Chapter 18- Blood

Question 1

Hematology

Answer 1

branch of science that studies the blood, blood-forming tissues and blood disorders

Question 2

functions of blood

Answer 2

-nutritive & excretory function
-respiratory function
-transport of hormones and enzymes
-regulation of water & acid-base balance
-regulation of body temp
-restricts fluid loss (clotting)
-blood has white blood cells= protect against disease

Question 3

Physical Characteristics of
Blood

Answer 3

• Blood is a type of connective tissue, the matrix is the plasma and this
  dissolves and suspends various substances, cells, and cell fragments
• Maintains a temperature of 38°C
• Denser and about 5 x more viscous than water
• pH of 7.35 – 7.45 (average of 7.4)
• Adult volume: male – 5-6L female 4-5L; about 8% of body weight in kg
• Regulated by several hormones (e.g., aldosterone, ADH)

Question 4

why do we draw blood from veins

Answer 4

1)Superficial veins – easier to locate
2)Vein walls are thinner and easier to
penetrate than comparable sized arteries
3) Blood pressure lower in venous system,
puncture seals quickly

Question 5

components of blood

Answer 5

-plasma (55% of whole blood)
-buffy coat: leukocytes and platelets (<1% of whole blood)
-erythrocytes (formed elements) (45% of whole blood)

Question 6

plasma proteins

Answer 6

-albumins (60%) major contributors to osmotic pressure of plasma; transport lipids, steroid hormones
-globulins (36%) trasnport ions, hormones, lipids; immunity function
-fibrinogens (4%) essential component of clotting system; can be converted to insoluble fibrin

Question 7

fibrinogen

Answer 7

-a precursor for fibrin
-soluble plasma protein
fibrin
-insoluble protein
-forms clots

Question 8

plasma composition

Answer 8

-plasma proteins 7%
-other solutes 1%
-water 92%

Question 9

blood cell composition

Answer 9

1. erythrocytes (majority RBC)
2. thrombocytes (platelets)
3. leukocytes (WBC)
   ALL MADE IN RED BONE MARROW

Question 10

hematopoiesis

Answer 10

-hematocytoblast (HSC)
-myeloid cell (erythropoietin, hormone from kidneys)
-progenator cell
-blast cells
-proerythroblast (EPO)
-erythroblast (last stage with nucleus)
-reticulocyte (no nucleus, found in patient with regnerative anemia)
-erythrocyte (RBC)

Question 11

erythrocytes 2 functions

Answer 11

1) Pick up oxygen from lungs and deliver it to tissues
2) Pick up carbon dioxide from tissues and unload
it in the lungs

Question 12

how does structure of erythrocytes aid function

Answer 12

1) Large surface area allows for rapid exchange of oxygen as cells pass through capillaries of the lungs
or peripheral tissue.
2) Allows RBCs to temporarily form stacks that smooth their flow through narrow blood vessels.
3) The strong and flexible plasma membrane allows them to deform without rupturing as they squeeze
through narrow capillaries

Question 13

lifespan of erythrocytes

Answer 13

No nucleus, ribosomes, or mitochondria means no
repair. RBCs have a finite life span of about 120 days

Question 14

Hematocrit (Hct) – percentage of blood volume occupied by RBCs
NORMAL

Answer 14

female 42% (range: 37 -47); male 46% (range: 40-54)
* Testosterone stimulates RBC production whereas estrogen does not
* Also, loss of blood during menstruation impact Hct in females

Question 15

Hematocrit (Hct) – percentage of blood
volume occupied by RBCs
ANEMIA

Answer 15

• Reduction in the oxygen-carrying capacity of the RBCs
• Significant decrease in hematocrit is present
• Many types of anemia: decrease in absolute number of RBCs (increased loss –hemorrhagic/hemolytic or decreased production) or insufficient hemoglobin (or iron or
  vitamin B12)

Question 16

Hematocrit (Hct) – percentage of blood
volume occupied by RBCs
POLYCYTHEMIA

Answer 16

• Increase in hematocrit is present (>65%)
• Abnormal increase in RBC production (absolute polycythemia) or due to dehydration
  (relative polycythemia)
• Blood becomes too viscous, harder for heart to pump, increases blood pressure and
  increase risk for stroke or heart attack

Question 17

Structure of hemoglobin

Answer 17

-gives blood its red colour
-Hb is a protein with 4 identical chains
-Each chain is made up of a polypeptide chain called a globin, a
chemical group called a heme, which contains and iron molecule that can bind to an oxygen molecule
-1 RBC can carry 1 billion O2 molecules

Question 18

Erythropoiesis occurs in the red bone marrow and typically it takes 3 – 5 days and involves four major steps

Answer 18

1) Reduction in cell size
2) Increase in cell number
3) Synthesis of hemoglobin (erythroblast stage)
4) Loss of the nucleus and other organelles (reticulocyte & mature RBC)

Question 19

transport ions for proteins

Answer 19

-gastroferrin (stomach)
-transferrin (blood)

Question 20

storage protein for iron

Answer 20

ferritin (in liver)