Lecture 20 - Blood function and composition 2

Question 1

What are some characteristics of an erythrocyte?

Answer 1

-Biconcave shape for increased surface area
-Flexible (to pass through capillaries)
-No nucleus or mitochondria
-produced in bone marrow
-Primary cell content is hemoglobin

Question 2

What do yogurt-making bacteria and RBC’s have in common?

Answer 2

Lactic acid fermentation

Question 3

What is hemoglobin made up of?

Answer 3

• 2 alpha subunits
• 2 beta subunits
• heme group

Question 4

How many hemoglobin molecules can one erythrocyte have?

Answer 4

300 million

Question 5

How does iron bind with oxygen?

Answer 5

Reversibly

Question 6

What colour is oxyhemoglobin and deoxyhemoglobin?

Answer 6

Oxyhemoglobin - bright red
Deoxyhemoglobin - dark red

Question 7

Does hemoglobin release all of its oxygen at one time?

Answer 7

Not usually, amount of oxygen released depends on tissue need for oxygen

Question 8

What does CO2 bind to in hemoglobin?

Answer 8

Amino acids. Forms carbaminohemoglobin

Question 9

How does the binding of oxygen affect hemoglobin?

Answer 9

It reduces its affinity for CO2 and H+, allowing the CO2 to be displaced

Question 10

If hemoglobin is in a deoxygenated state, what does it carry more of?

Answer 10

CO2

Question 11

What is carbon monoxide poisoning?

Answer 11

Carbon monoxide binds competitively with oxygen and has a higher affinity. It binds to Hb irreversibly and therefore oxygen cannot bind

Question 12

What characterizes anemia?

Answer 12

-Insufficient RBC’s
-Decreased Hb content
-Abnormal Hb

Question 13

What is sickle cell anemia?

Answer 13

Hb is abnormal in shape, limiting its ability to carry oxygen and travel through capillaries

Question 14

What is polycythemia?

Answer 14

An abnormal excess of RBC’s that increases the viscosity of the blood

Question 15

What are 3 common causes of polycythemia?

Answer 15

-Bone marrow cancer
-A response to reduced availability of oxygen at high altitudes
-Kidney malfunction

Question 16

How are old RBC’s removed from the system?

Answer 16

Phagocytosis by macrophages of the spleen

Question 17

What can happen to an RBC as it ages?

Answer 17

It may acquire senescent antigens and lose its flexibility, which can cause it to become trapped in the spleen and destroyed by macrophages

Question 18

What happens after an RBC is destroyed?

Answer 18

• Hb is converted to heme and globin
• Iron is released and stored in macrophage or released into circulation to go back to marrow
• Heme is converted to bilirubin

Question 19

What are characteristics of leukocytes?

Answer 19

-Defend against bacteria, viruses, and other microbes
-Provide immunity
-about 1% of blood
-Has a nucleus
-Produced in bone marrow and lymphatic tissue

Question 20

What are the 2 groups of leukocytes?

Answer 20

-Granulocytes
-Agranulocytes

Question 21

What are granulocytes?

Answer 21

-Contain cytoplasmic membrane-bound granules
-neutrophils, eosinophils, basophils

Question 22

What are agranulocytes?

Answer 22

-Lack obvious granules
-Lymphocytes and monocytes

Question 23

What happens to the number of WBC’s during an infection?

Answer 23

It increases

Question 24

What does pus consist of?

Answer 24

Dead WBC’s

Question 25

What is the lifespan of an erythrocyte?

Answer 25

120 days

Question 26

What is the lifespan of a WBC?

Answer 26

Depends on the cell: -Several hours to days for most WBC's -Many years for a few memory cells

Question 27

What are characteristics of neutrophils?

Answer 27

-40-70% of WBC's -Small granules that stain lilac -Nucleus is multi-lobed -6-9 days for development -6 hours to a few days lifespan

Question 28

What is the function of neutrophils?

Answer 28

Phagocytize bacteria

Question 29

What are characteristics of eosinophils?

Answer 29

-1-4% of WBC's -Larger granules that stain orange -Nucleus bi-lobed -6-9 days for development -8-12 days lifespan

Question 30

What is the function of eosinophils?

