circulatory system

Question 1

what is the skeletal muscle pump?

Answer 1

when muscles contract and relax meaning they change shape and press on nearby veins to make a pumping effect. This squeezes blood towards the heart

Question 2

what is the respiratory pump?

Answer 2

when muscles contract and relax during breathing in and out, pressure changes in the thoracic (chest) and abdominal (stomach) cavities.These changes in pressure press on nearby veins and assist blood return to the heart.

Question 3

what are pocket valves?

Answer 3

the presence of valves in veins to prevent the back flow of blood which ensures the blood travels towards the heart and not away from it.

Question 4

what mechanisms aid with venous return?

Answer 4

• skeletal muscle pump
• respiratory pump
• pocket valves
• gravity

Question 5

what is venous return?

Answer 5

the return of blood to the right side of the heart via the vena cava.

Question 6

What is pulmonary circulation?

Answer 6

Deoxygenated blood moving from the heart to the lungs and oxygenated blood moving back to the heart.

Question 7

What is systemic circulation?

Answer 7

Oxygenated blood moving from the heart to the body and then the return of deoxygenated blood from the body to the heart.

Question 8

Flow chart showing the order of the key blood vessels:

Answer 8

Heart -> Arteries -> Arterioles -> capillaries -> venules -> veins -> heart

Question 9

What is the structure of arteries?

Answer 9

They have a thick outer layer to be able to carry blood at a higher pressure.
Outer layer is also elastic to cope with fluctuations in pressure

Question 10

What is the structure of capillaries?

Answer 10

Only wide enough to allow one blood cell through at a time to slow down blood flow and allow time for diffusion. Walls are only one cell thick to allow a short distance for diffusion. There are also a lot of them to allow quicker diffusion.

Question 11

What is the structure of veins?

Answer 11

Thinner muscle/outer layer as blood is at a lower pressure. They also have valves and a wider lumen to allow blood flow to easily return back to heart.

Question 12

What is the definition of blood pressure?

Answer 12

The force exerted by the blood against the blood vessel wall

Question 13

What is systolic pressure?

Answer 13

The pressure in the arteries when the ventricles are contracting

Question 14

What is diastolic pressure?

Answer 14

The pressure in the arteries when the ventricles are relaxing

Question 15

What happens to blood pressure during aerobic activity?

Answer 15

Systolic pressure will increase but diastolic pressure will remain relatively constant

Question 16

What happens to blood pressure during anaerobic activity?

Answer 16

The skeletal muscle pump is working harder causing an increase in venous return which causes an increase in both systolic and diastolic blood pressure

Question 17

what is the largest artery in the body called?

Answer 17

The aorta

Question 18

What is the largest vein in the body called?

Answer 18

The vena cava

Question 19

what are pre-capillary sphincters?

Answer 19

rings of smooth muscle which help direct blood flow into capillaries.
They also control the redistribution of blood

Question 20

how would a cool down help venous return?

Answer 20

a cool down helps to keep the skeletal muscle pump and respiratory pump working which prevents blood pooling

Question 21

what is blood pooling?

Answer 21

when blood stays in veins and is not sent back to the heart properly. It can cause nausea, dizziness

Question 22

How does blood redistribution occur?

Answer 22

Through vasoconstriction and vasodilation which is controlled by the pre-capillary sphincters

Question 23

what is vasoconstriction?

Answer 23

the narrowing of the blood vessels to reduce blood flow into the capillaries (e.g. to the digestive system during exercise)

Question 24

what is vasodilation?

Answer 24

the widening of the blood vessels to increase the flow of blood into the capillaries (e.g. to working muscles during exercise allowing more oxygen to be delivered)

Question 25

Why should you not eat just before doing exercise?

Answer 25

Just after eating, blood flow will be aimed mainly at the digestive system in order to digest the food. If you do exercise whilst the food is still digesting, more blood flow will be required to go to the muscles meaning the food cannot digest. Or the muscles won’t be able to receive the oxygen they need as blood is going the digestive system

Question 26

what is plasma?

Answer 26

the fluid part of the blood (mainly water) that surrounds blood cells + transports them

Question 27

what is haemoglobin?

Answer 27

an iron-containing pigment found in red blood cells and transports oxygen

Question 28

what is oxyhemoglobin dissociation?

Answer 28

when oxygen is released from oxyhaemoglobin

Question 29

what is myoglobin?

Answer 29

Where oxygen is stored in the muscles so it can be quickly used when exercise begins.

Question 30

what has a higher affinity for oxygen, haemoglobin or myoglobin?

Answer 30

Myoglobin

Question 31

what is the Bohr shift?

Answer 31

When the curve shifts right during exercise as haemoglobin dissociates with oxygen due to the increased partial pressure of CO2 and decreased partial pressure of O2 in the muscles meaning haemoglobin experiences a reduced affinity for it and therefore more oxygen goes into muscles

Question 32

what 3 conditions cause the Bohr shift?

Answer 32

decrease in pH, increase in carbon dioxide, increase in temperature

Question 33

what effect does the Bohr shift have on working muscles during exercise?

Answer 33

oxygen delivery increases to working muscles as the oxygen that leaves haemoglobin diffuses into the myoglobin which is found in the working muscles

Question 34

what is atria-venous oxygen difference?

Answer 34

the difference between the oxygen carried by the blood in arteries and veins. It also represents the amount of oxygen delivered to working tissue in the capillary system

Question 35

what 3 factors are responsible for an increase in the dissociation of oxygen from haemoglobin

Answer 35

• increase in blood temp => when blood and muscle temp increases, oxygen dissociates more readily
• partial pressure of carbon dioxide increasing
• decrease in pH