UNIT III: Internal Systems and Regulation

Chapter 10

Nutrients, Digestion and Nutrition

Section 10.1: Obtaining and Processing Food

• Essential Nutrients: the basic raw material needed to make cell/organ structures, to perform life functions and to obtain energy for survival.

• Heterotrophs: Organisms that depend on organic molecules manufactured by other living things (organisms that lack chlorophyll: animals, fungi, some bacteria, protists, and plants)

• Autotrophs: Organisms that can nourish themselves using inorganic material can build organic molecules from simple inorganic materials such as H2O and CO2

– All photosynthetic organisms: chlorophyll containing plants, protists, and bacteria

Green Plants and Nutrients

• Green plants need only mineral elements therefore don’t need the function of digestion.

• These mineral elements are obtained from the soil.

Feeding Devices and Behaviours• Filter Feeding: filtering food from its

surroundings, (water).

• Fluid Feeding: piercing/sucking juices of plants and animals; absorbs nutrient rich fluids from its host– Mosquitoes, leeches – Tapeworm: uses hooks and suckers

Digestion• Food Processing• The food taken in either by pinocytosis/ other

means of consumption, are not readily available to the digestive tract.

• Organisms need to distribute nutrients to their cells by developing digestive and circulatory systems.

• The digestive tract breaks down food masses into useful substances that can be absorbed into the circulatory system.– The circulatory system then transports these substances

to the individual cells where they are again absorbed.

• Food must be broken down into smaller substances and must be in solution in order to move across a cell’s membrane.

• The job of the digestive system is to break food down into small soluble units that can pass through cell membranes.

Anatomy of Digestion1. Digestive tract food

travels

2. Mechanism of food movement

3. Chemical digestion of food

4. Liver, pancreas, gall bladder

5. Nutrients, diet and health

Tube digestion• Digestion is carried out in a small isolated

portion of an organism’s internal environment.

• Food enters at intake (mouth) end, and leaves at outlet (anus).

Intracellular Digestion• Food particles taken into cell first before

enzymes break them down

• Extracellular digestion: tube digestion

                                                                                                                                                                   

Homework• pp. 337 # 1-6

• Read section 10.2 and make notes for next class