Answer 30

-Kill parasitic worms -Destroy antigen-antibody complexes -Inactivate some inflammatory chemical of allergy

Question 31

What are characteristics of basophils?

Answer 31

-0.5% of WBC's -Large granules that stain blue/purple -3-7 days for development -Few hours to days lifespan

Question 32

What is the function of basophils?

Answer 32

-Release histamine and other mediators of inflammation -Contain heparin (anticoagulent)

Question 33

What are characteristics of lymphocytes?

Answer 33

-T and B cells -20-45% WBC's -Large nuclei with little cytoplasm -days to weeks for development -hours to years lifespan

Question 34

What is the function of lymphocytes?

Answer 34

Mount an immune response by direct cell attack (T cells) or via antibodies (B cells)

Question 35

What are characteristics of monocytes?

Answer 35

-4-8% WBC's -U-shaped nucleus -2-3 days development -months lifespan

Question 36

What is the function of monocytes?

Answer 36

-Phagocytosis -Develop into macrophages in tissues

Question 37

What is the smallest blood cell?

Answer 37

Platelet

Question 38

What is the size of an erythrocyte?

Answer 38

6.5-8 um

Question 39

What is the size range of leukocytes?

Answer 39

6 (lymphocyte) - 20 (monocyte) um

Question 40

Why is leukopenia common in chemotherapy?

Answer 40

Because chemotherapy destroys fast growing cells, like leukocytes, hair, and intestinal epithelial cells

Question 41

What is leukemia?

Answer 41

An abnormally high level of WBC's in the bone marrow, which impairs normal marrow function

Question 42

What are platelets?

Answer 42

Fragments from the cytoplasm of megakaryocytes without a nucleus

Question 43

What do platelets usually look like?

Answer 43

Round, oval, or spiky

Question 44

What is the lifespan of a platelet?

Answer 44

8-12 days

Question 45

What is the primary function of platelets?

Answer 45

To limit blood loss

Question 46

Where do platelets go after entering circulation?

Answer 46

A third go to the spleen for storage if a blood vessel ruptures, the rest remain in circulation

Question 47

What is hematopoiesis?

Answer 47

The formation of new blood cells

Question 48

How is hematopoiesis controlled?

Answer 48

Factors in the environment of the developing cell

Question 49

How many blood cells are made on average per day?

Answer 49

100 billion

Question 50

Where does hematopoiesis usually take place in adults?

Answer 50

Bone marrow of the axial skeleton

Question 51

Where does hematopoiesis usually take place as a fetus?

Answer 51

Yolk sac, liver, and spleen

Question 52

Where does hematopoiesis usually take place early in life?

Answer 52

Bone marrow of long bones

Question 53

What are pluripotent stem cells?

Answer 53

The divide into committed stem cells, which then divide and differentiate into mature cells

Question 54

What type of stem cell produces RBC's and platelets?

Answer 54

Myeloid stem cell

Question 55

What type(s) of stem cells produce WBC's?

Answer 55

Myeloid stem cell -> myeloblast Lymphoid stem cell -> lymphoblast

Question 56

What is erythropoiesis and where does it take place?

Answer 56

-Formation of RBC's -Occurs in bone marrow from hematopoietic stem cells

Question 57

What happens as an RBC matures?

Answer 57

Nuclei and most organelles are released from the cell and the cell becomes smaller

Question 58

What is erythropoiesis regulated by?

Answer 58

Renal oxygen content

Question 59

What is erythropoietin?

Answer 59

A hormone produced by renal cells (liver cells as a fetus) in response to decreased renal blood oxygen content

Question 60

What does erythropoietin stimulate?

Answer 60

Erythrocyte production in the bone marrow

Question 61

What can cause a drop in renal blood oxygen level?

Answer 61

-Reduced RBC's (hemorrhage or excess RBC destruction) -Reduced availability of oxygen to blood (high altitudes, pneumonia) -Increased demand for oxygen

Question 62

What are the 3 dietary requirements for erythropoiesis?

Answer 62

-Iron -Vitamin B12 -Folic acid