Alterations in the Pulmonary System

What is the primary function of the respiratory system:

GAS EXCHANGE 

What is the definition of gas exchange

process by which oxygen (O₂) and carbon dioxide (CO₂) move across the air–blood barrier in the lungs, involving ventilation, perfusion, and diffusion.

Other functions of pulmonary system

• Lungs serve as a host defense by providing a barrier between the inside of the body and the external environment;

• Lung is a metabolic organ that synthesizes and metabolizes certain compounds 

Lungs serve as a host defense by providing…

a barrier between the inside of the body and the external environment;

Conducting airways

• Section in which air moves as it passes between the atmosphere and the lungs (do not participate in gas exchange) 

• Warms, filters, moistens, and removes foreign materials via mucociliary blanket from air as it moves through structures 

• STRUCTURES:

  • nasal passages

  • mouth and pharynx

  • larynx

  • tracheobronchial tree

What Conducting airways is being described

• Preferred route of entrance for air 

• Filters, warms, humidifies air; coarse hairs filter and trap large particles from the air 

Nasal passages 

What conducting airway is being described

• Mouth is alternate airway when nasal passages are plugged or large volumes of air are needed (Exercise) 

• Oropharynx is the only opening between nose, mouth, and lungs

  • obstruction leads to immediate cessation of ventilation 

mouth and pharynx

What is an alternate airway when nasal passages are plugged or large volumes of air are needed (Exercise) 

mouth

What is the only opening between nose, mouth, and lungs- obstruction leads to immediate cessation of ventilation 

oropharynx

What conducting airway is being described

• Connects oropharynx with trachea between upper airways and lungs 

• Two functions: speech & protecting the lungs from foreign substances 

• Epiglottis is located above the larynx- opens during breathing and closes during swallowing to keep foreign substances out 

• Substances other than air (liquid, food, etc.) that enter the airway are not easily removed. When they enter the lungs, aspiration(choking) pneumonia can occur  

larynx

What are the two functions of the larynx

speech & protecting the lungs from foreign substances 

What is located above the larynx- opens during breathing and closes during swallowing to keep foreign substances out 

epiglottis

Substances other than air (liquid, food, etc.) that enter the airway are not easily removed. When they enter the lungs, what can occur

aspiration(choking) pneumonia can occur  

What conducting airway is being described here

• Trachea

  • “windpipe;” connects larynx with major bronchi 

• Bronchi

  • right and left mainstem bronchus; carina is a highly sensitive area between bronchi; each bronchus enters the lungs through a slit called the hilum; bronchi divide into segments and get smaller at the distal ends 

• Bronchioles

  • Segmental bronchi continue to branch until they become the smaller, terminal bronchioles. Bronchospasm can narrow these conducting airways and impair airflow. 

Tracheobronchial Tree  

What is the

“windpipe;” connects larynx with major bronchi 

trachea

What is the

• right and left mainstem bronchus;

• carina is a highly sensitive area between bronchi;

• each bronchus enters the lungs through a slit called the hilum;

• bronchi divide into segments and get smaller at the distal ends 

bronchi

What is a highly sensitive area between the bronchi

carina

each bronchus enters the lungs through a slit called the

hilum

What are..

segmental bronchi continue to branch until they become the smaller, terminal bronchioles. Bronchospasm can narrow these conducting airways and impair airflow. 

bronchioles

Lungs & Respiratory Airways 

• Area of gas exchange 

• Other functions: inactivate vasoactive substances such as bradykinin, convert angiotensin I to angiotensin II, & serve as a reservoir for blood storage 

• Lobules

• alveoli

What are the

• Smallest functional units of lungs 

• A branch of a terminal bronchiole, an arteriole, the pulmonary capillaries, and a venule supply each lobule 

• Blood enters lobules through a pulmonary artery and exits through a pulmonary vein. 

lobules

What is the

• Specific site of gas exchange 

• Alveolar sacs are thin-walled, cup shaped structures separated from each other by thin alveolar septa. A single network of capillaries occupies most of the septa. 

