Respiration II Flashcards
T/F: The majority of Oxygen in the blood is dissolved.
FALSE
Hemoglobin carries about 98% of oxygen in the blood
T/F: Hemoglobin is a tetrameric molecule.
True
Has 4 protein subunits
What is in a hemoglobin protein subunit?
Heme group with an iron atom that can reversibly bind O2
How many O2 molecules can each hemoglobin carry?
4
T/F: Binding of O2 to Hb changes the conformation of Hb, but not Oxygen.
True
As the partial pressure of Oxygen in blood increases, what happens to Hb?
Conformation changes make it more probable to pick up Oxygen
During the _______ phase, small changes in partial pressure of Oxygen will have little effect on Hemoglobin saturation.
loading
During the _________ phase, small changes in partial pressure of Oxygen will have a large effect on the saturation of Hb.
unloading
What is P50?
The partial pressure of O2 where half of Hb is saturated
T/F: Only dissolved O2 can diffuse into tissues.
True
T/F: O2 bound to Hb can be diffused into the tissues.
False
Must be released first
What effect will an increase in temperature have on Hb affinity?
Decrease affinity. Hb will give up O2 to the tissues more easily
What effect will a decrease in pH have on Hb affinity?
Decrease affinity. Hb will give up O2 to the tissues more easily
What effect will an increase in metabolism (DPG) have on Hb affinity?
Decrease affinity. Hb will give up O2 to the tissues more easily
______ results in less Hb in the blood but will not change partial pressure of oxygen or Hb saturation.
Anemia
Describe how carbon monoxide poisoning affects the hemoglobin?
CO will replace O2 on the Hb
Hb has much higher affinity for CO than O2
T/F: CO poisoning changes partial pressure of O2.
False
How is CO poisoning a double edged sword?
- CO replaces O2 on Hb
2. Hb affinity for O2 actually goes up, so it does not release bound O2 to tissues
What are the three forms of transported CO2?
- Dissolved
- Bound to Hb
- As HCO3 (70%)
T/F: CO2 is more soluble than O2.
True
T/F: CO2 directly competes with O2 for hemeglobin binding sites.
FALSE
O2 binds heme portion
CO2 binds globin portion
T/F: CO forms carbaminohemoglobin when bound to Hb.
FALSE
CO = carboxyhemoglobin CO2 = carbaminohemoglobin
What is the Haldane effect?
When P(O2) is increased -> Hb affinity for CO2 decreases
When P(O2) is decreased -> Hb affinity for CO2 is increased
Describe O2 vs CO2 Hb saturation in systemic arteries vs veins.
In arteries P(O2) is high -> Hb is saturated with oxygen
In veins P(CO2) is high -> Hb is more saturated with CO2
What is carbonic anhydrase (CA)?
An enzyme found in erythrocytes that catalyzes formation of carbonic acid
After being made in the erythrocyte, how is HCO3 transported to plasma?
HCO3/Cl transporter in the erythrocytes
T/F: When HCO3 is being produced, the pH of plasma will decrease.
True
T/F: CO2 diffuses from tissues into the blood plasma.
True
T/F: HCO3 diffuses from erythrocytes into the blood plasma.
FALSE
Transporter
What happens to the carbonic acid reaction once the blood gets to the pulmonary system?
As blood CO2 is diffused into alveoli, the HCO3 goes back into the erythrocyte, gets reversed to CO2 which diffuses out of the erythrocyte and into the alveoli
T/F: When oxygen is bound to Hb, it has a high affinity for H+.
FALSE
Low
How does Hb affinity for H+ help defend against acidic blood?
As the blood gets CO2 from tissues and forms HCO3, the Hb picks up the H+ to buffer pH.
