Respiratory system
52 flashcards covering Respiratory system for the MCAT Biology & Biochemistry section.
The respiratory system is the body's network of organs and tissues responsible for breathing, which involves taking in oxygen and expelling carbon dioxide. It includes structures like the lungs, airways, diaphragm, and blood vessels that work together to facilitate gas exchange. This process is vital for delivering oxygen to cells for energy production and removing waste, maintaining overall homeostasis and supporting functions like pH balance in the blood.
On the MCAT, the respiratory system frequently appears in Biology and Biochemistry questions that test anatomy, physiology, and related concepts. You'll encounter multiple-choice questions on topics like gas exchange mechanisms, respiratory volumes, and the impact of conditions such as emphysema. Common traps include mixing up ventilation with cellular respiration or overlooking how altitude affects oxygen levels, so focus on integrating anatomical knowledge with physiological processes like the role of hemoglobin and acid-base regulation.
A helpful tip: Practice sketching the respiratory pathway to visualize gas flow.
Terms (52)
- 01
Alveoli
Tiny air sacs in the lungs where gas exchange occurs between the air and the bloodstream, allowing oxygen to enter and carbon dioxide to leave the blood.
- 02
Diaphragm
The primary muscle of respiration that contracts and flattens to increase thoracic volume during inspiration, drawing air into the lungs.
- 03
Trachea
The windpipe that conducts air from the larynx to the bronchi, lined with ciliated epithelium to trap and remove particles.
- 04
Bronchi
The main airways branching from the trachea into each lung, which further divide and help distribute air to the lung tissues.
- 05
Bronchioles
Smaller branches of the bronchi that lead to the alveoli, regulating airflow with smooth muscle that can constrict or dilate.
- 06
Alveolar sacs
Clusters of alveoli that increase the surface area for efficient gas exchange in the lungs.
- 07
Pleural membranes
Two layers of tissue surrounding the lungs, with the pleural fluid between them reducing friction during breathing movements.
- 08
Inspiration process
The active phase of breathing where the diaphragm and intercostal muscles contract to expand the thoracic cavity, creating negative pressure to draw air in.
- 09
Expiration process
The passive phase of breathing where the diaphragm and intercostal muscles relax, decreasing thoracic volume and pushing air out of the lungs.
- 10
Tidal volume
The amount of air that moves in and out of the lungs with each normal breath, typically around 500 milliliters in adults.
- 11
Inspiratory reserve volume
The additional air that can be inhaled after a normal inspiration by maximum effort, exceeding the tidal volume.
- 12
Expiratory reserve volume
The extra air that can be exhaled after a normal expiration by maximum effort, beyond the tidal volume.
- 13
Residual volume
The amount of air that remains in the lungs after a maximum exhalation, preventing lung collapse and allowing gas exchange to continue.
- 14
Vital capacity
The maximum amount of air that can be exhaled after a maximum inhalation, calculated as inspiratory reserve volume plus tidal volume plus expiratory reserve volume.
- 15
Total lung capacity
The total volume of air in the lungs after a maximum inhalation, including vital capacity and residual volume.
- 16
Functional residual capacity
The volume of air remaining in the lungs after a normal expiration, consisting of expiratory reserve volume and residual volume.
- 17
Boyle's law
A gas law stating that the pressure of a gas is inversely proportional to its volume at constant temperature, explaining how lung volume changes affect air pressure during breathing.
- 18
Partial pressure of gases
The pressure exerted by a single gas in a mixture, such as oxygen or carbon dioxide in air, which drives gas exchange in the alveoli based on concentration gradients.
- 19
Gas exchange in lungs
The process where oxygen diffuses from alveoli into the blood and carbon dioxide diffuses from blood into alveoli, facilitated by the thin alveolar membrane.
- 20
Diffusion of oxygen
The movement of oxygen from areas of higher concentration in the alveoli to lower concentration in the pulmonary capillaries, following Fick's law.
- 21
Diffusion of carbon dioxide
The movement of carbon dioxide from the blood, where it is in higher concentration, into the alveoli for exhalation.
- 22
Hemoglobin structure
A protein in red blood cells with four subunits, each containing a heme group that binds oxygen, enabling efficient transport in the bloodstream.
- 23
Oxygen binding to hemoglobin
The reversible process where oxygen attaches to hemoglobin in the lungs and releases in tissues, influenced by factors like pH and temperature.
- 24
Oxyhemoglobin dissociation curve
A sigmoid curve showing the relationship between oxygen partial pressure and hemoglobin saturation, indicating how easily oxygen is released to tissues.
