Term
| What are the Functions of the Respiratory System? |
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Definition
Primary: Gas Exchange System Secondary: Aiding in acid-base balance. Defends the body against inhaled particles. Acts as a filter to prevent clots from entering the systemic circulation. Regulate hormonal and humoral concentrations using the pulmonary vascular endothelium. |
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Term
| What are the Major Components of the Respiratory System? |
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Definition
1. The Respiratory Muscles 2. The lungs 3. The CNS (Central Nervous System) |
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Term
| Most respiratory organs are concerned with what part of the respiratory process? |
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Definition
Ventilation (movement of air through respiratory passages) |
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Term
| On expiration, air is released from what area first? |
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Definition
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Term
| How does air flow velocity change through the respiratory tract? |
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Definition
It moves by bulk flow at high velocity through the pharynx to the terminal bronchioles. From there on the velocity decreases quickly ending with movement by diffusion at the alveoli. |
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Term
| What are the 4 functions of the Respiratory System? |
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Definition
Ventilation Diffusion Perfusion (Circulation) Blood Gas Transport (Exchange) |
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Term
| What factors does Efficient Pulmonary Gas Exchange depend on? |
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Definition
Adequate Ventilation Volume Even Ventilation Distribution Adequate Gas Diffusion Adequate Perfusion Adequate Air and Circulatory Pumps |
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Term
| What Pressures are involved in breathing? |
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Definition
Atmospheric Pressure Alveolar Pressure: Referenced to Atmospheric Pleural Pressure: Referenced to Atmospheric Transpulmonary Pressure: Alveolar - Pleural |
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Term
| What are the Respiratory Muscles? |
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Definition
Diaphragm: Contracts every inspriation, relaxation causes passive expiration. Active Expiration Muscles: Internal Intercostal Muscles, Abdominal Muscles Accessory Muscles of Inspriation: Sternocleidomastoid, Scalenus |
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Term
| What causes Inspriation and Expiration? |
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Definition
Inspiratory neurons fire activating the motor neurons that supply the inspiratory muscles. Once the inspiratory neurons cease firing, the motor neurons are no longer activated causing expiration. Expiration is normally passive, accomplished by relaxing muscles of inspiration. |
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Term
| What effect does the diaphragm have on inspiration / expiration? |
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Definition
During inspriation it contracts increasing thoracic cavity volume resulting in a decrease in pressure causing air to rush into the lungs. During expiration it relaxes reducing volume of thoracic cavity increasing pressure forcing air out of the lungs. |
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Term
| How do respiratory pressures change during inspiration? |
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Definition
Pleural Pressure and Alveolar become more negative |
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Term
| Describe the relationship between the lungs and chest wall. |
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Definition
The lungs have an inward elastic recoil that wants to collapse them while the chest wall has an outward elastic recoil to balance. These generate a subatmospheric (negative) intrapleural pressure. |
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Term
| How is a Pneumothorax treated? |
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Definition
The air must be removed from the pleural space. For less serious cases a syringe can be used. If more than 30% of a lung collapses, a thorcostomy tube is typically placed in the second intercostals space to re-expand the lung. |
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Term
| What are the four lung capacities? |
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Definition
Inspiratory Capacity (IC) Functional Residual Capacity (FRC) Vital Capacity (VC) Total Lung Capacity (TLC) |
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Term
| What are the four lung volumes? |
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Definition
Tidal Volume (TV) Inspiratory Reserve Volume (IRV) Expiratory Reserve Volume (ERV) Residual Volume (RV) |
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Term
| What is VC used for clincally? |
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Definition
Indicates strength of respiratory muscles and pulmonary compliance. Changes with paralysis of respiratory muscles, increased pulmonary compliance, pulmonary vascular congetsoin, left hard failure (pulmonary edema) |
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Term
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Definition
Reduces alveolar opening pressure and the work of breathing. O2 buffer inbetween breaths. Increases with age, anesthesia, emphysema, and bronchitis. Decreases with obesity and pregnancy.
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Term
| What comprises Dead Space Volume? |
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Definition
Anatomic dead-space volume: due to lung anatomy, 30% of total ventilation wasted here.
