Respiratory System Quiz

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Questions and Answers

What is tidal CO2 in arterial blood during resting state?

4 ml CO2 / 100 ml (correct)

8 ml CO2 / 100 ml

6 ml CO2 / 100 ml

2 ml CO2 / 100 ml

Which type of hypoxia is characterized by an impaired ability of hemoglobin to carry oxygen?

Hypoxic hypoxia

Stagnant hypoxia

Anemic hypoxia (correct)

Histotoxic hypoxia

What process is responsible for the downward movement of the diaphragm during breathing?

Inspiration (correct)

Passive recoil

Forced expiration

Expiration

In which situation would you most likely see hypoxic hypoxia?

High altitude environments Signup and view all the answers

What is the primary function of the larynx during phonation?

To produce sound Signup and view all the answers

What is cyanosis a direct indication of?

Abnormal increase of reduced hemoglobin Signup and view all the answers

What is the primary function of the respiratory system?

To supply the cells of the body with O2 and remove CO2 Signup and view all the answers

Which of the following best describes the mechanism of expiration?

It is primarily a passive process. Signup and view all the answers

What is the primary purpose of negative intrapleural pressure (IPP)?

To assist lung expansion Signup and view all the answers

Which type of hypoxia occurs due to slow circulation affecting tissue oxygen supply?

Stagnant hypoxia Signup and view all the answers

Which part of the respiratory system is primarily involved in gas exchange?

The alveoli Signup and view all the answers

How is pulmonary ventilation primarily regulated?

By respiratory centers in the brain stem Signup and view all the answers

During tidal breathing, how much air on average reaches and ventilates normal alveoli?

350 ml Signup and view all the answers

Which of the following is NOT a function of the conducting zone?

Gas exchange Signup and view all the answers

Which muscle group is primarily responsible for forced expiration during muscular exercise?

Abdominal muscles and internal intercostal muscles Signup and view all the answers

What causes the negative pressure in the pleural cavity?

Elastic recoil of lung tissue Signup and view all the answers

Which of the following describes internal respiration?

Utilization of oxygen and production of carbon dioxide by cells Signup and view all the answers

What is the relationship between tidal volume and the conducting air passage during normal breathing?

150 ml of the tidal volume does not participate in gas exchange. Signup and view all the answers

Which zone of the respiratory system is responsible for conducting air to the gas exchange sites?

Conducting zone Signup and view all the answers

What is one function of the mucus secreted by the conducting zone?

It traps small particles in inspired air Signup and view all the answers

What does pulmonary perfusion refer to?

Distribution of blood through the lungs Signup and view all the answers

What is the formula for calculating Minute Ventilation at rest?

Tidal volume X breathing rate Signup and view all the answers

What is the primary function of surfactant in the lungs?

It lowers surface tension and prevents lung collapse. Signup and view all the answers

Which factors stimulate the formation of surfactant?

Thyroid hormones and glucocorticoid hormones Signup and view all the answers

What results from surfactant deficiency in adults?

Increased work of breathing Signup and view all the answers

In preterm infants, a lack of surfactant primarily causes which of the following conditions?

Infant respiratory distress syndrome Signup and view all the answers

What is the normal volume of blood that perfuses the lungs per minute?

5 L/min Signup and view all the answers

What is the process by which O2 and CO2 are exchanged between the alveoli and blood termed?

Diffusion Signup and view all the answers

Which of the following accurately describes ventilation?

The inflow and outflow of air into and out of the lungs. Signup and view all the answers

What factor affecting the rate of gas diffusion across the respiratory membrane is directly proportional?

Pressure gradient of gases Signup and view all the answers

What percentage of O2 transported in blood is chemically combined with hemoglobin?

20% Signup and view all the answers

Which statement regarding the transport of CO2 is correct?

Bicarbonate is responsible for 90% of CO2 transport. Signup and view all the answers

What happens to dissolved O2 levels in the blood when O2 is released from hemoglobin?

PaO2 decreases. Signup and view all the answers

Which of the following factors is inversely proportional to the rate of gas diffusion across the respiratory membrane?

Molecular weight of gases Signup and view all the answers

How much dissolved O2 is present in arterial blood compared to venous blood?

100 mm Hg in arterial blood and 40 mm Hg in venous blood. Signup and view all the answers

Which percentage of CO2 is physically dissolved in plasma?

5% Signup and view all the answers

What is the primary form of oxygen transport in the blood?

O2 chemically combined with hemoglobin Signup and view all the answers

Study Notes

Physiology of the Respiratory System

The respiratory system's function is to supply the body's cells with oxygen (O2) and remove carbon dioxide (CO2) produced by cellular activities.
The respiratory system consists of respiratory passages, including the nose, pharynx, larynx, trachea, bronchi, bronchioles, and an area for gas exchange containing alveoli.

