Ch. 24 Physiology of the Respiratory System
*ADEGQUATE AND EFFICIENT REGULATION OF GAS EXHANGE BETWEEN BLOOD AND CELLS UNDER CHANGING CONDITIONS*
Discuss the primary goal of respiratory physiology.
2.Gas exchange in lungs and cells*
3.Transportation of gases
4.Regulation of respiration
list 4 major processes involced in repiratory physiology.
define pulmonary ventilation.
1. inspiration: moves air into lungs
2. expiration: moves air out of lungs
list and define the phases in pulmonary ventilation.
BASIC PRINCIPLE: ESTABLISH A PRESSURE GRADIENT BETWEEN ATMOSPHERE AND ALVEOLI OF LUNGS
- Atmospheric Pressure Constant At Sea Level (760 mm Hg)
- Establishing a Pressure Gradient Means Changing the Pressure Within the Alveoli
discuss the basic principle of pulmonary ventilation. In establishing the pressure gradient between atmosphere and alveoli, where does pressure have to be changed? Why?
‑ Boyle's Law: Pressure and Volume are Inversely Relate as Long as Temperature is Held Constant
‑ When Volume Increases, Pressure Decreases (as Long as Temp. is Constant)
‑ This Occurs in Inspiration: Size of Thoracic Cavity(and Alveoli) Increases, Pressure Within Thoracic Cavity (and Alveoli) Decreases (Becomes Less Than Atmospheric), Air Moves into Alveoli
‑ Likewise, When Volume Decreases, Pressure Increases(as Long as Temp. is Constant)
‑ This Occurs in Expiration: Size of Thoracic Cavity(and Alveoli) Decreases, Pressure Within Thoracic Cavity (and Alveoli) Increases (Becomes Greater Than Atmospheric), Air Moves out of Alveoli
Discuss how the pressure gradient is established by changing the size of the thoracic cavity. Include a discussion of Boyles' Law.
Importance of Compliance and Elastic Recoil of Lungs/Thorax
- Compliance: Stretch; Important in Inspiration
- Elastic Recoil: Return to Resting; Important in
Define compliance and elastic recoil as related to the repiratory system. Hoe is each important with respect to pulmonary ventilation?
‑ Respiratory Muscles (Normal Quiet Breathing)
‑ Diaphragm (Chief):When Contracts, Moves Down; This Increases the Size of the Thoracic Cavity from Top to Bottom When Relaxes Moves Back Up to Original Position
- External Intercostals:When Contract, Elevate the Ribs; This Increases the Size of the Thoracic Cavity from Front to Back and from Side to Side
When Relax, Depress the Ribs
‑ Additional Respiratory Muscles (Forced Breathing)
‑ Forced Inspiration: Sternocleidomastoid, Serratus Anterior, Pectoralis Minor ‑ Forced Expiration: Abdominal Muscles (4), Internal Intercostals
List the respiratory muscles involved in quite breathing as well as in forced breathing and dicuss how the size of the thoracic cavity is changed by contraction and relaxation of these muscles
Respiratory Muscles Contract ‑‑‑‑‑> Size of Thoracic Cavity (and Lungs) Increases ‑‑‑‑‑> Pressure Decreases (Intrathoracic and Intra‑alveolar) ‑‑‑‑‑>Inspiration Occurs
Respiratory Muscles Relax ‑‑‑‑‑> Size of Thoracic Cavity (and Lungs) Decreases ‑‑‑‑‑> Pressure Increases (Intrathoracic and Intra‑alveolar) ‑‑‑‑‑>
Summarize the basic mechanism of inspiration and expiration.
Intrathoracic/Intrapleural Pressure: Normally Negative(Less Than Atmospheric)--->Prevents Collapse of Alveoli(Negative Pressure Lost in Pneumothorax)
Define intrathoracic/intrapleural pressure. what is the normal intrathoracic.intrpreural pressure?
Amounts of Air Moved In and Out of the Lungs & Remaining in the Lungs During Breathing
Define pulomonary volumes (lung volumes).
SPIROMETER‑ Apparatus Used to Measure Pulmonary Volumes
‑ Produces Spirogram: Graphic Record of Pulmonary Volumes
Define spirometer and spirogram.