Hypoventilation leads to respiratory _________.
acidosis
Increase in P(CO2) and H+
Not exhaling CO2 when blood passes lung so pH lowers
Hyperventilation leads to respiratory _________.
alkalosis
decrease in P(CO2) and H+
Blowing off excess CO2
________ requires action potentials in motor neurons.
Inspiration
________ is due to the cessation of motor neuron activity and lung recoil.
Expiration
Rhythmic contractions are controlled by _________ neurons.
pacemaker
What three factors can regulate activity of pacemaker neurons?
- Pulmonary stretch receptors
- Drugs
- Partial pressures and [H+]
When P(O2) decreases, ventilation rate _______.
Increases
When P(CO2) or [H+] increases, ventilation rate _______.
increases
Increase in [H+] or decrease in P(O2) will stimulate _________ chemoreceptors.
peripheral
Only an increase in ____ will stimulate central chemoreceptors in the brain.
[H+] in the extracellular fluid
T/F: Peripheral receptors are stimulated to increase ventilation when Hb is depleted of oxygen.
FALSE
Stimulation can begin when when Hb is still 90% saturated
T/F: Ventilation rate is more sensitive to P(CO2) than P(O2).
True
A P(CO2) of above _____ would typically increase ventilation rate.
40 mmHg
Describe the process that leads to increased ventilation when P(O2) levels are low.
Peripheral receptors increase firing -> reflex via medullary resp neurons -> resp muscles increase contractions -> increase ventilation
Describe the process of resolving an increase in alveolar and arterial P(CO2).
Increase in arterial [H+] -> firing of peripheral receptors -> increased ventilation
Increase in brain ecf P(CO2) and [H+] -> firing of central chemoreceptors -> increased ventilation
What other sources of [H+] can lead to altered ventilation rates?
Metabolic acidosis or alkalosis
T/F: Anemia and CO poisoning will both alter ventilation rates.
False
Production of non-CO2 acids (metabolic acidosis) will lead to firing of which receptors?
Peripheral chemoreceptors
T/F: Exercise can increase ventilation by 20x.
True
What happens to arterial and venous P(CO2) and P(O2) during exercise?
Arterial P(CO2) and P(O2) does not change until strenuous
Venous CO2 and O2 both increase
The increase in ventilation during exercise is proportional to ….?
O2 use and production of CO2 by the cells
Makes sense why venous levels change
T/F: Increase [H+] causes increased ventilation during exercise.
False
Requires intense exercise for this to be a factor
What are the four major factors that are thought to lead to increased ventilation during exercise?
- Temperature
- Proprioceptors (joints, muscles, motor cortex)
- Epinephrine and K+
- Conditioned response
______ is a deficiency of O2 at the level of the tissues.
Hypoxia
______ hypoxia is decreased arterial P(O2).
Hypoxic
_______ hypoxia is normal arterial P(O2) with decreased hemoglobin and O2 blood content.
Anemic
______ hypoxia is when blood flow to tissues is too low.
Ischemic
_______ hypoxia is when cells are unable to utilize the O2.
Histotoxic
What are several different conditions that can lead to hypoxic hypoxia?
- Hypoventilation
- Diffusion impairment (thickened alveolar wall)
- Vascular shunt
- Ventilation-perfusion inequality (COPD)
T/F: P(atm) decreases as altitude increases.
True
P(O2) _______ as altitude increases.
decreases
What are the immediate responses to increased elevation?
- Stimulate ventilation
2. Increased dependence on anaerobic glycolysis
T/F: Acclimatization to high altitude takes days to weeks.
True
What are the bodies responses in order to acclimate to high altitude?
- Increased erythropoiesis
- Increased 2,3 DPG -> shifts Hb-O2 curve to right
- Increased capillary density, mitochondria, myoglobin
What are some dangerous side effects of blood doping?
- increased blood viscosity
- Increased risk of stroke
- High BP
- Autoimmune anemia
How can an athlete utilize altitude to increase performance?
Live high and train low - increase O2 availability and utilize it
Live low train high - stimulate EPO production when P(O2) gets low
