Respiratory Physiology Overview
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Questions and Answers

What is the main function of adrenaline when inhaled through an inhaler?

  • To dilate bronchioles (correct)
  • To suppress the immune response
  • To increase heart rate
  • To thicken alveolar walls

What role do type 1 alveolar cells play in the alveoli?

  • They produce pulmonary surfactant
  • They provide structure to the alveolar walls (correct)
  • They engulf foreign particles
  • They absorb oxygen from the air

How are the principles of Boyle's Law reflected in respiratory mechanics?

  • Increased volume leads to increased gas pressure
  • Volume and pressure remain constant during inhalation
  • Decreased pressure causes the lungs to collapse
  • Increased volume within the lungs decreases pressure (correct)

What is the distance between the alveolar fluid lining and pulmonary capillary known as?

<p>The blood-gas barrier (B)</p> Signup and view all the answers

What is the composition of the pulmonary capillaries in relation to erythrocytes?

<p>They are thicker than an erythrocyte (D)</p> Signup and view all the answers

What is the primary purpose of cellular respiration?

<p>To produce ATP from glucose (B)</p> Signup and view all the answers

What occurs during external respiration?

<p>Gas exchange between the atmosphere and alveoli happens (B)</p> Signup and view all the answers

What sequence correctly describes the path of air through the respiratory system?

<p>Nasal cavity -&gt; pharynx -&gt; larynx -&gt; trachea -&gt; bronchioles -&gt; alveoli (D)</p> Signup and view all the answers

What role does the bloodstream play in respiration?

<p>It transports oxygen and carbon dioxide between lungs and tissues (A)</p> Signup and view all the answers

What effect does smooth muscle in bronchioles have during an asthma attack?

<p>It constricts, making airflow difficult (D)</p> Signup and view all the answers

What is a common characteristic of air trapping in the lungs?

<p>Retention of excessive air (B)</p> Signup and view all the answers

Which condition is classified as a restrictive lung disease?

<p>Pulmonary fibrosis (D)</p> Signup and view all the answers

How does surface tension in the alveoli affect lung function?

<p>It opposes expansion of the alveolus (B)</p> Signup and view all the answers

What role does pulmonary surfactant play in the lungs?

<p>Reduces tendency of lungs to collapse (A)</p> Signup and view all the answers

In gas exchange, what does partial pressure represent?

<p>Sum of individual gas pressures (D)</p> Signup and view all the answers

How many hemoglobin binding sites are available for oxygen on a single red blood cell?

<p>4 (D)</p> Signup and view all the answers

What happens to oxygen when red blood cells reach systemic tissues with low oxygen levels?

<p>Oxygen is released from hemoglobin (A)</p> Signup and view all the answers

What primarily creates the surface tension within the alveoli?

<p>Hydrogen bonding of water molecules (D)</p> Signup and view all the answers

What happens to alveolar pressure during inspiration?

<p>It decreases as the alveoli expand. (C)</p> Signup and view all the answers

What is barreometric pressure at sea level?

<p>760 mmHg (B)</p> Signup and view all the answers

When is expiration typically a passive process?

<p>During relaxed, quiet breathing. (B)</p> Signup and view all the answers

How does lung compliance affect breathing?

<p>Higher compliance means less effort is required for volume changes. (A)</p> Signup and view all the answers

What defines elastic recoil in the lungs?

<p>The readiness of lungs to return to their resting volume after stretching. (C)</p> Signup and view all the answers

Which muscle contraction occurs during forced expiration?

<p>Internal intercostal and abdominal muscles. (D)</p> Signup and view all the answers

What characterizes obstructive lung diseases?

<p>Difficulty in exhaling air. (A)</p> Signup and view all the answers

What is the relationship between intra-alveolar pressure and atmospheric pressure during inhalation?

<p>IAP is less than atmospheric pressure, allowing air to flow in. (C)</p> Signup and view all the answers

What is the primary form in which most of the carbon dioxide (CO2) is transported to the lungs?

<p>As bicarbonate ions (HCO3-) in blood plasma (D)</p> Signup and view all the answers

Which enzyme is responsible for converting carbon dioxide and water into carbonic acid in the red blood cells?

<p>Carbonic anhydrase (C)</p> Signup and view all the answers

During the process of transporting carbon dioxide, what happens to bicarbonate ions (HCO3-) after they are formed?

<p>They are expelled into the plasma with chloride ions (B)</p> Signup and view all the answers

What do the axes of the oxygen-hemoglobin dissociation curve represent?

<p>Oxygen saturation and hemoglobin binding sites (A)</p> Signup and view all the answers

Which statement best explains the process of CO2 transport in the blood?

