Diffusion

THE NUTRITION FUNCTION I.The respiratory system.

Obtaining energy.We have just studied the DIGESTIVE SYSTEM. Its function is to get nutrients from food.

To transform NUTRIENTS INTO ENERGY, in the mitochondria, our cells NEED OXYGEN.

These molecules are essential for cellular respiration: the process through we obtain energy.

Expeling waste substances.In respiration, oxygen is consumed to release energy (ATP) from nutrients, and carbon dioxide is produced.

The respiratory system is also in charge of expelling that carbon dioxide that we dont need.

Parts of the respiratory system

https://www.youtube.com/watch?v=hc1YtXc_84A

Parts of the respiratory system.Our respiratory systems consists on:The AIRWAYS or RESPIRATORY TRACT: The air passes through this tube or pipe. They are:Nasal cavityPharynx (shared with digestive system)LarynxTracheaBronchiBronchiolesThe LUNGS: Organs that contain bronchi, bronchioles, pulmonary alveoles and capillaries.

Transport and modification of air.Nasal cavity: In here air isFiltered by cilia and mucus. The nasal cavity is covered with a respiratory mucosa lined with a ciliated columnar epithelium.Warmed by capillaries in that tissue.Moistened.Is in this part of our body where sense of smell resides.Pharynx: Tract shared with digestive system. Communicates nasal and oral cavity. Here we find tonsils, that produce white blood cells.

Larynx. Separated from the oesophagus by the epiglottis. Here we find the vocal cords.

Transport and modification of air.

Transport and modification of air.

Trachea. Tube surrounded by rings of cartilage that keep it open. It is also covered by mucus, that traps foreign particles, and force them out.Transport and modification of air.

Mechanics of breathing.

Inspiration and expiration.https://www.youtube.com/watch?v=SWJHSTAWTCk

Lungs model. Pulmonary ventilation.https://www.youtube.com/watch?v=DAR9Ne57Cl4

Inside the lungs.Lungs are formed by lobes. The right one is formed by 3 lobes, and the left one by two. As we have our heart is pointed slightly to the left in our chest, the left lung is smaller that the right one.

Lungs are surrounded by pleura, two membranes separated by a fluid (to slide smoothly).

Inside the lungs.Once the air enter the lungs, it passes through the bronchi, bronchioles and alveoli, where GAS EXCHANGE takes place.

This gas exchange is produced through a DIFFUSION process.

Diffusion

What is diffusion through the membrane?Diffusion is a form of transportation of certain substances through the cell membrane.

InsideOutsideCell membraneHIGHERconcentrationLOWERconcentration

InsideOutsideCell membraneHIGHERconcentrationLOWERconcentration

Diffusion through the membraneDiffusion is the process where substances pass from one side of a membrane where the concentration is higher to the other side where the concentration is lower.If the concentration of a substance is higher on the outside, the substance enters.If the concentration of the substance is higher on the inside, the substance leaves.

After inhalation, the concentration of O2 in the alveoli is higher than in the capillaries. The O2 therefore passes by diffusion from the alveoli into the blood.

Inside the alveolusMembrane of the alveolus

Diffusion of O2 during gaseous exchangeBlood

O2

HIGHER concentration of O2LOWER concentration of O2Oxygen (O2) is transported by diffusion from the alveoli into the blood.* Blood does not only transport oxygen, but also carbon dioxide. So

The blood that goes to the lungs has a higher concentration of CO2 than that outside the alveoli. Therefore, the CO2 passes into the alveolus.Diffusion of CO2 during gaseous exchange

CO2

Membrane of the alveolusLOWER concentration of CO2HIGHER concentration of CO2Inside the alveolusBloodThe carbon dioxide (CO2) is transported by diffusion from the blood to the inside of the alveoli.

Diffusion inside the lungs.https://www.youtube.com/watch?v=d-f3RL0KiUg