Types of Respiration

External Respiration: The inhalation of O2 and removal of CO2. This process occurs in the lungs.
Internal Respiration: The utilization of O2 and the production of CO2 by cells, also known as cellular respiration. This happens throughout the body's tissues.

External Respiration Detail

Divided into four main parts:
- Pulmonary Ventilation: The inflow and outflow of air between the atmosphere and lung alveoli, and distribution of air in the lungs. It happens through breathing movements and controlled by respiratory centers in the brain stem.
- Pulmonary Perfusion: The distribution of blood through the lungs. The normal blood volume is 5 liters per minute, equal to the cardiac output of the right ventricle.
- Diffusion of Gases: The exchange of oxygen (O2) and carbon dioxide (CO2) between the air in the alveoli and blood in the pulmonary capillaries. This is a passive process driven by pressure gradients.
- Gas Transport: The transport of O2 from the lungs to tissues and CO2 from tissues to the lungs in the blood.

Respiratory Airways

The airways are branching tubes that become narrower, shorter, and more numerous as they enter the lungs.
Functionally divided into conducting and respiratory zones.
Conducting Zone: Contains the passageways that conduct air to the gas exchange sites, including the trachea, bronchi, and bronchioles. This area helps with air conduction, conditioning, humidification, immunity, filtration, and phonation (sound production).
Respiratory Zone: This area, encompassing respiratory bronchioles, alveolar ducts, alveoli sacs, and alveoli, is the actual site of gas exchange.

Mechanism of Breathing

Inspiration: An active process involving the diaphragm moving downward and the external intercostal muscles elevating the ribs, expanding the chest cavity, and drawing air into the lungs.
Expiration: A passive process where the diaphragm relaxes, the ribs return to their resting position, and the elastic recoil of the lungs forces air out.
Tidal Volume (TV): The volume of air inhaled or exhaled in a normal breathing cycle.

Intra-pleural Pressure

The pressure within the pleural space (between the lungs and chest wall).
It is negative, meaning it is less than atmospheric pressure, and this causes the lungs to expand along with the chest wall.
Negative pressure is maintained due to the lack of air in the pleural cavity, elastic recoil of the lungs, surface tension of fluid lining the alveoli, and elastic properties of the chest wall.
Important for lung expansion, negative intrathoracic pressure (enabling venous return), and overall mechanics of breathing.

Minute Respiratory Volume

The volume of air breathed in per minute, calculated by multiplying tidal volume and respiratory rate.
Normal values are in the 6 liter/minute range.
Note: Respiratory rates vary by age.

Surfactant

Definition: A surface tension-lowering agent produced by Type II alveolar epithelial cells that decreases the surface tension in the fluid lining the alveoli.
It keeps the alveoli dry and prevents them from collapsing during expiration. This reduces the work of breathing.
Factors that affect its formation:
- Stimulatory: Thyroid hormones and glucocorticoids
- Inhibitory: Smoking, insulin, long-term pure O2 inhalation, and prolonged pulmonary circulation stoppage.
Deficiency can lead to:
- Adults: Increased work of breathing
- Preterm infants: Respiratory distress syndrome

Gas Exchange and Transport

External Gas Transfer at Lungs: Exchange of (02 and CO2) between the air in alveoli and blood in pulmonary capillaries (an example of diffusion).
- Factors affecting gas exchange rate: thickness of respiratory membrane (inversely proportional), surface area of respiratory membrane (directly proportional), pressure gradient (directly proportional), solubility of gases in respiratory membrane (directly proportional), and molecular weight (inversely proportional).
Gas Transport
- Oxygen Transport: About 3% dissolved in plasma, the remaining 97% bound to hemoglobin in red blood cells, which carries a total of 4 oxygen molecules per Hb molecule.
- Carbon Dioxide Transport: Mostly (95%) as bicarbonate in the blood. A smaller portion (5%) is bound to hemoglobin and/or dissolved in plasma.

Hypoxia and Cyanosis

Hypoxia: Oxygen deficiency at the tissue level.
- Types of Hypoxia: Hypoxic, anemic, stagnant, and histotoxic. Specific causes of each subtype are discussed throughout the notes.
Cyanosis: Bluish discoloration of the skin and mucous membranes. Occurs when the amount of reduced hemoglobin (deoxygenated blood) in the blood is above 5 grams/100mL of blood.

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Description

Test your knowledge of the respiratory system with this quiz focused on key concepts related to respiration, gas exchange, and related physiological processes. Explore questions about hypoxia, the function of the larynx, and the mechanics of breathing.