Nutrition

UNIT 1: Nutrition for life
1. THE THREE FUNCTIONS OF LIVING BEINGS: Nutrition
There is a huge range of living organisms on Earth, but all of them carry out the three life processes: nutrition, reproduction and sensitivity. These are the functions that make them alive.
Nutrition is the function that beings use to obtain matter and energy to sustain life. This function requires the intake oforganic matter (food) and oxygen. Nutrition also enables living things to maintain and repair tissues.
All living beings need organic matter (glucose) to produce energy in their cells.
2. TYPES OF NUTRITION
There are two types of nutrition:
- Heterotropic: Characteristic of those living beings that feed on other beings to produce the organic matter they need. Ex: Animals. There are 4 types ofAnimal Nutrition
1. Holozoic Nutrition: The most common type of heterotrophic nutrition with 3 subtypes- Carnivores, Herbivores and Omnivores
2. Saprophytic Nutrition: Animals that have saprophytic nutrition feed on organic waste when they are decomposing.
3. Parasitic Nutrition: One being feeds off another and causes it harm.
4. Symbiotic Nutrition: A feeding relationship betweentwo beings in which both benefit.

- Autotrophic: characteristic of those living beings that use an energy source to make their own “food” (organic matter from inorganic matter). There are two possibilities:
1. Photosynthesis: The energy source is the sun. Example- plants make their own food using energy from the sun.
2. Chemosynthesis: Energy from chemical reactions help some bacteriato make their own food.

3. HETEROTROPHIC NUTRITION__________________________________
3.1. Processes and systems involved in heterotrophic nutrition
There are five steps in heterotrophic nutrition:
1. Ingestion of food: the intake of food through the mouth.
2. Digestion: it consists of the transformation of food into simpler molecules (nutrients) so that they can be absorbed and used by thecells.
3. Absorption: Is the passage of nutrients from the digestive system into the blood. The blood carries the nutrients to the cells.
4. Circulation: The transport of nutrients to the cells is made thanks to the circulatory system.
5. Cellular metabolism: nutrients are transformed inside the cells to obtain energy or to create matter. There are two types of metabolic reactions:
-CATABOLISM: The breakdown of complex organic substances into simple substances. It produces energy.
FISHPROTIEN + ENERGY

- ANABOLISM: The production of more complex organic substances from simple substances. It requires energy.
PROTIEN + ENERGY MUSCLE

6. Excretion: wastes are thrown out to the exterior through the excretory system. Egestion is the elimination of undigested and wasteproducts from the digestive system.
Four systems are involved in all the processes of nutrition: circulatory, digestive, respiratory and excretory systems.
3.2. Digestion
There are different types of digestion:
a. Intracellular digestion
It occurs inside the cells of unicellular and simple multicellular organisms. Digestion takes place inside the cells.
b. Extracellular digestion
It occursinside the digestive tube and not inside the cells. The transformation of food into nutrients follows two steps:
- Mechanical digestion: Food is broken down into smaller pieces. It occurs in the mouth and stomach.
- Chemical digestion: food is chemically transformed in the digestive system. Digestive enzymes are molecules that transform food into nutrients.

mouth
mouth
Salivary glandsSalivary glands

liver
liver
Pancreas (behind stomach)
Pancreas (behind stomach)
esophagus
esophagus
Small intestine
Small intestine
stomach
stomach
Large Intestine
Large Intestine
Gall bladder
Gall bladder

3.3. Respiration (Breathing)
Living beings need oxygen to transform nutrients into energy. To obtain that energy living beings need to obtain oxygen from the air. After nutrients...