NURS 8022 Exam 3 Study Guide
Respiratory
Understand basic structure and function of alveoli
● Gas exchange airways: acinus - “berry”
● Respiratory Bronchioles
● Alveolar Ducts
● Alveoli
○ Primary gas exchange units
○ Oxygen enters the blood and carbon dioxide is removed
○ Epithelial cells
■ Type 1 alveolar cells: provide alveolar structure
■ Type 2 alveolar cells: surfactant production – prevents lung collapse
■ Contain alveolar macrophages: ingest foreign material and remove it through
lymphatic system
Surfactant – its function and where it comes from
● Detergent like substance secreted by type 2 alveolar epithelial cells in lungs
● Keeps alveoli open and free of fluid and pathogens (collectins)
● Decrease surface tension by blocking H20 and H+ binding in alveolar space
○ Prevents collapse – allow airflow in more easily
Understand the mechanics of the pulmonary circulation and how it relates to systemic circulation
● Pulmonary Circulation Functions
○ Facilitate gas exchange
○ Deliver Nutrients To Lung Tissue
○ Acts As A Blood Reservoir For The Left Ventricle
○ Serves as a filtering system that removes clots, air, and other debris from the circulation
● Pulmonary system pressure is 18mmHg compared to systemic circulation of 90mmHg
○ Gas exchange airways are served by the pulmonary circulation
○ Low Pressure System, high flow
■ Supplies Venous Blood from all parts of the body to the alveolar capillaries
where O2 is added and CO is removed
■ Contains 100% of CO Bronchi and other lung structures are served by systemic
circulation– bronchial circulation
○ High pressure system, low flow
, ○ Supplies blood to trachea, bronchial tree,bronchioles,and out coats (adventia) of
pulmonary arteries and veins
○ Contains 1-3% of CO
● Pulmonary circulation
○ Begins at the pulmonary artery, which receives venous blood from the right side of the
heart.
○ The pulmonary artery divides into the left and right branches and forms the capillaries
that surround the alveoli.
○ After blood is oxygenated via gas exchange, blood returns to the left side of the heart
through the pulmonary veins.
○ Pulmonary artery and accompanying smaller arteries and arterioles have large diameter;
systemic vessels are small
■ Gives the pulmonary artery tree large compliance - accommodate stroke
volume and pressure from RV
○ Pulmonary capillaries surround the acinus
● Mechanics of breathing
○ Major and accessory muscles
■ Major muscle of breathing is the diaphragm, which performs 80% of the work of
breathing.
■ External intercostals function as accessory muscles to raise the ribs up and out,
often during respiratory distress.
● Airway resistance
○ Resistance of the respiratory tract to air flow during inspiration and expiration.
○ Increased with bronchitis, asthma, mucous, edema, or spasm.
● Work of breathing
○ Amount of work that must be performed to overcome the elastic and resistive
properties of the lung
○ Determined by lung recoil, chest wall recoil, and surface tension of the alveoli
● Alveolocapillary membrane
○ Formed by shared alveolar and capillary walls
○ Contains the pulmonary capillaries
○ Where gas exchange occurs
● Alveolar surface tension
○ Surfactant plays a major role in alveolar surface tension
○ Pulmonary surfactant functions to decrease alveolar surface tension to increase lung
compliance and ease the work of breathing.
, ● Elastic properties of the lung and chest wall
○ The lung and chest wall have elastic properties that permit expansion during inspiration
and return to resting volume during expiration.
○ Elastic recoil is the tendency of the lungs to return to the normal resting state after
inspiration.
○ Compliance is the measure of the lung and chest wall distensibility.
○ Increased compliance indicates the lungs are abnormally easy to inflate and has lost
some elastic recoil.
○ A decrease in compliance indicates the lungs are abnormally stiff and difficult to inflate.
