Respiratory Physiology (struc) Flashcards

1
Q

WHY DO WE BREATHE?

WHY DO WE NEED OXYGEN?

The body’s metabolism require ? (recall biochemical pathways such as oxidative phosphorylation!)

An animal/organism needs a certain volume of air into the lungs, especially its ?, each minute → to supply oxygen demand

A

WHY DO WE BREATHE?

WHY DO WE NEED OXYGEN?

The body’s metabolism require oxygen (recall biochemical pathways such as oxidative phosphorylation!)

An animal/organism needs a certain volume of air into the lungs, especially its alveoli, each minute → to supply oxygen demand

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2
Q

TERMINOLOGY

EUPNEA: normal ? breathing (normal, good, healthy and unlabored breathing)

DYSPNEA: ? breathing

HYPERPNEA: increased or decresed? breathing depth, frequency or both (deeper breaths than usual, which increases the volume of
air in the lungs)
* This condition is often a response to an increase in ? demand when the body needs more ?, such as during exercise

POLYPNEA: ? shallow breathing (like ?)
* Like hyperpnea regarding frequency, but is unlike hyperpnea regarding ?

APNEA: ? of breathing (could be a transient state)

TACHYPNEA: a breathing rate that is ? than the normal breathing rate (could be physiologic or pathologic)

BRADYPNEA: abnormal slow or fast? breathing rate

The Respiratory System Transports O2 and CO2 Between the ? and the ?

A

TERMINOLOGY

EUPNEA: normal quiet breathing (normal, good, healthy and unlabored breathing)

DYSPNEA: difficult breathing

HYPERPNEA: increased breathing depth, frequency or both (deeper breaths than usual, which increases the volume of
air in the lungs)
* This condition is often a response to an increase in metabolic demand when the body needs more oxygen, such as during exercise

POLYPNEA: rapid shallow breathing (like panting)
* Like hyperpnea regarding frequency, but is unlike hyperpnea regarding depth

APNEA: cessation of breathing (could be a transient state)
(note: AP similar to ab meaning not/stop)

TACHYPNEA: a breathing rate that is higher than the normal breathing rate (could be physiologic or pathologic)

BRADYPNEA: abnormal slow breathing rate

The Respiratory System Transports O2 and CO2 Between the Environment and the Blood

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3
Q

The respiratory system provides ? to support tissue metabolism and ? the byproduct of metabolism → ? (cellular respiration)

O2 consumption and CO2 production vary with the ? ? and metabolic ?:

 Basal metabolism
* the metabolism rate of the ? animal, is a function of metabolic body ? (body weight in 𝑀𝑀0.75)

 Metabolic rate
* dependent on the animal’s level of ? and ? condition
* 𝑉 O2 max (maximal oxygen consumption) is directly related to the total mass of ? within the ? muscle

A

The respiratory system provides oxygen to support tissue metabolism and removes the byproduct of metabolism → Co2 (cellular respiration)

O2 consumption and CO2 production vary with the basal metabolic and metabolic rate:

 Basal metabolism
* the metabolism rate of the resting animal, is a function of metabolic body weight (body weight in 𝑀𝑀0.75)

 Metabolic rate
* dependent on the animal’s level of activity and physical condition
* 𝑉 O2 max (maximal oxygen consumption) is directly related to the total mass of mitochondria within the skeletal muscle

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4
Q

The respiratory system is also involved in:

 ? mechanism of the respiratory system (mucociliary system, cough, phagocytic cells)
 ? fluid exchange (production of ? and pleural fluid)
 Metabolism and elimination of ? and ? substances i.e.:
→ ? and ? of hormones and toxins, biogenesis of platelets,
→ ?, redistribution and ? of drugs (e.g. propofol, inhalant anesthetics)

 Protection against inhaled ?, ? gases, and ? agents
 Communication (by sound and ?)
 ?
 Facilitates urination, ?, and parturition
→ due to the increase in abdominal ? exerted by the active participation of the respiratory muscles

