ch. 13 | the respiratory system

functions: gas exchange 

• delivering oxygen from air to cells & tissues
• removing carbon dioxide from cells & tissues
• expelling carbon dioxide into the air

UPPER RESPIRATORY TRACT: nose, pharynx (throat)

• nasal septum: divides nasal cavity into right & left sides
• bronchioles: smaller tubes that branch from tertiary bronchi
• oropharynx & laryngopharynx can transport food & air 
• the nasal pharynx is continuous w the nasal cavity & only transport air 
• the right lung has 3 lobes; the left has 2 lobes
• serous fluid is located in the pleural cavity
• terminal bronchioles sends air directly into the respiratory bronchioles

LOWER RESPIRATORY TRACT: larynx, trachea, bronchi, bronchioles, lungs

• the thyroid cartilage of the larynx is the largest
• the epiglottis forms a lid over the larynx when we swallow 
• during swallowing, muscles of the pharynx & larynx move the larynx superiorly

BRANCHING OF BRONCHIAL TREE: trachea-->primary bronchi--> secondary bronchi--> tertiary bronchi--> bronchioles--> terminal bronchioles--> respiratory bronchioles--> alveolar ducts--> alveolar sacs--> alveoli

alveoli:

alveolus: air sac in the lungs 

• pulmonary ventilation: (breathing) flow of air into & out of the lungs
• external respiration: gas exchange btwn alveoli & blood in pulmonary capillaries (blood picks up oxygen from air & releases carbon dioxide into the air)
• internal respiration: gas exchange btwn tissue cells & blood in the systemic capillaries (blood releases oxygen into the tissues & picks up carbon dioxide from them)

• inhale: pressure inside lungs < atmospheric air pressure
• exhale: pressure inside lungs > atmospheric air pressure
• with each inhalation and exhalation moves about 500 mL of air into & out of the lungs

• diffusion moves gases across the capillary membranes (high-->low)
• oxygen is transported through the blood attached to hemoglobin
• 1 hemoglobin molecule can bind to 4 oxygen (oxyhemoglobin)

• carbon dioxide travels through the blood:

7% in the plasma

23% bound to hemoglobin (carbaminohemoglobin)

70% as bicarbonate ions

• transport of oxygen:

1.5% dissolved in plasma
98.5% as oxyhemoglobin

• smoking can damage lung tissue; major contributing factor of pulmonary disease 
• internal respiration does not occur in the lungs