Animal Nutrition Flashcards
Nutrition
The process by which food is taken in, taken apart, and taken up
3 things an animal’s diet supplies
Chemical energy (produce ATP)
Organic building blocks (biosynthesis)
Essential nutrients
Essential nutrients
Those materials that an animal’s cells require but cannot synthesize
4 classes of essential nutrients
Essential amino acids
Essential fatty acids
Vitamins
Minerals
Amino acid requirements of animals
Animals require 20 amino acids, about half of which they can synthesize from molecules in their diet
Essential amino acids must be obtained from food in preassembled form
Essential amino acids
Found in meat, cheese, and eggs
“Complete” proteins
Most plant proteins are incomplete
Essential fatty acids
Animals can synthesize most of the fatty acids they need
Obtained from diet and include certain unsaturated fatty acids (alpha-linolenic acid: omega-3 fatty acid; linoleic acid: omega-6 fatty acid)
Deficiencies in these are rare
Vitamins
Organic molecules required in diet in small amounts
13 are essential for humans
2 categories: fat-soluble (vitamins A, D, E, K) and water-soluble (B vitamins, vitamin C)
Minerals
Simple inorganic nutrients
Usually required in small amounts
Important in bone/teeth development, water balance, nerve/muscle function, oxygen transport, and blood clotting
Ingesting large amounts can upset homeostatic balance
Main stages of food processing
Ingestion
Digestion
Absorption
Elimination
Ingestion
Act of eating
Digestion
Process of breaking food down into molecules small enough to absorb
Absorption
Uptake of nutrients by body cells
Elimination
Passage of undigested material out of digestive system
4 main feeding mechanisms
Suspension feeders
Substrate feeders
Fluid feeders
Bulk feeders
Suspension feeders
Sift small food particles from water
Example: whale that eats using baleen
Substrate feeders
Animals that live in or on their food source
Example: caterpillar living on and eating leaf
Fluid feeders
Suck nutrient-rich fluid from a living host
Example: mosquito that sucks blood
Bulk feeders
Eat relatively large pieces of food
Example: boa constrictor eating mouse
Mechanical digestion
Breaking food down into pieces, increasing surface area for chemical digestion
Chemical digestion
Break food down using acids
Digestive compartments
Most animals process food in specialized compartments
Compartments reduce risk of an animal digesting its own cells and tissues
Intracellular digestion
Food particles are engulfed by phagocytosis
Food vacuoles, containing food, fuse with lysosomes containing hydrolytic enzymes
Extracellular digestion
Breakdown of food particles outside cells
Occurs in compartments that are continuous with the outside of the animal’s body (ex- gastrovascular cavity)
Alimentary canal
Digestive tube with 2 openings, a mouth, and an anus
Specialized regions that carry out digestion and absorption in a stepwise fashion
Mammalian accessory glands
Salivary glands
Pancreas (releases HCO3-, a buffer)
Liver
Gallbladder
Peristalsis
Pushes food along using alternating waves of contraction and relaxation in smooth muscle
Sphincters
Valves that keep food material in its proper place in the digestive tract
Order of mechanical digestion in humans
Takes place in oral cavity
Salivary glands deliver saliva to lubricate food
Teeth chew food into smaller particles that are exposed to salivary amylase (enzyme that breaks down glucose polymers) and mucus (viscous mixture of water, salt, cells, and glycoproteins) in saliva
Tongue shapes food into a bolus and provides help with swallowing
Pharynx (throat) is the junction that opens to both the esophagus and trachea
Swallowing causes epiglottis to block entry to trachea
Bolus of food is guided by larynx (upper part of respiratory tract) into esophagus, which conducts food down to stomach by peristalsis
Digestion in stomach
Stomach stores food and secretes gastric juice to convert food to acid chyme
Mucus protects the stomach lining
Churning
Sphincters prevent chyme from entering esophagus and regulate its entry into the small intestine
Gastric juice
Low pH (about 2)
Kills bacteria and denatures proteins
Made up of HCl and pepsin (protease: protein-digesting enzyme)
Digestion in small intestine
Small intestine is largest section of alimentary canal
Duodenum (1st section): most digestion occurs
Jejunum (2nd section) and ileum (3rd section): mainly absorption of nutrients and water
Bile (made in liver and stored in gallbladder) aids in digestion and absorption of fats and destroys nonfunctional red blood cells
Absorption occurs across villi and microvilli, which are exposed to the intestinal lumen
Hepatic portal vein
Carries nutrient-rich blood from the capillaries of the villi to the liver, and then to the heart
Liver
Regulates distribution of nutrients throughout body Detoxifies toxins (alcohol, drugs, etc.)
Absorption in the large intestine
Colon is connected to small intestine
Colon recovers water and houses bacteria which live on unabsorbed organic material
Some bacteria produce vitamins
Feces, including undigested material and bacteria, become more solid as they move through the colon
Feces are stored in the rectum until they can be eliminated through the anus
2 sphincters between the rectum and anus control bowel movements
Carbohydrate digestion
Oral cavity, pharynx, esophagus: salivary amylase breaks polysaccharides down into smaller polysaccharides or maltose; disaccharides aren't digested until small intestine Small intestine (enzymes from pancreas): pancreatic amylases break smaller polysaccharides down into disaccharides Small intestine (enzymes from epithelium): disaccharidases break disaccharides and maltose down into monosaccharides
Protein digestion
Stomach: pepsin breaks proteins down into small polypeptides Small intestine (enzymes from pancreas): pancreatic trypsin and chymotrypsin breaker small polypeptides into even smaller polypeptides and then pancreatic carboxypeptidase breaks these smaller polypeptides down into small peptides Small intestine (enzymes from epithelium): dipeptidases, caryboxypeptidase, and aminopeptidase break small peptides down into amino acids
Nucleic acid digestion
Small intestine (enzymes from pancreas): pancreatic nucleases break DNA and RNA down into nucleotides Small intestine (enzymes from epithelium): nucleotidases break nucleotides down into nucleosides (nucleotides minus PO4) and then nucleosidases and phosphatases break nucleosides down into nitrogenous bases, sugars, and phosphates
Fat digestion
Small intestine (enzymes from pancreas): pancreatic lipase breaks fat triglycerides down into glycerol, fatty acids, and monoglycerides
Function of B vitamins
Coenzymes
Function of vitamin C
Collagen synthesis and antioxidant
Function of vitamin A
Comprise visual pigments
Maintenance of epithelial tissue
Function of vitamin D
Absorption and use of calcium and phosphorus
Function of vitamin E
Antioxidant
Helps prevent damage to cell membranes
Function of vitamin K
Blood clotting