Objectives: Respiratory System – Flashcards
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Describe the functions of the respiratory system
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1. Oxygen and carbon dioxide exchange: gets rid of CO2 lvels to prevent it effecting pH 2. Speech and vocalization 3. Sense of smell 4. pH homeostasis: hypercapnia → acidosis 5. Synthesis of angiotensin II (hormone that increases BP) 6. Venous return (thoracic pump)
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Essay Question: Be able to trace a molecule of oxygen through the respiratory system into the blood, naming the major structures it passes by or goes through.
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Nasal cavity → pharynx → trachea → main bronchus → lobar bronchus → segmental bronchus → bronchiole → terminal bronchiole →respiratory bronchiole → alveolar duct → atrium alveolus
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Understand the purpose of the sinuses
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1. Reduce the weight of the skull 2. Serve as resonant chamber for sound 3. Warm and moisten air
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Explain how sound is produced by the vocal folds
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The inferior vocal cords (vocal folds) produce sound when air passes between them and they vibrate. Faster vibrations, higher pitch Slow vibrations, low pitch sound
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Distinguish between the "false" and "true" vocal folds
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The superior vestibular folds play no role in speech but close the larynx during swallowing. They are known as the false vocal chords. The inferior vocal cords (vocal folds) produce sound when air passes between them
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Know the types of alveolar cells, and their individual functions
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Type I (squamous) alveolar cell is the most prominent in surface area; Thin wall; Very flat; Makes up aveolar wall. On the other hand, Type II (great) alveolar cell secretes surfactant. Surfactant keeps tension on outside so pops back open by decreasing the surface tension on the inside of the elveoli. The last alveolar cell is the Alveolar macrophage, For protection and clean-up. Engulf particles and bacteria in the lungs. Move with amoeboid motion. Dead macrophages carried away by mucous and cilia to be swallowed
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Describe the components of the respiratory membrane
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Two fused basement membrane: shared membrane layer between alveoli and capillaries Epithelial cells of alveolus Endothelial cells of capillary
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Explain the role of alveolar surface tension
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Alveolar surface tension is the cohesion of H2O molecules within alveoli. It is the primary cause of elastic recoil of lungs. Elastic recoil resists stretching and helps return lungs to resting size. But... that same force tries to reduce surface area and collapse alveoli
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Explain the role of alveolar surfactant
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Alveolar Surfactant decreases surface tension inside the aveoli and makes sure the aveoli do NOT collapse. Surfactant is synthesized by Type II (great) alveoli.
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Explain how inspiration work - what muscles are involved? Why does air move in or out?
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Inspiration is breathing in so the diaphragm is contracted (flat-shaped). The volume is increasing along with surface area. Pressure is ↓ due to the thoracic cavity expanding. Chest expands due to diaphragm and external intercostal muscles contracting. As chest expands, lungs also expand due to surface tension between the two layers of pleura.
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Explain how expiration work - what muscles are involved? Why does air move in or out?
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Expiration is breathing out. Diaphragm is relaxed (dome-shaped) It is a passive compressing thoracic cavity. Pressure ↑; Air pressure is ↓ in lungs; Volume ↓ Due to elastic recoil of muscle and lung tissue, and from the surface tension of alveoli. Forced expiration aided by the thoracic and abdominal wall muscles that compress the abdomen against the diaphragm
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Essay Question: Explain how forced inspiration and forced expiration work. What muscles are involved? Why are they called "forced"?
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Normal Inspiration muscles: diaphragm and external intercostals Forced Inspiration muscles: sternocleidomastoid, scalenes, and pectoralis minor Normal Expiration muscles: passive relaxation of diaphragm and intercostals Forced Expiration muscles: Internal intercostals, Diaphragm, Rectus abdominis, and External abdominal oblique They are called "forced" bc it is unusually deep or rapid breathing, as in the state of exercise.
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Essay Question: Know the different lung volumes and their relationships to each other
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1. Total lung capacity (TLC) - maximum amount of air the lungs can contain 2. Tidal volume (TV) - normal breath ~500mL 3. Inspiratory reserve volume (IRV) - extra volume that can be inspired above tidal volume (3000mL) 4. Expiratory reserve volume (ERV) - extra volume that can be forcibly exhaled 5. Residual volume (RV) - volume that remains in lungs; allows constant gas exchange; keeps alveoli inflated 6. Vital capacity (VC) - maximum expiration after maximum inspiration
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Essay Question: Understand how respiration is controlled by the Respiratory Centers including VRG and DRG.
