Biology - Coronary Heart Disease

Hey guys,

I'm revising CHD, and the effect salt has on it. In my book it says that salt decreases the water potential of your blood, which results in more water being held in the blood thus blood pressure increases.

If the water potential has been reduced, surely that means less water is in the blood and more solute (salt)?

Also, how does hypertension and how it damages the lining of the arteries result in CHD?

Reply 1

Tarte Tatin

8

Water moves by osmosis from an area of high water potential to an area of low water potential. Because salt decreases the water potential, this means water will remain where the water potential is low. No, there isn't less water in the blood; there is simply a lower concentration as there is a higher concentration of salt. I hope this makes sense.

Sorry, I'm not sure about the other question.

(edited 9 years ago)

Reply 2

rm_27

OP

11

Original post by Tarte Tatin

Water moves by osmosis from an area of high water potential to an area of low water potential. Because salt decreases the water potential, this means water will remain where the water potential is low. No, there isn't less water in the blood; there is simply a lower concentration as there is a higher concentration of salt. I hope this makes sense.

Sorry, I'm not sure about the other question.

Thanks dude, makes sense! Are you doing A Level?

Reply 3

Tarte Tatin

8

Original post by rm_27

Thanks dude, makes sense! Are you doing A Level?

AS (OCR)

Reply 4

rm_27

OP

11

Original post by Tarte Tatin

AS (OCR)

Ah same! How is it going?

Reply 5

Tarte Tatin

8

Original post by rm_27

Ah same! How is it going?

Not too bad :smile:

Mainly coming out with Bs and Cs in past papers. It's the key words and not understanding questions properly that are my downfalls :frown:

What about you?

Reply 6

rm_27

OP

11

Original post by Tarte Tatin

Not too bad :smile:

Mainly coming out with Bs and Cs in past papers. It's the key words and not understanding questions properly that are my downfalls :frown:

What about you?

Yeeah, I feel you. I did a mock, and got a B. Really want the A though, but finding it to be quite challenging. I think I tend to over think a lot of the questions sometimes, and need to brush up on Food and Health.

Reply 7

Harantony

10

Original post by rm_27

Hey guys,

I'm revising CHD, and the effect salt has on it. In my book it says that salt decreases the water potential of your blood, which results in more water being held in the blood thus blood pressure increases.

If the water potential has been reduced, surely that means less water is in the blood and more solute (salt)?

As Tarte Tatin said, a reduced water potential doesn't mean there's less water in the blood, it means that the concentration of water has reduced - there is a greater proportion of salt molecules compared to water than before.

Original post by rm_27

Also, how does hypertension and how it damages the lining of the arteries result in CHD?

Not sure what you mean by "how does hypertension" - I'm guessing you're asking why it happens? If so, it's due to many reasons: lots of times, it's idiopathic (no one knows why it happens). Blood pressure generally goes up with age, and smoking and poor diet along with little exercise can increase blood pressure.

Having hypertension can put strain on your arteries: imagine how blood is constantly pushing and flowing faster against their walls - it will increase the chance of the endothelium (wall) of the arteries getting damaged. There's also the fact that the higher your blood pressure, the higher your cholesterol etc. tends to be, which also increases the chance of CHD. Once your arteries are damaged, LDLs can move into the wall - the immune system targets the LDL and foam cells start to form, which causes fatty streaks. These build into plaques, causing atherosclerosis. This can then lead to CHD as vessels become occluded. :smile:

Reply 8

nexttime

22

Theoretically, its as stated above.

In reality: high salt intake barely effects blood pressure at all. In the TOPH I and II trials decreasing salt intake by 25-30% resulted in a blood pressure fall of just 1.2/0.7mmHg (you will recall that normal blood pressure is about 120/70, so this fall is just 1%).

However other studies suggest that halving your salt intake drops your stroke rate by a full 23% and heart attack risk by 17%. Blood pressure medications can change your blood pressure by a lot more than 1% but do not have such a great effect on atherosclerosis as reducing salt does. So it seems likely that salt increases deaths from cardiovascular disease in some way other than increasing blood pressure. Your two questions aren't necessarily related.

Just FYI.

Biology - Coronary Heart Disease

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