• Approximately 300 million alveoli in an adult lung (large surface area) 

• Type I and Type II alveolar cells (Type II synthesize pulmonary surfactant) 

• Surfactant: Lipoprotein that reduces surface tension, allowing alveoli to stay “open” 

  • When they are open they can participate in gas exchange, they collapse when there’s no surfactant  

• Alveolar macrophages: Responsible for destroying inhaled pathogens and removing inhaled particulate matter (dust or pollen). Expelled after activation by coughing or swallowing. 

alveoli

What are

thin-walled, cup shaped structures separated from each other by thin alveolar septa. A single network of capillaries occupies most of the septa.

alveolar sacs

How many alveoli are in an adult lung (large suface area)

300 million

what is the Lipoprotein that reduces surface tension, allowing alveoli to stay “open” 

• When they are open they can participate in gas exchange, they collapse when there’s no surfactant  

surfactant

What happens when alveoli have no surfactant?

they collapse

What are alveolar macrophages

Responsible for destroying inhaled pathogens and removing inhaled particulate matter (dust or pollen). Expelled after activation by coughing or swallowing.  

What are the ..

• Thin, transparent, double-layered serous membrane lining the thoracic cavity and encasing the lungs 

• Allows for no separation between the lungs and chest wall 

• Pleural cavity is an area where inflammation can occur and exudate can accumulate. 

• Pleural effusion: fluid in the pleural space 

  • Lungs won’t be able to expand/ fill up with air  

pleura

Pleural cavity is an area where what can happen

inflammation can occur and exudate can accumulate

What is a pleural effusion?

• fluid in the pleural space 

  • Lungs won’t be able to expand/ fill up with air  

What is pulmonary vasculature

• Pulmonary circulation 

  • Review circulation of blood through the heart to and from the lungs 

    • Pulmonary arteries (only arteries that carry deoxygenated blood)

    • vs

    • Pulmonary veins(went to the lungs and got oxygenated)  

  • Participates in gas exchange 

• Bronchial circulation 

  • Distributes blood to the conducting airways and the supporting structures of the lungs 

  • Does not participate in gas exchange 

 

What is pulmonary circulation

• Review circulation of blood through the heart to and from the lungs 

  • Pulmonary arteries (only arteries that carry deoxygenated blood)

  • vs

  • Pulmonary veins(went to the lungs and got oxygenated)  

• Participates in gas exchange 

What is bronchial circulation

• Distributes blood to the conducting airways and the supporting structures of the lungs 

• Does not participate in gas exchange 

What is innervation?

• Pain fibers found only in the pleura  

  • Pain receptors ARE located in the pleura 

• No pain receptors in lung tissue= no perception of pain 

• Autonomomic nervous system, 

  • Parasympathetic nervous system stimulation (rest and digest)= airway constriction(broncoconstriction) and increased glandular secretions 

  • Sympathetic nervous system stimulation (fight or flight) = airway relaxation bronchodilation, blood vessel constriction, and inhibition of glandular secretions,  

 

Pain fibers found only in where

pleura

Are there

no pain receptors in lung tissue= no perception of pain 

true

(innervation)

Autonomomic nervous system, 

• Parasympathetic nervous system stimulation (rest and digest) =

airway constriction(bronchoconstriction) and increased glandular secretions

(innervation)

Autonomomic nervous system,

• Sympathetic nervous system stimulation (fight or flight) =

airway relaxation bronchodilation, blood vessel constriction, and inhibition of glandular secretions,  

EXCHANGE AND TRANSPORT OF GASES 

• Basic Properties of Gases 

  • Nitrogen is the most abundant gas in the air 

  • Oxygen is about 21% 

    • Room air  

  • Arterial Blood Gases 

  • Inhale O2 —> Exhale CO2 

What is the most abundant gas in the air?

nitrogen

oxygen is about how much percent

• room air

21%

What is ventilation

Movement of air into and out of the lungs. The act of breathing in and out. 

• Influenced by: 

  • Body position 

    • Easier to breathe when sitting up 

  
  

  • Lung volumes 

    • How much volume of air (how big of a breath your taking) 

  
  

  • Blockages in the airway 

    • Ex: aspirating a peppermint or mucus blocking airway 

What is ventilation influenced by

• Body position 

  • Easier to breathe when sitting up 

• Lung volumes 

  • How much volume of air (how big of a breath your taking) 

• Blockages in the airway 

  • Ex: aspirating a peppermint or mucus blocking airway 

What factors does ventilation depend on?