A

The respiratory system is also involved in:

 defense mechanism of the respiratory system (mucociliary system, cough, phagocytic cells)
 pulmonary fluid exchange (production of lymph and pleural fluid)
 Metabolism and elimination of endogenous and exogenous substances i.e.:
→ removal and inactivation of hormones and toxins, biogenesis of platelets,
→ metabolism, redistribution and elimination of drugs (e.g. propofol, inhalant anesthetics)

 Protection against inhaled dust, toxic gases, and infectious agents
 Communication (by sound and pheromones)
 thermoregulation
 Facilitates urination, defecation, and parturition
→ due to the increase in abdominal pressure exerted by the active participation of the respiratory muscles

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5
Q

RESPIRATORY SYSTEM - STRUCTURE

CONDUCTING ZONE (Also known as the ? ? SPACE → gas exchange does not occur in these pathways) Conducting zone brings ? into and out of the ? zone for gas exchange

 Includes: nasal cavity, ?, larynx, trachea, bronchi, bronchioles and ? bronchioles
 Important to ?, warm and ? the air before it reaches the gas exchange area

The tracheobronchial tree (trachea and bronchi):
 supported by ? (preventing them from ?)
 contain ?-secreting and ? cells
 filter small particles that enter the airways
→ swept upward or downward? by the rhythmic beating of the ?

The walls of the conducting airways contain
 ? muscle
 ?
* Sympathetic (? – ? of airways)
* Parasympathetic (Ach – ? of airways)

A

RESPIRATORY SYSTEM - STRUCTURE

CONDUCTING ZONE (Also known as the ANATOMIC DEAD SPACE → gas exchange does not occur in these pathways) Conducting zone brings air into and out of the respiratory zone for gas exchange

 Includes: nasal cavity, nasopharynx, larynx, trachea, bronchi, bronchioles and terminal bronchioles
 Important to humidify, warm and filter the air before it reaches the gas exchange area

The tracheobronchial tree (trachea and bronchi):
 supported by cartilage (preventing them from closing)
 contain mucus-secreting and ciliated cells
 filter small particles that enter the airways
→ swept upward by the rhythmic beating of the cilia

The walls of the conducting airways contain
 smooth muscle
 innervation
* Sympathetic (epinephrine – dilation of airways)
* Parasympathetic (Ach – constriction of airways)

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6
Q

RESPIRATORY ZONE

Respiratory zone lined with alveoli where ? exchange occurs
 Includes: respiratory ?, alveolar ? and alveolar ?

Respiratory bronchioles: ? structures, have cilia and ? muscle, ? occasionally bud off their walls

Alveolar ducts are completely lined with alveoli, contain no ? and little ? muscle

Alveolar sacs: lined with ?

Alveoli: thin or thick?? walled pouchlike evaginations of the walls of respiratory ?, alveolar ducts and sacs.
Large or small? surface area, covered by ? (gas exchange)

A

RESPIRATORY ZONE

Respiratory zone lined with alveoli where gas exchange occurs
 Includes: respiratory bronchioles, alveolar ducts and alveolar sacs

Respiratory bronchioles: transitional structures, have cilia and smooth muscle, alveoli occasionally bud off their walls

Alveolar ducts are completely lined with alveoli, contain no cilia and little smooth muscle

Alveolar sacs: lined with alveoli

Alveoli: thin walled pouchlike evaginations of the walls of respiratory bronchioles, alveolar ducts and sacs.
Large surface area, covered by capillaries (gas exchange)

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7
Q

RESPIRATORY ZONE

Alveolar walls contain 2 types of epithelial cells (pneumonocytes) and macrophages:

Type I pneumonocyte: covers ?% of alveolar surface
 Extremely thin, efficient ? exchange between alveolus and ? capillaries

Type II pneumonocyte: covers ?% of alveolar surface.
 Synthesize pulmonary ? (reduce surface tension of ? and prevent it from collapsing)
 Secrete ? (recruitment of inflammatory cells)
 ? capacity for type I and type II cells

Macrophages: ? line of defense against invading respiratory ?. Also remove inhaled particles from the ?

