The circulatory system

Question 1

What are the different types of blood vessels?

Answer 1

Large arteries, small arteries, arterioles, capillaries, venules, small veins, large veins

Question 2

What is pulmonary circulation?

Answer 2

Circulation of blood between the heart and the lungs to oxygenate it

Question 3

What is systemic circulation?

Answer 3

Circulation of blood between the heart and the rest of the body to transport oxygen and carbon dioxide to and from the respiring tissue

Question 4

Where does gas exchange take place?

Answer 4

In the capillaries, at the alveoli and respiring tissue

Question 5

How are capillaries suited for gas exchange?

Answer 5

They have a single layer of endothelial cells that allow gasses and nutrients to diffuse through

Question 6

What is cardiac output?

Answer 6

The volume of blood pumped out of the ventricles on each contraction multiplied by the number of beats per minute (stroke volume x heart rate)

Question 7

What are the stages of the cardiac cycle?

Answer 7

Atrial systole (contraction)
Ventricular systole (contraction)
Diastole (relaxation)

Question 8

How is a pulse created?

Answer 8

Blood pumped into the aorta stretches the wall and creates a pressure wave or ‘shock wave’ which is very quickly transmitted through the walls of the arterial system

Question 9

Where can a pulse be felt?

Answer 9

When arteries are close to the surface or pass over a bony part against which a finger can be pressed

Question 10

What can you find out from the pulse?

Answer 10

Heart rate - bradycardia/tachycardia
Heart rhythm
Strength - stroke volume

Question 11

What is arterial blood pressure measured in?

Answer 11

mmHg (millimetres of mercury)

Question 12

Why does blood pressure not drop to zero in diastole?

Answer 12

Because of the elastic recoil of the arteries

Question 13

What equipment measures blood pressure?

Answer 13

Sphygmomanometers

Question 14

What factors can affect arterial BP?

Answer 14

Cardiac output and total peripheral resistance

Question 15

What is total peripheral resistance?

Answer 15

The resistance of arterioles - arterioles fare the smallest arteries and create the most resistance

Question 16

What factors can affect cardiac output?

Answer 16

If the heart contracts with less strength this will reduce stroke volume and therefore CO
If the blood volume is low and the heart fills less, this will reduce stroke volume and therefore CO
If heart rate drops this will cause a fall in CO

Question 17

How do arterioles constrict and how does this affect BP?

Answer 17

Through contraction of smooth muscle cells in their walls - increases the resistance to the flow of blood making the pressure higher on their arterial side

Question 18

How is blood pressure controlled in the short term?

Answer 18

Via the baroreceptor reflex - nerve endings that act as pressure sensors are present in the arterial wall in the aortic arch and the carotid sinus

Question 19

How is blood pressure controlled in the long term?

Answer 19

Hormonal control - directed at controlling blood volume (acting at the kidney)

Question 20

How is cardiac output controlled to meet demand?

Answer 20

The autonomic nervous system controls cardiac output - increased activity of the sympathetic nervous system increases release of noradrenaline and increases force of contraction by acting on ventricular myocytes