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Respiratory centers of the medulla and the pons. Causes inspiration/expiration and controls rate and depth of breathing. Composed of VRG and DRG. Ventral respiratory group (VRG): sets basic rhythm of breathing; fires signals via phrenic and intercostal nerves; diaphragm and intercostals contract when signaled, passively relax Dorsal respiratory group (DRG): integrates input from stretch and chemoreceptors; communicates to VRG. Taking input from other sources and inputting it to the VRG Input (DRG) → output (VRG)
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Essay Question: Understand how respiration is controlled by the peripheral chemoreceptors.
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Peripheral chemoreceptors in carotid sinuses and aortic arch sense changes in oxygen concentration, transmit to respiratory center which responds accordingly Breathing rate, tidal volume adjusted Similar to central chemoreceptors ↑ CO2,= ↑ H+ = ↓ pH
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Essay Question: Understand how respiration is controlled by the central chemoreceptors.
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Central chemoreceptors are associated with the respiratory center in the brain stem; associated with medulla directly Sample Cerebral Spinal Fluid, sensitive to pH and CO2 concentrations Low pH = high CO2 = stimulate breathing to "blow off" the CO2 ↑ CO2,= ↑ H+ = ↓ pH
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Essay Question: Understand how respiration is controlled by the stretch and irritant receptors.
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Stretch and irritant receptors are sensitive to the degree of stretch; making sure we don't overstretch them Inhibits breathing, stimulate cough reflex Something is stuck in bronchi
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Essay Question: Understand how respiration is controlled by the receptors in muscles and joints.
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Receptors in muscles and joints are proprioceptors i.e. exercise makes the brain prepare for use Increases breathing in preparation for demand
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Essay Question: Understand how respiration is controlled by hyperventilation.
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Hyperventilation: Lowers CO2 levels in the blood; pH of blood is low so becoming acidic. The body's way of compensating is to enhance breathing and bow off CO2 into the air
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Know what partial pressure is, and how is it calculated
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Partial Pressure is the Individual pressure exerted by a particular gas in a mixture of gases Partial Pressure = % of gas mixture x Total Pressure Gas diffuses down its individual partial pressure gradient. This means that . . . different gases can be diffusing in different directions simultaneously!(because gas molecules are so far apart they don't interfere with one another...) Both exert pressure but not dependent on each other
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Understand how the partial pressure gradient influences gas transfer:
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Partial pressure gradient is the primary influence! ↑ gradient = ↑ rate of transfer
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Understand how the surface area influences gas transfer:
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↑ surface area = ↑ rate of transfer Ex: emphysema
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Understand how the membrane thickness influences gas transfer.
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↑ thickness = ↓ rate of transfer Ex: pneumonia
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Understand how the Diffusion Coefficient influences gas transfer.
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Diffusion coefficient is the Solubility of a gas ↑ diffusion coefficient = ↑ rate of transfer eg. CO2 has a higher D.C. than O2 Needs steeper gradient bc less soluble than O2
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Understand how the Ventilation-Perfusion Coupling influences gas transfer:
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Ventilation-perfusion coupling is matching airflow with blood flow (and vice versa).
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Know the different ways oxygen is transported in the blood
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Some of oxygen is transported in a dissolved gas. Over 98% of oxygen in blood is bound to hemoglobin of RBCs, forming oxyhemoglobin.
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Explain the basics of hemoglobin structure, and where it binds oxygen
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Hemoglobin is a Protein specialized to bind and transport oxygen. Contains four globin peptide chains and four iron-containing heme groups (one per globin). One oxygen binds to each of the iron-containing heme groups. Can bind up to 4 O2 molecules per hemoglobin, molecule
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Understand the oxygen-hemoglobin dissociation curve. Specifically What is the significance of the steep part of the curve?
