Chapter 16 - Respiratory Physiology Flashcards
What are the two types of Alveolar cells
Type I and Type II
Which alveolar cells is used primarily in gas exchange with blood? Why?
- Type I. These are the thin cells that basically make up the basement membrane/outer lining of the alveoli.
What do Type II alveolar cells do?
- Secrete Surfactant
- Reabsorb Na+ and H2O, preventing fluid build-up in alveoli
The [] [] is the region where gas exchange occurs, and it therefore includes the respiratory bronchioles.
Respiratory Zone
The [] [] includes all of the anatomical structure through which air passes before reaching the respiratory zone.
Conducting Zone
What is the narrowest of the airways that do not have alveoli and do not contribute to gas exchange?
Terminal Bronchioles
What are the 2 layers of wet epithelial membrane in the central region of the thoracic cavity?
- Pleural membranes
- Visceral Pleura - covers teh surface of the lung (Inner)
- Parietal Pleura - lines the inside of the thoracic wall (outer)
What is the tiny space between the two pleural membranes called?
Intrapleural space.
The transpulmonary pressure is the difference betwen [] and [] ?
Intrapulmonary pressure (pressure in lungs) and the Intrapleural pressure (pressure outside lungs)
How does Boyles Law relate to Inspiration/Expiration?
- Boyles Law states - pressure of a given quantity of gas is inversely proportional to its volume.
- So if the volume increases (during inspiration and expansion of lungs) the pressure will decrease…allowing the higher “pressurized” gas in the atmosphere flow in.
In the lungs - this ion, [] , drives fluid absorption and this ion, [] , drives fluid secretion.
Cystic Fibrosis - is thought to be caused by a genetic defect in one of those ions membrane channels, which one?
- Na+, Cl-
- Cl-, (Cystic Fibrosis transmembrane regulator or CFTR)
A [] occurs when air enters the pleural space, raising the intrapleural pressure sot that the pressure difference keeping the lung against the chest wall is abolished.
pneumothorax
What is the primary muscle of ventilation?
What are the 3 “main” muscles that aid the primary muscle?
- Diaphragm
- External Intercostal, Internal Intercostal, Parasternal Intercostal muscles.
What are the main muscles used during Inspriation?
- Diaphragm used in passive breathing
- Then its recruits - external and parasternal intercostals
- For deep breathing - Scalenes and Sternocleidomastoid are recruited.
Quite expiration is a [] process
passive
What muscles are recruited in expiration?
- Passively - the diaphragm merely retracts to normal size (due to elasticity)
- Forced Expiration - internal intercostal muscles
- The abdomen can be recruited if need because its contraction will push the organs up, further decreasing the volume and increasing the pressure to expire.
Define - Tidal Volume
The volume of gas inspired or expired in an unforced respiratory cycle
Define - Inspiratory Reserve Volume
Maximum volume of gas that can be inspired during forced breathing in addition to tidal volume
Define - Expiratory Reserve Volume
The maximum volume of gas that can be expired during forced breathing in addition to tidal volume
Define - Residual Volume
The volume of gas remaining in the lungs after a maximum expiration
Define - Lung Capacities
Measurements that are the sum of two or more lung volumes
Define - Total Lung Capacities
The total amount of gas in the lungs after a maximum inspiration
Define - Vital Capacity
The maximum amount of gas that can be expired after a maximum inspiration
Define - Inspiratory Capacity
The maximum amount of gas that can be inspired after a normal tidal expiration
Define - Functional Residual Capacity
Amount of gas remaining in the lungs after a normal tidal expiration
How does a restrictive breathing disorder effect the vital capacity?
- The vital capacity will be lower. However, the rate at which the vital capcity can be forcibly exhaled remains normal.
How do Obstructive breathing disorders affect Vital Capacity?
- Vital capacity remains constant, however expiratino is more difficult and takes a longer time.
- These are diagnosed by tests that measure the rate of expiration.
What is COPD?
- Chronic Obstructuve Pulmonary Disease - Characterized by chronic inflammation with narrowing of the airways and destruction of alveolar walls
The partial pressure is…
Equal to the product of the total pressure and the fraction of that gas in the mixture.
What effect would breathing from a tank of 100% oxygen have on the total oxygen content of blood?
- Little to no effect since our bodies already saturate Hemoglobin with Oxygen (97% oxyhemoglobin concentration
- It would however double plasma Oxygen levels, and significantly increase oxygen deliveyr to the tissues.
Why do pulmonary arterioles constrict once they have sensed lowered Po2 (as opposed to systemic aterioles that dilation to bring in more Oxygen)?
- They are trying to match ventilation to perfusion
- They are trying to restrict blood flow to the poorly ventilated alveoli so the high Po2 blood doesnt mix with the low Po2…this would decrease the Po2 of blood leaving the lung
Where is the Inspiratory Control Center located in the brain?
Where is the Expiratory Control Center located in the brain?
Bilateral dorsal medulla. (Rhythmicity area)
Bilateral ventral medulla
Where are the apneustic and pneumotaxic centers located? What is their function?