<p>Most CO2 is converted into bicarbonate ions through a reversible reaction. (D)</p> Signup and view all the answers

What role does bicarbonate play in the blood?

<p>It serves as a buffer for pH equilibrium. (A)</p> Signup and view all the answers

What happens to CO2 in the lungs during respiration?

<p>It is released from bicarbonate ions through a series of reactions. (C)</p> Signup and view all the answers

What percentage of CO2 is typically bound to hemoglobin during transport?

<p>23% (D)</p> Signup and view all the answers

What does a right shift of the O2-Hb curve indicate?

<p>Decrease in pH, increase in CO2, or increase in temperature (B)</p> Signup and view all the answers

Which factors influence the rate of oxygen unloading from hemoglobin?

<p>Ambient PO2, temperature, and Bohr effect (A)</p> Signup and view all the answers

What do spirograms measure over time?

<p>Changes in lung volume with breathing efforts (C)</p> Signup and view all the answers

What does acidosis refer to in terms of blood pH?

<p>Blood pH lower than 7.35 (B)</p> Signup and view all the answers

How does hyperventilation correct respiratory acidosis?

<p>By reducing H+ content and shifting the equilibrium to the left (B)</p> Signup and view all the answers

What is the tidal volume in quiet breathing under resting conditions?

<p>Average volume of air around 500 mL (B)</p> Signup and view all the answers

What happens to hemoglobin's ability to hold oxygen when pH increases?

<p>It increases significantly (D)</p> Signup and view all the answers

What does hypoventilation help with in the respiratory system?

<p>Accumulation of CO2 (B)</p> Signup and view all the answers

Flashcards

Cellular Respiration

The process inside mitochondria where cells use oxygen to break down nutrients (like glucose) and release energy in the form of ATP. It produces carbon dioxide and water as waste products.

External Respiration

The complete process of breathing, involving gas exchange between the atmosphere and the lungs, and between the lungs and the blood.

What is Respiration?

The process of obtaining oxygen from the environment and delivering it to cells, while removing carbon dioxide waste produced by cellular respiration back to the environment.

Alveoli: The Gas Exchange Zone

Tiny air sacs in the lungs where oxygen passes from inhaled air into the bloodstream and carbon dioxide moves from the blood into the air to be exhaled.

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Bronchioles and Asthma

The tiny airways in the lungs that contain smooth muscle, which can constrict during an asthma attack, making it harder to breathe.

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Intra-alveolar Pressure (IAP)

The pressure inside the alveoli, which changes during breathing to allow air to flow in and out of the lungs.

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Pressure Gradient

The difference in pressure between two areas, which drives the movement of air during breathing.

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Inspiration

The process of breathing in, where the lungs expand, increasing alveolar volume and decreasing intra-alveolar pressure.

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Expiration

The process of breathing out, where the lungs recoil passively, decreasing alveolar volume and increasing intra-alveolar pressure.

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Lung Elasticity

The ability of the lungs to stretch and return to their original shape.

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Compliance

How much effort is needed to stretch the lungs. Higher compliance means easier stretching.

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Elastic Recoil

The tendency of the lungs to return to their pre-inspiration volume after being stretched.

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Obstructive Lung Diseases

Conditions that make it difficult to exhale air from the lungs.

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Alveoli: What are they?

Tiny air sacs at the end of the bronchioles, where gas exchange happens. They have thin walls for easy diffusion, and are surrounded by pulmonary capillaries.

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What do Type 1 alveolar cells do?

They make up the wall and shape of the alveoli, creating the thin, gas-permeable structure for diffusion.

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What is pulmonary surfactant?

A substance found inside the alveoli, it helps keep them from collapsing by reducing surface tension.

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Boyle's Law: How does it work?

It states that the pressure of a gas is inversely proportional to its volume. So, as the volume of a container increases, the pressure inside decreases, and vice versa.

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Respiratory Mechanics: How do we breathe?

We breathe due to pressure differences. Air moves from areas of high pressure to low pressure. Muscles around the lungs help change lung volume, which affects pressure and drives breathing.

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Air Trapping

A condition where the lungs retain an excessive amount of air after exhalation, leading to difficulty breathing.

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Restrictive Lung Disease

A lung condition characterized by difficulty inhaling air, often due to stiffening or scarring of lung tissue.

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Alveolar Surface Tension

The force that causes the surface of the alveoli to contract, due primarily to the attraction between water molecules.

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Pulmonary Surfactant

A soapy liquid secreted by lung cells that reduces surface tension in the alveoli, making breathing easier.

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Benefits of Surfactant

Pulmonary surfactant increase lung compliance, reduces the effort needed to inflate lungs, and prevents them from readily collapsing.

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Partial Pressure

The pressure exerted by a particular gas in a mixture of gases, such as air.

