewed food can pass between them.
What is the combination of the rumen and the reticulum called?
The reticulorumen.
Where is the omasum in the line up of the ruminant digestive system and what is its function?
It comes second and absorbs water and inorganic minerals into the blood stream.
What is the difference between organic and inorganic minerals?
Organic minerals contain carbon and can form an ionic bond with the body to assist in bodily function. Inorganic minerals do not contain carbon and have electrons that spin counterclockwise, preventing the body from absorbing them.
What is the “true stomach” of the ruminant?
The abomasum.
What happens in the small intestine of a ruminant?
The absorption of nutrients and the digestion of microbes from the reticulorumen.
What is a ruminant with a three chambered stomach called?
A pseudoruminant. (Some examples include rhinos and camels)
What is a non-ruminant herbivore called?
A monogastric herbivore.
How do monogastric herbivores digest cellulose?
They have an enlarged cecum. Also, symbiotic bacteria in the small intestine and the large intestine help them to ferment and digest cellulose.
True or false, the teeth of a ruminant grow throughout its life.
True.
How are ruminants contributing to global warming?
The bacteria in the rumen produce methane, which the ruminants then release into the atmosphere.
Why is the Venus flytrap carnivorous?
It requires extra nutrients because of the poor soil it lives in.
What is the expanded, muscular pouch near a bird’s esophagus that stores food called?
The crop.
How do sharks expel toxins from their digestive systems?
They turn their stomach inside out.
How do capybaras and some other rodents maximize nutrients from their plant based diet?
They eat their poop to pass it through the gut again.
Why do young elephants, pandas, koalas, and hippos eat their mother’s poop after birth?
To gain the bacteria necessary to absorb nutrients from plant matter.
Where does protein digestion occur?
The stomach.
What are canine teeth used for?
Holding food and tearing it apart.
What are usually the largest teeth in a mammal’s mouth?
The canines.
How many canine teeth do most mammals have?
Four.
What teeth keep the canines separated?
The incisors.
If an animal is not a mammal and its teeth are like canines, what are they called?
Caniniform teeth.
What are the front teeth in most mammals?
Incisors.
What is the purpose of incisors?
They shear food sharply.
What kinds of animals have incisors that grow throughout their life?
Rodents.
What kind of tooth is an elephant’s (and hyrax’s) tusk?
An incisor.
What kind of tooth is a narwhal’s “horn”?
Canine.
How many teeth do humans usually have?
32.
What are molars and premolars used for?
Grinding things such as plant matter.
What is a carnassial?
A sharp back tooth used to shear meat in carnivores.
What is another name for a carnassial?
Sectorial teeth.
How many carnassial pairs do most mammals have?
One.
How many carnassial pairs do marsupials have?
Three.
What effects the size of canine and carnassial teeth?
The size of the carnivorous animal, the extent to which the diet is carnivorous, and the size of the chunk of meat that can be swallowed.
What is the digestive purpose of the tongue?
To manipulate food so it can be more easily swallowed.
Where is fat mostly digested?
The small intestine.
Where is DNA and RNA broken down?
In the pancreas.
Where does chyme go between the stomach and the small intestine?
The pancreas.
What is the purpose of the pancreas?
It excretes digestive enzymes that aid in digestion in the small intestine.
What do the digestive enzymes from the pancreas help to break down?
Lipids, carbohydrates, and proteins.
