Chapter 9 Biology Flashcards
What are the two main types of digestion?
Intracellular digestion: part of metabolism that involves the oxidation of glucose and fatty acids for energy.
However, our diets do not cosist of pure glucose and fatty acids; rather, these subtances must be extracted from our food.
Extracellur digestion: The process by which these nutrients are obtained from food occurs in the lumen of the alimentary canal and is known as extracellular digestion. This is technically outside of the body, because the lumen of the gastrointestinal tract communicates directly with the outside world.
Explain the anatomy of the alimentary canal?
The alimentary canal runs from the mouth to the anus and is sectioned off by the sphincters, which are small muscles around the canal that can contract to allow compartmentalization of function.
The human digestive tract has specialized sections with different functional roles. The most basic functinoal distinction is between digestion and absorption.
What is meant by digestion (involves what)?
What is meant by absorbtion (involves what)?
Digestion involves the breakdown of food into its constituent organic molecules: starches and other carbohydrates into monosaccharides, lipids into free fatty acids and glycerol, and proteins into amino acids.
Absorption involves the transport of products of digestion from the digestive tract into the circulatory system for distribution to the body’s tissues and cells.
Digestion can also be subdivided into what other two digestion process? Explain each one?
Mechanical digestion: physical breakdown of large food particles into smaller food particles, but does not involve breaking chemical bonds.
Chemical digestion: enzymatic cleavage of chemical bonds, such as the peptide bonds of proteins or the glycosidic bonds of starches.
Explain the full pathway of the digestive tract?
- The digestive tract begins with the oral cavity (mouth)
- Followed by the pharynx, which is a shared pathway for both food entering the digestive system and air entering the respiratory system.
- From the pharynx, food then enters the esophagus, which transports it then to the stomach.
- Finally, waste products of digestion enter the rectum, where feces are stored there unitl an apporpriate time of release.
In addition to the digestive tract and its organs, what are the 4 others things/organs in the digestive systema and what is their overall function?
In addition to the digestive tract itself, the salivary glands, pancreas, liver, and gallbladder help to provide the enzymes and lubrication necessary to aid in the digestion of food.
What is the enteric nervous system and its function?
it is a collection of one hundred million neurons that govern the function of the gastrointestinal system.
These neurons are present in the walls of the digestive tract and trigger peristalsis, which is rhythemic contractions of the gut tube, in order to move materials through the system.
This system can function independently of the brain and spinal cord, although it is heavely regulated by what system? Also, explain what is the parasympathetic division is involved in and what is the sympathetic division involved in?
By the autonomic nervous system.
The parasympathetic division is involved in stimulation of digestive activities, increasing secretions from exocrine glands and promoting peristalsis.
The sympathetic division is involved in the inhibition of these activities (opposite)
NOTE:
The fact we often feel sleepy and lethargic after eating a big meal is due, in part, to parasympatic activity.
On the other hand, during periods of high sympathetic activity, bloodflow is decreased to the digestive tract, and gut motility slows significantly.