A

RESPIRATORY ZONE

Alveolar walls contain 2 types of epithelial cells (pneumonocytes) and macrophages:

Type I pneumonocyte: covers 95% of alveolar surface
 Extremely thin, efficient gas exchange between alveolus and pulmonary capillaries

Type II pneumonocyte: covers 5% of alveolar surface.
 Synthesize pulmonary surfactant (reduce surface tension of alveoli and prevent it from collapsing)
 Secrete cytokines (recruitment of inflammatory cells)
 regenerative capacity for type I and type II cells

Macrophages: first line of defense against invading respiratory pathogens. Also, remove inhaled particles from the alveolus

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8
Q

Respiration consists of 4 distinct processes:

  1. Pulmonary Ventilation
     moving air into and out of the ?
     ? and ? muscles promote ventilation
  2. Pulmonary gas exchange (alveoli-blood)
     diffusion of gases from the ? to the blood of the ? capillaries
  3. Gas transport
     transport of oxygen and carbon dioxide from the ? to tissues
  4. Peripheral gas exchange (blood ↔ tissue)
     diffusion of gases from the blood of the ? capillaries to the cells
A

Respiration consists of 4 distinct processes:

  1. Pulmonary Ventilation
     moving air into and out of the lungs
     diaphragm and intercoastal muscles promote ventilation
  2. Pulmonary gas exchange (alveoli-blood)
     diffusion of gases from the alveoli to the blood of the pulmonary capillaries
  3. Gas transport
     transport of oxygen and carbon dioxide from the lungs to tissues
  4. Peripheral gas exchange (blood ↔ tissue)
     diffusion of gases from the blood of the systemic capillaries to the cells
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9
Q

Difference between breathing and respiration?

Types of respiration
1. external respiration = breathing
2. internal respiration = exchange of ?
3. cellular respiration = breakdown of food molecules in the cells; ? of biological fuels

PULMONARY VENTILATION

Pulmonary ventilation = breathing

 Physical movement of air flowing into the lungs during ? and out of the lungs during ?

 Depends on ? and ? changes in the thoracic cavity → air flows from areas of high pressure to areas of low pressure (so towards conc gradient)

 requires ? energy and lung ?

Respiratory pressure is always described relative to ? pressure

Boyle’s law: P1V1 = P2V2; decreasing volume increases pressure

A

Difference between breathing and respiration?

Types of respiration
1. external respiration = breathing
2. internal respiration = exchange of gases
3. cellular respiration = breakdown of food molecules in the cells; oxidation of biological fuels

PULMONARY VENTILATION

Pulmonary ventilation = breathing

 Physical movement of air flowing into the lungs during inhalation and out of the lungs during exhalation

 Depends on volume and pressure changes in the thoracic cavity → air flows from areas of high pressure to areas of low pressure (so towards conc gradient)

 requires muscular energy and lung elasticity

Respiratory pressure is always described relative to atmospheric pressure

Boyle’s law: P1V1 = P2V2; decreasing volume increases pressure

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10
Q

Respiratory cycle: begins with ? and ends with ?

INHALATION - requires ? contraction (muscular energy) of:
 ?
 External ? muscles
 ? muscles attached to external nares, pharynx and ?

↑ Intrapulmonary volume ↓ Pressure (air inhaled)

  • during inhalation, diaphragm moves up or down?

EXHALATION – relaxation of ? muscles
 Normally ? at rest
 Elastic energy stored in the stretched lungs and thorax causes them to increase or decrease? volume
 Can be assisted during exercise and in some disease conditions (abdominal and intercostal muscles)
↓ Intrapulmonary volume ↑ ? (air exhaled)

A

Respiratory cycle: begins with inhalation and ends with exhalation

INHALATION - requires active contraction (muscular energy) of:
 diaphragm
 External intercostal muscles
 abductor muscles attached to external nares, pharynx and larynx

↑ Intrapulmonary volume ↓ Pressure (air inhaled)

  • during inhalation, diaphragm moves down

EXHALATION – relaxation of inspiratory muscles
 Normally passive at rest
 Elastic energy stored in the stretched lungs and thorax causes them to decrease volume
 Can be assisted during exercise and in some disease conditions (abdominal and intercostal muscles)
↓ Intrapulmonary volume ↑ pressure (air exhaled)