- 25
Factors affecting oxygen dissociation
Variables like decreased pH, increased temperature, and higher 2,3-DPG levels that shift the oxyhemoglobin dissociation curve to the right, facilitating oxygen release.
- 26
Carbon dioxide transport in blood
The carriage of carbon dioxide in the blood as bicarbonate ions, dissolved gas, or bound to hemoglobin, with most converted via the chloride shift.
- 27
Chloride shift mechanism
The exchange of chloride ions for bicarbonate ions across red blood cell membranes to maintain electrical neutrality during carbon dioxide transport.
- 28
Bohr effect
The phenomenon where increased carbon dioxide or decreased pH reduces hemoglobin's affinity for oxygen, promoting oxygen release in active tissues.
- 29
Haldane effect
The increased ability of deoxygenated hemoglobin to bind carbon dioxide compared to oxygenated hemoglobin, aiding in carbon dioxide transport.
- 30
Respiratory control center
A group of neurons in the medulla oblongata that regulate breathing rate and depth by responding to blood gas levels and sending signals to respiratory muscles.
- 31
Peripheral chemoreceptors
Sensors in the carotid and aortic bodies that detect changes in blood oxygen, carbon dioxide, and pH, sending signals to adjust breathing.
- 32
Central chemoreceptors
Neurons in the medulla oblongata that respond primarily to changes in blood pH due to carbon dioxide levels, influencing respiratory drive.
- 33
Regulation of breathing rate
The automatic adjustment of breathing frequency and depth based on feedback from chemoreceptors and the respiratory control center to maintain homeostasis.
- 34
Hyperventilation effects
Rapid or deep breathing that lowers carbon dioxide levels, leading to respiratory alkalosis and symptoms like dizziness.
- 35
Hypoventilation effects
Slow or shallow breathing that raises carbon dioxide levels, resulting in respiratory acidosis and potential oxygen deprivation.
- 36
Respiratory acidosis
A condition of decreased blood pH due to excess carbon dioxide, often from hypoventilation, which the kidneys attempt to correct by retaining bicarbonate.
- 37
Respiratory alkalosis
A condition of increased blood pH due to low carbon dioxide levels, typically from hyperventilation, which the kidneys counter by excreting bicarbonate.
- 38
Surfactant function
A substance in the alveoli that reduces surface tension, preventing alveolar collapse and making breathing easier, especially in newborns.
- 39
Infant respiratory distress syndrome
A condition in premature infants lacking sufficient surfactant, leading to difficult breathing and potential lung collapse.
- 40
Asthma pathophysiology
A chronic inflammatory disease causing airway narrowing due to bronchoconstriction and mucus production, resulting in wheezing and shortness of breath.
- 41
Emphysema causes
A lung disease often from smoking that destroys alveolar walls, reducing surface area for gas exchange and causing air trapping.
- 42
Ventilation-perfusion ratio
The balance between air reaching the alveoli and blood flow through pulmonary capillaries, ideally 1:1 for efficient gas exchange; mismatches cause hypoxia.
- 43
Hypoxic vasoconstriction
The narrowing of pulmonary blood vessels in response to low oxygen levels, redirecting blood to better-ventilated areas of the lung.
- 44
Dead space volume
The portion of each breath that does not participate in gas exchange, including anatomical dead space in airways and any alveolar dead space.
- 45
Alveolar ventilation equation
A formula calculating effective ventilation as tidal volume minus dead space volume, multiplied by breathing rate, to determine gas exchange efficiency.
- 46
Fick's law of diffusion
A principle stating that the rate of gas diffusion is proportional to the surface area and concentration gradient, and inversely proportional to membrane thickness.
- 47
Henry's law in respiration
A gas law indicating that the amount of gas dissolved in a liquid is proportional to its partial pressure, explaining oxygen and carbon dioxide solubility in blood.
- 48
Mucociliary clearance
The process where cilia in the respiratory tract move mucus and trapped particles upward to the throat for removal, defending against infections.
- 49
Ciliated epithelial cells
Cells lining the airways with hair-like projections that beat to propel mucus and debris out of the respiratory tract.
- 50
Epiglottis role
A flap of tissue that covers the larynx during swallowing to prevent food and liquids from entering the airway.
- 51
Pharyngeal structures
Parts of the throat including the nasopharynx, oropharynx, and laryngopharynx, which serve as a passageway for air and food.
- 52
Laryngeal functions
The voice box that houses the vocal cords for sound production and acts as a sphincter to protect the lower airway during swallowing.