B2: BLOOD + THE CIRCULATORY SYSTEM

Question 1

What are the 4 components of blood?

Answer 1

-red blood cells
-white blood cells
-platelets
-plasma

Question 2

Red blood cells

Answer 2

-carry O2 around the body
-biconcave shape (large surface area)
-no nucleus (can carry more O2)
-contain haemoglobin (which binds with O2 in the lungs to produce oxyhaemoglobin) (in tissues oxyhaemoglobin splits up into haemoblobin and O2 to release O2 to the cells)

Question 3

White blood cells

Answer 3

-part of immune and defence system against pathogens
- phagocytes engulf and digest pathogens (phagocytisis)
-lymphocytes produce antibodies and antitoxins

Question 4

Platelets

Answer 4

-fragments of cells
-clot blood at wounds to prevent microorganisms from entering the body

Question 5

Plasma

Answer 5

-liquid part of the blood
-carries:
-red and white blood cells
-nutrients (eg: glucose and amino acids)
-CO2 (from organs to lungs)
-urea (from liver to kidneys)
-hormones
-proteins
-amtibodies and antitoxins produced b white blood cells

Question 6

What is a double circulatory system?

Answer 6

-consists of 2 circuits
-pulmonary circuit (transports blood to lungs and then back to the heart)
-systemic circuit (transports blood to the rest of the body then back to the heart)

Question 7

What are the 4 chambers in the heart?

Answer 7

-right atrium
-right ventricle
-left atrium
-left ventricle

Question 8

How does blood flow through the heart?

Answer 8

-blood flows into the 2 atria from the vena cava/pulmonary vein
-the atria contract, pushing the blood into the ventricles
-the ventricles contract, forcing the blood into the pulmonary artery/aorta and out of the heart
-the blood then flows to the rest of the body through arteries and returns through veins

Question 9

Where is the pacemaker located?

Answer 9

right atrium

Question 10

Arteries

Answer 10

-carry blood AWAY from the heart
-THICK outer walls
-THICK layers of muscle and elastic fibres
-NARROW lumen
-blood under HIGH pressure (elastic fibres allow artery to stretch under high pressure)

Question 11

Veins

Answer 11

-carry blood BACK to the heart
-THIN outer walls
-THIN layers of muscle and elastic fibres
-WIDE lumen (irregular shape)
-blood under LOW pressure (valves prevent backflow, muscles squeeze blood through veins)

Question 12

Capillaries

Answer 12

-carry blood close to cells (to exchange substances, supply cells with O2 and nutrients and take away waste like CO2)
-permeable walls (so substances can diffuse through)
-1 cell thick (short diffusion pathway, increases rate of diffusion)
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