Respiratory System – V3 The purpose of the respiratory system is to exchange gases. In aerobic organisms oxygen (O 2 ) must be brought to cells and carbon dioxide (CO 2 ) removed. In humans the respiratory system is divided into the upper and lower respiratory system. Here are the human respiratory structures.

Nasal Cavity Nose Oral Cavity Right Bronchus Bronchiole Alveoli Diaphragm Pharynx (Throat) (Trachea) (Windpipe) Left lung Ribs with intercostal muscles attached Epiglottis

Upper Respiratory System 1.Nose and Nasal Cavity A hollow area inside the nose where air enters Hairs line the nose and trap dirt Air is warmed and moistened Mucus is secreted to trap dirt 2.Pharynx Common tube that connects nasal cavity and oral cavity to the trachea and esophagus Carries food and air 3. Oral Cavity Also allows air to enter the body going to lungs

Upper Respiratory System 4. Epiglottis A flap of cartilage that covers the glottis when food is swallowed The glottis is the hole that is the opening from the pharynx to the trachea 5. Trachea Tube that carries air from the nasal passages to the lungs It is a flexible tube held open by rings of cartilage The surface is covered in mucus and moving cilia to remove dirt particles and protect the lungs 6. Larynx Voice box makes sounds as air passes

Motile Cilia

Lower Respiratory System Each lung is made of bronchi, bronchioles, and alveoli covered with capillaries. The right lung has 3 lobes while the left lung only has 2 lobes to make room for the heart. Lungs are encased in a pleural membrane. Who smoked?

Lower Respiratory System 1. Bronchi The trachea divides into the right bronchus and left bronchus Like the trachea bronchi are held open with rings of cartilage 2. Bronchiole Many bronchioles branch off from the bronchi Bronchioles are not held open with cartilage rings

L: bronchioles, R: blood vessels The alveoli air sacs are surrounded by blood vessels

Lower Respiratory System 3. Alveoli Tiny damp hollow sacs covered outside with capillaries Gas exchange occurs across the alveoli membrane by diffusion Carbon dioxide goes from the blood into the alveoli and oxygen enters the blood from alveoli The singular is alveolus Flattening all your alveoli would cover a tennis court. This huge surface area increases the amount of gas exchange possible.

Alveoli Structure

Gas Exchange in Alveolus

Lower Respiratory System 4. Diaphragm Strong muscle separating the thoracic cavity from the abdominal cavity Contracts along with intercostal muscles to produce breathing movements 5. Intercostal Muscles Intercostal muscles are attached to the ribs. 6. Pleura Each lung is covered in tissue called pleuron (singular) Pleurisy is an infection of the pleura (plural)

Quick self test – name and function?

3.5 min british video Part 1 a 3.5 min british very anatomy based nose to bronchusPart 1 a 3.5 min british very anatomy based nose to bronchus Part 2 bronchus to alveoli 7 min – super anatomy