Digestion (Test Three) Flashcards
What does Saprophagous mean?
Animals that feed on decaying plants and other animals
Briefly explain what and how suspension feeders eat.
Suspension feeders eat microscopic particles consisting of plankton and organic debris by using ciliated surfaces to draw the particles into their mouths, and oftentimes mucous sheets trap that food en route to digestive tract.
Briefly explain what deposit feeders eat, and give a few examples of them.
Deposit feeders extract organic material or detritus from the sand/dirt etc.
Example is some annelids that pass substrate through their bodies as they move and extract nutrients
Another example is some molluscs/ tube dwelling annelids who use appendages to gather organic debris
Describe how fluid feeders eat.
They feed on their host’s body fluids.
Internal parasites are able to absorb the nutrients around them directly
External parasites may pierce or rasp to access host’s blood
What is contained in many fluid feeder’s saliva to avoid clotting?
Anticoagulant
What is the general feeding mechanism of the sand worm?
It seizes food with jaws on muscular pharynx
How do fish, some amphibians, and non avian reptiles use their teeth?
To grip prey until it is swallowed.
In what group does chewing (true mastication) occur?
(very few exceptions)
mammals
Name the four types of teeth and what their functions are.
- Incisors - bite, cut, and strip food
- Canines - seize, pierce, and tear food
- Premolars - grind and crush food
- Molars - grind and crush food
Explain the details of the human molar tooth.
- Enamel (hard outer covering) 98% mineral hard material
- Dentine (next layer down) 75% mineral and makes up most of the mass
- Cementium (covering around the dentine) similar in composition to dense bone
Explain the variation of teeth in reference to food habits.
What type of teeth an animal has gives insight into their diet.
For example carnivores have large canines and blade-like molars
While herbivores have heavy ridged molars for grinding and crushing
Elephant tusks are what type of tooth modified, and how are they used?
They are modified incisors
They are used for digging plant roots, breaking branches, and drilling in waterbeds
Give a very general overview of the process of digestion.
- Mechanical and Chemical digestion break own food into small units for absorption
- Once broken down into monomers, they are eventually reassembled
- Digestion can be intracellular or extracellular
Describe the process of intracellular digestion.
- Digestion is entirely intracellular in sponges/protozoa
- Food particles are phagocytized, and become a food vacuole that fuses with a lysosome (from the golgi), to form an endosome, which is then absorbed, and the rest is excreted by exocytosis
How does extracellular digestion happen?
A system called the alimentary system is used in which specialized lining cells help with digestion and absorption.
Development of mouth to anus (complete gut) allowed for specialized regions.
All of this relies on activity of digestive enzymes, which split molecules by adding water.
Explain the Receiving region of the alimentary system.
Where food initially enters, parts include (jaws, teeth mandibles, radula, bills), further in (buccal cavity and pharynx)
This region usually contains salivary glands, which lubricate and may contain digestive enzymes, toxins, anesthetics, etc
Explain the Conduction / Storage area of the alimentary system.
Includes the esophagus, which leads from the pharynx to the stomach
Peristalsis happens when food is propelled downwards by contracting smooth muscle
Food can also be stored in the esophagus (crop) in annelids, insects octopods
Explain the Grinding / Early Digestion in the alimentary system.
In vertebrates and some invertebrates, the stomach is were food is initially digested and stored.
Herbivores continue the grinding and crushing of food in the muscular stomach.
In birds and oligiochaets, stones or grit swallowed may assist in digestion
Explain the Terminal Digestion area in the alimentary system.
The small intestine is where most digestion/absorption take place.
Vertebrates have a special small intestine with a large surface area
Cell lining this area have special digestive enzymes in them as transmembrane proteins, and most of the nutrients is absorbed by the villi
Explain the Water Absorption and Concentration of Solids in the alimentary system.
The large intestine makes undigested material semisolid feces
This is very important for insects, so they must reabsorb water using special rectal glands, and birds and reptiles do the same with their cloaca.
Extra Info (about 1/3rd of the dry weight in human feces is bacteria)