Alveolar dead-space volume: alveoli that receive inadequate blood flow, no perfusion. Equipment dead space volume |
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Term
| Efficiency of Pulmonary Ventilation depends on what? |
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Definition
Total Ventilation Dead Space Volume Respiratory Rate |
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Term
| What's a condition that can cause low compliance? High compliance? |
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Definition
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Term
| What properties influence lung elastic recoil? |
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Definition
Elastic fibers of the lungs. Surface tension of fluid lining the alveoli (tries to collapse) |
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Term
| What can we infer about the collapsing pressure of an alveoli from it's size? |
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Definition
| Larger alveoli (greater radius) have lower collapsing pressures, and are thus easier to keep open than smallern alveoli. |
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Term
| What helps prevent Alveoli from collapsing? |
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Definition
| Alveoli are linked together and to airways distributing forces among them. Lung Surfactants also help. |
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Term
| What disorders can affect Chestwall Compliance? |
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Definition
Extreme Obesity Abdominal Disorders resulting in marked elevation of the Diaphragm Skeletal Muscle Disorders resulting in plasticity or rigidity of the thoracic or abdominal musculature. |
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Term
| How can the ANS alter airway resistance? |
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Definition
Parasympathetic can use Acetylcholine causing constriction. Sympathetic can use Epinephrine for Dilation or Norepinephrine for Constriction |
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Term
| Where is airflow resistance greatest? |
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Definition
| Large and medium airways where turbulent flow occurs. |
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Term
| What factors determine how much work it takes to breathe? |
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Definition
Compliance of Lungs and Thoracic Cavity Surface Tension of Alveoli Airway Resistance |
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Term
| What is the difference between Ventilation and Respiration? |
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Definition
Ventilation involves contraction of the respiratory muscles, changes of the thorax, and movement of air through the airways and into the alveoli Respiration involves gas exchanges at either the alveolar-capillary level or tissue-cellular level. |
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Term
| What diseases can affect ventilation? |
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Definition
Inadequate muscle contraction - either failure to stimulate or failture to respond to stimulation. Rigidity of Chest Wall - difficult to increase thoracic volume Flaccidity of Chest Wall - reduced efficiency of inspiration. Stiffness of Lung Parenchyma - decreased lung compliance |
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Term
| How does Pulmonary Circulation differ from Systemic Circulation? |
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Definition
Serves one organ (the lung) One main function (gas exchange) Little control Low pressure head Low resistance Short hydrostatic columns |
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Term
Pulmonary Blood Flow is controlled mainly by: |
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Definition
Alveolar Oxygen Changes in Lung Volume
Changes in Pulmonary Resistance
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Term
| A small increase in pulmonary arterial pressure causes: |
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Definition
Marked decrease in pulmonary resistance in lung Marked increase in pulmonary blood flow |
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Term
| The shape of the Lung Volume / Vascular Resistance curve is: |
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Definition
| A parabola. Decreasing or increasing lung volume from the median point increases vascular resistance. |
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Term
| What theories are there to explain the Hypoxia-Induced Pulmonary Vasoconstriction mechanism? |
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Definition
Hypoxia stimulates production of local vasoconstrictors Hypoxia supresses production of local vasodilators Hypoxia affects pulmonary vascular smooth muscle, closing potassium channels, depolarizing calcium channels causing constriction of vascular smooth muscle. |
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Term
| How is pulmonary blood flow normally distributed? |
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Definition
Evenly when supine Unevently when standing due to gravity, which pulls blood towards the base of the lung. |
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Term
| What are factors than decrease the pathway for diffusion? |
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Definition
Intra-alveolar edema Thickening of the alveolar wall Interstitial edema Thickened capillary endothelium Capillary dilation |
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Term
| What determines the rate of Pulmonary Gas Diffusion? |
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Definition
Weight and Solubility of the Gas (diffusion coeff.) Surface Area Available for Diffusion Diffusion Distance Diffusion Pressure Gradient |
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Term
| What is the Mean RBC Capillary Transit Time? Minimum RBC Oxygen Equilibrium Time? |
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Definition
| 0.75 seconds, 0.25 seconds |
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Term
| During rest, when does the alveolus and a RBC achieve oxygen equilibrium? During exercise? |
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Definition
1/3 of the way through the alveolar capillary During exercise equilibrium is achieved further along due to increased cardiac output. |
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Term
| How is oxygen transported through the body? |
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Definition
Physically Dissolved Oxygen (3%) Chemically Bound Oxygen (97%, bound to hemoglobin) |
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Term
| What is the average percentage of red blood cells in blood? What are conditions describing deviations in this percentage? |
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Definition
48%, anemia is a decrease in RBC percentage, polycythemia is an increase
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Term
| What is the average content of 100 ml of blood? What is the oxygen carrying capacity? |
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Definition
Blood normally contains 15 gm of Hb / 100 mL. Each hemoglobin can normally combine with 1.34 mL of oxygen. Oxygen carrying capacity is the maximal amount of oxygen that can be carried in the blood by hemoglobin. 15 gm Hb * 1.34 mL O2 = 20.1 mL oxygen / 100 mL blood |
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Term
| What contributes to the partial pressure of oxygen PO2? |
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Definition
| Only physically dissolved oxygen, not chemically bound. |
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Term
| What is the average difference between Arterial and Venous PO2, Hb saturation, O2 bound to Hb, and Total O2 content? |
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Definition
PO2 = 100 mmHg, Hb Sat = 22.5%, O2 bound to Hb = 4.5 mL/dL, Total O2 = 4.7% |
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Term
| How does HbO2 affect the loading/unloading of CO2? |
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Definition
For a given PCO2, CO2 content of blood increases as PO2 falls. The more hemoglobin that breaks from it's oxygen in transport, the more CO2 is able to be carried out by the same hemoglobin.
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Term
| Cutting at what transection of the brainstem causes apnea? Ie. contains the inspiratory and expiratory neurons. |
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Definition
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Term
| How do Glomus Cells respond to Hypoxia, Hypercapina and Acidosis? |
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Definition
| Inhibition of Potassium channels, rise in glomus cell Calcium and release of neurotransmitters (probably dopamine) |
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Term
| When do the Arterial Peripheral Chemoreceptors stimulate breathing? How does PCO2 affect this? |
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Definition
When PO2 drops below 60 mmHg, breathing is stimulated. The higher the PCO2 content, the greater volume of air brought in per minute.
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Term
| When do Central Chemoreceptors stimulate breathing? |
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Definition
| When pH decreases from an increase in PCO2 |
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