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.