Any biology experts

gsidecturbo

gsidecturbo

gsidecturbo

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Just a quick question.

Why does the rate of breathing increase if the CO2 levels are increased?

Am i right in thinking that as it lowers the amount of O2 in the air so breathing is increased, so the pp02 in the blood reamains at the right levels to keep the blood ph balanced?

thanks
 
Breathe faster to take in more O2 to supress the effect of higher CO2 levels. Don't mention O2 levels dropping as it's not neccessarily the case. Read the question.
 
increased co2 in the blood increases the blood acidity
this is detected by chemoreceptors
Breathing rate increased to reduce c02 conc of blood.

this occurs as the body assumes a normal conc of co2 in the atmosphere, hence why in high co2 environments you breath faster even though it doesnt really help.
 
Yeah that is tru. Think i should have worded my question better.

I am not on about the co2 levels in the body. I am talkin about why does my breathing rate increase if the amount of co2 in the atomosphere is raised. ie the percentage of co2 goes up from 0.04% to say 10%
 
My guess is that CO2 levels in the blood will increase due to diffusion into the blood in the Alveoli. I might be wrong, I haven't done Biology since GCSE, I did proper sciences at A Level :D
 
To put it simply. If the carbon dioxide levels rise you will take in more when you breath in, because an elevated CO2 corresponds to a depletion in O2 in the body, that means that you have to increase your breathing rate, getting rid of the carbon dioxide and taking in more oxygen
Carbon Dioxide is the body's regulator of the breathing function. Normally present in the air at a concentration of 0.03% by volume. Any increase above this level will cause accelerated breathing and heart rate.
 
gsidecturbo said:
the percentage of co2 goes up from 0.04% to say 10%
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A concentration of 10% can cause respiratory paralysis and death within a few minutes, so you would not be breathing at all then :D
 
If the atmospheric pCO2 is raised, such as to 10% in your example, the concentration gradient for alveolar gas exchange will be drastically reduced, so less CO2 is removed from the blood (basically). Thus the rate of ventilation increases to compensate, to try and blow off more CO2.
 
j00ni said:
Don't locust have spiracles though :confused:
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yeah they do.

The experiment i done was with a locust. Had to change the % of gases' in the air and moniotr its breathing rate. Now i have to explain the results accurately
 
there is another side to it as well

instead of the composition of the atmospheric gases changing wrt co2 and altering the resp rate, the amount of 'acidosis' in the body may rise and cause increased formation of co2 and corresponding increase in resp rate as the person essentially 'blows off' the excess acid in the form of co2 via breathing quicker

common things causing this are sepsis, diabetic ketoacidosis and salicylate (aspirin) OD

just mention to your locust test boss that there may be a component of this coming into play as well as the atmospheric changes increasing its resp rate:)
 
What I meant by my spiracles comment is that isn't the air delivered to cells as a gas through trachea (as opposed to dissolved/bound in blood) - thus comments about acidosis, chemoreceptors, etc irrelevant as the gas only dissolves into haemolymph for a short period whilst transferring between trachea and cell?

Also, increased ventilation rate (whilst increasing the conc gradient) will not overly affect the rate of diffusion - which is the rate limiting step.
 
Righty, time to get my notes out!

But oh no. I can't open my online lecture notes because I don't have my computer which is compatible with the file. If only a certain company would deliver a certain thing soon.

ANYWAY - Something which no one has mentioned is the ever increasing H+ ions in the cerebro spinal fluid. I'm still trying to get some better notes than my own, so I may expand later.......
 
Sorry about the double post - Thought it was better to make a new one, or some people who wanted it might miss the info they wanted.

Heres some info I have taken from my text book - NOT MY OWN WORDS.

"A rise in Pco2 causes an increased production of carbonic acid (h2co3) which is formed from carbon dioxide and water, acting to lower the pH. Carbonic acid dissociates into HCO2- and H+, increasing H+ concentration hence acidity. This stimulates nuerons in the aortic and carotid bodies which are sensory structures known as the peripheral chemoreceptors, found int he aorta and carotid artery. These send impulses to the respiritory control centre in the medulla oblongata which stimulates increased breathing.

The brain also contains chemoreceptors, but they are not able to detect H+ in the blood as blood can not enter the brain. After a brief delay, the increased blood Pco2 also causes a decrease in the in the pH of the cerebro spinal fluid bathing the brain. This occurs because blood does cross the blood brain barrier and combines with water to form the carbonic acid and the H+. The H+ ions stimulate the central chemoreceptors in the brain"

Taken from Biology - Raven, Johnson, Losos, Singer. 7th Edition. International Edition, chapter 44 (p.932 "mechanisms that regulate breathing") 2005 (A dam fine book!)

So that clears that up! Some extra stuff -

The peripheral chemoreceptors make short term changes regaurding the loss of C02 from the blood, accounting for 30% (ish) of repiration increase. The central ones take longer to act, but are more long term.

Theres loads of diagrams and chemical reactions if you want to look at the book in more detail. (A dam fine book!)

About the locusts - I checked my notes, but can't find if they have chemoreceptors or not, but yes, no lungs. Spiracles do indeed open into trachea which diffuse O2 directly into cells.
 
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gsidecturbo said:
oh and what is the book?
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Well as I said "Biology" by raven etc. Look to my last post about the full authors. You can proberly get it for around £40-50. However if you are doing this at A-level don't bother, a cheaper 'simpler' textbook would easily suffice and its a lot of money for just this coursework. There isn't much more left to say either, unless your a fan of haemoglobins chemical reactions! (Bleh!)

Good luck :)
 
S-Cool said:
Chemoreceptors

There are also chemoreceptors in the medulla and certain blood vessels that are sensitive to changes in carbon dioxide levels in the blood.

If the level is too high (the pH would drop, enzyme action would be affected with serious results), impulses are sent from these cells to the inspiratory part of the centre so that breathing rate increases.

This means that carbon dioxide is got out of the body as quickly as possible and more oxygen comes in.
Click to expand...

http://www.s-cool.co.uk/topic_quick...d=5&subject_id=3&ebt=72&ebn=&ebs=&ebl=&elc=13
 
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