Respiratory System

• Main function– Transports GASES to and from the

circulatory system

Parts of the Respiratory System

1. Nasal Cavity

2. Oral Cavity

3. Pharynx

• Cavity at the back of the mouth• Epiglottis is located in the pharynx

4. Epiglottis

• Thin flexible cartilage structure• Guards the entrance to the larynx• Prevents food material from entering the

trachea during swallowing

5. Larynx

• Voice box (Glottis) • Contains vocal cords

6. Trachea

• Cartilage rings• Windpipe

7. Bronchi

• Made of up of smooth muscle & cartilage

8. Bronchioles

• Same structure and function as bronchi, BUT smaller

9. Alveoli

• Air sacs • Tiny pouches

surrounded by capillaries where gases are exchanged

Cilia and Mucus

• Air filtered by cilia • Warmed & moistened

by mucus• Lines the nasal cavity,

trachea, bronchi, bronchioles

Trachea

• Cilia will move debris up to trachea opening where the material will end up in the esophagus & will be swallowed.

Breathing

Inspiration/Inhalation

• Diaphragm CONTRACTS – “Down” position• Chest expands and enlarges• Ribs are PUSHED UP and OUT• Thoracic cavity INCREASES• More pressure outside than inside the lungs • Allow air INTO the lungs

Expiration/Exhalation

• Diaphragm RELAXES - “Up” position • Chest relaxes• Ribs ARE IN and DOWN• Thoracic cavity DECREASES, therefore pushes

air OUT of the lungs• More pressure inside the lungs than outside of

the lungs• Air is pushed

Animation of Breathing

Respiratory control

Medulla oblongata

• Located in the brain stem• Controls respiratory rate • Detects CO2 levels in the blood

Diaphragm

• Respiratory muscle• Regulates breathing• Changes the

VOLUME of the thoracic cavity

Gas Exchange

Gas exchange

• External gas exchange – between the ATMOSPHERE and the BLOOD

• Internal gas exchange– Between the BLOOD/CAPILLARY and the CELLS.

http://www.unis.org/UNIScienceNet/BodyCells_cap_big.jpg

General Process of Gas Exchange

http://www.innerbody.com/image/card06.html

Gas Transport

Oxygen

1. A small amount of oxygen in gas form dissolves in the BLOOD

2. Most oxygen is carried by HEMOGLOBIN– Lungs: Hemoglobin picks up oxygen

Hb + O2 HbO2 (oxyhemoglobin)

– Cells: Hemoglobin drops off oxygen HbO2 Hb + O2

Carbon dioxide

1. A small amount of carbon dioxide in gas form dissolves in the BLOOD (8%)

2. 25% - carried by the HEMOGLOBIN– Lungs: Hemoglobin drops off carbon dioxide

HbCO2 Hb + CO2

– Cells: Hemoglobin picks up carbon dioxide Hb + CO2 HbCO2

Carbon Dioxide

3. 67% converted to BICARBONATE ions which dissolve in the PLASMA– Cells - Carbon dioxide gets picked up

CO2 + H2O H2CO3 H+ + HCO3-

carbonic acid bicarbonate ion

– Lungs - Carbon dioxide gets dropped off H+ + HCO3

- H2CO3 CO2 + H2O bicarbonate ion carbonic acid

CO2 release to lungs

CO2 pick up by RBC

Body and Breathing Activity

Bronchitis

• Inflammation of the air passages of the lungs• Develops from a respiratory infection such as a cold• Mucous lining become irritated/swollen• Coughing is a reflex to clear secretions

Asthma

• Narrowing of the bronchi making breathing difficult• Symptoms – wheezing, difficulty breathing (particularly exhaling

air), tightness in the chest• Irritants – Rapid changes in temperature or humidity,

allergies, upper respiratory infections, exercise, stress, or smoke (cigarette)

Emphysema

• Damage to the tiny air sacs in your lungs (alveoli) • Can cause you to feel short of breath• Cigarette smoking is the major cause of emphysema,

accounting for more than 80 percent of all cases

Carbon dioxide

• CO2 produced by cellular respiration leaves the CELLS

• CO2 enters the BLOOD VESSELS (veins)

• CO2 enters the CAPILLARIES IN LUNGS

• CO2 crosses the ALVEOLAR wall by DIFFUSION

• Exhale air

Oxygen

• Inhale O2

• O2 crosses the ALVEOLAR wall by DIFFUSION• O2 enters the CAPILLARIES IN LUNGS• O2 enters the BLOOD VESSELS (arteries)• O2 travels to the CELLS to be used in cellular

respiration

Transport of Gases in Blood

• Oxygen is mainly transported bound to hemoglobin though a small amount will dissolve in the blood

• Some carbon dioxide is transported bound to hemoglobin and some dissolves in plasma

• Most carbon dioxide molecules are transported in the form of bicarbonate ions

• Once in the lungs, the bicarbonate ions are converted back to carbon dioxide