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UNC CH Biology 252

How do we protect ourselves from having microorganisms and dust particles passing through the respiratory membrane?

Mechanical protections such as the hairs/cilia and the mucous membrane coating most of the respiratory pathway leading to the respiratory membrane. Or chemical/cellular protections such as phagocytes and antibodies eliminating foreign contaminates within the lung-fluid.

How does smoking affect our defense system in the trachea?

Smoking degrades the mucous membrane (bronchial membrane 'elevator') in the trachea which helps to trap foreign particles/cells from making it to the lungs and blood.

What structures make up the respiratory membrane? What is its function?

The alveolar and capillary walls make up the respiratory membrane. Its function is to exchange gases between the lungs and circulatory system.

The pleural fluid is constantly being pumped out of the pleural cavity (and into the lymphatic vessels). Why is that so important?

Excessive fluid in the pleural cavity can lead to respiration impairment by making it more difficult for the lungs to expand.

Elasticity of the alveoli drives them to recoil and we need to oppose that to prevent the lung from collapsing. How?

Surfactant. Refer to the slides below.

Why do we need surfactant?

Surfactant helps to keep the alveoli within the lungs from collapsing. If the alveoli were to collapse then respiration would not be possible because air and specific gases in air could not diffuse across the alveolar-vascular junctions.

People who smoke may begin to develop emphysema, a homeostatic imbalance characterized by loss of alveolar elasticity. this makes expiration - normally a passive process - to become consciously an active process. why do emphysema patients need to exhale actively and how do they do that?

Naturally expiration is performed by the relaxation of the diaphragm, the internal intercostal muscles, and relaxation of the alveoli (loosing pressure within the lungs). If the alveoli do not relax and close naturally then air is not properly expelled from the lungs meaning you must put forth an active effort to expel the air. When you actively expire you consciously contract your internal intercostals and relax the diaphragm to force air out almost like a cough.

How is breathing regulated? What is the role of CO2 in breathing regulation?

Breathing is regulated by the medulla oblongata. Because of its presence as waste in the blood (carbon dioxide greatly affects blood pH), CO2 helps indicate when increased respiration is necessary to rid the body of CO2.

Dalton's law states that the total pressure exerted by a mixture of gases is the sum of the pressures exerted independently by each gas in the mixture (True/False)

True

More or less, as long as the gases are nonreactive and by "exerted independently" the question means partial pressure then yes this statement is true. Just make sure to understand that P-total = P-1 + P-2 +P-3... etc.

Surfactant helps to prevent the alveoli from collapsing by____.
a. humidifying the air before it enters
b. warming the air before it enters
c. interfering with the cohesiveness of water molecules, thereby reducing the surface tension of alveolar fluid
d. protecting the surface of alveoli from dehydration and other environmental variations

C. Interfering with the cohesiveness of water molecules, thereby reducing the surface tension of alveolar fluid

Which of the following blood vessels has a CO2 partial pressure of 46 mm Hg?
a. Pulmonary arteries
b. Pulmonary capillaries
c. Systemic veins
d. both the pulmonary arteries and systematic veins

D. Both the pulmonary arteries and systemic veins

Which of the following are the muscles of inspiration?
a. Abdominal muscles and internal intercostal muscles
b. Diaphragm and the skeletal intercostal muscles
c. Diaphragm and the intercostal smooth muscles
d. None of the above

B. Diaphragm and the skeletal intercostal muscles

More specifically the external intercostal muscles and the diaphragm.

Oxygen and CO2 are exchanged in the lungs and through all cell membranes by ____.
a. osmosis
b. diffusion
c. filtration
d. active transport

B. Diffusion

The process of diffusion also accounts for the inefficient uptake of oxygen from air into the blood stream, and for the excretion of waste products such as CO2 through expiration.

During expiration, the diaphragm:
a. relaxes and progresses inferiorly toward the stomach
b. contracts and progresses inferiorly toward the stomach
c. relaxes and the dome rises into the thoracic cage
d. contracts and the dome rises into the thoracic cage

C. Relaxes and the dome rises into the thoracic cage

Physics behind this indicate that during inspiration a negative pressure (or increase in volume, PV=PV) causes air to rush into the lungs, this increase in volume is caused by the downward contraction of diaphragm. Expiration is just the opposite.

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