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At the Steep region of the Oxygen-Hb Disassociation oxygen binding is fast bc of cooperative binding. O2 binds Hb in a cooperative manner meaning the binding of 1 O2 to HB facilitates the second then third. Steep curve means that if tissues are using more O2 (↓ Po2), then lots of O2 can unload from Hb; Binding easier and faster so O2 is dumped where needed
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Understand the oxygen-hemoglobin dissociation curve. Specifically The plateau portion?
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At the Plateau region of the Oxygen-Hb Disassociation oxygen binding slows down bc HB is near full saturation. Because of plateau, moderate PO2 decreases do NOT result in changes of Hb saturation Ex: High altitude Give the body a little "Wiggle room" bc if the alveolar air its ok bc HB is still saturated
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Understand the oxygen-hemoglobin dissociation curve. Specifically What is the oxygen reserve? It's significance?
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Oxygen reserve - During exercise (Hb = 15% saturated)
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Explain what a "right shift" of the oxygen-Hb curve means
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When temperature rises, the oxyhemoglobin dissociation curve shifts to the; in other words, elevated temperature promotes oxygen unloading
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Explain how CO poisoning works
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Carbon Monoxide is an Odorless, colorless gas. Hb has over 200x greater affinity for CO than O2, so CO displaces O2 forming a carboxyhemoglobin (= CO + Hb). CO greatly decreases blood's ability to transport O2 leading to carbon monoxide poisoning. The Hyperbaric chamber with ↑Po2 to displace the bond of CO and Hb
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Understand how CO2 affect Hb saturation and oxygen loading/unloading
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↑ CO2 = ↓ Saturation of Hb = O2 unloading easier = ↓pH CO2 binds slightly with Hb; increased PCO2 = right shift of curve
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Understand how pH affect Hb saturation and oxygen loading/unloading
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↑ Acids = ↓ pH; = ↓ Hb saturation e.g., CO2, lactic acid decreases Hb affinity for O2
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Understand how temperature affect Hb saturation and oxygen loading/unloading
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↑ Temperature = ↓ Saturation of Hb = O2 unloading easier Increased temperature = right shift of curve; as in exercising tissue
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Know the different ways CO2 is transported in the blood, and the relative proportion of each
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CO2 is Transported via hemoglobin (carbaminohemoglobin = CO2 + Hb), dissolved in plasma (5-10%), or as bicarbonate. Most CO2 (80-90%) is transported as bicarbonate. Bicarbonate is aided by carbonic anhydrase in RBCs. Process reversed in lungs
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How does increased CO2 result in decreased blood pH?
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CO2 + H2O → H2CO3 → H+ + HCO3-
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Be able to explain gas exchange at the tissues and the lungs for carbon dioxide. Specifically, explain where each gas goes and the ways they are transported (dissolved gas, Hb, bicarbonate, etc).
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1. CO2 diffuses into the bloodstream, where it is carried in the three forms , bicarbonate, carbaminohemoglobin, and dissolved in plasma. 2. Most of it reacts with water to produce bicarbonate (HCO3−) and hydrogen (H+) ions. 3. This reaction occurs slowly in the blood plasma but much faster in the RBCs, where it is catalyzed by the enzyme carbonic anhydrase. 4. An antiport called the chloride-bicarbonate exchanger then pumps most of the HCO3− out of the RBC in exchange for Cl− from the blood plasma. This exchange is called the chloride shift. 5. Most of the H+ binds to hemoglobin or oxyhemoglobin, which thus buffers the intracellular pH.
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Understand why CO2 diffusion into the blood aids O2 release, and vice versa at the lungs
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Aerobic respiration produces a molecule of CO2 for every molecule of O2 it consumes. CO2 loading releases hydrogen ions in the erythrocyte, and hydrogen ions promote O2 unloading.
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Be able to explain gas exchange at the tissues and the lungs for oxygen. Specifically, explain where each gas goes and the ways they are transported (dissolved gas, Hb, bicarbonate, etc).
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Hydrogen binds to a oxyhemoglobin.
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Understand what the "chloride shift" is, and its significance.
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An antiport called the chloride-bicarbonate exchanger then pumps most of the HCO3− out of the RBC in exchange for Cl− from the blood plasma. This exchange is called the chloride shift. Most of the H+ binds to hemoglobin or oxyhemoglobin, which thus buffers the intracellular pH.
