Bio307 - Test #3 - Chapter 17 (Mechanics of Breathing)

Ventilation

movement of air into and out of the lungs

Inspiration

Movement of air into the lungs: Alveolar pressure decreases, air flows into the lungs. Requires the contraction of inspiratory muscles and the diaphragm.

Expiration

The movement of air out of the lungs, usually passive, results from elastic recoil of the lungs

Alveoli

series of interconnected sacs, and associated pulmonary capillaries. Form the exchange surface, where oxygen moves from inhaled air to the blood, and carbon dioxide moves from the blood to air that is about to be exhaled.

Diaphragm

a muscular partition separating the abdominal and thoracic cavities; functions in respiration

Pleura

the thin serous membrane around the lungs and inner walls of the chest

Surfactant

decreases surface tension in the fluid lining the alveoli. Reduced surface tension prevents smaller alveoli from collapsing and makes it easier to inflate the lungs.

Partial Pressure

pressure contributed by a single gas in a mixture

Tidal Volume

amount of air taken in during a single normal inspiration

Inspiratory reserve volume

additional volume inspired above the tidal volume

expiratory reserve volume

amount of air forcefully exhaled at the end of a normal expiration

residual volume

amount of air in the respiratory system after maximal exhalation

total lung capacity

composed of vital capacity (sum of inspiratory reserve volume, expiratory reserve volume, tidal volume) and the residual volume

vital capacity

sum of inspiratory reserve volume, expiratory reserve volume, tidal volume

bronchoconstriction

increases resistance to blood flow, decreases amount of fresh air reaching the alveoli, occurs in response to irritant stimulation

bronchodilation

increased CO2 in expired air relaxes bronchiolar smooth muscle, result of presence of epinephrine causes dilation

total pulmonary ventilation

volume of air moved into and out of the lungs each minute

COPD (chronic obstructive pulmonary diseases)

chronic disease of the lungs, where bronchioles can collapse/close off before a forced expiration is completed, where constriction of airways and difficulty in breathing can occur

ex: emphysema, chronic bronchitis

Why we need Oxygen

O2 is necessary for aerobic cellular respiration, for production of ATP from glucose

When CO2 is present, it affects the ability of hemoglobin to bind oxygen, as CO2 is an allosteric inhibitor to O2 binding hemoglobin

Order of Air Passage into Lungs

Nasal Cavity -> Pharynx -> Larynx -> Trachea -> Primary Bronchi -> Secondary Bronchus -> Bronchiole -> Alveoli -> Pulmonary Capillaries adjacent to the Alveoli

Label 17.2a

Label 17.2e

How do Upper Airways Condition Air

- Temperature Control (Warming air)

- Humidify (Adding water vapor until air reaches 100% humidity, so moist exchange epithelium does not dry out)

- Filters out Foreign Material (so that viruses, bacteria, and inorganic particles do not reach alveoli)

Partial Pressure Gradients

Gases always flow down their own partial-pressure gradients

Cause of Airflow into Lung

1) Diaphragm contracts
2) Causes lower air pressure in the thoracic cavity relative to outside of the body
2) Air moves from outside the body to lungs
3) Volume of Thoracic Cavity increases

What causes air to move into the lungs (Inspiration)

Pressure Decrease in Thoracic Cavity (due to higher volume)

What causes Expiration of Air

Pressure Increase in Thoracic Cavity (due to lower volume)

Respiratory Volumes

Ex: What is used for B-Day Cake:

Ans: Vital Capacity (Inspiratory Capacity [ Inspiratory Reserve Volume + Tidal Volume]) + Expiratory Reserve Volume

Bronchoconstriction/Bronchodilation Effect on Tidal Volume:

Bronchoconstriction increases resistance to air flow and decreases the amount of fresh air reaching the alveoli

Bronchodilation: increased CO2 in expired air relaxes bronchiolar smooth muscle, causes bronchodilation

Factors for Bronchi Dilation

Histamine Presence: causes bronchial constriction

Parasympathetic causes Bronchoconstriction

Stimulation of Beta-2 Receptors: bronchodilation