Respiratory System Flashcards
Explain why humans need a respiratory system
Humans have a low surface area to volume ratio and a high metabolic rate, which increases the demand for oxygen for aerobic respiration. The respiratory system facilitates efficient gas exchange to meet these demands.
Describe the process of ventilation
Ventilation is the exchange of air between the lungs and the surrounding environment. It involves inhalation, where air enters the lungs, and exhalation, where air exits the lungs.
State the function of the pulmonary arteries and pulmonary veins
Pulmonary arteries carry deoxygenated blood from the right ventricle to the lungs, while pulmonary veins carry oxygenated blood from the lungs to the left atrium.
Describe the role of ciliated epithelium in the respiratory system
Ciliated epithelium contains goblet cells that secrete mucus to trap debris and pathogens. The cilia waft the mucus upwards to the throat, where it can be swallowed, preventing harmful substances from reaching the lungs.
Explain the importance of cartilage in the trachea and bronchi
Cartilage provides structural support, keeping airways open during breathing. Its “C” shape in the trachea allows flexibility for the oesophagus to expand when swallowing food.
State the main function of bronchioles
Bronchioles transmit air to and from the alveoli and help regulate airflow through smooth muscle contraction and relaxation.
Describe the features of alveoli that make them efficient for gas exchange
Alveoli have a large surface area, thin walls made of squamous epithelial cells, and are surrounded by a dense capillary network. They are also moist and maintain a steep concentration gradient for efficient diffusion of gases.
Explain the role of surfactant in the alveoli
Surfactant reduces surface tension within the alveoli, preventing their walls from sticking together and collapsing, thereby maintaining open airways.
Describe the mechanism for inspiration
During inspiration, external intercostal muscles contract, pulling the rib cage up and out, and the diaphragm flattens. This increases the volume of the thoracic cavity, decreases pressure in the lungs, and draws air in.
Explain how the concentration gradient is maintained during gas exchange in the lungs
The concentration gradient is maintained by constant blood flow removing oxygenated blood and bringing deoxygenated blood, along with regular ventilation replacing air in the alveoli.
state the role of elastic fibers in the respiratory system
Elastic fibers allow the airways to stretch and recoil during breathing, ensuring that the airways return to their original shape after stretching.
explain how changes in CO2 levels affect breathing rate
Increased CO2 lowers blood pH, which is detected by chemoreceptors in the carotid artery and aorta. These send signals to the ventilation center, which adjusts the rate of breathing to restore pH balance.
Describe the role of the pleural membranes during ventilation
The pleural membranes and pleural fluid create surface tension, ensuring the lungs move with the thoracic cavity during breathing. This allows changes in chest cavity volume to affect lung volume directly.
Explain why the trachea has C-shaped cartilage rings instead of complete rings
The C-shaped cartilage provides structural support to keep the airway open while allowing flexibility for the oesophagus to expand during swallowing.
state the function of smooth muscle in the respiratory system
Smooth muscle controls airflow by contracting to narrow airways and relaxing to widen them. This helps regulate the flow of air to and from the alveoli.
describe how oxygen is transported in the blood
Oxygen diffuses into red blood cells in the alveoli and binds to haemoglobin, forming oxyhaemoglobin. It is transported to tissues where it diffuses into cells for respiration.
explain the role of the diaphragm in ventilation
During inspiration, the diaphragm contracts and flattens, increasing the volume of the thoracic cavity and reducing lung pressure, drawing air in. During expiration, it relaxes and returns to a dome shape, reducing thoracic volume and forcing air out.
state the structural differences between bronchi and bronchioles
Bronchi have cartilage rings, ciliated epithelium, and glandular tissue, while bronchioles lack cartilage rings and are smaller in diameter, with smooth muscle and elastic fibers instead.
describe the role of the nasal cavity in respiration
The nasal cavity warms, moistens, and filters incoming air. Its blood supply warms the air, mucus traps particles, and hairs filter out debris.
explain the significance of thin alveolar walls in gas exchange
Thin alveolar walls, made of squamous epithelium, create a short diffusion pathway, enabling efficient gas exchange between the alveoli and capillaries.
