Circulatory System

Question 1

Main functions

Answer 1

1. Transportation
2. Regulates temperature
3. Protects against blood loss and diseases

Question 2

The structure of blood vessels

Answer 2

Three main types of blood vessels:
- Arteries
- Veins
- capillaries

Question 3

Arteries

Answer 3

• thick, elastic walls
• all carry blood away from the heart
• most carry oxygen-rich blood EXCEPT for the pulmonary artery

Question 4

Veins

Answer 4

⚫ have thinner walls which are not elastic
⚫ muscles help keep blood flowing to the heart
⚫ have one-way valves

Question 5

Capillaries

Answer 5

⚫ smallest blood vessels
⚫ capillary wall is a single layer of cells
⚫ connect arteries and veins

Question 6

The Beating heart

Answer 6

⚫ stimulated by an electrical signal in order to beat
⚫ heart beat is set by the sinoatrial (SA) node, a specialized muscle tissue, located in the right atrium
⚫ sends a signal that makes the atria contract at the same time
⚫ as the atria contract the signal is sent to the atrioventricular (AV) node
⚫ sends the signal through a bundle of fibres called the bundle of His which divide into Purkinje fibres
⚫ cause the ventricles to contract at almost the same time

Question 7

Blood pressure

Answer 7

⚫ When blood pushes against vessels walls as it passes through the blood vessels
⚫ Systolic pressure – maximum pressure when the ventricles contract
⚫ Diastolic pressure – lowest pressure before ventricles contract again
⚫ Usually measure in the arm
⚫ Measured in mmHg (millimeters of
mercury)
⚫ Measured using a sphygmomanometer
⚫ Healthy blood pressure is 120mmHg over 80mmHg

Question 8

Pathways

Answer 8

⚫ The circulatory system has three different pathways that it travels

Question 9

The pulmonary pathway

Answer 9

• transports oxygen-poor blood to the lungs and takes oxygen-rich blood back to the heart

Question 10

The systemic pathway

Answer 10

• takes the oxygen-rich blood from the heart to the rest of the body and then takes the oxygen-poor blood from the body and returns it to the heart

Question 11

The coronary pathway

Answer 11

– provides blood to the heart itself

Question 12

Arteriosclerosis

Answer 12

⚫walls of the arteries thicken and become harder (no longer elastic)
⚫common type is atherosclerosis
⚫build up of plaque on the artery walls (fatty deposits, calcium and fibrous tissues)
⚫ decreases blood flow and increases blood pressure
⚫ can lead to: chest pains (angina), blood clots, shortness of breath, heart attack, heart failure (cardiac arrest)

Treatments:
⚫ aspirin or other medications
⚫ Angioplasty – tube is inserted into a clogged artery and a tiny balloon is inflated to force artery open
⚫ Coronary bypass operation – take healthy artery from elsewhere and create a new pathway

Question 13

Heart murmur

Answer 13

⚫ when valves in the heart do not close completely or do not open properly
⚫ blood leaks past the closed heart valve
⚫ often found in AV valves
⚫ often people with this disorder have faster heart beats

Treatment:
⚫ mild (“innocent”) – left alone
⚫ medications to :
⚫ help the heart squeeze harder
⚫ prevent blood clots
⚫ remove extra water
⚫ surgery to fix or replace valve

Question 14

Aneurysm

Answer 14

⚫ bulge that forms in the wall of a weakened blood vessel, usually an artery
⚫ often due to atherosclerosis
⚫ there is less support and it eventually ruptures
⚫ needs to be treated surgically