29 Questions
What is the function of absorption in the digestive process?
Uptake of nutrients by body cells
Which type of digestion involves the engulfment of food particles by endocytosis?
Intracellular digestion
What is the purpose of specialized compartments in the digestive process of most animals?
To reduce the risk of digesting own cells and tissues
Why do animals with simple body plans have a gastrovascular cavity with one opening?
To function as both mouth and anus
What is the alternative name for a one-way digestive tube with a mouth and an anus?
Complete digestive tract
How does extracellular digestion differ from intracellular digestion?
Extracellular digestion involves breaking down food outside cells
What is the primary function of the liver in the digestive system?
Production of bile
Which organ in the digestive system is responsible for reabsorbing water from undigested food?
Cecum
What is the main function of the colon in the digestive process?
Hosts beneficial bacteria
Which part of the digestive system is responsible for storing feces until defecation?
Rectum
What is an essential role of the large intestine in digestion?
Reabsorb water
Which sphincter controls the elimination of waste material voluntarily?
Outer sphincter
Which organ conducts food from the pharynx down to the stomach by peristalsis?
Esophagus
What is the first stage of digestion that takes place in the oral cavity?
Mechanical digestion
Which organ delivers saliva to lubricate food?
Salivary glands
What enzyme initiates the breakdown of glucose polymers in the mouth?
Salivary amylase
What is the purpose of peristalsis in the digestive system?
Mix food with digestive juices
What is the function of the trachea in relation to food digestion?
Leads to the lungs
What type of muscle is the Internal Anal Sphincter?
Thin muscle
Which sphincter can be voluntarily clenched or unclenched?
External Anal Sphincter
What is the most important source of ATP generation in animals?
Oxidation of energy-rich molecules
Which animal group has the most elaborate adaptations for an herbivorous diet?
Ruminants
Where do animals primarily store excess calories?
Glycogen in the liver and muscles
In what part of the digestion process does the blood glucose level rise after eating?
Reticulum Intestine
How do ruminants like cows and sheep chew their food?
Lacking upper incisor teeth, using lower teeth, tongue, and lips
What are the chambers of the ruminant stomach responsible for digesting cellulose?
Rumen, reticulum, omasum, and abomasum
Which chamber of the ruminant stomach functions as the 'true' stomach?
Abomasum
What does fermentation in the ruminant stomach produce?
Gases that need to be eliminated
Which organ of the digestive system is responsible for absorbing nutrients in ruminants?
Small intestine
Study Notes
Chemical Digestion
- Enzymatic hydrolysis splits bonds in molecules with the addition of water.
Absorption and Elimination
- Absorption is the uptake of nutrients by body cells.
- Elimination is the passage of undigested material out of the digestive compartment.
Food Processing in Specialized Compartments
- Most animals process food in specialized compartments to reduce the risk of self-digestion.
- Intracellular digestion occurs when food particles are engulfed by endocytosis and digested within food vacuoles.
- Extracellular digestion occurs outside of cells in compartments continuous with the outside of the animal's body.
Digestive Systems in Animals
- Simple animals have a gastrovascular cavity with one opening that functions as both mouth and anus.
- More complex animals have a digestive tube with two openings, a mouth and an anus, called a complete digestive tract or alimentary canal.
Valves in the Digestive System
- Valves called sphincters regulate the movement of material between compartments.
The Mammalian Digestive System
- The human digestive system consists of the mouth, esophagus, stomach, small intestine, large intestine, rectum, anus, liver, pancreas, and gallbladder.
The Oral Cavity, Pharynx, and Esophagus
- Mechanical digestion occurs in the oral cavity, where teeth chew food into smaller particles.
- Salivary glands deliver saliva to lubricate food and initiate carbohydrate digestion.
- The tongue shapes food into a bolus and helps with swallowing.
Swallowing and Peristalsis
- The swallowing reflex and peristalsis move food from the mouth to the stomach.
Elimination of Undigested Waste
- The large intestine reabsorbs water from undigested food and processes waste.
- The colon is home to many bacteria that aid in digestive processes.
- The rectum stores feces until defecation, and the anus is the exit point for waste material.
Ruminant Digestion
- Herbivores have fermentation chambers where symbiotic microorganisms digest cellulose.
- Ruminant stomach is multi-chambered, consisting of the rumen, reticulum, omasum, and abomasum.
- Microbes in these chambers break down cellulose and ferment ingested food.
Energy Balance and Storage
- Food energy balances the energy from metabolism, activity, and storage.
- Animals store excess calories primarily as glycogen in the liver and muscles.
- Energy is secondarily stored as adipose, or fat, cells.
The Liver and Accessory Organs
- The liver produces bile, a digestive juice required for the breakdown of fatty components of food.
- The liver processes vitamins and fats, synthesizes many plasma proteins, and detoxifies blood.
Test your knowledge on the key concepts of the digestive system including enzymatic hydrolysis, absorption, elimination, and intracellular digestion.
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