Respiratory SystemWe need a respiratory system for gas exchange

and to provide O2 for cellular respiration!

Gas exchange is the physical method that organisms use to obtain oxygen from their surroundings and remove carbon dioxide.

The respiratory surface is the physical location of gas exchange in the organism.

Gas exchange helps maintain homeostasis in the body.

Importance of the Respiratory System:

1. Surface must be thin - Diffusion will occur faster.

2. Surface must be moist. O2 and CO2 must be dissolved in a liquid before they can diffuse.

3. Surface must be in contact with a supply of O2 in the surroundings. The surroundings must have a supply of needed O2 and be able to remove CO2 for the organism.

4. Surface must be in contact with a transport system that carries dissolved materials to and from the cells.

Requirements of a Respiratory Surface

Lungs gas exchange organs in air-

breathing vertebrates and some other animals.

made up of many small chambers (aveoli).

each chamber is surrounded by capillaries (where the exchange of O2 and CO2 occur).

diaphragm - thin muscle which forms the floor of the chest cavity and is involved in breathing; separates lungs from abdominal cavity.

ribs -part of the skeletal system which protects the chest cavity which along with intercostal muscles are involved in breathing.

Structures involved in human gas exchange:

pleura - two layered membrane which completely encloses the lung.

1. Visceral pleura: inner pleura which covers the lungs.

2. Parietal pleura – outer pleura is in contact with the diaphragm and other chest cavity organs.

air passage - pathway through which air flows to and from the environment and the respiratory surface during breathing.

Nose: Air enters through 2 nostrils; Hair filter large particles from the air (dust, pollen).

Nasal cavity: (sinuses, nasal passages) - cilia and mucus help trap dust, bacteria, and other particles in the air. - capillaries present to warm the air as it flows through. This prevents damage to lung tissue by the cold air.** Because the nose helps warm, moisten, and cleanse the air, breathing through the nose is better than mouth breathing.

Pharynx - connects mouth and nasal cavity to the larynx and esophagus.

Larynx – (Adam’s apple, voice box)- Contains vocal cords which stretch across the larynx and vibrate as

air flows over them. - found at the top of the trachea. - Contain cartilage (largest is the thyroid cartilage: Adam’s apple).

Parts of the Air Passage

Epiglottis: flap-like structure at top of larynx that prevent food

from entering the trachea.

trachea (windpipe)

- connects the air to the lungs.

- tube supported by “U” shaped cartilage rings.

- ciliated mucous membrane moves mucus and trapped debris

up into the nose and throat area where it can be removed by

sneezing, swallowing, coughing, or spitting.

- Tobacco smoke will stop cilia for 20 minutes and increase the

amount of mucus present in the air passage, causing coughing

and a greater risk of respiratory infection.

bronchi – two short cartilage-ringed tubes that carry air from the trachea to the left and right lung. The bronchi are lined with a ciliated mucous membrane.

Bronchioles - Inside the lung, each bronchi divides into a tree-like network of smaller and thinner tubes called bronchioles which regulate the flow of air to the aveoli.

  Alveoli – found at end of each

bronchiole; grape-like cluster; Tiny air sacs surrounded by capillaries; function to exchange oxygen and carbon dioxide. This is the respiratory surface.

(300 million with a surface area of 70 m2 = size of classroom; 1/5th the area of a basketball court).