• pressure

• lung compliance

• airway resistance

Ventilation depends on these factors: 

• Pressure 

• Atmospheric pressure = 0 mmHg 

• Intrathoracic pressure is negative (assists to stay inflated) 

• Air moves between the lungs and atmosphere because of a pressure difference 

  • Difference in pressure keeps our lungs expanded, keeps it from collapsing  

What is the Atmospheric pressure (ventilation

0 mmHg

Is the Intrathoracic pressure, negative or positive (ventilation)

negative (assists to stay inflated) 

ventilation depends on this factor :

Air moves between the lungs and atmosphere because of..

• a pressure difference 

• Difference in pressure keeps our lungs expanded, keeps it from collapsing  

What is the..

• Ease with which the lungs can be inflated(expanded) 

  • How easily they can inflate or deflate 

• Dependent upon elastin, collagen fibers, water, and surface tension within the lungs/thoracic cavity 

• Decreased lung compliance: Stiff lungs or chest wall, lungs are difficult to inflate (pneumonia, pulmonary edema, fibrosis, ARDS) 

• Increased lung compliance: Lungs are very easy to inflate and have lost some elastic recoil (aging, emphysema) 

  • Lungs expand and can’t go back to original position  

lung compliance

Ventilation depends on this factor

What is decreased lung compliance

Stiff lungs or chest wall, lungs are difficult to inflate (pneumonia, pulmonary edema, fibrosis, ARDS) 

What is increased lung compliance

• Lungs are very easy to inflate and have lost some elastic recoil (aging, emphysema) 

  • Lungs expand and can’t go back to original position  

What is the..

• Opposition to flow caused by the forces of friction. 

  • Ex: edema,  mucus  

• Impacted by bronchial smooth muscle, lung volume, and the bronchial tree 

 

airway resistance

• ventilation depends on this factor

What is perfusion

Primary function of pulmonary circulation is to provide blood flow to gas exchange portion of lung and facilitate gas exchange.

(Remember the blood flow through the heart and lungs!) 

Perfusion:

What is pulmonary circulation

• Pulmonary artery pressure (PAP) = about 25/10 mmHg 

  • Pressure inside pulmonary arteries, lower than BP in rest of the body, it should stay low 

  • If it stays high for long time= pulmonary hypertension —> Right-sided HF(don’t need to know this just a fact) 

• Increased pressures may lead to pulmonary edema 

Pulmonary artery pressure (PAP) =

about 25/10 mmHg 

Pressure inside pulmonary arteries, lower than BP in rest of the body, it should stay low

What happens if presures increased ?

may lead to pulmonary edema

Perfusion:

What is Hypoxia-induced vasoconstriction 

• Pulmonary blood vessels are highly sensitive to hypoxia  

• Severe pulmonary vasoconstriction when oxygen levels drop to <60 mmHg 

• Prolonged hypoxia may lead to pulmonary hypertension, or pulmonale (right-sided heart failure) 

Perfusion:

What..

• Occurs when blood moves from the right to the left side of circulation without being oxygenated 

• Anatomic shunt: Blood moves from venous to arterial without moving through the lungs. May happen with some congenital heart defects. 

  • Physical defect in the heart 

• Physiologic shunt: “mismatching” of ventilation and perfusion within the lung; results in insufficient ventilation to be able to oxygenate the blood flowing through alveolar capillaries. Occurs with certain respiratory or heart diseases. 

  • Nothing anatomically wrong, blood is circulated through lungs, but something prevented it from picking up o2 

  • For example: pulmonary edema  

shunt

What kind of shunt is being descibed

• Blood moves from venous to arterial without moving through the lungs. May happen with some congenital heart defects. 

  • Physical defect in the heart 

anatomic shunt

What kind of shunt is being descibed

• “mismatching” of ventilation and perfusion within the lung; results in insufficient ventilation to be able to oxygenate the blood flowing through alveolar capillaries. Occurs with certain respiratory or heart diseases. 