● Lymphatics
○ Lymph vessels present in all supportive tissues of the lung
○ Particulate material entering the alveoli is partly removed by the lymph channels
○ Plasma protein leaking from lung capillaries is removed from lung tissue
■ Helps prevent pulmonary edema and supports the negative pressure in the
lungs to help them from collapsing – sucking motion
Understand the role of the ANS on the pulmonary system
● Phrenic nerve (C3-C5) innervates the diaphragm
○ Receives voluntary and involuntary respiratory messages from CNS Respiratory center
● Located in the brainstem
● Dorsal respiratory group: sets the basic automatic rhythm
○ Receives impulses from peripheral chemoreceptors in the carotid and aortic bodies
○ Detects the PaCO2 and the amounts of oxygen in the arterial blood
● Ventral respiratory group: contains inspiratory and expiratory neurons
○ Becomes active when increased ventilatory effort is required
● Pneumotaxic and apneustic centers: located on the pons Modifiers of the inspiratory depth and
rate are established by the medullary centers
, ● Brainstem receives feedback
○ Carbon dioxide and hydrogen
■ Increased blood CO2 or H+ (decreased pH – acidic) stimulate brainstem
respiratory centers to increase respiration to allow blowing off CO2 and
decrease blood acidity
■ Increased CO2 and H+ (decreased pH – acidic) stimulate increased firing of
aortic and carotid bodies (peripheral chemoreceptors)
○ Relay messages to brainstem via CN9 and CN10 to increase respiration
○ Oxygen Decreased
■ PaO2 carotid and aortic bodies increase signaling to brainstem
■ Exercise Motor cortex send direct innervation to stimulate brainstem
■ Proprioceptive info from contracting skeletal muscle or nerve impulses
generated locally for skeletal hypoxia return to brainstem to stimulate
respiratory center
○ Hering-Breuer inflation reflex
■ Stretch receptor in bronchiolar and bronchial tree send inhibitory impulses to
brainstem that limit excessive inspiration
○ Central chemoreceptors
■ Reflects PaCO2 Stimulated by H+ (pH) in CSF (low pH/acidosis)
■ Increases respiratory rate and depth
○ Peripheral chemoreceptors
■ Located in the aorta and carotid bodies
■ Stimulated by hypoxia (PaO2)
■ Responsible for all the increase in ventilation that occurs in response to arterial
hypoxemia
Understand perfusion and ventilation and how it relates to each other, shunting
● Ventilation: amount of air getting to the alveoli
● Minute volume= RR x TV
○ Normal is 6L/min
● Alveolar ventilation: how much air is getting to parts where gas exchange takes place
○ Normal is 4.2L/min
○ Accounts for dead space (150 mL) ABG – PaCO2
● Perfusion: amount of blood being sent to the lungs
○ Normal V/Q ratio = 4L/min ventilation and 5L/min perfusion
○ 4/5 = 0.8
● Perfusion exceeds ventilation in the bases of the lungs because of gravity
○ Lower ratio Low PaO2 and high PaCO2
● Ventilation exceeds perfusion in the apices of the lungs
○ Higher ratio High PaO2 and low PaCO2
● Changes will change normal ratio
○ Can be physiologically controlled Just by standing up!
Respiratory
Understand basic structure and function of alveoli
● Gas exchange airways: acinus - “berry”
● Respiratory Bronchioles
● Alveolar Ducts
● Alveoli
○ Primary gas exchange units
○ Oxygen enters the blood and carbon dioxide is removed
○ Epithelial cells
■ Type 1 alveolar cells: provide alveolar structure
■ Type 2 alveolar cells: surfactant production – prevents lung collapse
■ Contain alveolar macrophages: ingest foreign material and remove it through
lymphatic system
Surfactant – its function and where it comes from
● Detergent like substance secreted by type 2 alveolar epithelial cells in lungs
● Keeps alveoli open and free of fluid and pathogens (collectins)
● Decrease surface tension by blocking H20 and H+ binding in alveolar space
○ Prevents collapse – allow airflow in more easily
Understand the mechanics of the pulmonary circulation and how it relates to systemic circulation
● Pulmonary Circulation Functions
○ Facilitate gas exchange
○ Deliver Nutrients To Lung Tissue
○ Acts As A Blood Reservoir For The Left Ventricle
○ Serves as a filtering system that removes clots, air, and other debris from the circulation
● Pulmonary system pressure is 18mmHg compared to systemic circulation of 90mmHg
○ Gas exchange airways are served by the pulmonary circulation
○ Low Pressure System, high flow
■ Supplies Venous Blood from all parts of the body to the alveolar capillaries
where O2 is added and CO is removed
■ Contains 100% of CO Bronchi and other lung structures are served by systemic
circulation– bronchial circulation
○ High pressure system, low flow
, ○ Supplies blood to trachea, bronchial tree,bronchioles,and out coats (adventia) of
pulmonary arteries and veins
○ Contains 1-3% of CO
● Pulmonary circulation
○ Begins at the pulmonary artery, which receives venous blood from the right side of the
heart.
○ The pulmonary artery divides into the left and right branches and forms the capillaries
that surround the alveoli.
○ After blood is oxygenated via gas exchange, blood returns to the left side of the heart
through the pulmonary veins.
○ Pulmonary artery and accompanying smaller arteries and arterioles have large diameter;
systemic vessels are small
■ Gives the pulmonary artery tree large compliance - accommodate stroke
volume and pressure from RV
○ Pulmonary capillaries surround the acinus
● Mechanics of breathing
○ Major and accessory muscles
■ Major muscle of breathing is the diaphragm, which performs 80% of the work of
breathing.
