Chapter 15: Blood

Question 1

functions of blood

Answer 1

1) transportation of dissolved gases, nutrients, hormones and waste
2) regulation of pH and ionic composition of interstitial fluids
3) restriction of fluid losses at injured sites
- activation plasma proteins and platelets
- initiating clot formation
4) defence against toxins and pathogens using WBC and antibodies
5) stabilization of body temperature

Question 2

major components of blood

Answer 2

1) plasma (least dense)
2) buffy coat
- leukocytes and platelets
3) erythrocytes (most dense)
- called hematocrit

Question 3

what is blood plasma?

Answer 3

• an aqueous solution that solutes are dissolved in
• is the liquid component of blood

Question 4

what components are found in plasma?

Answer 4

(1) water
(2) proteins
(3) small nutrients: glucose, lipids, amino acids
(4) waste products
(5) gases: O2, CO2, N2
(6) electrolytes: Na2+, K+, Cl-

Question 5

3 categories of plasma proteins

Answer 5

1) albumins
2) globulins
3) fibrinogen

Question 6

key function of albumins

Answer 6

• most abundant
• contribute to osmotic pressure of plasma which affects the movement of fluid across capillaries

Question 7

key function of globulins

Answer 7

• help transport lipids, steroid hormones and other substances
• defends against foreign substances

Question 8

key function of fibrinogen

Answer 8

• key to forming blood clots and helping with injuries

Question 9

what are the formed components of blood?

Answer 9

1) erythrocytes (RBC)
- help with gas exchange
2) leukocytes (WBC)
- only true cell
- immune system cells
3) platelets
- a piece of large cells in the bone marrow called megakaryocytes
- help form blood clots to heal wounds

Question 10

characteristics of red blood cells

Answer 10

• most abundant in the blood
• lack nuclei, mitrochondria and other organelles required for producing proteins
• shaped like disks and are biconcave
• contain hemogloin and carbonic anhydrase that carry gases for exchange

Question 11

why do erythrocytes have a unique shape?

Answer 11

• biconcave shape results from presence of spectrin
• spectrin is a fibrous protein that is flexible so it provides erythrocytes the ability o bend and flex
• flexibility allows RBC to move through narrow capillaries
• the biconcave shape provides a large surface area which is good for exchange (O2 and CO2)

Question 12

major function of erythrocytes

Answer 12

• to transport oxygen and carbon dioxide in the blood
• RBC deliver oxygen from the lung to respiring cells - also deliver carbon dioxide from respiring cells to the lungs where its eliminated

Question 13

what is hematocrit?

Answer 13

• the percentage of whole blood that is RBC
  –> low hematocrit = thin blood
  –> high hematocrit = thick blood

Question 14

what happens if hematocrit is too high?

Answer 14

if hematocrit is too high = it can clog arteries and causes disruptions in circulation (like heart attack or stroke)

Question 15

what is hemoglobin?

Answer 15

• the most abundant protein in erythrocytes
• composed of 4 polypeptide chains (2 alpha and 2 beta chains)
• also has an iron-containing ring structure called heme, allowing oxygen to bind to it (x4)

Question 16

how does colour of RBC change?

Answer 16

• oxyhemoglobin: when O2 binds to iron = RBC is ruby reed
• deoxyhemoglobin: when O2 detaches iron = RBC is dark red

Question 17

what is the life cycle of erythrocytes?

Answer 17

• once an erythrocyte is released into the blood stream, it stays for 120 days
• they cannot undergo cell division so new erythrocytes are produced on a regular basis
• bone marrow undergoes erythropoiesis = synthesis of new RBC
• the spleen breaks down and removes old erythrocytes from the blood

Question 18

how are erythrocytes produced?

Answer 18

• all blood cells develop from precursor cells called hematopoietic stem cells in the bone marrow
• the HGF (hematopoietic growth factor) that stimulates production of RBC is called erythropoietin
• erythropoietin is released from kidney cells when blood oxygen levels are too low or there is an increased need for oxygen
• erythropoietin will travel to the bone barrow and signal it to produce more red blood cells