Life processes and living things.

Life processes and living things.

All living things are called organisms. We can distinguish between plants and animals. All organisms do life processes which are: nutrition, sensitivity and reproduction.

a) Nutrition: is the process needed to obtain energy and growth. On the one hand, animals take food from other animals or plants, take advantage of it, and then remove waste products. On the other hand, plants are able to make their own food by photosynthesis, using sunlight to turn simple molecules (carbon dioxide, water) into more complex molecules.

b) Interaction/ sensitivity: is the process by which organisms are aware of changes in their environment (heat, light, sounds, food, danger, etc.), and accordingly, they act and do different things.

c) Reproduction: is the process needed to produce organisms like themselves, in order to perpetuate/survive the species. Reproduction can be: sexual, which involves two parents (union of two gametes), and asexual, when one parent can reproduce itself.

In this session we are going to explain animal’s nutrition.

NUTRITION.

Food provides the necessary nutrients, that is to say, essential matter and energy in order to growth and do life processes. In this process of “nutrition” there are four systems involved: digestive system, respiratory system, circulatory system and excretory system.

a) Digestive system: long tube where digestion takes place. Digestion is the process which turns the food they/we eat (big molecules) into small, simple and soluble molecules, so as to be able to assimilate and carry nutrients through their/our body. People spend 2-4 hours doing it. Digestive system consists of: mouth, pharynx, esophagus, small intestines, large intestine, anus.

b) Respiratory system: process of extracting energy out of the food. It takes place in the mitochondria of the cell, and this process is called gas exchange. It is distinguished two types: on the one hand aerobic which uses oxygen, and on the other hand anaerobic which doesn’t use oxygen. Aerobic: some of the oxygen go through the blood to the lungs, then the carbon dioxide is a waste product, so it goes to the air again. Respiratory system consists of: nostrils, larynx, windpipe/trachea, bronchia, lungs.

c) Circulatory system: whose function is to carry nutrients to the cells: the oxygen from lungs to the cells, and waste products outside. Circulatory system consists of: blood (red blood cells, white blood cells, platelets), blood vessels (arteries, veins, capillaries), and heart.

d) Excretory system: is the process of getting rid of metabolic waste. Excretory system consists of: urinary system (kidney, bladder, ureters, urethra) and sweat glands which produce sweat that eliminate waste products and regulate the temperature through the pores.