1.1.1- CARDIOVASCULAR SYSTEM

Question 1

Why does blood flow to the brain remain the same at rest and during exercise (2)

Answer 1

• Brain requires oxygen for energy to function

Question 2

Why should an athlete not eat at least 1 hour before competition? (3)

Answer 2

• During exercise , more blood goes to the gut for o2 to provide energy to digest food
• This less blood is available for the muscles
• And can result in a lower standard of performance

Question 3

How is oxygen transported in the blood? (2)

Answer 3

• It dissolves into plasma and combines with haemoglobin to form oxy-haemoglobin

Question 4

Evaluate the importance of blood redistribution for a netballer (8)

Answer 4

AO1-KNOWLEDGE OF BLOOD DISTRIBUTION

1. Blood flow is controlled by vasomotor centre in the medulla oblongata of the brain
2. During exercise there is an increase in co2 which is detected by chemoreceptors
3. Receptors stimulate the vasomotor centre which will redistribute blood flow by vasodilation and vasoconstriction
4. Vasodilation occur in arterioles suppling the muscles, increasing blood flow by widening and bringing in needed o2
5. Vasoconstriction occurs in arterioles supplying non essential organs such as the liver by narrowing
6. Pre capillary sphincters contract blood flow is restricted through the capillary and when they relax blood flow increases

AO2- APPLICATION TO NETBALLER

1. Important for netballer to redistribute blood flow during game
2. More blood goes to the heart because the heart muscle needs o2 to beat faster. More blood goes to her muscles as they need more o2 for energy. More blood goes to her skin so she can cool down
3. Blood flow to brain remains constant as it needs o2 for energy to maintain function because through the game she needs to make decisions

A03- EVALUATE IMPORTANCE OF BLOOD REDISTRIBUTION

1. It will increase the supply of o2 to her working muscles and remove waste products such as co2 and lactic acid
2. Ensures more blood gets to her skin during exercise to regulate body temp and get rid of radiation, evaporation, and sweating
3. Direct more blood to her heart as it is a muscle that needs lots of 02 in exercise so it can beat faster and pump oxygenated blood to her muscles
4. Less blood will be directed to her nonessential organs which are not used during gameplay

Question 5

During exercise, heart rate will increase to meet the extra o2 demands
Explain how increasing level of co2 in the blood raises Heart rate (3)

Answer 5

Increasing co2 is detected by chemoreceptors

Nerve impulses are sent to the Medulla

Sympathetic nervous impulses are sent to the SAN

Decreases parasympathetic impulses

Question 6

Just before the start of an 800m race, the athlete will experience a change in HR. What change occurs in the athlete’s heart rate and why? (2)

Answer 6

Increase in heart rate prior to exercise

Caused by increased adrenaline

Question 7

Explain what is meant by the term cardiovascular drift? (2)

Answer 7

HR increases/beats more and decrease in stroke volume

Fluid lost as sweat

Reduced venous return

Starlings law

Cardiac output increases due to more energy needed to cool body

Question 8

What is understood by the term Sterlings law?

Answer 8

Increased venous return 
Greater diastolic pressure 
Cardiac muslce strtached
More force of contraction 
Increased ejection fraction