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Oxygen Transport in Blood

Oxygen binds to hemoglobin in red blood cells, which transports it throughout the body.

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Oxygen Release at Tissues

Oxygen detaches from hemoglobin in tissues where oxygen levels are low, supplying oxygen for cellular processes.

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Hemoglobin's Oxygen Binding

When oxygen binds to hemoglobin, it's represented as HbO2. Hemoglobin's ability to bind to oxygen is crucial for oxygen transport throughout the body.

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CO2 Transport: Bicarbonate

The majority of CO2 is transported in the blood as bicarbonate ions (HCO3-). This conversion occurs in the RBC with the help of carbonic anhydrase, an enzyme that catalyzes the reaction between CO2 and H2O to form carbonic acid.

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CO2 Transport: Steps

CO2, a waste product of cellular respiration, diffuses from tissues into RBCs. Some binds to hemoglobin, but most converts to bicarbonate (HCO3-) by carbonic anhydrase. HCO3- moves into plasma, while Cl- enters the RBC (chloride shift). In the lungs, this process reverses to release CO2 for exhalation.

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Oxygen-Hemoglobin Dissociation Curve

This curve illustrates the relationship between the partial pressure of oxygen in the environment and the saturation of hemoglobin with oxygen. It shows how readily hemoglobin binds to oxygen.

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Oxygen Availability and Hemoglobin

The amount of oxygen available in the environment influences the number of binding sites on hemoglobin occupied by oxygen molecules.

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Lower Saturation on the Curve

A lower percent saturation on the oxygen-hemoglobin dissociation curve means most binding sites on hemoglobin are available for more oxygen.

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Carbonic Anhydrase: The CO2 Converter

This enzyme, found in red blood cells, speeds up the reversible reaction between carbon dioxide (CO2) and water (H2O) to form carbonic acid (H2CO3). This reaction allows for efficient CO2 transport as bicarbonate.

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Bicarbonate Buffer

Bicarbonate ions (HCO3-) act as a buffer, maintaining a stable pH in the blood. This prevents drastic changes in blood pH, which could be harmful to cells and organs.

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Oxygen-Hemoglobin Saturation Curve

A graph showing the relationship between the partial pressure of oxygen (PO2) in the blood and the percentage of hemoglobin saturated with oxygen. This curve reflects the affinity of hemoglobin for oxygen.

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Right Shift of the Curve

A shift to the right on the oxygen-hemoglobin saturation curve indicates decreased affinity of hemoglobin for oxygen. This means hemoglobin releases oxygen more readily at a given PO2.

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Left Shift of the Curve

A shift to the left on the oxygen-hemoglobin saturation curve indicates increased affinity of hemoglobin for oxygen. This means hemoglobin holds onto oxygen more tightly at a given PO2.

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Bohr Effect

The phenomenon where a decrease in blood pH (becoming more acidic) causes hemoglobin to release oxygen more easily.

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Blood pH

A measure of the acidity or alkalinity of blood, with a normal range of 7.35 to 7.45.

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Respiratory Acidosis

A condition where blood pH is lower than 7.35 due to an accumulation of CO2 in the body.

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Hyperventilation

Increased breathing rate and depth, often a response to respiratory acidosis to remove excess CO2.

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Spirometry

A technique used to measure lung volumes and capacities by using a scientific apparatus.

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Study Notes

Respiratory Physiology

  • Types of Respiration:

    • Cellular Respiration: An intracellular process occurring in mitochondria, using oxygen to create energy from nutrients. CO2 and H2O are waste products. O2 and glucose are the fuels.
    • External Respiration: The entire process of respiration, encompassing the exchange of gases between the external world and the body's internal systems.

  • What is Respiration?:

    • Obtaining oxygen (O2) from the atmosphere for body cells.
    • Removing carbon dioxide (CO2) produced by body cells and returning it to the atmosphere.
    • Tissues and cells produce a lot of CO2 due to cellular respiration.

  • External Respiration Steps:

    • 1. Air Exchange: Gas exchange (ventilation) happens between the atmosphere and alveoli in the lungs.
    • 2. Gas Exchange (Diffusion): O2 and CO2 flow across the pulmonary capillaries inside the alveoli, following diffusion principles. Each inhalation brings in O2 and exhalation releases CO2.
    • 3. Blood Transport: Blood circulation transports O2 and CO2. Oxygenated blood leaves the heart's left side, delivering O2 to tissues for cellular respiration. CO2, a waste product of respiration, travels back to the right side of the heart.
    • 4. Oxygenation: Blood returns to the heart oxygen-deprived, receiving fresh O2 to become oxygenated.