- Apneustic
- Located in Pons
- promot inspiration by stimulating inspiratory neurons in medulla (Works round the clock)
- Pneumotaxic
- Located in Pons
- antagonize the apneustic center and inhibit inspiration
- Also helps to stimulate expiratory center to control inspiration
Where are the 2 groups of chemoreceptors that automatially control breathing through the sensation of changes in brain interstitial fluid, cerebrospinal fluid, and in the PCO2, pH, and PO2 of blood.
- Central Chemoreceptors - medulla oblongata
- Peripheral Chemoreceptors
- Aoritc bodies - aortic arch
- use the vagus nerve to send sensory information to medulla.
- Carotid bodies - common carotid artery (at point where it branches to internal/external cortid arteries.)
- use the glossopharyngeal nerve to send sensory information to medulla.
- Aoritc bodies - aortic arch
Why would an increase hypoventilation lead to increased PCO2 and a lowered pH?
- Hypoventilation means there is less Oxygen, so naturlly there will be an increased PCO2.
- CO2 reacts wiht water to form bicarbonate. Bicarbonate can release H+ into the blood to make the pH fall (acidic)
Changes in [] [] serve as the most potent stimulus for the reflex control of ventilation.
Plasma CO2
What is the condition called during hypoventilation that causes a rise in PCO2?
- Hypercapnia
- Hypocapnia - occurs during hyperventilation, so a decrease in PCO2
Which chemoreceptor is responsbile for 70% of the increased ventilation that occurs in response to asustained rise in arterial PCO2?
- Medulla chemoreceptors
- Carotid bodies, aortic chemoreceptors acount for 30%
The production of hemoglobin and red blood cells in bone marrow is controlled by the hormone, [] , which is produced by the [] in response to tissue []
- erythropoietin
- kidney
- hypoxia
What is the PO2 content in the following situations:
- Blood delivered to systemic capillaries
- Blood leaving through systemic veins
- 100 mmHG, 97% oxyhemoglobin saturation, 20 mL O2 per 100 mL
- 40 mmHG, 75% oxyhemoglobin saturation, 15.5 mL o2 per 100 mL
What is the Bohr effect on oxygen/blood/hemoglobin etc…
The affinity of hemoglobin for oxygen is decreased when the pH is lowered and increased when the pH is raised.
What do changes in blood pH do to the Oxyhemoglobin saturation curve?
- An increase in blood pH will see the oxyhemoglobin saturation curve shift to the left.
- will experience less oxygen unloading at tissues
- A decrease in blood pH will see the oxyhemoglonin saturation curve shift to the right
- will experience more oxygen unloading at tissues (exercising)
What is the effect of 2,3-DPG on oxygen unloading?
- 2,3-DPG makes deoxyhemoglobin more stable -> so oxyhemoglobin will look to convert to deoxyhemoglobin
- This decreases the affinity of hemoglobin for oxygen, therefore increasing unloading of oxygen and shifting the oxyhemoglobing saturation curve to the right
Why does hemoglobin unload oxygen at lower venous PO2 levels than myoglob?
- False! it doesnt.
- At venous PO2 levels myoglobin retains almost all of its Oxygen. It has a higher affinity for oxygen than hemoglobin.
- Myoglobin releases oxygen at very low PO2 values (found inside mitochondria.)
What are the three ways that CO2 is carried by the blood?
- Dissolved CO2 in plasma (1/10 of total blood CO2)
- Carbaminohemoglobin (1/5 of total blood CO2)
- Bicarbonate ion
- accounts for most of th CO2 carried by the blood.
Which enzyme located on RBCs, catalyzes CO2 into Carbonic Acid (H2CO3)
Carbonic Anhydrase
The Chloride shift happens because?
- Bicarbonate (HCO3-) forms from the disassociation of H2CO3 –> H+ and HCO3-
- bicarbonate leaves the cell giving it a positive charge
- Chloride then migrates in to balance out the charge (Cl-)
Where does the reverse chloride shift take place?
What does it do?
- Pulmonary arteries where PCO2 is lower
- In these conditions - carbonic anhydrase catalyzes the conversion of carbonic acid into CO2 and H20…which is elininted in the expire breath.
What is the only “blood acid” that can be regulated by breathing?
carbonic acid
Through their ability to produce bicarbonate (and excretion of H+ in urine), the [] are responsible for maintaining a normal concentration of free bicarbonate in teh plasma.
Kidneys
Describe:
Respiratory Acidosis
Respiratory Alkalosis
- Acidosis - inadequate ventilation, which results in a rise in plasma concentration of carbon dioxide and thus, carbonic acid (HYPOVENTILATION)
- Alkalosis - excessive ventilation.
- raises pH
- Hyperventilation
- Can cause dizziness becuase it raises pH of CSF/ brain intersitial fluid which induces cerebral vasoconstriction (reduced blood flow)
When is the “hypoxic ventilatory response” used?
When decreased arterial PO2 stimulates teh carotid bodie to produce an increase in ventilation
What is the Haldane Effect?
At any given PCO2, there is more total CO2 carried in deoxygenated blood.
