Purpose of nutrions:

Obtain raw materials and energy from food.

Inorganic nutrients:Oxygen and water/Organic nutrients:Glucose in organic matter exclusively

Obtaining and consumption of nutrients

Humans are heterotrops:must obtain organic and inorganic nutrients form surroundings.

Oxygen:Thanks to respiratory system. It enters our bloodstream whithout any chemical transformation.

Nutrients in food:Ingerested as complex molecules, after it the digestive system breaks down in to nutrients.

What do we need nutrients for? As raw materials for building new molecules. So cell increase in size and the it can divide to create a new cell. The production of new molecules takes place during all life, but especially during he organism’s growth phase.

As source of energy:Thanks to the mitochondia that makes the cellular espiration.The most commonly used to obtain energy is the Glucose

The respiratory system:Thanks to it we can obtain oxygen from the air and CO2 is released

Division of the respiratory system:

Upper:nose,pharynx and larynx

Trachea, bronchi,bronchioles and alveoli

Trachea:Rings of cartilage it helps to the passageway to be opened./Lungs:Two organs in the thoracic cavity protected by ribs./Larynx:Funnel-shaped structure./Epiglottis:Cartilaginous structure to stop food./Vocal cords:Produce sounds./Bronchi:Two tubes leading from trachea./Bronchioles:Narrower tubes arising from bronchi/Diaphragm:It forms the base of thoracic cavity/Alveoli:Small, thin-walled air sacs.Here happens the gas exchange.

Flow of air:Pulmonary ventilation happens when air enters the lungs and thorax moves. (ribcage expands and lungs inflate “inhalation”) and relaxes (ribcage downwardas and lungs deflate “exhalation”).

Gas exchange:It occurs in the Alveoli

A part of O2 coming from the air entering goes to the capilars, at the same time CO2, coming from the capilar goes to the alveolus into the air exiting.

Gases traverse membranes of cells by Diffusion, so from where there is higher concentration to the other.

Characteristics of the Alveoli:Total surface area is enormous, Each alveolus is surrounded by capillaries and the Wall of alveolus is extremely thin, one micrometers.

Respiratory System and Health:We can introduce microorganisms or harmful particulates that can damage our respiratory system.

Respiratory illnesses caused by Microorganisms

Upper: Common cold or influenza (can be serious)

Lower: Bronchitis or pneumonia

Illnesses caused by tobacco smoke

Chronic bronchitis: The excess secretion of mucus obstructs the passageways.

Lung cancer:The 90% of lung cancers are caused by tobacco.

Composition of food:All food is composed o the same basic molecules

Water:The most abundant chemical compound in our body. We need to take water, drinking or from food because we are constantly losing it.

Mineral salts:Carbonate, phosphate and chlorides of sodium, potassium and calcium 

Forms our bones and teeth: Structural strength

Dissolved in our fluids (blood or tears)

We need a few of them 

Organic Molecules:


Simple carbohydrates:Sugar

Glucosa,Sucrose/Sweet taste/Cannot be broken into a smaller carbohydrates

Complex carbohydrates:

Stach, glycogen and cellulose/No sweet taste /Are macromolecules of simple sugars



Can be broken down into Glycerol and Fatty acids


Plant origin/Oils “Liquid at room temperature


Animal origin/Solid at room temperature/Butter.



Macromolecules of amino acids/20 types of amino acids/The order of the amino acids makes one protein or other


We need a very few of the/They are essential/Most cannot be synthesized by our bodies so we have to obtain from food

Digestive system:

The substances we eat are too large, so we broken them in nutrients: This is done by the digestive system.

Digestive system’s goot digestive tract and digestive glands.

The digestive glands:

Produce digestive juices and realease into the digestive tract.

Digestive juices have got enzymes, to convert food into nutrients

Types of digestive glands:They are incorporated into interior walls of the digestive tract.

Accessory glands, for example pancreas. They put secretions into the digestive passageways.

The stages of digestion:

Mechanical digestion: Reduce the particle  size of the ingested food.

Grinding: by teeth

Swallowing: movement of food from the mouth to the esophagus.

Applying pressure: By contractions of the smooth muscle  in organs’ walls

  1. Churning: Constricting motion to mix food with digestive juices.

  2. Peristalsis: Contraction to push food

Chemical Digestion: Enzymatic breakdown of food into nutrients

Intestinal Absorption:Process where nutrients pass from digestive tract into bloodstream.

In the small intestine: 7-8m longs. Most nutrients are absorbed here.

Nutrients are absorbed by villis. And go to the capillaries.

In the large intestine:Water and mineral salts are absorbed here.

The intestinal flora produces some vitamins that are absorbed too.

The digestive system and our health:

Unhealthy teeth:

  • Cavities:Caused by a bacteria that form plaque and produce acids that hurts the enamel

Digestive troubles:

  1. Constipation:It’s difficult to expel faeces. Because there is few cellulose in the diet or a sedentary lifestyle.

  2. Diarrhea: Abundant faeces with too much water