1.TIDAL VOLUME (TV) ‑ Volume of Air Expired After a Normal (Typical) Inspiration‑ Average: 500 ml
2.EXPIRATORY RESERVE VOLUME (ER)‑ Largest Additional Volume of Air That Can Be FORCIBLY Expired (Over and Above a Normal Expiration)‑ Average: 1000ml‑1200ml
3.INSPIRATORY RESERVE VOLUME (IRV)‑ Largest Additional Volume of Air That Can Be FORCIBLY Inspired (Over and Above a Normal Inspiration) ‑ Average: 3000ml‑3300ml
4.RESIDUAL VOLUME (RV)‑ Volume of Air That Remains in the Lungs After ERV Expired (Volume of Air That Can't Be Forcibly Expired)‑ Average: 1200 ml
5. MINIMAL VOLUME (MV) ‑ The Percentage of RV That Remains After the Majority of RV is Eliminated‑ 40% of RV
List and Discuss 5 important pulmonary volumes
sum of 2 or more pulomary volumes
Define pulmonary capacities.
a. DEFINITION ‑ The Largest Volume of Air an Individual CAN MOVE IN AND OUT of the Lungs;
VC = IRV + TV + ERV
‑ Average: 4500‑5000 ml
b. FACTORS THAT DETERMINE:
1. Sex: VC Higher in Males
2. Size: The Larger the Person the Higher the VC
3. Age: VC Decreases With Age
4. Posture: VC is Highest When Standing Erect
5. General Health/Health Habits: VC Higher When General Health/ Health Habits Are Good(i.e., No Pre‑existing Disease, Exercise,Non‑smoker)*these Are Just a FEW of the MANY FactorsThat Affect VC
discuss the pulmonary capacity, vital capacity (VC)
2.INSPIRATORY CAPACITY (IC)‑The Maximal Amount of Air an Individual Can Inspire (After a Normal Expiration);IC = TV + IRV ‑ 3500‑3800 ml
3. FUNCTIONAL RESIDUAL CAPACITY (FRC)‑ The Amount of Air Left in the Lungs After a Normal Expiration; FRC = ERV + RV ‑ Average: 2200‑2400 ml
4. TOTAL LUNG CAPACITY (TLC)‑ The Total Volume of Air the Lungs CAN HOLD;
TLC = IRV + TV + ERV+ RV (Compare This Formula to the Formula For VC) ‑ Average: 5700‑6200 ml
discuss the pulmonary capacities, inspiratory capacity(IC), Functional residual capacity (FRC), and total lung capacity (TLC)
‑The Volume of Air That ACTUALLY REACHES THE ALVEOLI in a Normal Inspiration
‑Average: 70% of TV
‑Importance: It is Only This Volume That ACTUALLY TAKES PART IN GAS EXCHANGE
Define, give the average % and discuss the importance of alveolar ventilation.
All Respiratory Passageways EXCEPT the Alveoli; Contains Dead Air
-Dead Air: The Volume of Air That DOES NOT REACH THE Alveoli in a Normal Inspiration; Average: 30% of TV
Define anatomical dead space and dead air. Give the average % for dead air.
‑ Definition: Pressure Exerted By Any One Gas When Contained in a Mixture of Gases‑Example: Atmosphere
‑ How Determined? Multiply the Concentration of the Gas in the Mixture (%) by the Total Pressure of the Mixture
‑ Why Important?
1) Because Gases Usually Occur in a Mixture (Atmosphere,Lungs, Blood)
2) Because Gas Exchange Occurs Due to Pressure Differences(Partial Pressure Differences) of Gases
‑ How Abbreviated? P + Chemical Symbol for the Gas
Define partial pressure of gases. Discuss how partial pressure is determined, why its important, and how its abbreviated.
1.OCCURS WHERE? Between Alveolar Air and Blood in Lung Caps
2.WHAT OCCURS AND WHY?
‑ What?‑ 02 Diffuses From Alveolar Air ‑‑‑> Blood in Lung Caps
‑ C02 Diffuses From Blood in Lung Caps ‑‑‑> Alveolar Air
‑ Why? Because of Pressure Gradients of Gases Between These 2 Areas
3.RESULTS ‑Blood in Lung Caps Changes From Unoxy. to Oxyg.
Discuss the mechanism of pulmonary gas exchange.
1.OXYGEN PRESSURE GRADIENT BETWEEN ALVEOLAR AIR AND BLOOD
‑ There's a Direct Relationship Between the 02 PG (Between Alveolar Air and Blood) and the Amount of 02 That Diffuses into Blood
2.TOTAL FUNCTIONAL SURFACE AREA OF RESPIRATORY MEMBRANE
‑ Resp. Membrane: Walls of the Alveoli and the Lung Caps
‑ There's a Direct Relationship Between the Total Functional Surface Area of Resp. Membrane and the Amount of 02 That Diffuses into Blood
3.RESPIRATORY MINUTE VOLUME
‑ Definition: RMV = Vol Inspired/Resp x Resps/Min (Vol/Min)‑ There's a Direct Relationship Between RMV and the Amount of 02 That Diffuses into Blood
4.ALVEOLAR VENTILATION‑ There's a Direct Relationship Between Alveolar Ventilation and the Amount of 02 that Diffuses into Blood
Discuss 4 structural facts that faciliatae oxygen diffusion from alveolar air into blood.
