Bio 392 2/24/11

Checkpoint Questions

1.What is the basic function of the Respiratory System?

2.What is the pathway for food and air?

3.What is the piece of tissue that covers the trachea when you swallow called?

4.What is another name for the vocal cords?

Bio 392 2/24/11

Lower Respiratory TractTrachea (windpipe) - long tube that connects the larynx to the lungs.

Bronchi (singular, bronchus) -The trachea branches into smaller tubes which lead to the lungs.

Bronchioles - found within the lung, the bronchi divide into these smaller and smaller tubes

Bio 392 2/24/11

Alveoli

Bronchiole

Capillary

Gas Exchange at the Alveoli

Alveoli• Found at the end of the smallest bronchioles • clusters of tiny air sacs which are surrounded by capillaries of the

pulmonary circulation.

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Gas Exchange/Transport• After oxygen molecules reach the alveoli, they move into

the blood to be carried throughout the body.

• Oxygen is transported bound to hemoglobin inside red blood cells. Each hemoglobin molecule contains four iron atoms. Each iron atom binds with one molecule of O2.

• Most CO2 is chemically changed to be carried in the blood as bicarbonate ions.

• When the blood reaches the lungs, the reactions reverse and the bicarbonate ions return to CO2 which

diffuses into the alveoli and is exhaled.

Bio 392 2/24/11

Bio 392 2/24/11

Breathing

• Definition: Movement of air into and out of lungs

• Air is drawn into and out of the lungs by changes in pressure in the chest cavity.

• No muscles connected to lungs – found in 2 sealed sacs called pleural membranes

• The diaphragm and rib muscles control the movement of the chest cavity.

Bio 392 2/24/11

• When the diaphragm and rib muscles contract, the chest cavity expands and air rushes in.

• When these muscles relax, the chest cavity returns to a resting position and air rushes out.

Breathing

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Control of Breathing

• Breathing is not completely voluntary

• A part of the brain called the medulla oblongata controls breathing

• Carbon dioxide levels in the blood are measured by the “breathing center” and tell it when to signal

changes in breathing via nerve impulses

CO2 increases, diaphragm contracts, breathe

Bio 392 2/24/11

Tobacco and the Respiratory SystemThree dangerous substances from tobacco smoke:

1. nicotine - stimulant drug2. carbon monoxide – poisonous gas, odorless,

blocks the transport of oxygen3. tar – contains compounds that cause cancer

• Nicotine and carbon monoxide enter the upper respiratory tract

• Cilia are destroyed, allowing particles to enter respiratory tract and cause the accumulation of mucus in airways

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Diseases of the Respiratory System• Chronic Bronchitis: bronchi are swollen, clogged with mucus

• Emphysema: loss of elasticity of lung tissue, breathing becomes difficult

• Lung Cancer: poor survival, preventable, spreads to other tissues

• Heart Disease: smokers twice the rate of heart disease of non-smokers; nicotine contracts blood vessels, increasing heart rate and blood pressure

Bio 392 2/24/11

nostril

Nasal passage

pharynx

epiglottis

esophagus

trachea

lung larynx

pleura

bronchi diaphragm

Blood vessels

bronchioli

Bronchial tubes

alveolus

capillaries

alveoli