Blood + Immunity

Question 1

Blood

Answer 1

• Blood is a connective tissue as it links all the cells and organs in the body
• Blood consists of two elements:
• Fluid portion: plasma (consists of water, dissolved gases, proteins, sugars, etc)
• Solid portion: formed portion (consists of red blood cells, white blood cells and platelets)

Question 2

ERYTHROCYTES (red blood cells)

Answer 2

􏰀 Make up about 44% of the total volume of blood
􏰀 Specialized for oxygen transport
◦ Each RBC contains about 280 million hemoglobin molecules
􏰀 Have no nucleus
􏰀 Live only 120 days
􏰀 If there are too few RBC or too little hemoglobin a condition called anemia occurs

Question 3

LEUCOCYTES (white blood cells)

Answer 3

􏰀 Less numerous than red blood cells (outnumber white 700 to 1)
􏰀 Have a nucleus and appear colourless
􏰀 Part of the body’s response to infection

Question 4

PLATELETS

Answer 4

􏰀 Do not contain a nucleus
􏰀 Play a key role in clotting blood
􏰀 When injury occurs at a blood vessel substances are released that attract platelets
􏰀 The platelets will rupture and combine with other blood components to create an enzyme: thromboplastin
􏰀 If calcium ions (Ca2+) are present the thromboplastin will react to produce thrombin
􏰀 Thrombin reacts with fibrinogen to produce fibrin
􏰀 This will then form a mesh of strands around the injury which traps the blood and makes a clot

Question 5

Plasma

Answer 5

􏰀 Fluid portion of blood
􏰀 Blood cells are suspended inside
􏰀 Carries blood cells and other substances (refer to table 8.3 on page 284)
􏰀 Transports carbon dioxide

Question 6

Functions of blood (transport

Answer 6

􏰀 Transport
􏰀 One of the primary functions
􏰀 Transports nutrients, hormones, waste, gases

Question 7

Function of blood (homeostatic regulation)

Answer 7

􏰀 Homeostatic Regulation
􏰀 Regulates our body temperature
􏰀 Blood coming to the skin is warmer than the skin and heat can be lost this way (refer to figure 8.19, pg 286)

􏰀 If the body becomes too warm it must rid itself of heat
􏰀 It does this by dilating the blood vessels close to the skin (vasodilation) which increases the amount of heat lost from the blood through the skin
􏰀 If the external environment is cold the blood vessels near the surface constrict (vasoconstriction) so that no extra heat is lost