Accelerated Biology

The job of the respiratory system is to obtain oxygen and eliminate carbon dioxide CO2 is a waste

product of cellular respiration and is toxic to cells

Then, the circulatory system transports the oxygen and carbon dioxide throughout the body

Nasal cavity – lined with cilia to trap inhaled particles and moisten and warm the air mucus – traps inhaled

particles cilia – sweeps mucus

up to throat to be swallowed

Pharynx – where oral and nasal cavities meet. Passageway for air

and food Larynx – voice box

Ciliated epithelium of the respiratory system.

SEM X5000

Epiglottis – flap of cartilage that covers the trachea when swallowing to prevent food and liquids from entering your lungs

Trachea – wind pipe with cartilaginous rings

Bronchi – two branches of the trachea that lead to each lung

Bronchiole – smaller branches of the two bronchi that end in tiny air sacs called alveoli

Alveoli – You have 300,000,000 air sacs in your lungs where gas exchange occurs

Increase the surface area of your lungs to 42x the surface area of your body

Their membranes are one cell thick and are surrounded with capillaries.

Diaphragm – thin sheet of smooth muscle spanning the rib cage that moves up and down to bring air into and out of the lungs

Breathing occurs because of air pressure differences between the lungs and the atmosphere

Lungs have no muscles, so the work is done by the diaphragm and intercostal muscles

Intercostals – muscles between the ribs

Gain O2 by inhaling Intercostals and

diaphragm contract Diaphragm flattens

and pulls downward Rib cage is pushed up

and out causing a decrease in the air pressure in the lungs (air pressure in lungs is now lower than atmospheric pressure)

Air is sucked into lungs

Rid body of CO2 by exhaling

Passive - also due to change in lung air pressure

Intercostals and diaphragm relax, decreasing the volume in the chest cavity

Increases the air pressure in the lungs (higher than atmospheric pressure)

Air is forced out

The exchange of CO2 and O2 in both the body tissues and the lungs. Occurs as a result of diffusion

O2 from alveoli diffuses into the blood in the capillaries, in turn CO2 in the blood diffuses into the alveoli

Body tissues – CO2 levels high, O2 levels low

RBC in lungs – O2 levels high, CO2 levels low

Receptors in the brain and the cardiovascular system continually monitor the levels of O2 and CO2 in the blood

As CO2 levels increase, the pH decreases (blood becomes more acidic) causing a person’s breathing rate to increase. Thus, they will expel more CO2 and take in more O2

CO2 combines with H2O to form carbonic acid (H2CO3)

Carbonic acid breaks up to form bicarbonate ions (HCO3) and Hydrogen ions (H+)

Most CO2 travels to the lungs as bicarbonate ions (HCO3)

The H+ ions is what makes the blood acidic, causing an increase in breathing.

The Equation:

H2O + CO2 H2CO3 HCO3- + H+

Carbon Monoxide binds more readily to hemoglobin than oxygen and carbon dioxide

If present, it will prevent oxygen from being delivered and lead to hypoxia, an inadequate oxygen supply

Asthma – Chronic condition where the bronchioles of the lungs become inflamed due to sensitivity of stimuli in the air

Bronchial walls tighten and extra mucus is produced causing airways to narrow

Strenuous exercise and stressful situations can trigger an asthma attack

Emphysema – Elastic fibers in the lungs are destroyed

Begins with the destruction of the alveoli

Results in fatigue and breathlessness

Smoking causes 90% of emphysema cases

Lung Cancer – abnormal cell growth One of the leading of causes of death in the

world Accounts for 28% of all cancer deaths Smoking is the major cause of lung cancer