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11
Q

PHYSICAL FACTORS INFLUENCING PULMONARY VENTILATION

  1. FRICTIONAL RESISTANCE
     Is the major ? source of resistance to airflow
    Flow = ΔP /R*
    *ΔP = atmospheric pressure – alveolar pressure
    R = resistance is determined primarily by the ? of the airways (resistance is proportional to 1/radius4)
  2. ELASTICITY
     Is how readily the lungs ? (recoil) after being stretched
     Elasticity of ? tissue (mainly due to ?) causes lungs to return to its original shape after it has been stretched or compressed
  3. COMPLIANCE
     Is the ability to stretch, the ease with which lungs can be expanded due to change in transpulmonary pressure
     Determined by 2 main factors:
    a) ? of the lung tissue and surrounding thoracic cage
    b) ? ? of the alveoli*

Alveoli and alveolus -> which one is singular and plural?

A

PHYSICAL FACTORS INFLUENCING PULMONARY VENTILATION

  1. FRICTIONAL RESISTANCE
     Is the major nonelastic source of resistance to airflow
    Flow = ΔP /R*
    *ΔP = atmospheric pressure – alveolar pressure
    R = resistance is determined primarily by the radius of the airways (resistance is proportional to 1/radius4)
  2. ELASTICITY
     Is how readily the lungs rebound (recoil) after being stretched
     Elasticity of connective tissue (mainly due to elastin) causes lungs to return to its original shape after it has been stretched or compressed
  3. COMPLIANCE
     Is the ability to stretch, the ease with which lungs can be expanded due to change in transpulmonary pressure
     Determined by 2 main factors:
    a) distensibility of the lung tissue and surrounding thoracic cage
    b) surface tension of the alveoli*

alveolus: singular
Alveoli: plural

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12
Q

*Surface Tension of the alveoli:
* Is the tension that results from the forces acting on the ? surfaces of the alveoli
(thin fluid layer between alveolar cells and the air)
* Acting to reduce the alveoli to the ? possible size

 Surfactant: a ?-like complex secreted by Type I or II? pneumocytes, reduces ? tension and helps keep the alveoli from ?

LAPLACE’S LAW
For spherical alveoli, the pressure exerted by the surface tension increases as the radius of the alveolus goes down

alveoli without surfactant with smaller radius (volume) will have higher pressure

HOWEVER alveoli 1 and 2 both WITH surfactant will have EQUAL pressure even alveoli has a smaller radius
alveoli 1 will have less surface tension (more surfactant per area); 1 will inflate at a faster rate than 2 until equal in size.

A

*Surface Tension of the alveoli:
* Is the tension that results from the forces acting on the liquid surfaces of the alveoli
(thin fluid layer between alveolar cells and the air)
* Acting to reduce the alveoli to the smallest possible size

 Surfactant: a detergent-like complex secreted by Type II pneumocytes, reduces surface tension and helps keep the alveoli from collapsing

LAPLACE’S LAW
For spherical alveoli, the pressure exerted by the surface tension increases as the radius of the alveolus goes down

alveoli without surfactant with smaller radius (volume) will have higher pressure

HOWEVER alveoli 1 and 2 both WITH surfactant will have EQUAL pressure even alveoli has a smaller radius
alveoli 1 will have less surface tension (more surfactant per area); 1 will inflate at a faster rate than 2 until equal in size.

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13
Q

The velocity of airway flow ? progressively from the trachea toward the bronchioles

  • As a result of the ? pattern of the tracheobronchial tree, the TOTAL CROSS-SECTIONAL AREA increases or decreases? dramatically toward the ? of the lungs

FRICTIONAL RESISTANCE
Flow = Δ? /?*

  • The high-velocity turbulent airflow in the ? and ? produces the lung sounds heard through a stethoscope in normal animals
  • ? velocity flow in the bronchioles produces no sound
A

The velocity of airway flow diminishes progressively from the trachea toward the bronchioles

