Lecture 22: Transportation of Gases and Regulation of Respiration Flashcards
(22 cards)
Describe the hemoglobin structure.
Hemoglobin is composed of 4 globin polypeptide subunits and four heme groups with iron atom attached on each. Oxygen binds to the iron atom whereas carbon dioxide binds to the globin protein.
What are the four factors that affect hemoglobin’s affinity for oxygen?
- PO2
- Temperature
- Blood pH (Concentration of H+)
- PCO2
What is the relation between PO2 and hemoglobin?
Greater the PO2 in the surrounding tissues the more hemoglobin will bind to it. As oxygen rich blood goes through peripheral tissues that have lower PO2, more likely O2 will dissociate from hemoglobin and go to tissues.
What is the relation between O2 and temperature?
As temperature increases, so does the amount of oxygen released from hemoglobin. Active cells require more oxygen and liberate more heat.
What is the relation between O2 and pH?
In an acidic environment (low pH), O2 leaves more readily from the hemoglobin. Metabolic tissues produce CO2 which increases H+ concentration and decreases pH.
As PCO2 rises with exercise, O2 is released more easily.
How is carbon dioxide transported out of the body?
Your body turns CO₂ into bicarbonate in red blood cells to carry it safely in the blood, then turns it back into CO₂ in the lungs so you can breathe it out — all while helping keep your blood’s pH balanced.
Which are the most plentiful and powerful pH buffers?
Amino acids and proteins take up the hydrogen ions which were freed in the formation of bicarbonate.
How is internal respiration driven by the Bohr effect?
Cells produce CO2 which makes the blood more acidic. This causes hemoglobin to release oxygen more easily.
How is external respiration driven by Haldane effect?
Increased oxygen entering the erythrocytes causes the release of H+ and conversion of bicarbonate to CO2. CO2 moves down its gradient and is exhaled.
What is carbon monoxide poising?
CO has a high affinity to bind to hemoglobin at the oxygen heme binding site. Can make a person’s body hypoxic.
How is inspiration initiated by the medulla oblongata?
The Ventral respiratory group sends a stimulatory impulse down the spinal cord and out through the phrenic and intercostal nerves. This causes the diaphragm to contract and intercostal muscles to contract.
How is expiration initiated by the medulla oblongata?
Expiratory neurons in the VRG inhibit the stimulatory impulses to the diaphragm and external intercostal muscles causing them to relax.
What is the function of dorsal respiratory group of the medulla?
The DRG receives and integrates inputs from the proprioceptors and chemoreceptors and sends impulses to the VRG to modify the rhythm accordingly.
What are pontine respiratory centers?
Located in the pons, it helps to smooth the transitions between inspiration and expiration during certain activities such as vocalization, sleep and exercise.
How can basic respiratory rhythm be altered?
- Chemoreceptors
- Proprioceptors
- Higher Brain Centers (Cerebrum and Limbic System)
- Irritant and inflation reflexes
How are chemoreceptors related to respiration?
Central chemoreceptors: In the brainstem and are stimulated when H+ concentration in ECF is elevated (low pH).
Peripheral chemoreceptors: Located in aortic arch and carotid bodies and are stimulated when there is an increase in PCO2, H+ and low PO2.
How does the presence of carbon dioxide have an impact on brain extracellular fluid (ECF)?
Carbon dioxide can cross the blood brain barrier. Once inside, it reacts with water to produce bicarbonate and H+. H+ cannot cross the blood brain barrier.
What is the relation between PCO2 and arterial pH?
An increase in arterial PCO2 is associated with a decrease in arterial pH due to production of bicarbonate and H+.
What is hyperventilation?
An increase in the rate and depth of breathing that exceeds the body’s need to remove CO2. This causes hypocapnia (low blood CO2) and constricts cerebral blood vessels.
How do proprioceptors help during exercise?
Increased ventilation during exercise is aiming to maintain oxygen and carbon dioxide levels within normal range.
What is acute mountain sickness?
Acute mountain sickness is when your body struggles to get enough oxygen after quickly going to a high place, causing headaches and tiredness.
What is acclimatization to high altitude?
Peripheral chemoreceptors become more responsive to PCO2 when PO2 declines.
Decline in blood O2 stimulates the kidneys to accelerate production of erythropoietin.
