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Questions and Answers
What is the primary function of the mucus in the trachea?
What is the primary function of the mucus in the trachea?
What structural feature allows the oesophagus to expand during swallowing?
What structural feature allows the oesophagus to expand during swallowing?
Which layer of pleura is directly attached to the surface of the lungs?
Which layer of pleura is directly attached to the surface of the lungs?
What happens to the gas exchange process in smokers?
What happens to the gas exchange process in smokers?
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Which muscles are primarily responsible for the movement of the ribs during respiration?
Which muscles are primarily responsible for the movement of the ribs during respiration?
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Where does the gas exchange occur in the lungs?
Where does the gas exchange occur in the lungs?
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What type of epithelium lines the alveoli?
What type of epithelium lines the alveoli?
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What is the main role of the diaphragm during respiration?
What is the main role of the diaphragm during respiration?
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What is the primary function of external respiration?
What is the primary function of external respiration?
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Which organ is NOT considered part of the Upper Respiratory Tract?
Which organ is NOT considered part of the Upper Respiratory Tract?
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What role do the vocal cords play in the respiratory system?
What role do the vocal cords play in the respiratory system?
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Which muscle is primarily responsible for inhalation during breathing?
Which muscle is primarily responsible for inhalation during breathing?
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What does cellular respiration primarily involve?
What does cellular respiration primarily involve?
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What is the function of the epiglottis during swallowing?
What is the function of the epiglottis during swallowing?
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Which component is NOT a structure associated with the respiratory system?
Which component is NOT a structure associated with the respiratory system?
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Where does internal respiration occur?
Where does internal respiration occur?
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What happens to the diaphragm during inspiration?
What happens to the diaphragm during inspiration?
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What is the tidal volume during normal breathing?
What is the tidal volume during normal breathing?
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Which of the following factors does NOT affect the diffusing capacity (DLCO or TLCO)?
Which of the following factors does NOT affect the diffusing capacity (DLCO or TLCO)?
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What is the primary mechanism controlling breathing rate?
What is the primary mechanism controlling breathing rate?
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At sea level, what is the partial pressure of oxygen (PO2)?
At sea level, what is the partial pressure of oxygen (PO2)?
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What percentage of oxygen transport is carried out by hemoglobin?
What percentage of oxygen transport is carried out by hemoglobin?
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Which type of muscle contraction allows for some voluntary control over breathing?
Which type of muscle contraction allows for some voluntary control over breathing?
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What happens during expiration?
What happens during expiration?
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Study Notes
Respiratory System Overview
- The respiratory system facilitates gas exchange, taking in oxygen and releasing carbon dioxide.
- It comprises a network of tubes, filtering and transporting air to microscopic alveoli for gas exchange.
Respiratory System Objectives
- Define external (pulmonary), internal (tissue), and cellular respiration.
- Identify and describe the function of each organ in the respiratory system.
- Detail the mechanisms of inspiration and expiration, with a focus on the role of respiratory muscles.
Respiration Definitions
- External Respiration: Gas exchange between blood capillaries and air sacs (alveoli) in the lungs.
- Internal Respiration: Gas exchange between blood capillaries and body cells.
- Cellular Respiration: The breakdown of organic molecules (usually glucose) within cells to release energy.
Respiratory System Structures
- Upper Respiratory Tract (URT): Includes the nose, nasal cavity, pharynx (throat). The nose and nasal cavity filter, warm, and humidify the air. The pharynx is a common passageway for air and food.
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Lower Respiratory Tract (LRT): Consists of the trachea, bronchi, and lungs.
- Trachea: A tube supported by cartilaginous rings, preventing collapse and allowing the esophagus to expand during swallowing. Lined with a mucous membrane containing ciliated epithelium to trap and remove foreign particles.
- Bronchi: Branching tubes that deliver air deeper into the lungs, and further divide into smaller tubes called bronchioles.
- Lungs: Spongy, cone-shaped organs enclosed by the diaphragm and thoracic cage. They house the alveoli (air sacs) where gas exchange occurs.
