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Flashcards in Respiratory System Part 2 Deck (24):

What is the basis of the transportation of oxygen and carbon dioxide in blood?

Most oxygen is transported reversibly combined with hemoglobin.
Most carbon dioxide is transported as bicarbonate ion in the plasma.


Why is hemoglobin needed in the blood?

Oxygen is very insoluble in plasma water. A carrier protein (hemoglobin) is needed to help transport lots of oxygen at arterial partial oxygen, so it can be release to tissues at venous partial oxygen.
21.15ml O2/100mL of blood.


What is the structure of hemoglobin?

Has two alpha and two beta polypeptide chains, each polypeptide chain has a heme group; four heme groups total with an iron group that strongly binds iron.


What is significant from Hemoglobin-Oxygen Dissociation Curves?

There is a sigmoid shape that results from co-operatively. The binding of oxygen in one site increases the affinity of other site (in the same hemoglobin) for oxygen. There is communication between the four heme groups. Changes in the pressure of the tissues is more significant than changes in the pressure of the alveoli.


What is the affinity of hemoglobin for oxygen affected by?

Temperature, pH, and carbon dioxide. It favours oxygen binding in the respiratory epithelia and oxygen release in tissues.


Increased carbon dioxide, H+, and temperature leads to ___ saturation of hemoglobin.

Less saturation (10% loss), meaning the tissue is more efficient at unloading oxygen at tissues. This is more common than seeing an decrease in the variables.


Decrease carbon dioxide, H+, and temperature leads to ___ saturation of hemoglobin.

More saturation (10% gain) of hemoglobin.


What does it mean the oxygen diffuses into body cells?

Oxygen concentration in interstitial fluid and body cells is lower than in blood plasma. Oxygen diffuses from blood into interstitial fluid, and from interstitial fluid into body cells.


Why does the carbon dioxide transfer in body tissues work?

The Partial pressure of carbon dioxide is higher in tissues than in blood. About 10% of carbon dioxide dissolves in blood plasma, 70% is converted into H+ and HCO3- (bicarbonate) ions, and 20% combines with hemoglobin.


Why does the carbon dioxide transfer work in lungs?

In the lugs, partial pressure of carbon dioxide is higher in blood than in the alveolar air. Reactions packing CO2 into blood are reversed, and CO2 is released from blood into alveolar air. Most of the CO2 is going to go into the red blood cell, where is becomes (mostly) bicarbonate. RBC or Plasma bicarbonate.


Where is most of the CO2 produced?

CO2 is largely transported as HCO3- in plasma although most is produced in RBC’s with the aid of carbonic anhydrase enzyme.


What factors increase the respiratory rate?

Large decreases in blood levels of oxygen, an increase in blood levels of carbon dioxide or H+, conscious effort/exercise/stress.


What factors inhibit the respiratory rate?

Stretching of the lungs during inhalation, conscious effort, sleep.


What is the Central Controller of the neural regulation of breathing?

This system is modified by inputs from the brain and peripheral receptors.
Brainstem -- Neurons intrinsic periodic firing of action potential, rhythm generator determines the frequency, depth and amplitude of breathing. Breathing initiated by inspiratory neuron. Contraction of diaphragm (phrenic nerve) and intercostal
muscles (intercostal motorneurons), lung inflates, which activates stretch receptors and inactivate inspiratory neurons and stops inspiration (Hering-Breuer reflex). During exercise, the expiratory neurons work.
The cortex is where voluntary control happens.


What are Chemoreceptors in the neural regulation of breathing?

Peripheral = carotid bodies and aortic bodies, they sense mostly oxygen in the arteries.
Central = sense carbon dioxide in the cerebronspinal fluid.


What are the Lung Receptors in the neural regulation of breathing?

Stretch receptors = Hering-Breure inflation reflex.
Irritant, pain, and temperature receptors (e.g. coughing).
Juxtacapillary receptors = engorgement of capillaries = dyspnea (sensation of difficulty of breathing, sense fluid).


What do the Carotoid Body Peripheral Receptors do?

They sense blood changes; sense chemical concentration of the blood in the carotid artery. If there is a low concentration of oxygen in the blood, the carotid body will try to fix it by sending signals to the medullary respiratory centre to breathe faster. As arterial oxygen falls, there is an increase frequency of nerve firing.


What do the Aortic Body Peripheral Chemoreceptors do?

They sense chemical concentration of blood right after it goes through the heart; the aorta.


Why are Peripheral Chemoreceptors important?

Because they are the only significant source of hypoxic ventilatory drive; where the body uses oxygen chemoreceptors instead of carbon dioxide receptors to regulate the respiratory cycle. This is a relatively weak response compared to CO2 response. Modulation by PCO2.


Why are Central Chemoreceptors important?

They are located in the medulla oblongata, and are responsible for the ventilatory responses to carbon dioxide. Central chemoreceptor cells respond to increased CO2 in arterial blood in order to increase breathing. Modulation by PO2. Ventilatory response to CO2 close to a straight line relationship.


What gas dominates the control of breathing in air breathing animals?

Carbon dioxide.


What gas dominated the control of breathing in aquatic animals?

Oxygen. Oxygen is less soluble in water, so if ventilation is adequate for oxygen than it must be for carbon dioxide as well. The oxygen concentration is variable in water, and under most conditions ventilation does not limit CO2 excretion in animals.


What part of the brain controls breathing?

The medulla.


What can change the rate of breathing?

Changes in carbon dioxide, and to a lesser degree, oxygen levels.