Respiratory System Overview

  • Nasal cavity -> pharynx -> larynx -> trachea -> left & right primary bronchus -> bronchioles (smooth muscle) -> alveoli

Alveoli

  • Structure: Located at the end of the respiratory tract/terminal bronchioles, as part of the alveolar sacs. Well-suited for diffusion (thin walls).
  • Zoomed In: Type 1 alveolar cells form the wall, alveolar sacs have pulmonary surfactant, and alveoli are surrounded by capillaries for gas exchange.

Respiratory Mechanics

  • Gas pressure depends on collisions, higher pressure means more collisions.
  • Boyle's Law explains the inverse relationship between pressure and volume in a container, including the lungs & thoracic cavity.
  • Changes in lung volumes cause ventilation, the mechanical process of breathing.
  • Pressure gradient drives air flow: Air moves from high to low pressure.

Important Pressures for Breathing

  • Barometric Pressure: The pressure exerted by the weight of the air in the atmosphere.

Intra-alveolar Pressure (IAP)

  • Pressure inside the alveoli.
  • Air flow occurs when IAP differs from atmospheric pressure

Inspiration and Expiration

  • Inspiration: To expand the lungs and increase alveolar volume, decreasing alveolar pressure, muscles contract to use energy for breathing.
  • Expiration: Quiet breathing is usually passive, driven by elastic recoil of the lungs. Forced expiration uses muscles for more forceful exhalation.

Lung Elasticity

  • Compliance: Describes how easily the lungs stretch. High compliance means easier stretching, low compliance means harder stretching.
  • Elastic Recoil: Ability of the lungs to return to their normal size after being stretched, important for exhalation.

Respiratory Dysfunction

  • Obstructive Lung Diseases: Conditions like asthma, chronic bronchitis, and emphysema, where exhalation is difficult due to airflow blockage.
  • Restrictive Lung Diseases: Conditions like asbestosis, sarcoidosis, and pulmonary fibrosis, where inhalation is difficult due to lung stiffness or scarring.

Alveolar Surface Tension

  • Alveoli are lined with a thin liquid film, primarily water and surfactant.
  • Surface tension: Water molecules' tendency to stick together, creating a force that resists lung expansion.
  • Surfactant: Reduces surface tension in alveoli, preventing collapse. Secreted by type 2 alveolar cells.

Pulmonary Surfactant Benefits

  • Increases pulmonary compliance, making lung inflation easier.
  • Decreases the lungs tendency to recoil preventing collapse.

Gas Exchange (Partial Pressure)

  • The sum of pressures of different gases making up total air pressure.
  • Each gas's pressure considered separately.

Oxygen Transport

  • Hemoglobin (Hb) binds oxygen (O2).
  • O2 attaches to hemoglobin's Fe3+ transitional metal.
  • Oxygen levels in tissues determine oxygen release from Hb.

Carbon Dioxide Transport

  • Most CO2 transported as bicarbonate ions (HCO3-) dissolved in blood plasma.
  • Carbonic anhydrase converts CO2 and H2O into H2CO3 (carbonic acid) and then into HCO3- and H+ ions in RBC.

Oxygen-Hemoglobin Dissociation Curve

  • Shows how readily hemoglobin binds oxygen depending on oxygen availability and environmental conditions.
  • Curve shifts based on pH, temperature, and CO2 concentration (Bohr effect): lower pH, higher CO2, and higher temperature cause a rightward shift, where hemoglobin releases oxygen more readily, a response to increased tissue metabolic demand.

Adjustments to Tissue Needs

  • Factors like pH, CO2, and temperature control the rate of oxygen unloading from hemoglobin to meet tissue metabolic demands.
  • Ambient PO2, temperature, and blood pH regulate O2 unloading.

Lung Volumes

  • Tidal Volume (TV): Volume of air inhaled or exhaled during normal breathing. ~500 mL
  • Inspiratory Reserve Volume (IRV): Extra volume of air that can be forcefully inhaled. ~3000 mL (males) and ~1900 mL (females)
  • Expiratory Reserve Volume (ERV): Extra volume of air that can be forcefully exhaled.
  • Residual Volume (RV): Amount of air remaining in the lungs after maximal forced exhalation.
  • Inspiratory Capacity (IC): Maximum volume of air taken in. ~3500 mL
  • Functional Residual Capacity (FRC): Volume of air in the lungs at the end of normal expiration.
  • Vital Capacity (VC): Maximum volume of air exchanged during one breath.
  • Total Lung Capacity (TLC): Total volume of air the lungs can hold.

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Description

Explore the fundamental concepts of respiratory physiology, including cellular and external respiration. Understand the processes of gas exchange and the role of oxygen and carbon dioxide in the body. This quiz covers vital steps involved in respiration and the exchange of gases.

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