  • As a result of the branching pattern of the tracheobronchial tree, the TOTAL CROSS-SECTIONAL AREA increases dramatically toward the periphery of the lungs

FRICTIONAL RESISTANCE
Flow = ΔP/R*

  • The high-velocity turbulent airflow in the trachea and bronchi produces the lung sounds heard through a stethoscope in normal animals
  • low velocity flow in the bronchioles produces no sound
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14
Q

The pulmonary circulation and the bronchial circulation

Pulmonary circulation → blood from the right ventricle → perfuses the ? capillaries (gas exchange)

Pulmonary ? carry deoxygenated blood from the right ventricle to the pulmonary ? (becomes oxygenated) → return to the left side of the heart in pulmonary ?

The bronchial circulation provides a ? blood supply to airways and other structures within the lung

Bronchial arteries carry ? blood and veins carry ? blood (does the opposite of pulmonary so pulmonary arteries carry deoxygenated blood thus bronchial arteries will do the opposite which is carrying oxygenated blood)

A

The pulmonary circulation and the bronchial circulation

Pulmonary circulation → blood from the right ventricle → perfuses the pulmonary capillaries (gas exchange)

Pulmonary arteries carry deoxygenated blood from the right ventricle to the pulmonary capillaries (becomes oxygenated) → return to the left side of the heart in pulmonary veins

The bronchial circulation provides a nutritional blood supply to airways and other structures within the lung

Bronchial arteries carry oxygenated blood and veins carry deoxygenated blood (does the opposite of pulmonary so pulmonary arteries carry deoxygenated blood thus bronchial arteries will do the opposite which is carrying oxygenated blood)

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15
Q

BLOOD FLOW THROUGH THE LUNGS

The Distribution of Pulmonary Blood Flow Within the Lung Differs Between Quadrupeds and Bipeds

Bipedal animals → pulmonary circulation is ?-dependent → so blood flow highest at the ? of the lungs and lowest at the ? of the lungs

Quadrupeds animals → blood flow distributed to the caudodorsal region of the lungs
* It is not determined by ? → the branching pattern of pulmonary ? and ? and the relative ? of each vessel are the major determinants of blood flow distribution

A

BLOOD FLOW THROUGH THE LUNGS

The Distribution of Pulmonary Blood Flow Within the Lung Differs Between Quadrupeds and Bipeds

Bipedal animals → pulmonary circulation is gravity-dependent → so blood flow highest at the bottom of the lungs and lowest at the top of the lungs

Quadrupeds animals → blood flow distributed to the caudodorsal region of the lungs
* It is not determined by gravity → the branching pattern of pulmonary arteries and arterioles and the relative resistances of each vessel are the major determinants of blood flow distribution

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16
Q

PULMONARY CIRCULATION

The total cardiac output of the right side of the heart passes through the pulmonary circulation:
 10% to ?% of the total blood volume

When cardiac output increases (i.e., during exercise) → pulmonary circulation accommodates this increase in blood flow with or without? a large increase in the work of the right ventricle (pulmonary vascular resistance is low)
 control mechanisms exist to regulate the distribution of blood within the lung so that
blood preferentially perfuses the well-? regions of the lung (HPV - hypoxic
pulmonary vasoconstriction)
 the ability to regulate blood flow depends on the presence of ? muscle in the
walls of small pulmonary arteries

A

PULMONARY CIRCULATION

The total cardiac output of the right side of the heart passes through the pulmonary circulation:
 10% to 20% of the total blood volume

When cardiac output increases (i.e., during exercise) → pulmonary circulation accommodates this increase in blood flow without a large increase in the work of the right ventricle (pulmonary vascular resistance is low)
 control mechanisms exist to regulate the distribution of blood within the lung so that
blood preferentially perfuses the well-oxygenated regions of the lung (HPV - hypoxic
pulmonary vasoconstriction)
 the ability to regulate blood flow depends on the presence of smooth muscle in the
walls of small pulmonary arteries

17
Q

PULMONARY CIRCULATION CONTINUED..

