BIOLOGY-CHAPTER 33
What are the four main feeding mechanisms of animals?
1. Filter (suspension) feeders 2. Substrate feeders 3. Fluid feeders 4. Bulk feeders
What are the four stages of food processing?
1. Ingestion 2. Digestion 3. Absorption 4. Elimination
What is the difference between malnutrition and undernutrition?
1. Malnutrition is a failure to obtain adequate nutrition when a diet lacks one or more essential nutrients or consistently supplies less chemical energy than the body requires. 2. Undernutrition is when a diet fails to provide adequate sources of chemical energy, resulting in the body using stored-up carbohydrates and fat and then beginning to break down its own proteins for fuel. Both can cause permanent damage or death.
16. Using Figure 33.8 as a guide, label the interior surface of the stomach, gastric gland, mucus cells, chief cells, and parietal cells. After labeling, explain the function of each labeled structure.
16. Using Figure 33.8 as a guide, label the interior surface of the stomach, gastric gland, mucus cells, chief cells, and parietal cells. After labeling, explain the function of each labeled structure.
17. Label and explain the positive feedback loop involved in the production of gastric juice.
17. Label and explain the positive feedback loop involved in the production of gastric juice.
22. Many enzymes are involved in the process of digestion. Begin by labeling the columns(carbohydrates, proteins, nucleic acids, and fats) and rows (oral cavity, stomach, lumen of small intestine (enzymes from pancreas), and epithelium of small intestine). Now add the enzymes produced or functioning in each organ, and their substrates and products. Review the figure until you can visualize digestion as a single process not divided into organic categories
22. Many enzymes are involved in the process of digestion. Begin by labeling the columns(carbohydrates, proteins, nucleic acids, and fats) and rows (oral cavity, stomach, lumen of small intestine (enzymes from pancreas), and epithelium of small intestine). Now add the enzymes produced or functioning in each organ, and their substrates and products. Review the figure until you can visualize digestion as a single process not divided into organic categories
25. Although most nutrients leave the small intestines through the blood stream, fats take another route. Use the figure to explain in five steps how fats are absorbed from the small intestines.
25. Although most nutrients leave the small intestines through the blood stream, fats take another route. Use the figure to explain in five steps how fats are absorbed from the small intestines.
37. Regulation of digestion involves several hormonal feedback pathways. Label the figures below then explain the hormonal interactions below each figure. Note whether the interactions are positive or negative feedback pathways.
37. Regulation of digestion involves several hormonal feedback pathways. Label the figures below then explain the hormonal interactions below each figure. Note whether the interactions are positive or negative feedback pathways.
38. The synthesis and breakdown of glycogen are central not only to energy storage, but also to maintaining glucose homeostasis. Label the figure below and then explain the steps to homeostatic regulation of glucose. Explain the role of the two pancreatic hormones, insulin and glucagon, in glucose homeostasis.
38. The synthesis and breakdown of glycogen are central not only to energy storage, but also to maintaining glucose homeostasis. Label the figure below and then explain the steps to homeostatic regulation of glucose. Explain the role of the two pancreatic hormones, insulin and glucagon, in glucose homeostasis.
Why does saliva contain so much amylase? Amylase begins the breakdown of starches and sugars in the mouth and is the first enzyme in the digestive pathway. (Remember that bacteria release acid waste products that begin the process of tooth decay.)
A current hypothesis is that amylase in saliva releases food particles that are stuck to the teeth, thereby reducing the nutrients available to microorganisms living in the mouth.
Why do herbivores have longer alimentary canals than carnivores?
A longer digestive tract furnishes more time for digestion and more surface area for nutrient absorption for the plant matter that is more difficult to digest.
What is a major function of the colon?
A major function of the colon is to recover water that has entered the alimentary canal as the solvent of digestive juices.
What are the building blocks of protein?
Amino Acids.
What is an alimentary canal? Where does it start and end?
An alimentary canal is a complete digestive tract in which food moves along in a single direction, encountering a series of specialized compartments that carry out stepwise digestion and nutrient absorption. It begins at the mouth and ends at the anus.
Define Absorption.
Animal cells take up (absorb) small molecules such as amino acids and simple sugars.
Use three sentences to explain the three nutritional needs an adequate diet must satisfy.
Animals need food to satisfy three nutritional needs. They need chemical energy for cellular processes. They need organic building blocks for macromolecules. They need essential nutrients to serve as substrate of enzymes, coenzymes, and as cofactors in biosynthetic reactions.
In what sense are nutrients from a recently ingested meal not really "inside" your body before they enter the absorption stage of food processing?
As long as nutrients are within the cavity of the alimentary canal, they are in a compartment that is continuous with the outside environment via the mouth and anus and have not yet crossed a membrane to enter the body.