State the differences in oxygen and carbon dioxide concentrations between alveoli and blood during gas exchange
Oxygen concentration is higher in alveoli and lower in blood, causing oxygen to diffuse into the blood. Carbon dioxide concentration is higher in blood and lower in alveoli, causing carbon dioxide to diffuse into the alveoli.
describe how moisture in the alveoli aids gas exchange
Moisture in the alveoli dissolves gases, making it easier for oxygen to diffuse into the blood and for carbon dioxide to diffuse into the alveoli.
explain the role of elastic fibers in alveoli
Elastic fibers allow alveoli to stretch during inspiration and recoil during expiration, aiding efficient air movement in and out of the lungs.
state the function of chemoreceptors in controlling ventilation
Chemoreceptors detect changes in blood pH caused by CO2 levels. They send signals to the ventilation center to adjust breathing rate and depth to restore pH balance.
describe the process of forced expiration
During forced expiration, internal intercostal muscles and abdominal muscles contract, reducing thoracic volume and increasing pressure, expelling air from the lungs quickly.
explain how gas exchange ensures a steep concentration gradient in the lungs
Continuous blood flow removes oxygenated blood and brings deoxygenated blood, while ventilation replenishes alveolar air, maintaining a high oxygen concentration and low carbon dioxide concentration.
state the role of pleural fluid
Pleural fluid lubricates the pleural membranes, reducing friction and allowing smooth movement of the lungs during ventilation.
describe the importance of a large surface area in the lungs
A large surface area, provided by numerous alveoli, maximizes the space available for gas exchange, ensuring sufficient oxygen uptake and carbon dioxide removal.
describe the role of external intercostal muscles during inspiration
External intercostal muscles contract, pulling the rib cage upwards and outwards. This increases the volume of the thoracic cavity, reducing pressure in the lungs and allowing air to flow in.
explain how the diaphragm contributes to the process of inhalation
During inhalation, the diaphragm contracts and flattens, increasing the vertical volume of the thoracic cavity. This reduces lung pressure below atmospheric pressure, causing air to flow in.
state the function of internal intercostal muscles during forced exhalation
Internal intercostal muscles contract, pulling the rib cage downwards and inwards, decreasing thoracic volume and increasing pressure, forcing air out of the lungs.
explain the difference between normal and forced exhalation in terms of muscle activity
Normal exhalation involves relaxation of the diaphragm and external intercostal muscles, while forced exhalation involves contraction of the internal intercostal muscles and abdominal muscles to rapidly decrease thoracic volume.
describe how the diaphragm and intercostal muscles work together during inspiration
The diaphragm contracts and flattens, while the external intercostal muscles contract to lift the rib cage up and out. These combined actions increase thoracic volume, decreasing lung pressure to draw air in.
explain the role of the pleural membranes in facilitating the moments of the diaphragm and intercostal muscles
The pleural membranes and pleural fluid allow the lungs to adhere to the chest wall and diaphragm. As the intercostal muscles and diaphragm move, the lungs are pulled along, facilitating ventilation.
state what happens to the diaphragm during exhalation
During exhalation, the diaphragm relaxes and returns to its domed shape, reducing the thoracic cavity’s volume and increasing pressure to expel air.
explain how the intercostal muscles and diaphragm maintain the pressure gradient needed for ventilation
By altering thoracic cavity volume, the diaphragm and intercostal muscles create pressure changes. Reduced pressure during inspiration draws air in, while increased pressure during exhalation forces air out.
explain the action of the intercostal muscles during forced exhalation
Internal intercostal muscles contract to pull the ribs down and in, reducing thoracic volume more quickly and increasing pressure to expel air rapidly.
state why the diaphragm is considered both a skeletal and involuntary muscle
The diaphragm is a skeletal muscle because it is striated and controlled during voluntary breathing. However, it is also involuntary because it contracts automatically during normal breathing controlled by the respiratory center.
explain how changes in activity level affect the diaphragm and intercostal muscles
Increased activity raises the demand for oxygen, causing the diaphragm and intercostal muscles to contract more frequently and forcefully to increase ventilation rate and volume.
describe the importance of the diaphragm in maintaining effective ventilation at rest
At rest, the diaphragm’s rhythmic contraction and relaxation dominate breathing, efficiently changing thoracic volume to sustain ventilation without excessive energy use.
state what happens to the rib cage during inhalation and exhalation
During inhalation, the rib cage is lifted up and out by the external intercostal muscles. During exhalation, it returns to its resting position due to muscle relaxation or contraction of internal intercostal muscles during forced exhalation.
explain how the diaphragm’s structure supports its function in ventilation
The diaphragm’s dome shape allows it to flatten effectively when contracted, increasing thoracic volume. Its central tendon and strong muscle fibers ensure efficient force generation during breathing.
