Respiratory System

1. Respiratory System

2. Functions • Gas exchange = respiration [series of events that includes ventilation, external respiration, transport of gases & internal respiration] • Regulation of blood pH = reliant on CO2 levels • Voice production = in larynx • Olfaction = sense of smell : CN I • Protection = mucus membranes, cilia

3. terminology • Respiration = exchange of carbon dioxide and oxygen between atmosphere and body cells • External respiration – exchange of gases at level of lungs • Internal respiration – exchange of gases at tissue level • Ventilation = breathing • inspiration – inhalation • expiration -exhalation

4. Upper respiratory tract = nose, sinuses, pharynx & larynx Lower respiratory tract = trachea, bronchial tree & lungs

5. Nose – nasal bones and cartilage Nasal cavity is separated by septum [formed by vomer & perpendicular plate of ethmoid] Rhinitis = inflammation of nasal mucusa & excessive mucus production. Can be caused by virus, bacteria or irritants. Sinuses: air filled cavities Reduce the weight of the skull Produce mucus Influence voice quality – act as resonating chambers Pharynx = throat. Nasophayrnx – posterior to the nasal cavity and extend to uvula. Oropharynx – posterior to the oral cavity extends from uvula to the hyoid bone. Laryngopharynx – from hyoid bone to the larynx

6. Larynx [also known as the voice box] Passageway for air. 9 cartilages: hyaline except for epiglottis, which is elastic. During swallowing, epiglottis covers respiratory tract Thyroid cartilage [Adam's apple] Vocal cords- vestibular folds /false vocal cords, help to keep particles out of respiratory tract. True vocal cords – controlled by muscles that change tension for speaking. Opening between true cords is called glottis.

7. Trachea = windpipe. Supported by 15-20 ‘C’ shaped rings Lined with a pseudostratified columnar epithelium similar to nasal passages. Has ciliary escalator Divides into the right and left bronchi

8. The bronchial tree begins after the last tracheal ring – the carina. The right bronchi is shorter and more vertical. The bronchi branch into smaller and more numerous branches. The smallest bronchi are called bronchioles. They lead to the alveolar ducts – which terminate in the air sacs known as alveoli. Bronchioles are primarily composed of smooth muscle. Alveoli are primarily simple squamous epithelium. This allows rapid diffusion of oxygen and carbon dioxide. Area of gas exchange = external respiration.

9. The lungs contain the bronchial tree and alveoli. They are soft and spongy. The lungs are encased by a double layered serous membrane called the pleura. The left has the ‘cardiac notch’.

10. terminology • Respiration = exchange of carbon dioxide and oxygen between atmosphere and body cells • External respiration – exchange of gases at level of lungs • Internal respiration – exchange of gases at tissue level • Ventilation = breathing inspiration – inhalation expiration -exhalation

11. Breathing is dependant on muscle movement and air pressure

12. Oxygenated air rushes down tract to the alveolar sacs where external respiration occurs. The exchange of gases is driven by CO2 diffusion.

13. External Respiration

14. Gases are transported by the blood. RBCs are primarily responsible for O2 transport, and the plasma transports the majority of the CO2. Hemoglobin + Oxygen  Oxyhemoglobin Hb + O2  HbO2

15. Oxyhemoglobin --- Hemoglobin + Oxygen HbO2 Hb + O2 Carbon Dioxide + Hemoglobin  Carbaminohemoglobin CO2 + Hb  HbCO2

16. Carbon Dioxide is transported: 70% in the plasma as bicarbonate ions [ driven by carbonic anhydrase enzyme carried by RBCs] 23% combines with Hb to form HbCO2 7% dissolves in the plasma and is carried as CO2