- Alveoli: Microscopic air sacs in the lungs with thin walls of simple squamous epithelium, a rich network of capillaries, facilitating efficient gas exchange.
- Diaphragm, ribs & intercostal muscles: The diaphragm contracts and pulls downward, while the intercostal muscles raise the ribs, expanding the chest cavity and creating negative pressure, drawing air into the lungs.
Structures of the Nose and Mouth
- The nose and nasal cavity are supported by bone and cartilage, providing an entrance for air.
- The nasal passages are lined with mucous membrane containing fine hairs that filter the air, warming it and making it moist.
- The hard and soft palate separate the nasal passage from the oral cavity and food, diverting air from the food passage.
The Air Passages and Associated Structures
- Larynx: A cartilaginous structure supporting the trachea and preventing foreign particles from entering the trachea. Houses the vocal cords for sound production.
- Trachea: Main airway; keeps open via C-shaped cartilage rings; lined with mucous membrane with cilia to remove debris.
The Lungs
- The lungs are spongy, cone-shaped organs that occupy most of the thoracic cavity.
- They are separated medially by the mediastinum, and enclosed by the diaphragm and thoracic cage.
- There's visceral pleura surrounding the lungs, and the parietal pleura lining the thoracic cavity. The pleural layers create a lubricating fluid.
- In smokers, tar in the airways can irritate the lungs, leading to difficulty in gas exchange.
Microscopic Structure of the Lungs
- Bronchi continually divide to form bronchioles that feed into alveolar ducts ending in alveoli.
- Alveoli contain a rich supply of capillaries to facilitate oxygen-carbon dioxide exchange.
- Oxygen diffuses from alveoli to blood and carbon dioxide from the blood to alveoli.
Diaphragm, Ribs and Intercostal Muscles
- Diaphragm: Dome-shaped sheet of muscle that plays a key role in breathing by contracting and relaxing to change the volume of the thoracic cavity.
- Ribs: Protect the heart and lungs; raising and lowering of the ribcage by intercostal muscles aids breathing.
Breathing Rate
- Breathing rate is primarily controlled by the brain and is involuntary.
- During and after exercise, breathing increases to remove more carbon dioxide expelled from the bloodstream.
- Some voluntary control of breathing is possible.
- Breathing rate varies by age.
Gas Transport and Diffusion
- Partial Pressure: Pressure exerted by a gas in a mixture of gases (e.g., atmospheric gases). At sea level, atmospheric pressure is 760 mmHg.
- Oxygen and Carbon Dioxide Diffusion based on the partial pressure differences in Alveoli, blood and tissues.
- Gas exchange happens due to the difference of partial pressures across the alveolar-capillary membrane. Oxygen moves from alveoli to blood into hemoglobin, while carbon dioxide moves from blood to alveoli.
Mechanisms of Breathing
- Inspiration: Inhalation, involving contraction of the diaphragm and intercostal muscles, expanding the thoracic cavity decreasing the internal air pressure to pull air into the lungs.
- Expiration: Exhalation, through relaxation of these muscles allowing the ribs to descend and the diaphragm to rise, decreasing the thoracic cavity volume increasing air pressure forcing air out.
Oxygen Transport
- Oxygen is primarily transported by hemoglobin. (97%)
Carbon Dioxide Transport
- Most carbon dioxide is transported as bicarbonate ions.
Control Mechanisms
- Neural (Nerve): Brain stem regulates breathing patterns through neural pathways.
- Chemical: Peripheral and central chemoreceptors sensitive (especially Central chemoreceptors) to changes in blood pH, and CO2 concentration.
- Intra-pulmonary (Lung): Stretch receptors and other receptors in the lungs send afferent information to the brain to fine-tune the breathing process.
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Description
Explore the intricacies of the respiratory system, including the processes of gas exchange and the functions of key organs. This quiz covers the definitions of respiration types and the mechanisms involved in breathing. Test your knowledge on the structure and function of this vital system.
