Digestion Part I

Heterotrophic organisms-

Organisms that can not make their own high energy, organic compounds. Must get their nutrition from the environment.

Nutrition is needed for

1. Energy

2. Building blocks for their own organic molecules

Plants are autotrophs

Bacteria-Absorptive heterotrophs (some are autotrophs)

Fungi-Absorptive heterotrophs

Animals-Ingestive

heterotrophs

Protista can vary (algae are autotrophs, others are heterotrophs)

Terms

Saprophytes- Heterotrophs that get their nutrition from dead organisms

Parasites-Heterotrophs that get their nutrition from living tissue.

Digestion-nutrients are taken in and broken down. The basic plan is a tube within a tube of higher organisms.

Herbivores-use only plant material for nutrition

Carnivores-use only animal materials for nutrition

Omnivores- nutrition from animal and plant materials

Nutrients-Organic compounds need for life (carbohydrates, fats, proteins, and vitamins)

Nutritional Requirements varies from species to species for example some bacteria only require carbohydrates and inorganic minerals, while other bacteria need all 3 organic nutrients.

Carbohydrates are needed mainly as a source of energy. Glucose levels in the blood remain relatively constant. When it decreases, glycogen in the liver and muscles are broken down into glucose. Some carbohydrates are also used for structure and lubricants.

Carbohydrates are called empty calories because in general they are needed only for energy.

Proteins are needed as a source of amino acids so that the organism can generate their own proteins as needed and dictated by their DNA. Some organisms can make their own amino acids, however, essential amino acids are amino acids that an organism cannot make and must have in their diet. These vary from species to species. Most have at least nine essential amino acids. Animal material rather than plant material is the most reliable source of protein. Humans that rely on only one plant nutrient (rice or corn) may be deficient in amino acids resulting in kwashiorkor disease (degeneration of liver anemia and inflammation of skin)

Fats are needed for cell membranes. Also fats are the most efficient way to store energy. Gram for gram, there is twice as much energy in a gram of lipid as carbohydrates. Lipids are stored in the liver and in adipose tissue. This is because lipids are so highly reduced. Carbohydrates have more oxygen than lipids.

Essential fatty acids-are those fatty acids that an organism needs but can not make. Usually not as severe a problem as essential amino acids because animals have the ability to make carbohy-drates into fatty acids.

Vitamins- organic compounds that are needed by an organism in their diet. Not a carbohydrate, protein or fat. Usually used as a coenzyme.

Water soluble-Can't be stored vitamins(C+Complex B)

Fat soluble-can be stored vitamins A, E, K and D

Scurvy- lack of vitamin C connective tissue, bleeding gums, anemia, delayed wound healing

Beriberi- lack of vitamin B causes muscle atrophy, paralysis, mental confusion, congestive heart failure.

Xerophthalmia-lack of vitamin A keratinization of tissues of the eye which can lead to blindness.

Rickets-lack of vitamin D results in soft bones so a growing skeleton can become deformed.

Lack of K- slow blood clotting

Lack of E-malfunction of muscular nervous systems

Minerals are inorganic nutrients essential for the organism but cannot be made by the organism.

Survey of how nutrition is procured.

Nutrient Procurement Fungi- Uses extracellular digestion as fungi secretes digestive enzymes which break down the organic compounds, and then absorb nutrients. Can be saprophytic (bread mold) or parasitic (athlete's foot).

Amoeba- phagocytosis or intercellular digestion in vacuoles. *Food must be digested before it crosses a cell membrane.

Animation Paramecium

Animation Paramecium

Paramecium- intracellular is similar

Cnidarian nutrient procurement (Jelly fish and hydra)

-Radial symmetry

-2 layers of cells with jelly layer between called mesoglea

1. Food is paralyzed by tentacles with nematocysts

2. Food brought inside gastrovascular cavity via tentacles

3. Digestive juices released by specialized digestive glands (extracellular digestion). Phagocytosis takes place with the other cells.

Flat worm- bilateral symmetry

1. Anterior (front) and posterior (rear) end

2. Ventral(tummy side) dorsal (upper) sides

Food enters and wastes exit (the same tube ) mouth

Pharynx- muscular tube which leads to the gastrovascular cavity

The G.V.C. (gastro vascular cavity) branched extensively this helps in greater absorptive surfaces.

Digestion in the G.V.C. is some extracellular but mainly intracellular

note- Tape worm- parasite has lost its digestive system because it is bathed in nutrients

Some examples of

actual flatworms

Complete digestive tracts- one way tube with a mouth and an anus.

Advantage-Tube can be differentiated into digestive organs to treat the food in various ways to maximize nutritional value.

Pharynx- Forces food down the tube

Esophagus- tube connects to the crop

Crop- storage area

Gizzard- muscular organ that mechanically grinds food

Intestine- enzymes released more digestion occurs- Nutrients are absorbed- also has fold called typhlosole which increases surface area.

Different types of Annelids

Insects- Very diversified digestive tracts

Mouth parts also very diversified.

Foregut- mouth esophagus, pharynx-moves food into tract

crop- storage of food

ceca- secretes digestive enzymes into midgut

Midgut- chemical digestion occurs

Hindgut- nutrient absorption, water absorption, and cellular wastes secreted out.

Vertebrates

Shark- replaceable teeth

Intestine-Spiraled valve slows down food and increase surface area

Fish

Herbivore fish intestine: long and winding

Carnivore fish intestine: short (animal matter easier to digest)

Amphibian digestive tract like herbivore fish but tongue moveable

Reptiles- mostly carnivores

Snakes- unhinge jaws and swallow food whole releasing very powerful digestive enzymes- some poisonous

Jacobson organ- smell food via tongue; heat sensory organs

Turtles lack teeth but have a razor sharp bill

Alligators- have many unspecialized teeth

Birds- specialized beaks for food procurement

Teeth Adaptations

incisors- gnawing

canine- tearing

molars- grinding

premolars- grinding

Number and type depend on nutrition

Carnivores- well developed canines

Herbivores- well developed molars and premolars

Omnivore- in between

The digestive tract of an herbivore is usually longer than the digestive tract of a carnivore as plant matter is more difficult to digest. The cecum in herbivores is more fully developed as it serves a chamber where bacterial

Cow has a four chambered stomach

Rumen- bacteria aids in digestion and allows regurgitated and chewed again

Reticulum-removes indigestible material

Omasum-absorbs water and nutrients

Abomasum-true stomach

The End