glossary


 * GLOSSARY**

** 1. The function of nutrition includes: ** Nutrition is the process by which our body obtains the necessary to live. This function includes:


 * digestion, which takes place in the digestive system
 * respiration, which takes place in the respiratory system
 * circulation, which occurs in the circulatory system
 * excretion, which occurs in the excretory system

**2. Blood** is a red liquid substance in our body that reaches all the body cells and is made up of: plasma, red blood cells, white blood cells, platelets.

** 3. Components of blood **
 * Plasma is a clear fluid which transports nutrients and waste around the body. Both white and red blood cells as well as platelets are in this liquid.
 * Red blood cells are the most numerous. They distribute oxygen and make blood red.
 * White blood cells protect the body from illnesses. They are part of our inmune system.
 * Platelets are fragments of old cells and they contribute to coagulation.



**4. Blood vessels** are hollow tubes distributed throughout our body. They circulate our blood. there are three types of blood vessels: arteries, veins and capillaries.

** 5. Types of blood vessels **
 * Arteries which carry blood away from the heart to other organs.
 * Veins, which carry blood to the heart.
 * Capillaries which connect arteries to veins and circulate blood inside the organs.



**6. Heart** is an organ made up of muscles, which are working all the time to pump blood around the body. It is located in the thoracic cavity and lies a little to the left of the middle of the chest, between the two lungs. The heart is divided in two halves, separated by a thick wall of muscle. Each one is made up of two different areas, atria and ventricles.Video: How a normal heart pumps blood
 * Atria (singular: atrium) are the two upper chambers of the heart. Blood comes from the veins enters the heart here.
 * Ventricles are the two lower chambers of the heart. Blood leaves the heart in the ventricles and travels through arteries.



**7. Valve:** connects each atrium to the ventricle on the same side of the heart and they also control the direction of blood circulation from the atria to the ventricles. Valves let blood in, then close to keep it there. (More info in the video in point 6.)

**8.Excretion:** is the elimination of waste substances from the blood. This waste substances are produced by body functions that pass to the blood. This excretion is not the same as the elimination of faeces. Substances contained in faeces have not passed into the blood.

**9. The excretory system** is made up of kidneys, ureters, bladder and urethra.
 * Kidneys are in the abdomen, at both sides of the spinal column. They filter the blood and retain waste substances which make up urine.
 * Ureters: are two tubes carry urine from the kidneys to the bladder.
 * Bladder: stores the urine until it is expelled from the body.
 * Urethra: urine is expelled through this tube.



**10. Sweat**: is a liquid that our body secretes. Consists primarily of water, but it also contains salts and small amount of waste substances. Consequently, sweats is also part of the excretory function.

**11. Sweat glands:** each gland is made up of a ball-shaped coil in the inner layer of the skin, and a tiny tube that connects with a pore on the outside surface of our skin.

1**2. Blood circulation** : Circulation is the constant movement of blood through the blood vessels and around the body. This allows to distribute nutrients, to take oxygen to the whole body and pick up waste substances.

** 13. Stages of the blood circulation: **
 * Systole, which is the contraction that makes blood flow to the arteries.
 * Diastole, that consists in the relaxation that makes blood enter the heart through the veins.

**14. Pulmonary circulation** is the movement of blood between the heart and the lungs. The circulation works like this: Blood that is high in carbon dioxide enters the right atrium, blood goes through the right ventricle towards the lungs, gas exchange takes place in the air sacs in the lungs, blood that is high in oxygen enters the left atrium then passes into the left ventricle.

**15. Systemic circulation** is the movement of blood between the heart and the rest of the body. First, blood leaves the left ventricle through the aorta; later it passes through all the body organs releasing oxygen and nutrients, and finally, it returns to the right atrium through the vena cava.

**16. Respiration:** it is a process that serves us to obtain oxygen and expel carbon dioxide.

**17. Inhalation:** the air enters through the nostrils and goes to the pharynx. After that, it travels to the larynx and the trachea, which is divided into two bronchi connected to each lung. Inside the lungs, the bronchi are divided into bronchioles. At the end of the bronchioles are the alveoli.

**18. Gas exchange** takes place in the alveoli and consist on the transport of the oxygen from the air passes into the blood, and the carbon dioxide passes from the blood into the air to be expelled.

**19. Exhalation:** the lungs and the thoracic cavity contract. This pushes the air that contains carbon dioxide out of our body. **20. Cellular respiration:** Cells combine oxygen with nutrients to obtain energy. During the process, carbon dioxide is produced. This gas must be expelled from our bodies. 