Respiration

How does respiration take place? There are two respiratory movements: Inspiration (inhalation) Expiration (exhalation) When you inhale, air enters the lungs through the respiratory airways. When you exhale, air leaves the lungs through the respiratory airways

The process of inhaling: The intercostal muscles contract, moving the ribs up and out, the diaphragm contracts and moves down. This means the thorax (chest cavity) and lungs expand, air enters the body.

The process of exhaling: The intercostal muscles relax, moving the ribs in and down, the diaphragm relaxes and moves up The thorax and lungs decrease in volume, and air leaves the body

The Physics of Respiration: Air has weight and it exerts a force. Air pressure varies: Air pressure decreases if the volume increases (more space to move = less collisions) Air pressure increases if the volume decreases (Less space = more collisions)

A decrease in air pressure can result in air entering the body An increase in air pressure can result in air leaving the body Changes in the thorax and lung volume result in changes in the “intrapulmonic pressure” (pressure in the lungs)

When you inhale, the intrapulmonic pressure decreases as the volume of the lungs increases – air rushes into the lungs When you exhale, the intrapulmonic pressure increases as the volume of the lungs decreases – air is forced out of the lungs

What is the function of respiration? Inhaling brings in fresh oxygen to the blood Exhaling removes the carbon dioxide from the blood The exchange takes place at the alveoli

Diffusion: Diffusion is the movement of particles from an area of high concentration to an area of lower concentration This includes crossing membranes to balance out the number of particles

When you inhale there is more oxygen in the alveoli than in the blood, so the oxygen diffuses into the blood across the alveolar membrane When you exhale, there is more carbon dioxide in the blood than in the alveoli; the carbon dioxide diffuses across the alveolar membrane into the alveoli

Page 83 and 85 Activities 1,2 3, and 4 Review Question 1,2,3,4 and 5