What is the function of bile? Where is it stored?
Bile contains bile salts, which act as emulsifiers that aid in digestion and absorption of lipids. Bile is stored in the gallbladder.
Which hormone controls the release of bile from the gallbladder?
CCK
From a study of the dentition of a mammal's skull, you should be able to determine its diet. Using Figure 33.12, explain how each animal below is specialized for its diet.
Carnivores generally have large pointed incisors and canines that can be used to kill prey and rip or cut away pieces of flesh. Herbivores usually have premolars and molars with broad, ridged surfaces that grind tough plant material. The incisors and canines are generally modified for biting off pieces of vegetation. Omnivores are adapted to eating both plants and meat. In humans, from front to back along either side of the mouth are four blade like incisors for biting, a pair of pointed canines for tearing, four premolars for grinding, and six molars for crushing.
What is diabetes mellitus?
Diabetes mellitus is an endocrine disorder marked by an inability to maintain glucose homeostasis.
What is enzymatic hydrolysis?
Enzymatic hydrolysis is the breaking of a chemical bond that holds together subunits of a macromolecule with water and digestive enzymes. Examples include the enzymatic hydrolysis of a dipeptide into two amino acids or the enzymatic hydrolysis of sucrose into glucose and fructose.
What are essential amino acids? What must vegetarians do in order to obtain them?
Essential amino acids are the amino acids that must be obtained from food in a prefabricated form. Many proteins in animal products such as eggs and meat have each of these amino acids in proper proportion. Vegetarians are able to obtain these amino acids by eating a varied diet of plant proteins.
Which of the following statements is not true?
Essential nutrients can be synthesized by the body.
What are the building blocks of Fat?
Fatty acids and glycerol.
What makes up the feces?
Feces are made up of the wastes of the digestive system.
Monosaccharides and amino acids move directly into capillaries in the villi and then travel to the liver via the hepatic portal vein. What two major functions does this arrangement serve?
First, it allows the liver to regulate the distribution of nutrients to the rest of the body. Because the liver can interconvert many organic molecules, blood that leaves the liver may have a very different nutrient balance than the blood that entered via the hepatic portal vein. Second, the arrangement allows the liver to remove toxic substances before the blood circulates broadly.
Define Digestion.
Food is broken down into molecules small enough for the body to absorb.
How is it countered by ghrelin?
Ghrelin is a hormone secreted by the stomach wall that triggers feelings of hunger before meals. These signals all act on the"satiety center" of the brain, which generates the nerve impulses that make us feel either hungry or full.
Mutualistic symbiosis is important to digestion in many other species besides man. How do herbivores manage to get their energy from plant cellulose material when they do not have the ability to make enzymes to digest cellulose?
Herbivores can get much of the chemical energy they need from the cellulose of plant cell walls because they host large populations of mutualistic bacteria and protists in fermentation chambers in their alimentary canals. These symbiotic microorganisms have enzymes that can digest cellulose to simple sugars and other compounds that the animal can absorb.
Explain the cause and treatment of type 1 diabetes.
Insulin-dependent diabetes is an autoimmune disorder in which the immune system destroys the beta cells of the pancreas. It usually appears during childhood and destroys the person's ability to produce insulin. Treatment consists of insulin injections, typically given multiple times daily.
What are the lacteals? Where are they found?
Lacteals are part of the vertebrate lymphatic system, which is a network of vessels filled with a clear fluid called lymph. Lacteals are found in the core of the villi in the small intestine.
What is the role of leptin?
Leptin is a product of fat cells, and as fat accumulates, more leptin is produced. Leptin suppresses appetite. Low leptin levels will increase appetite.
Distinguish between mechanical digestion and chemical digestion.
Mechanical digestion is the physical breaking apart of food into smaller particles to increase the surface area available for chemical processes. Chemical digestion uses a variety of enzymes to break large macromolecules into small monomers that may be absorbed into the cells of the body
Major components of saliva include mucus, buffers, and antimicrobial agents. Explain the role of each.
Mucus, a viscous mixture of water, salts, cells, and slippery glycoproteinslubricates food for easier swallowing, protects the gums against abrasion, and facilitates taste and smell. Buffers help prevent tooth decay by neutralizing acid, and antimicrobial agents (such as lysozyme) protect against bacteria that enter the mouth with food.
Explain the cause and treatment of type 2 diabetes.
Non-insulin dependent diabetes is characterized by a failure of target cells to respond normally to insulin. Insulin is produced, but target cells fail to take up glucose from the blood, and the blood glucose level remains elevated. Treatment includes increased exercise, a healthy diet, and medications.
What are the building blocks Nucleic acids?
Nucleotides.
Explain, based on tertiary structure, why pepsin does not function in the small intestine.
