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Herbivores

Are animals whose primary food source is plant-based

Carnivores

Are animals that eat other animals.• Obligate carnivores are those that rely entirely on animal flesh to obtain their nutrients• Facultative carnivores are those that also eat non-animal food in addition to animal food – but generally do best eating animals

Omnivores

Animals that eat both plant- and animal-derived food – and do well eating either

Incomplete Tracts “ Digestive Tracts”

single opening = Gastrovascular cavity

Ex: Planarian

Food enters through mouth and muscular pharynx• Wastes exit through mouth and muscular pharynx• Lacks specialized parts

Complete Tracts “Digestive Tracts”

two openings = Alimentary canal• Ex: Earthworm• Food enters through mouth• Wastes exit through anus

Birds “Vertebrate Digestive Systems”

crop, stores food

• Two stomachs: the proventriculus (enzymes) and the gizzard (grinding).

• One openings to excrete urine and feces = the cloaca

Ruminants

Four stomachs:

the rumen and the reticulum – contain prokaryotes and protists to digest cellulose fiber.

Cud is regurgitated chewed and swallowed in third stomach, the omasum – removes water.

Cud then passes onto the abomasum – enzymes produced by animal

Omnivores “ ADAPTATION TO DIET”

Variety of specializations•

Accommodate both vegetation and meat

Herbivores “ ADAPTATION TO DIET”

Incisors for clipping

Premolars and molars for grindin

Carnivores “ADAPTATIONS TO DIET”

Pointed incisors and enlarged canines

Shear off pieces small enough to swallow

Human Digestive Tract

complete (alimentary canal)

• Part of a tube-within-a-tube body plan

• Begins with a mouth and ends in an anus

• Digestion entirely extracellular

• Digestive enzymes are secreted by

• The wall of the digestive tract, or

• By nearby glands

Mouth “Human Digestive Tract”

• Three major pairs of salivary glands

• Saliva contains salivary amylase

• Salivary amylase initiates starch digestion

• Tongue is composed of striated muscle

• Mixes chewed food with saliva

• Forms mixture into bolus

Pharynx “ Human Digestive Tract”

• Where digestive and respiratory passages come together

• Soft palate closes off nasopharynx

• Epiglottis

• Covers opening into trachea

• Keeps food from air passages (most of the time)

Esophagus “Human Digestive Tract”

Takes food to stomach by peristalsis

Def. PERISTALSIS - Rhythmical contraction to move contents in tubular organ

Stomach “ Human Digestive Tract”

Stomach wall has deep folds

• Folds disappear as the stomach fills to an approximate volume of one liter

• Epithelial lining of the stomach has millions of gastric pits, which drain gastric glands

Pepsin

hydrolytic enzyme that acts on protein to produce peptides

Chyme

Food mixing with gastric juices become

Small intestine

• First segment is duodenum

• Chyme from stomach enters the duodenum

• Mixes with secretions from the liver and pancreas

Liver

Produces bile, which is stored in gallbladder

• Bile contains bile salts which break up fat into fat droplets via emulsification

•Helps maintain glucose concentration in blood by converting excess

Pancreas “ Small intestine”

Exocrine gland

• Produces pancreatic juice and digestive enzymes into the duodenum

Pancreatic amylase

digests starch to maltose

Trypsin

digest protein to peptides

Lipase

digests fat droplets to glycerol and fatty acids

Epithelial cells

intestine also produce enzymes

• These complete digestion of peptides and sugars

Mucous membranes of small intestine “ Absorption”

Has ridges and furrows that give it a corrugated surface

• Villi are ridges on the surface, which contain even smaller ridges, microvilli

• Greatly increase absorptive area

• Each villus contains blood capillaries and a lymphatic capillary (lacteal

Enzymes

Digestion of carbohydrates is performed by several

Amylase and Maltase

Starch and glycogen are broken down into glucose by

sucrase and lactase, respectively.

Sucrose (table sugar) and lactose (milk sugar) are broken down by

Protein Digestion

takes place in the stomach.

• The enzyme pepsin plays an important role in the digestion of proteins by breaking down the intact protein to peptides, which are short chains of four to nine amino acids.

Duodenum

other enzymes—trypsin, elastase, and chymotrypsin—act on the peptides reducing them to smaller peptides.

free amino acids.

Specifically, carboxypeptidase, dipeptidase, and aminopeptidase play important roles in reducing the peptides to

Lipid digestion

begins in the stomach with the aid of lingual lipase and gastric lipase.

• However, the bulk of lipid digestion occurs in the small intestine due to pancreatic lipase.

Large Intestine

Includes cecum, colon, rectum, and anal canal

• Larger in diameter, but shorter in length than small intestine

• Absorbs water, salts, and some vitamins

Cecum

has small projection – appendix

Colon

subdivided

Constipation:

feces are hardened because of excess water removal in the colon.

Diarrhea:

Not enough water is removed from the feces

Inorganic essential nutrients

Must be obtained from food.

They help in structure and regulation and are considered co-factors.

Vitamin A

Promotes eye health, helps form and maintain healthy skin, teeth, and bones

Vitamin D

helps the body absorb calcium, maintains strong bones

Vitamin E

Antioxidant, boost immune function

Vitamin K

aids in blood clotting

Vitamin B

Helps body produce energy, influence growth/ development

Vitamin C

boosts immune function, fights skin aging, antioxidant

Organic compounds

body is unable to produce, but are required for metabolic purposes

Antioxidants

• Cellular metabolism generates free radicals that carry extra electron

• Vitamins C, E, and A are believed to defend the body against free radicals

Type 2 diabetes and cardiovascular disease

often seen in people who are obese

Monosaccharides

• Glucose

• Fructose

Disaccharides

Lactose (milk sugar)

• Sucrose (table sugar)

Fiber

Includes various undigestible carbohydrates derived from plants

• Food sources rich in fiber include beans, peas, nuts, fruits, and vegetables

• Technically, fiber is not a nutrient for humans• Cannot be digested

• Soluble fiber combines with bile acids and cholesterol in the small intestine and prevents them from being absorbed

NUTRITION: LIPIDS

• Fat, oils, and cholesterol

• Essential for the storage and activity offat-soluble vitamins A, D, E and

• Provide energy, at nine calories per gram.

• fat storage is essential to protect your internal organs and to help insulate against cold temperatures

Saturated fats

solids at room temperature) usually come from animals• Butter and meats, such as marbled red meats and bacon, contain saturated fats• Palm oil and coconut oil are high in saturated fats