1.TRANSPORTED AS SOLUTE (Dissolved)
2.TRANSPORTED AS OXYHEMOGLOBIN (Oxygen + Hemoglobin)-Primary Way Oxygen is Transported
Discuss 2 ways that oxygen is transported in blood. Which is most important?
1. TRANSPORTED AS CARBAMINOHEMOGLOBIN (Carbon Dioxide +Hemoglobin)
2. TRANSPORTED AS BICARBONATE IONS - Primary Way Carbon Dioxide is Transported, helps maintain blood pH
Discuss 3 ways carbon dioxide is transported in blood. Which is most important?
Blood Levels of Each
1) If Blood PO2 is Increased à Hemoglobin Carries O2
(Increased Blood PO2 Increases the Assoc. B/T Hemoglobin and O2)
2)If Blood PCO2 is Increased à Hemoglobin Carries CO2
(Increased Blood PCO2 Increases the Assoc. B/T Hemoglobin and CO2)
Discuss what determines whether hemoglobin prefers to carry oxygen or carbon dioxide, listing 2 specific examples.
gas exchange in cells
Define systemic gas exchange.
1.OCCURS WHERE? Between Blood in Tissue Caps and Cells
2.WHAT OCCURS AND WHY?
‑ What?‑ 02 Diffuses From Blood in Tissue Caps ‑‑‑> Cells
‑ C02 Diffuses From Cells ‑‑> Blood in Tissue Caps
‑ Why? Because of Pressure Gradients of Gases Between These2 Areas
3.RESULTS ‑Blood in Tissue Caps Changes from Oxyg. to Unoxyg.
dicuss the mechanism of systemic gas exchange.
*GE in Cells is Regulated By the Rate of Catabolism in Cells
What regulates gas exchange in cells? explain how.
As 02 Diffuses into Cells and C02 Diffuses into Blood, This Increases the Unloading of 02 From Hemoglobin and Increases the Loading of C02 onto Hemoglobin
Explain the principle behind this statement and why this is so important.
BOHR EFFECT‑ Increased PC02 Decreases the Affinity Between 02 and Hemoglobin
HALDANE EFFECT‑ Decreased P02 Increases the Affinity Between C02 and Hemoglobin
Define Bohr and Haldane Effect. Explain how these relate to systemic gas excahnge.
A. By reflex (nervous) mechanism
B. By cerebal cortex
C. By unknown unestablished factors
*reflex mechanism is most important
List 3 ways resporation is regulated. Which is the most important?
a. ARTERIAL BLOOD PCO2‑ MAJOR STIMULUS for the Breathing Reflex
(i.e., CO2 is the MAJOR REGULATOR of Respirations)
‑ When Increased Slightly, Increases Respirb. b. ARTERIAL BLOOD pH‑ When Decreased, Stimulates Respirations‑ Note: Decreased pH Associated with Increased Co2
c.ARTERIAL BLOOD PO2‑ Backup Regulator of Respirations (Emergency)‑ When Decreased a Large Amount, Increases Respirations
d.ARTERIAL BLOOD PRESSURE‑ When Decreased, Stimulates Respirations
Discuss how arterial blood PCO2, arterial blood pH, arterial blood PO2, and arterial blood pressure act as stimuli for the respiratory reflex. Which of these if most important as a stimulus for the respiratory reflex?
a.MEDULLA ‑ MEDULLARY RHYTHMICITY AREA
1.INSPIRATORY CENTER: Major Respiratory Center‑ When Stimulated, Causes Inspiration; When Inhibited, Causes Expiration
2.EXPIRATORY CENTER‑ Important in Forced Expiration
b.PONS ‑ APNEUSTIC AND PNEUMOTAXIC CENTERS‑ Apneustic Center: Controls Length and Depth of Inspiration
Pneumotaxic Center: Controls Rhythm of Breathing
List and discuss the respiratory control centers located in the medulla and the pons. Which of these is considered the major respiratory center?
EFFECTORS ‑ RESPIRATORY MUSCLES
* The Respiratory Reflex (CO2 as Stimulus)
Discuss the repiratory reflex with CO2 as a stimulus.
‑ Cerebral Cortex Provides Limited, Voluntary Control of Respirations
Discuss the role of the cerebral cortex in the control of respiration.