 Main pulmonary arteries (bronchi) are ?
 Smaller arterioles (bronchioles and alveolar ducts) are ? and thicker or thinner? than systemic arteries and arterioles

 Small pulmonary arterioles lead into ? capillaries → form an extensive branching network of vessels within the ? septa → blanketing the ? surface → maximizing the * ? * for gas exchange

The amount of smooth muscle in the walls of small pulmonary arteries determines the ? of the ? to alveolar ? and other neural and humoral stimuli

 Pulmonary veins → thin or thick? walls, conduct oxygenated blood from pulmonary ? to the left atrium
 Blood within pulmonary veins serves as a ? of blood for the left heart
 available for sudden increases in cardiac output (e.g., at the start of a sudden burst of exercise)

A

PULMONARY CIRCULATION CONTINUED..

 Main pulmonary arteries (bronchi) are elastic
 Smaller arterioles (bronchioles and alveolar ducts) are muscular and thinner than systemic arteries and arterioles

 Small pulmonary arterioles lead into pulmonary capillaries → form an extensive branching network of vessels within the alveolar septa → blanketing the alveolar surface → maximizing the * surface * for gas exchange

The amount of smooth muscle in the walls of small pulmonary arteries determines the reactivity of the vasculature to alveolar hypoxia and other neural and humoral stimuli

 Pulmonary veins → thin walls, that conduct oxygenated blood from pulmonary capillaries to the left atrium
 Blood within pulmonary veins serves as a reservoir of blood for the left heart
 available for sudden increases in cardiac output (e.g., at the start of a sudden burst of exercise)

18
Q

ALVEOLAR PERFUSION AND VENTILATION

The distribution of ventilation depends on the local mechanical properties of the ?
 gas exchange cannot occur if an alveolus receives blood but no ?, or vice versa (ventilation-perfusion [V/Q] mismatch)

** Distribution of ventilation is always ? to some degree and becomes more so in ? **

Uneven distribution of ventilation can be caused by
 local decreases in lung ? (pulmonary edema)
 local airway ? (e.g., by mucus,
bronchoconstriction, foreign body obstruction)
 ? atelectasis (recumbency under anesthesia)

Hypoxic Pulmonary Vasoconstriction (HPV) of small pulmonary arteries

The distribution of air to alveoli can be reduced by the local presence of fluid, exudates, atelectasis, pulmonary thromboembolism or other airway obstructions
 alveolar hypoxia induces vasoconstriction of pulmonary ? serving the hypoxic region
 reduces blood flow to ? ventilated alveoli and redistributes pulmonary blood flow toward better-ventilated regions of the lung

HPV is beneficial when there is localized alveolar hypoxia to reduce the pulmonary shunt
Generalized pulmonary hypoxia (animals living at high altitude, lung disease) -> vasoconstriction can increase ? arterial pressure -> increases the work of the ? ventricle and leads to right-sided heart failure

A

ALVEOLAR PERFUSION AND VENTILATION

The distribution of ventilation depends on the local mechanical properties of the lungs
 gas exchange cannot occur if an alveolus receives blood but no ventilation, or vice versa (ventilation-perfusion [V/Q] mismatch)

** Distribution of ventilation is always uneven to some degree and becomes more so in disease **

Uneven distribution of ventilation can be caused by
 local decreases in lung compliance (pulmonary edema)
 local airway obstruction (e.g., by mucus,
bronchoconstriction, foreign body obstruction)
 alveolar atelectasis (recumbency under anesthesia)

Hypoxic Pulmonary Vasoconstriction (HPV) of small pulmonary arteries

The distribution of air to alveoli can be reduced by the local presence of fluid, exudates, atelectasis, pulmonary thromboembolism or other airway obstructions
 alveolar hypoxia induces vasoconstriction of pulmonary arteries serving the hypoxic region
 reduces blood flow to poorly ventilated alveoli and redistributes pulmonary blood flow toward better-ventilated regions of the lung

HPV is beneficial when there is localized alveolar hypoxia to reduce the pulmonary shunt
Generalized pulmonary hypoxia (animals living at high altitude, lung disease) -> vasoconstriction can increase pulmonary arterial pressure -> increases the work of the right ventricle and leads to right-sided heart failure