Respiratory System

It’s a gas!

Respiratory SystemPathway of Air:

• Nose/mouth• Nasal/oral

cavities• Pharynx• *Epiglottis• Larynx• Trachea• Bronchi• Bronchioles• Alveoli

Oral & Nasal Cavities & Pharynx

• Warm & moisten air to protect delicate lung tissue.• Sticky mucous lining &

mucous-covered hairs in nasal cavity filter particles from air.

Larynx & Voice

• Sound produced as 2 ligaments (vocal cords) vibrate when air passes through them.

• Pitch varies with tension of vocal cords – more tension = higher pitch

• Volume depends on amount of air forced past them – more air = greater volume.

• Laryngitis – inflammation of vocal cords due to overuse.

Airway

Trachea/bronchi • Made of rings of cartilage

(keeps airway open).• Lined with mucous membranes

(trap particles) and cilia (sweep particles up and out of airway).• Epiglottis closes trachea when

swallowing.• Bronchi branch into bronchioles

Lungs• Right is larger (3 lobes) than

left (2 lobes).• In thoracic cavity, lined w/

pleura (membranes that reduce friction.

• LARGE surface area.

Alveoli & CapillariesBronchioles terminate in dead-end sacs – alveoli – surrounded by a net of capillaries.

Gas Exchange• External Respiration -

Exchange of gases between atmosphere and blood by diffusion.

• Internal Respiration – Exchange of gases between blood and cells by diffusion.

• Diffusion happens when there is a concentration gradient (difference) in a fluid (gas or liquid).

• *The Respiratory System• Respiratory System

Oxygen & CO2 TransportIn Blood

97% of oxygen transported on hemoglobin in RBCs.67% of CO2 reacts w/ water to form carbonic acid, disassociates into bicarbonate ions (HCO3

-)

Mechanism of Breathing

• Diaphragm• Mechanism of Breathing• Mechanics of Breathing 2

Boyle’s Law – pressure exerted by a gas varies inversely with the volume of the gas.

Inspiration & Expiration

Respiratory System Review - Kahn Academy

Regulation of Breathing

Brain monitors the concentration of CO2 in the blood. Why not O2?

A: O2 is carried by hemoglobin inside RBCs, while CO2 is mostly carried in the plasma.

Disorders• Asthma –

inflammation of the lining of bronchioles causes reduced air flow.

• Emphysema – alveoli lose elasticity and rupture, reducing surface area and lung capacity.

Smoking• Tar and particles clog up lungs & paralyze cilia

so they can’t clear debris.• If a smoker quits, damage may be reversible.