Lesson 4: Blood redistribution and The Bohr Effect

Question 1

Define the vascular shunt.

Answer 1

The redistribution of cardiac output

Question 2

Describe the redistribution of blood flow.

Answer 2

• During exercise, the skeletal muscles require more oxygen so more blood needs to be redistributed to them in order to meet this increase in oxygen demand.
• Blood flow to the brain must remain constant to ensure brain function is maintained as the brain needs oxygen for energy.
• Heart muscle needs oxygen for energy to beat faster and more blood goes to the skin because energy is needed to cool the body down.

Question 3

Why should performers not eat food less than an hour before competition?

Answer 3

• Sports performers should not eat less than an hour before competition. A full gut would result in more blood being directed to the stomach instead if the working muscles. This would have a negative effect on performance as less oxygen is available.

Question 4

How is blood flow controlled?

Answer 4

• BP and blood flow are controlled by the vasomotor centre, located in the medulla oblongata.
• During exercise, chemical changes such as CO2 and lactic acid are detected by chemorecpetors.
• These receptors stimulate the vasomotor centre whcih will redistribute blood flow through vasodilation and vasocontriction.
• Vasodilation: blood vessel widens, increases blood flow.
• Vasocontriction: blood vessel narrows, decreases blood flow.
• During exercise, more oxygen is needed at the working muscles so vasodilation will occur in the arterioles.
• Vasoconstriction will occur in the arterioles supplying non-essential organs such as intestines and liver.
• Redirection of blood flow also occurs through stimulation of the sympathetic nerves located in rhe walls of the blood vessel. When sympathetic stimulation increases, vasconstriction occurs and blood flow reduces.

Question 5

What is myoglobin and what is its function?

Answer 5

• Heme protein found in the skeletal and cardiac muscle.
• Main function is to transport oxygen from the muscle cell membrane to the mitochondria.
• Serves as an extra reserve of oxygen to help exercising muscle maintain activity longer.
• Used to diagnse acute myocardial infarction.

Question 6

What is the oxyhaemaglobin dissociation curve?

Answer 6

• It helps us understand how haemaglobin in our blood transports and released oxygen. The curve represents the relationship between oxygen and haemaglobin.

Question 7

What is the Bohr shift?

Answer 7

• When an increase in blood CO2 and a decrease in PH results in a reduction of the affinity of haemaglobin for oxygen.
• During exercise, this S-shaped curve shifts to the right because when musles require more oxygen, the dissociation of oxygen from haemaglobin in the blood capiliaries to the muscle tissue occurs more readily. This shift to the right is known as the Bohr shift.

Question 8

What are the facrors that increase the dissociation of oxygen from haemaglobin?

Answer 8

• Increase in blood temperature
• Partial pressure of carbon dioxide increases.
• PH.