  • Nothing anatomically wrong, blood is circulated through lungs, but something prevented it from picking up o2 

    • For example: pulmonary edema  

physiologic shunt

Mismatching of Ventilation & Perfusion 

• Perfusion without ventilation (Examples: Atelectasis or obstruction) 

• Ventilation without perfusion (Example: pulmonary embolism) 

What is the

• Transfer of gases between the alveoli and the pulmonary capillaries to the red blood cells. (has interstitial space lining) 

  • Increased when high concentration of oxygen is supplied  

  • Decreased with diseases that destroy lung tissue or increase the thickness of the alveolar-capillary membrane  

diffusion

When is diffusion increased?

when high concentration of oxygen is supplied  

When is diffusion decresed?

with diseases that destroy lung tissue or increase the thickness of the alveolar-capillary membrane  

What is O2 and CO2 Transport:

• the movement of oxygen molecules to the cells

• and carbon dioxide molecules to the lungs by hemoglobin attached to red blood cells (RBCs). 

  • (Lungs —> hemoglobin —> Cells) 

  • Oxyhemoglobin-

    • % of Hemoglobin bound with oxygen.

      • 95%-98% saturated with O2 in arterial blood, and

      • 75% saturated in venous blood. 

  • Carbaminohemoglobin- Hemoglobin bound with carbon dioxide 

  • Binding Affinity of Hemoglobin for Oxygen 

What is the

% of Hemoglobin bound with oxygen. 95%-98% saturated with O2 in arterial blood, and 75% saturated in venous blood. 

oxyhemoglobin

Oxyhemoglobin:% of Hemoglobin bound with oxygen.

What % is saturated with O2 in arterial blood

95%-98%

Oxyhemoglobin:% of Hemoglobin bound with oxygen

What is the % saturated in venous blood

75%

What is carbaminohemoglobin

Hemoglobin bound with carbon dioxide

Binding Affinity of Hemoglobin for Oxygen 

• The hemoglobin molecule should bind to the oxygen molecule and release it as needed to the tissues/cells. 

• Affinity- Hemoglobin’s ability to bind to oxygen. (affinity: how attracted it is to something) 

• High affinity = Hemoglobin binds more readily to oxygen 

• Decreased affinity = Hemoglobin releases the oxygen to the cells more easily 

 

• Factors increasing affinity: 

  • ___decreased____ oxygen saturation 

  • ___increased____ pH (alkalosis) 

  • Decreased CO2 concentration 

  • Decreased body temperature 

 

• Factors decreasing affinity:  

  • ___increased____ oxygen saturation 

  • ___decreased_____ pH (acidosis) 

  • Increased CO2 concentration 

  • __increased body temperature_____ 

• Dissociation: process of hemoglobin letting go of the oxygen 

• Oxygen Dissociation Curve 

 

What is

Hemoglobin’s ability to bind to oxygen. (affinity: how attracted it is to something) 

• High affinity = Hemoglobin binds more readily to oxygen 

• Decreased affinity = Hemoglobin releases the oxygen to the cells more easily 

affinity

High affinity =

Hemoglobin binds more readily to oxygen 

Decreased affinity =

Hemoglobin releases the oxygen to the cells more easily 

What are some factors increasing affinity?

• decreased oxygen saturation 

• increased pH (alkalosis) 

• Decreased CO2 concentration 

• Decreased body temperature 

What are some facots decreasing affinity?

• increased oxygen saturation 

• decreased pH (acidosis) 

• Increased CO2 concentration 

• increased body temperature

What is the process of hemoglobin letting go of the oxygen

dissociation

Control of Breathing:

Respiratory Center of the Brain(medulla —> brain stem) 

• Muscles that control respiration require continuous input from the nervous system. 

• Movement of muscles responsible for ventilation is controlled by neurons in the pons and medulla. 

• Brain injuries in this area affect breathing! 

Regulation of breathing

• automatic components

• voluntary components

Regulation of Breathing:

• Automatic components:

• Chemoreceptors: Monitor O2, CO2, & pH; adjust ventilation to meet the body’s needs 

  • Central- Most important; sense changes in PCO2 levels. High PCO2 levels stimulate increase in ventilation for a short time. 

    • Focuses on CO2 levels 

      • If CO2 gets to high chemoreceptors will tell us to breathe faster  

    
    

    • Peripheral- Monitor PO2 levels. Exert little control over ventilation until PO2 < 60 mmHg, then stimulate increased ventilation. Important for people with chronically elevated PCO2 levels. 