■ External intercostals function as accessory muscles to raise the ribs up and out,
often during respiratory distress.
● Airway resistance
○ Resistance of the respiratory tract to air flow during inspiration and expiration.
○ Increased with bronchitis, asthma, mucous, edema, or spasm.
● Work of breathing
○ Amount of work that must be performed to overcome the elastic and resistive
properties of the lung
○ Determined by lung recoil, chest wall recoil, and surface tension of the alveoli
● Alveolocapillary membrane
○ Formed by shared alveolar and capillary walls
○ Contains the pulmonary capillaries
○ Where gas exchange occurs
● Alveolar surface tension
○ Surfactant plays a major role in alveolar surface tension
○ Pulmonary surfactant functions to decrease alveolar surface tension to increase lung
compliance and ease the work of breathing.
, ● Elastic properties of the lung and chest wall
○ The lung and chest wall have elastic properties that permit expansion during inspiration
and return to resting volume during expiration.
○ Elastic recoil is the tendency of the lungs to return to the normal resting state after
inspiration.
○ Compliance is the measure of the lung and chest wall distensibility.
○ Increased compliance indicates the lungs are abnormally easy to inflate and has lost
some elastic recoil.
○ A decrease in compliance indicates the lungs are abnormally stiff and difficult to inflate.
● Lymphatics
○ Lymph vessels present in all supportive tissues of the lung
○ Particulate material entering the alveoli is partly removed by the lymph channels
○ Plasma protein leaking from lung capillaries is removed from lung tissue
■ Helps prevent pulmonary edema and supports the negative pressure in the
lungs to help them from collapsing – sucking motion
Understand the role of the ANS on the pulmonary system
● Phrenic nerve (C3-C5) innervates the diaphragm
○ Receives voluntary and involuntary respiratory messages from CNS Respiratory center
● Located in the brainstem
● Dorsal respiratory group: sets the basic automatic rhythm
○ Receives impulses from peripheral chemoreceptors in the carotid and aortic bodies
○ Detects the PaCO2 and the amounts of oxygen in the arterial blood
● Ventral respiratory group: contains inspiratory and expiratory neurons
○ Becomes active when increased ventilatory effort is required
● Pneumotaxic and apneustic centers: located on the pons Modifiers of the inspiratory depth and
rate are established by the medullary centers
, ● Brainstem receives feedback
○ Carbon dioxide and hydrogen
■ Increased blood CO2 or H+ (decreased pH – acidic) stimulate brainstem
respiratory centers to increase respiration to allow blowing off CO2 and
decrease blood acidity
■ Increased CO2 and H+ (decreased pH – acidic) stimulate increased firing of
aortic and carotid bodies (peripheral chemoreceptors)
○ Relay messages to brainstem via CN9 and CN10 to increase respiration
○ Oxygen Decreased
■ PaO2 carotid and aortic bodies increase signaling to brainstem
■ Exercise Motor cortex send direct innervation to stimulate brainstem
■ Proprioceptive info from contracting skeletal muscle or nerve impulses
generated locally for skeletal hypoxia return to brainstem to stimulate
respiratory center
○ Hering-Breuer inflation reflex
■ Stretch receptor in bronchiolar and bronchial tree send inhibitory impulses to
brainstem that limit excessive inspiration
○ Central chemoreceptors
■ Reflects PaCO2 Stimulated by H+ (pH) in CSF (low pH/acidosis)
■ Increases respiratory rate and depth
○ Peripheral chemoreceptors
■ Located in the aorta and carotid bodies
■ Stimulated by hypoxia (PaO2)
■ Responsible for all the increase in ventilation that occurs in response to arterial
hypoxemia
Understand perfusion and ventilation and how it relates to each other, shunting
● Ventilation: amount of air getting to the alveoli
● Minute volume= RR x TV
○ Normal is 6L/min
● Alveolar ventilation: how much air is getting to parts where gas exchange takes place
○ Normal is 4.2L/min
○ Accounts for dead space (150 mL) ABG – PaCO2
● Perfusion: amount of blood being sent to the lungs
○ Normal V/Q ratio = 4L/min ventilation and 5L/min perfusion
○ 4/5 = 0.8
● Perfusion exceeds ventilation in the bases of the lungs because of gravity
○ Lower ratio Low PaO2 and high PaCO2
● Ventilation exceeds perfusion in the apices of the lungs
○ Higher ratio High PaO2 and low PaCO2
● Changes will change normal ratio
○ Can be physiologically controlled Just by standing up!
