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Respiratory Processes
Virginia Tech BMVS 4065
50
Physiology
Undergraduate 4
04/25/2008

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Cards

Term
What are the Functions of the Respiratory System?
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.

Term
What are the Major Components of the Respiratory System?
Definition

1. The Respiratory Muscles

2. The lungs

3. The CNS (Central Nervous System) 

Term
Most respiratory organs are concerned with what part of the respiratory process?
Definition
Ventilation (movement of air through respiratory passages)
Term
On expiration, air  is released from what area first?
Definition
The dead space.
Term
How does air flow velocity change through the respiratory tract?
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.
Term
What are the 4 functions of the Respiratory System? 
Definition

Ventilation

Diffusion

Perfusion (Circulation)

Blood Gas Transport (Exchange) 

Term
What factors does Efficient Pulmonary Gas Exchange depend on?
Definition

Adequate Ventilation Volume

Even Ventilation Distribution

Adequate Gas Diffusion

Adequate Perfusion

Adequate Air and Circulatory Pumps 

Term
What Pressures are involved in breathing?
Definition

Atmospheric Pressure

Alveolar Pressure: Referenced to Atmospheric

Pleural Pressure: Referenced to Atmospheric

Transpulmonary Pressure: Alveolar - Pleural 

Term
What are the Respiratory Muscles?
Definition

Diaphragm: Contracts every inspriation, relaxation causes passive expiration.

 

Active Expiration Muscles: Internal Intercostal Muscles, Abdominal Muscles

 

Accessory Muscles of Inspriation: Sternocleidomastoid, Scalenus 

Term
What causes Inspriation and Expiration?
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.
Term
What effect does the diaphragm have on inspiration / expiration?
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. 

Term
How do respiratory pressures change during inspiration?
Definition

Pleural Pressure and Alveolar become more negative 

Term
Describe the relationship between the lungs and chest wall.
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.
Term
How is a Pneumothorax treated?
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.
Term
What are the four lung capacities?
Definition

Inspiratory Capacity (IC)

Functional Residual Capacity (FRC)

Vital Capacity (VC)

Total Lung Capacity (TLC)

 

Term
What are the four lung volumes?
Definition

Tidal Volume (TV)

Inspiratory Reserve Volume (IRV)

Expiratory Reserve Volume (ERV)

Residual Volume (RV) 

Term
What is VC used for clincally?
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) 
Term
Why is RV important?
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.
Term
What comprises Dead Space Volume?
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 
Term
Efficiency of Pulmonary Ventilation depends on what?
Definition
Total Ventilation
Dead Space Volume
Respiratory Rate 
Term
What's a condition that can cause low compliance? High compliance?
Definition

Fibrosis

Emphysema 

Term
What properties influence lung elastic recoil?
Definition

Elastic fibers of the lungs.

 

Surface tension of fluid lining the alveoli (tries to collapse) 

Term
What can we infer about the collapsing pressure of an alveoli from it's size?
Definition
Larger alveoli (greater radius) have lower collapsing pressures, and are thus easier to keep open than smallern alveoli.
Term
What helps prevent Alveoli from collapsing?
Definition
Alveoli are linked together and to airways distributing forces among them. Lung Surfactants also help.
Term
What disorders can affect Chestwall Compliance?
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. 
Term
How can the ANS alter airway resistance?
Definition

Parasympathetic can use Acetylcholine causing constriction.

 

Sympathetic can use Epinephrine for Dilation or Norepinephrine for Constriction 

Term
Where is airflow resistance greatest?
Definition
Large and medium airways where turbulent flow occurs.
Term
What factors determine how much work it takes to breathe?
Definition

Compliance of Lungs and Thoracic Cavity

Surface Tension of Alveoli

Airway Resistance 

Term
What is the difference between Ventilation and Respiration?
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. 

Term
What diseases can affect ventilation?
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 
Term
How does Pulmonary Circulation differ from Systemic Circulation?
Definition
Serves one organ (the lung)
One main function (gas exchange)
Little control
Low pressure head
Low resistance
Short hydrostatic columns 
Term
Pulmonary Blood Flow is controlled mainly by:
Definition
Alveolar Oxygen
 
Changes in Lung Volume

Changes in Pulmonary Resistance
Term
A small increase in pulmonary arterial pressure causes:
Definition
Marked decrease in pulmonary resistance in lung
 
Marked increase in pulmonary blood flow 
Term
The shape of the Lung Volume / Vascular Resistance curve is:
Definition
A parabola. Decreasing or increasing lung volume from the median point increases vascular resistance.
Term
What theories are there to explain the Hypoxia-Induced Pulmonary Vasoconstriction mechanism?
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. 

Term
How is pulmonary blood flow normally distributed?
Definition

Evenly when supine

 

Unevently when standing due to gravity, which pulls blood towards the base of the lung. 

Term
What are factors than decrease the pathway for diffusion?
Definition
Intra-alveolar edema
Thickening of the alveolar wall
Interstitial edema
Thickened capillary endothelium
Capillary dilation 
Term
What determines the rate of Pulmonary Gas Diffusion?
Definition
Weight and Solubility of the Gas (diffusion coeff.)
Surface Area Available for Diffusion
Diffusion Distance 
Diffusion Pressure Gradient 
Term
What is the Mean RBC Capillary Transit Time? Minimum RBC Oxygen Equilibrium Time?
Definition
0.75 seconds, 0.25 seconds
Term
During rest, when does the alveolus and a RBC achieve oxygen equilibrium? During exercise?
Definition

1/3 of the way through the alveolar capillary

 

During exercise equilibrium is achieved further along due to increased cardiac output. 

Term
How is oxygen transported through the body?
Definition

Physically Dissolved Oxygen (3%)

Chemically Bound Oxygen (97%, bound to hemoglobin) 

Term
What is the average percentage of red blood cells in blood? What are conditions describing deviations in this percentage?
Definition
48%, anemia is a decrease in RBC percentage, polycythemia is an increase
Term
What is the average content of 100 ml of blood? What is the oxygen carrying capacity?
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 
Term
What contributes to the partial pressure of oxygen PO2?
Definition
Only physically dissolved oxygen, not chemically bound.
Term
What is the average difference between Arterial and Venous PO2, Hb saturation, O2 bound to Hb, and Total O2 content?
Definition
PO2 = 100 mmHg, Hb Sat = 22.5%, O2 bound to Hb = 4.5 mL/dL, Total O2 = 4.7%
Term
How does HbO2 affect the loading/unloading of CO2?
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.
Term
Cutting at what transection of the brainstem causes apnea? Ie. contains the inspiratory and expiratory neurons.
Definition
The Medulla.
Term
How do Glomus Cells respond to Hypoxia, Hypercapina and Acidosis?
Definition
Inhibition of Potassium channels, rise in glomus cell Calcium and release of neurotransmitters (probably dopamine)
Term
When do the Arterial Peripheral Chemoreceptors stimulate breathing? How does PCO2 affect this?
Definition
When PO2 drops below 60 mmHg, breathing is stimulated. The higher the PCO2 content, the greater volume of air brought in per minute.
Term
When do Central Chemoreceptors stimulate breathing?
Definition
When pH decreases from an increase in PCO2
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