Module 2M-A

Blood

Specialized organ that differs from other organs in that it exists in a fluid state. Composed of plasma and various types of cells.

Erythrocytes (RBC)

• transport oxygen from lung to tissues.

• transport carbon dioxide from tissues to lungs.

Hematocrit

% total blood volume (RBC)

Hemoglobin

Iron-containing protein of RBC, delivers oxygen to tissues, consists of four polypeptide chains (globin) and four heme group

Globin

4 protein molecules that bound with iron in heme to form hemoglobin or myoglobin

Heme

pigmented iron is present, non protein able to bind O2 loosely and reversibly

Oxyhemoglobin

combined O2 + hemoglobin, found in arterial blood brighter red than hemoglobin, dissociates easily when O2 concentration is low

Diffusion

Exchange of gas molecules (O2 and CO2) from areas of high concentration to areas of low concentration.

Perfusion “Pulmonary Perfusion”

• Passage of fluid through a specific organ/ area of the body.

• Filling of pulmonary capillaries with blood.

Inspiration

Movement of diaphragm and other muscles of respiration enlarges the thoracic cavity and lowers the pressure inside the thorax to a level below that of atmospheric pressure.

Expiration

Normal state/return previous position of chest wall and diaphragm.

External Respiration

Exchange between air in the lungs and blood.

Internal Respiration

Exchange between the blood and tissues.

Compliance

Measure of the force required to expand or inflate the lungs.

High or increased compliance

lost elasticity and thorax is overdistended (ex: emphysema)

Low or decreased compliance

stiff lungs and thorax (ex: pneumothorax,etc.)

Lung Recoil

The tendency for the lungs to decrease in size as they are stretched

Intrapulmonary Pressure

within the alveoli; constant rise and fall

Intrapleural Pressure

within pleural space; less than the intrapulmonary pressure

Cough Reflex

Reflex triggered by sensation of bronchus from glossopharyngeal nerve and sensory ending in the larynx, trachea, and bronchus.

Reflex bronchoconstriction

In response to the inhalation of large irritating substances (e.g., dust, aerosols), the bronchi constrict in an effort to prevent entry of the irritants

Lung Volumes

Directly measured; volume of gas in the lungs at a given time during the respiratory cycle.

Lung Capacities

Are inferred from lung volumes; Composites of 2 or more lung volumes. They are fixed as they do not change with the pattern of breathing.

Tidal Breathing

Resting breathing; Determined both by the depth of inspiration and by the end point of passive exhalation.

Tidal Volume

• The volume of air inspired/expired during normal breathing.

• Normal volume is 500 mL.

Inspiratory Reserve Volume (IRV)

• The maximum volume of air that can be inhaled after a normal exhalation.

• Normal value is 3,100 mL

Expiratory Reserve Volume (ERV)

• The maximum volume of air that can be exhaled forcibly after a normal exhalation.

• Normal value is 1,200 mL

Residual Volume (RV)

• The volume of air remaining in the lungs after a maximum exhalation.

• Normal value is 1,200 mL

Vital Capacity (VC)

• The maximum amount of air exhaled from the point of maximum inspiration.

• Normal value is 4,800 mL

Vital Capacity (VC)

TV + IRV + ERV

Inspiratory Capacity (IC)

• The maximum volume of air inhaled after normal expiration.

• Normal value is 3600 mL

Inspiratory Capacity (IC)

TV + IRV

Functional Residual Capacity (FRC)

• The volume of air remaining in the lungs after a normal expiration.

• Normal value is 2400 mL

Functional Residual Capacity (FRC)

ERV + RV

Total Lung Capacity (TLC)

• The volume of air in the lungs after a maximum inspiration.

• Normal value is 6000 mL

Total Lung Capacity (TLC)

TV + IRV + ERV + RV

Composition of Inspired Air

• Nitrogen (N) - 78.6%

• Oxygen (O2) - 20.8%

• Carbon Dioxide (CO2) - 0.04%

• Water Vapor - 0.05%

• Helium (He)

• Argon (Ar)

Hypoxemia

Decreased partial pressure in blood and oxygen available to the body or an individual tissue or organ.

Normal Ratio

A given amount of blood passes an alveolus and is matched with an equal amount of gas.

Low Ventilation-Perfusion Ratio (Shunts)

• Blood bypasses the alveoli without gas exchange occurring.

• When perfusion exceeds ventilation.

High Ventilation-Perfusion Ratio (Dead Space)

• The alveoli do not have an adequate blood supply for gas exchange to occur.

• When ventilation exceeds perfusion.

Silent Unit

Absence/limited ventilation and perfusion.

Shunting

Portion of cardiac output that does not exchange with alveolar air.

Dead Space

Portion of ventilation that does not exchange with an intact capillary (wasted ventilation).

Oxygen

• 98.5% in combination with Hgb

• 1.5% dissolved in plasma

Carbon Dioxide

• 23% is combined with Hgb

• 7% dissolved in plasma

• 70% as carbonate ions

Deoxyhemoglobin

Hemoglobin with no oxygen

Carbaminohemoglobin

Hemoglobin transporting carbon dioxide

Carboxyhemoglobin

Hemoglobin with carbon monoxide