Homeostasis Of Gas Concentration Flashcards
When oxygen levels are extremely low, they have an effect on the regulation of breathing. Provide 2 diseases or environmental situations in which this would happen.
Asthma.
High altitudes.
True or false: stimulation of the chemoreceptors by increased carbon dioxide will cause increased breathing rate?
True
Describe 3 steps that need to occur so that more oxygen can be delivered to skeletal muscles when they become active during exercise.
Increased rate of breathing.
Increased cardiac output.
Vasodilation of blood vessels to cause increase in muscle blood flow.
Describe the control of breathing.
- Controlled by respiratory centre in Medulla.
- To coordinate breathing, messages pass back and forth between inspiratory and expiratory regions.
- Inspiration: diaphragm and intercostals contract and move down to increase volume of lungs to make pressure lower than outside.
Describe the effect carbon dioxide concentration has on breathing rate.
Has a major effect on breathing,
Associated with hydrogen ions.
Increase in both chemicals stimulates chemoreceptors which transmit nerve impulses to respiratory centre = increased breathing rate.
Stimulates aortic and carotid bodies by increased hydrogen which increases breathing.
Describe how the need for oxygen changes when exercising.
Contracting muscles need more oxygen and produce more carbon dioxide so there is an increased demand for gas exchange.
Increases depth and rate of breaths.
How can breathing be controlled voluntarily?
Comes via connections from the cerebral cortex to descending tracts in the spinal cord, therefore bypassing medulla oblongata as a protective device.
Why is it impossible to stop breathing forever?
Carbon dioxide build up stimulates the inspiratory centre to send impulses to inspiratory muscles.
What is hyperventilation?
Rapid breathing that can provide and remove more oxygen and carbon dioxide than required.
Usually corrects itself. Because chemoreceptors aren’t stimulated there’s no urge to breathe until carbon dioxide is normal.
Describe how the concentration of oxygen affects breathing rate.
As oxygen is consumed by cells, it’s concentration in blood falls.
If concentration falls, breathing increases however it has to fall very low before having adverse effect.
Describe how hydrogen ion concentration effects breathing rate.
As hydrogen concentration increases, pH which stimulates chemoreceptors to transmit impulses to resp centre, increasing breathing rate.
Describe the feedback loop for control of breathing after exercise.
Stimulus: Increased carbon dioxide and hydrogen.
Receptor: Chemoreceptors in respiratory centre and carotid and aortic bodies.
Modulator: Respiratory centre in medulla oblongata.
Effector: Diaphragm and intercostals.
Response: increased stimulation of resp muscles causing increase in breathing rate and depth of breaths to reduce CO2 and H2 levels.
Divers who hyperventilate can risk drowning as a result, why?
Carbon dioxide and oxygen levels decrease due to no stimulation of breathing. This can make them unconscious, if they breathe underwater, they will die.
