Bio 004,CH22, College of the Desert
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Organisms that must acquire nutrients in the form of organic material from their environment.
Categories of Animals
- 1. Herbivores
- 2. Carnivores
- 3. Omnivores
Plant eaters, Cattle, gorillas, etc
Meat eaters, Sharks, lions, etc
Plant & meat eaters, crows, bears, etc
Chemical break-down of food by digestive enzymes. Breaks down food into smaller molecules for reassembly as required by the body.
- Physical processes such as chewing.
- 1. Homodont dentition
- 2. Heterodont dentition
Teeth are identical in shape; used for grasping and swallowing prey whole. Examples – fish, amphibians, reptiles.
- Teeth are different in shape; used for tearing and chewing, breaking food down into smaller pieces. Examples – mammals.
Four Stages of Food Processing
- 1. Ingestion
- 2. Digestion
- 3. Absorption
- 4. Elimination
Act of eating. Nutrients are taken into the body
Breakdown of food into small nutrient molecules. Carbohydrates, lipids, and proteins
Uptake of small nutrient molecules by the lining of the digestive tract.
Disposal of undigested materials left over from eating.
Intracellular organelles filled with digestive enzymes. Example: Amoeba
Compartments with a single opening that functions as both entrance for food and exit for undigested wastes. Example: Hydra
Tube with two separate openings extending between mouth and anus. Examples: invertebrates – mammals.
Food is mechanically (teeth) and chemically (salivary glands) broken down.
Protects the lining of mouth from abrasion, lubricates food for easy swallowing. Salivary amylase breaks down starch, glycogen. Antibacterial agents kill germs. Buffers neutralize acids.
Tastes food, manipulates it during chewing, shapes it into a ball (bolus). During swallowing, the tongue pushes the bolus to the back of the oral cavity and into the pharynx.
Junction that opens to both the esophagus and the trachea. Epiglottis - covers the glottis (opening in trachea) when swallowing
Rhythmic waves of contraction by involuntary smooth muscles in the wall of the tract that pushes food along.
Stores food and continues the process of digestion. Stretches to accommodate about 2L. Secretes: Gastric juice, Pepsin, HCl (pH 2).
1. Preventing self-digestion
- 1. Delaying activation of enzymes until in lumen of stomach.
- 2. Secreting a coating of mucus from cells lining the stomach.
- 3. Constantly regenerating stomach lining cells by mitosis.
- Site of enzymatic hydrolysis of macromolecules and absorption of nutrients into the blood stream. Longest section of the digestive tract (6 m).
- 1. Site of most nutrient absorption, also, some in stomach and large intestine.
- 2. Large surface area (300 m2) due to villi (fingerlike projections) & microvilli (microscopic finger-like projections).
- 3. Pancreas: Produces hydrolytic enzymes and bicarbonate which acts as a buffer.
- 4. Liver: Produces bile which contains bile salts that act as detergents that aid in digestion and fat absorption.
Produces hydrolytic enzymes and bicarbonate which acts as a buffer
Produces bile which contains bile salts that act as detergents that aid in digestion and fat absorption.
- (colon) Primary site of water absorption. Along with small intestine, reabsorbs about 90% of water in digestive tract.
- 1. Feces are formed here, becoming more solid as they move along by peristalsis. Takes between 12 and 24 hours to cover the distance of the colon (1.5 m).
- 2. Viral or bacterial infections irritate lining of small intestine, reducing water absorption, resulting in diarrhea.
- 3. Too slow, too much water is absorbed resulting in constipation.
- 4. Many organisms, mostly harmless bacteria, live inside large intestine (methanogens). Live on unabsorbed organic material. Byproducts include CH4 and H2S.
- 5. Rectum: Endpoint of the colon; stores feces until they can be eliminated.
- 6. Sphincters: (2) located between the rectum and anus – one voluntary and the other in-voluntary.
Endpoint of the colon; stores feces until they can be eliminated.
(2) located between the rectum and anus – one voluntary and the other in-voluntary.
Materials that must be obtained in preassembled form – can’t be manufactured by body. Example: ascorbic acid (orange juice). Required for metabolic reactions.
Essential Amino Acids
Animals require 20 AA for proteins; 12 AA can be made from diet while 8 AA must be obtained from food preassembled. Animal products are best sources of proteins - cheese, eggs, meat
Organic molecules required in small amounts preventing deficiencies which may result in severe problems. 13 essential vitamins for humans. Balanced diets prevent deficiencies.
Simple inorganic nutrients required in small amounts preventing deficiencies which may result in severe problems.
Ca, P – bone construction, maintenance
Fe – component in cellular respiration and hemoglobin in blood
I – thyroid hormones for metabolism
Na, K, Cl – nerve functioning, maintaining osmotic balance in cells
Essential Fatty Acids
- Certain fatty acids required by animals to construct cell membranes.
- Sources = plant-based oils
- Stores of glycogen and fat are depleted and the body begins breaking down proteins for metabolism. Muscles decrease in size.
- Brain becomes protein deficient. Death will eventually result. Causes: starvation, anorexia.
- Deficiency of one or more of the essential nutrients. Protein deficiency = #1 problem.
- Causes: inadequate intake, metabolic or digestive abnormalites.
Body hoards fat – storing fat in-stead of using it for fuel producing an inappropriately high weight to height ratio. Results in: Diabetes, Colon, breast cancer, Cardiovascular disease.
Causes: Diet, sedentary lifestyle, genetics.
Stomach and Intestine
- 1. Expandable stomach Allows for more eating at one time - in between time may be lengthy.
- 2. Long intestine allows for more surface area for absorption of hard to digest plant material.
- 1. Herbivores house symbiotic bacteria (methanogens) which contain enzymes to assist them in breaking down cellulose.
- 2. Location of symbiotic bacteria in digestive tract varies from species to species.
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