      • looking at O2 levelss

        • doesnt really kick in unless the O2 gets super low

• Lung Receptors: Monitor breathing pattern and function. 

What automatic component in regulation of breathing is being described:

Monitors O2, CO2, & pH; adjust ventilation to meet the body’s needs 

chemorecptors

• cental

• peripheral

What is the central chemorecptor

• Most important; sense changes in PCO2 levels. High PCO2 levels stimulate increase in ventilation for a short time. 

  • Focuses on CO2 levels

    • If CO2 gets to high chemoreceptors will tell us to breathe faster  

What is the peripheral chemorecptor

• Monitor PO2 levels. Exert little control over ventilation until PO2 < 60 mmHg, then stimulate increased ventilation. Important for people with chronically elevated PCO2 levels. 

  • Looking at O2 levels 

    • Doesn’t really kick in unless the oxygen gets super low  

What automatic component in regulation of breathing is being described:

Monitor breathing pattern and function. 

lung receptors

What do the voluntary components in the regulation of breathing do?

• Integrate breathing with voluntary acts such as speaking, blowing, singing, etc. 

  • Balances breathing with these acts 

• Temporarily suspend automatic breathing 

• Initiated by motor & premotor cortex 

What is the cough reflex

• One of the primary defense mechanisms in the respiratory system 

  • Important reflex  

• Sensitive receptors located in the tracheobronchial wall 

• Conditions interfering with the cough reflex: 

  • Weak abdominal or respiratory muscles  

  • Disease conditions affecting the closing of the glottis and laryngeal muscles  

  • Prolonged presence of nasogastric tube  

  • Depressed function of medullary centers in the brain 

  • Drugs that depress the cough center 

What is dyspnea

• Subjective(how patient feels about it) sensation of difficulty breathing 

• “Difficulty breathing” “Shortness of breath” “Breathlessness” 

• Observed in at least three major cardiopulmonary disease states: 

  • Primary lung diseases 

  • Heart disease characterized by pulmonary congestion 

  • Neuromuscular disorders 

Changes across the lifespan in CONTROL & REGULATION OF BREATHING 

• Older Adults: 

  • Decreased surface area and elasticity—> Less effective chest wall expansion; less effective gas exchange 

  • Increased respiratory dead space —> Ventilation/perfusion inequality 

  • Decreased ability to quickly increase respiratory rate —> Decreased compensation to acid/base imbalances 

Common characteristics/manifestations associated with respiratory diseases: 

• Cyanosis 

• dysnpnea

• hypercapnia

• hypoxemia

• tachycardia

• tachypnea

Common characteristics/manifestations associated with respiratory diseases: 

What is cyanois

• Blueish discoloration to skin= hypoxia  

• Can be peripheral or central  

Common characteristics/manifestations associated with respiratory diseases: 

What is dyspnea

SOB 

Common characteristics/manifestations associated with respiratory diseases: 

What is hypercapnia

Too much CO2, level is above 45  

Common characteristics/manifestations associated with respiratory diseases: 

What is hypoxemia

Low oxygen in blood stream

Common characteristics/manifestations associated with respiratory diseases: 

What is tachycardia

fast heart rate > 100

Common characteristics/manifestations associated with respiratory diseases: 

What is tachypnea

Fast breathing (Normal respiratory rate is 12-20)

What are manefestations of hypoexmia

• Changes in level of consciousness (LOC), first change that we see 

  • Stupor —> Coma 

• Cyanosis 

  • Central 

  • Peripheral 

• Diaphoresis 

  • Sweating  

• Hyperventilation 

  • Fast breathing  

• Pallor 

  • pale 

• SNS activation 

Hypoxemia may be so severe that what occurs?

systemic hypoxic cell injury occurs, resulting in an accumulation of lactic acid (metabolic acidosis) and increased serum lactate levels. 

What is chronic hypoxemia?

• Increased respiratory rate 

• Pulmonary vasoconstriction 

• Increased production of RBCs 

Hypercapnia = High levels of CO2 in the arterial blood: 

• Confusion 

• Respiratory acidosis 

Chronic hypercapnia in some patients may show…

no symptoms because they have adapted.