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Chapter 7: The Circulatory System

Chapter 7: The Circulatory System

Postby admin » Fri Aug 27, 2010 1:29 am

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Re: Chapter 7: The Circulatory System

Postby rcal » Sun Nov 23, 2014 11:16 am

In question 1 (see below), I don't see how statement "I." can properly be inferred from any statement in the passage. The only thing I can think of is that you could infer cooperative O2 binding from the sigmoidal shape of the o2 dissociation curve of haemoglobin. Is this the source of the inference?

1) Which of the following can properly be inferred from the passage?
I. The binding of O2 to hemoglobin enhances the binding of additional O2 to the same hemoglobin molecule.
II. Hemoglobin has a lower affinity for oxygen compared to myoglobin.
III. The affinity of myoglobin and hemoglobin for oxygen is dependent on the pH of the environment.


A) I and II only.
B) I and III only.
C) II and III only.
D) I, II, and III.

Result: Your answer is wrong.
Your choice: N/A Correct choice: A

Explanation: You can deduce from the passage or see the explanation to Q2.
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Re: Chapter 7: The Circulatory System

Postby goldstanda3269 » Mon Nov 24, 2014 3:04 am

"The only thing I can think of is that you could infer cooperative O2 binding from the sigmoidal shape of the o2 dissociation curve of haemoglobin. Is this the source of the inference? "
- Yes, that is correct.
- Or more precisely, according to the passage (P2): "That is, when fractional occupancy of the oxygen-binding sites are plotted against partial pressures of oxygen for either molecules, the myoglobin curves tend to be hyperbolic, while hemoglobin curves tend to be sigmoidal."
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Re: Chapter 7: The Circulatory System

Postby rcal » Mon Nov 24, 2014 11:43 am

Thanks.
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Re: Chapter 7: The Circulatory System

Postby horbowiec.7527 » Fri Jul 02, 2021 12:56 pm

This is regarding Biology Chapter 7 Worked solution for Q2 (BIO-168):

Why would a result of mitral valve stenosis, be that blood pressure is elevated in left atrium, pulmonary arteries & pulmonary capillaries but blood flow is decreased in aorta?

Regards,
Ania
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Re: Chapter 7: The Circulatory System

Postby horbowiec.7527 » Fri Jul 02, 2021 5:32 pm

This is regarding Biology Chapter 7 Worked solution Q5 (BIO-169):

The diagram has 100% next to lungs with red oxygenated blood, not zero. What's your reasoning here for putting zero? Is it the word "recieved"? Because lungs receive 100% deoxygenated blood, then they oxygenate it and then 100% oxygenated blood leaves the lungs (but it is not received by lungs), that's why kidneys is correct answer?
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Re: Chapter 7: The Circulatory System

Postby goldstanda3269 » Sat Jul 03, 2021 3:12 pm

horbowiec.7527 wrote:This is regarding Biology Chapter 7 Worked solution for Q2 (BIO-168):

Why would a result of mitral valve stenosis, be that blood pressure is elevated in left atrium, pulmonary arteries & pulmonary capillaries but blood flow is decreased in aorta?


Let's establish the order of the relevant key components (assumed knowledge):

pulmonary arteries -> pulmonary capillaries -> (pulmonary veins) -> left atrium -> (mitral valve) -> left ventricle -> aorta

Each component is "one after the other" or in "series" (like a circuit). You can imagine it being like a road: If there is congestion or a traffic jam at 'pulmonary capillaries' then cars accumulate at 'pulmonary arteries' (i.e. pressure rises at that point) while there will be less traffic AFTER the congestion (i.e. pressure decreases at pulmonary veins, and then left atrium, and then left ventricle, and then aorta.

However, in our situation, the traffic jam started because of the mitral valve so everything before the valve gets more cars accumulating (increased pressure), and everything after that point will have reduced pressure (from the question stem: "decreased blood flow between those two chambers of the heart").

Of course, this is blood circulation and so we are talking about pressure. However, you will see this identical reasoning used in metabolic pathways (BIO Chapter 3 and 4) in terms of which intermediates accumulate after a 'blockage' (i.e. mutation, or blocking/inhibitory agent, etc).
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Re: Chapter 7: The Circulatory System

Postby goldstanda3269 » Sat Jul 03, 2021 3:35 pm

horbowiec.7527 wrote:This is regarding Biology Chapter 7 Worked solution Q5 (BIO-169):

The diagram has 100% next to lungs with red oxygenated blood, not zero. What's your reasoning here for putting zero? Is it the word "recieved"? Because lungs receive 100% deoxygenated blood, then they oxygenate it and then 100% oxygenated blood leaves the lungs (but it is not received by lungs), that's why kidneys is correct answer?


Exactly!

Side note: Your understanding of basic cardiac anatomy and following flow percentages will be re-tested in BIO Chapter 14, Questions 11-12. More fun ahead!
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Re: Chapter 7: The Circulatory System

Postby horbowiec.7527 » Sun Jul 04, 2021 10:35 am

This is a brilliant simplification and its so clear now, thank you!

Regards,
Ania
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