Pepsin functions best in an acidic environment and is neutralized in the small intestine. At different pH levels, protein folding creates different molecular shapes. The tertiary structure of the globular protein of the enzyme pepsin is not folded into a functional shape at the pH of 7-8 found in the small intestine.
What is peristalsis and where does it begin?
Peristalsis is alternating waves of smooth muscle contraction and relaxation in the alimentary canal. It begins as a bolus of food is received by the pharynx and enters the esophagus.
What are the building blocks of carbohydrates?
Simple sugars.
Does stress cause ulcers? Discuss the finding that received the 2005 Nobel Prize.
Stress does not cause ulcers. Ulcers are caused by infection with the acid-tolerant bacterium Helicobacter pylori and can be cured by antibiotics. H. pylori infections lead to the near-complete elimination of all bacterial species commonly found in the stomach.
Define Ingestion.
The act of eating or feeding.
The small intestine connects to the large intestine at a T-shaped junction. One arm forms a blind pouch called the cecum. What is the cecum's role in grazing animals?
The cecum is important for fermenting ingested materials, which is especially important in grazing animals because they ingest a large amount of plant material.
Many distance runners "carb load" the day before a big race. How does this eating strategy provide an advantage to the runner?
The excess carbohydrates can be stored in the muscles as glycogen.
Where is the human appendix located? What function does it have?
The human appendix is a finger-like extension of the cecum; it has a minor and dispensable role in immunity and acts as a reservoir for symbiotic microorganisms.
Explain the difference between intracellular and extracellular digestion and give a description of each process in different organisms.
The hydrolysis of food inside vacuoles, called intracellular digestion, begins after a cell engulfs solid food by phagocytosis or liquid food by pinocytosis. A few animals, such as sponges, digest their food entirely by this process. Most animals break down food in compartments that are continuous with the outside of the animal's body. This is called extracellular digestion. Unlike organisms with gastrovascular cavity, most animals have a digestive tube extending between two openings, the mouth and the anus. Food moves in a single direction and passes through various specialized compartments that carry out digestion and nutrient absorption.
What is the digestive function of the liver?
The liver produces bile, which contains bile salts that are used to emulsify lipids to aid in their digestion and absorption.
The colon is inhabited by an immense number of bacteria that comprise part of your microbiome. What do these mutualistic symbiotic bacteria do for you?
The mutualistic symbiotic bacteria in humans produce vitamins and regulate the development of the intestinal epithelium and the function of the innate immune system.
About 7 L of water is secreted in digestive juices each day, but we only take in about 2L. Explain how water balance is achieved by the small intestine.
The small intestine recovers water and ions. Water is reabsorbed by osmosis when sodium and other ions are pumped out of the lumen of the small intestine.
What are the two functions of the stomach?
The stomach stores food and begins the process of protein digestion. The stomach secretes a digestive fluid called gastric juice and mixes it with the food through a churning action.
What are the two digestive functions of the small intestine?
The two main functions of the small intestine are the digestion of food and the absorption of food.
Remember the mantra: Structure fits function. How is that true for the villi of the small intestine?
The villi are finger-like projections studding the large folds of the small intestine. The villi function in the absorption of digested food; the structure of the villi maximizes surface area.
What is the target for all the hormones involved in appetite regulation?
These signals all act on the "satiety center" of the brain, which generates the nerve impulses that make us feel either hungry or full.
Define Elimination.
Undigested material passes out of the digestive system.
How is food kept from entering the trachea when we swallow?
When a food bolus arrives at the pharynx, the swallowing reflex is triggered. Movement of the larynx, the upper part of the airway, tips a flap of tissue called the epiglottis down, preventing food from entering the trachea.
The acidic nature of chyme is neutralized by ________.
bicarbonates.
What is the primary fuel for the body?
carbohydrates.
Which of the following conditions is most likely to cause constipation?
dehydration
Where does the majority of protein digestion take place?
duodenum
The digestive juices from the liver are delivered to the ________.
duodenum.
Define Bulk feeders.
eat relatively large pieces of food and digest it (humans, python).
Excess glucose is stored as ________.
glycogen.
Lipases are enzymes that breakdown ________.
lipids
Define Substrate feeders.
live in or on their food source (caterpillars, maggots).
A scientist dissects a new species of animal. If the animal's digestive system has a single stomach with an extended small intestine, to which animal could the dissected specimen be closely related?
snowshoe hare.
Which hormone stops acid secretion in the stomach?
somatostatin.
Define Filter (suspension) feeders.
strain small organisms or food particles from surrounding medium (Whales, flamingos).
Define fluid feeders.
such nutrient-rich fluid from living host (tsetse fly , mosquitos, aphids).
Which of the following is a water-soluble vitamin?
vitamin C.
