BPK 105 Study Guide - Final Guide: Medulla Oblongata, Sinoatrial Node, Adrenal Medulla
27 Apr 2018
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Module 10 - Review Questions - Part 6
10. Describe the chemical control of ventilation. When are blood oxygen levels
important? Describe the step-by-step response to an increase in carbon dioxide in the
blood. [7 marks]
- Holding your breath causes your CO2 level to increase by a small amount; elevated
levels of CO2 is known as hypercapnia.
- Doing something as simple as holding your breath can cause you to have a strong need
to breathe. With rising CO2 levels comes a change in blood pH.
- The blood CO2 that mixes with water leads to an increase in the concentration of
Hydrogen ions. The medulla oblongata has chemoreceptors that can detect any
changes there are to the concentration of Hydrogen ions, meaning that they have the
ability to detect changes in blood pH. Because of this, the chemoreceptors in the
medullary oblongata are significant when it comes to maintaining blood pH.
- Typically, when blood pH changes, changes in the level of blood CO2 is the reason why.
When you breathe more quickly, blood CO2 levels will decline, causing blood pH to rise.
In response to this, medullary chemoreceptors signal to lead to a slower rate of
breathing and so, more CO2 stays in the blood, leading to a rise in Hydrogen ion
concentration in the blood. Blood pH decreases within its normal range of values.
- When there is an increase in Carbon dioxide in the blood, the pH of the blood with lower,
meaning it’s more acidic.
- When the medullary chemoreceptors detect the increase in Hydrogen ions (decrease in
pH), it releases a signal to increase the breathing rate and more Carbon dioxide diffuses
out of the blood as the rate of respiration increases, which increases the pH.
- When a low blood pH is detected by medullary chemoreceptors, the adrenal medulla and
the heart also become more stimulated. This rise in stimulation is caused by the the
brain’s control centers. The cardiac muscle and the sinoatrial node increase activity,
which causes the stroke volume and the heart rate to both increase. This causes more
blood to flow to the lungs and blood pH increases, reinstating homeostasis.
- Despite not being a main force that drives respiration, blood oxygens levels are still
important. In both the aortic and carotid bodies, there are chemoreceptors that are
sensitive to O2 levels.
- Due to this, these bodies are greatly stimulated as Oxygen levels in the blood decrease,
leading to an inadequate amount of Oxygen reaching the tissues. This condition is called
hypoxia and can occur when the body experiences shock, asphyxiation, high altitude or
emphysema.
- The aortic and carotid bodies, in response to this condition, send action potentials, which
go to the respiratory center and ultimately, leads to a quicker breathing rate, as well as
Document Summary
Module 10 - review questions - part 6: describe the chemical control of ventilation. Describe the step-by-step response to an increase in carbon dioxide in the blood. Holding your breath causes your co2 level to increase by a small amount; elevated levels of co2 is known as hypercapnia. Doing something as simple as holding your breath can cause you to have a strong need to breathe. With rising co2 levels comes a change in blood ph. The blood co2 that mixes with water leads to an increase in the concentration of. The medulla oblongata has chemoreceptors that can detect any changes there are to the concentration of hydrogen ions, meaning that they have the ability to detect changes in blood ph. Because of this, the chemoreceptors in the medullary oblongata are significant when it comes to maintaining blood ph. Typically, when blood ph changes, changes in the level of blood co2 is the reason why.
