SCIENCEUNIT 4

BREATHING, CIRCULATION,EXCRETION

• Breathing and the respiratory systemBreathing is part of the nutrition function.

By breathing we obtein the oxygen our cellsneed to work.

We also excrete the carbon dioxide our cellsproduce as a residue.

We breathe with our respiratory system, whichincludes the airways (nasal passages, thepharynx, the larynx, the trachea, and thebronchial tubes) and the lungs.

Breathing has two phases: inhalation and exhalation.

• The respirtory system

• The circulatory systemThe circulatory system is formed of the bloodvessels and the heart.

In transports nutrients, oxygen and residuesaround the body in the blood.

• The circulatory system

• BloodBlood is a red liquid composed of: plasma and blood cells.

The most important functions of blood are:

• Transport nutriens and oxygen to the cells and take away the residues to where they are excreted.

• Defend our body from infections.

Lesson vocabularyTo obtein: obtener

To include: incluir

Airways: vías respiratorias

Nasal passages: fosas nasales

Pharynx: faringe

Larynx: laringe

Trachea: traquea

Bronchial tubes: bronquios

Lungs: pulmones

Inhalation: inhalar, inspirar

Exhalation: exhalación, espirar.

Blood vessels vasos sanguíneos

Heart: corazón

To transport: transportar

Blood: sangre

To defend: defender

Artery: arteria

Vein: vena