Blood

Question 1

What type of tissue is blood?

Answer 1

Specialised type of connective tissue

Question 2

Basic composition of blood

Answer 2

Erythrocytes, leucocytes, thrombocytes in a non-living fluid matrix/ plasma

Question 3

Functions of blood.

Answer 3

1- Delivery of nutrients and oxygen directly or indirectly to cells
2- Transport of wastes and carbon dioxide away from cells
3- Delivery of hormones and other regulatory substances to and from cells and tissues
4- Homeostasis:
-buffer
-participating in coagulation
-assisting with thermoregulatiom
5- Transport of humoral agents and cells of the immune system that protect the body from pathogenic agents, foreign proteins, and transformed cells eg cancer cells

Question 4

What is a haematocrit?

Answer 4

Microhaematocrit is a procedure to find ratio of the volume of packed red blood cells to volume of whole blood. ie % of RBC in blood.
Also called Packed Cell Volume.
Males- 40-52%
Females- 36-47%

Question 5

What does a centrifuge do?

Answer 5

Separates blood into layers.
Plasma 55%
Buffy coat <1% (WBC, Thrombocytes)
Red Blood Cells 45%

Question 7

What is a Complete blood count CBC/ Full blood count FBC?

Answer 7

Most frequent blood test.
Calculates the cellular or formed elements of blood.
99% of formed elements are RBC.
Red Cell Count-

Question 8

Do leucocytes contain nucleus?

Answer 8

yes and other major organelles

Question 9

Difference between white cell count and differential white cell count?

Answer 9

WCC- total number in blood
DWCC- Amount of different types

Question 10

Name for high WBC and low WBC count?

Answer 10

High- leucocytosis
Low- leucopenia
Number of leucocytes increases during inflammation

Question 11

Name the different types of white cells in order of abundance.

Answer 11

Neutrophils
Lymphocytes
Monocytes
Eosinophils
Basophils
Never let monkeys eat bananas

Question 12

Classification of leucocytes

Answer 12

Granulocytes:
-cytoplasm packed with granules
-Nucleus has 2 or more lobes (polymorphonuclear)
Neutrophils, Eosinophils, Basophils

Agranulocyte:
-Cytoplasm with few or no granules
-Nucleus not lobed
Lymphocytes and Monocytes

Question 13

What do neutrophils respond most to?

Answer 13

Tissue destruction by bacteria or fungus- Phagocytic
Numbers increase during acute bacterial infections eg meningitis and appendicitis
Migrate to areas of infection-chemotaxis

Question 14

Describe events leading to phagocytosis.

Answer 14

1- Activation of resting phagocytes by inflammatory mediators

2- Movement of phagocytes towards chemical attractants- chemotaxis

3- Margination- movement toward the vessel wall
Rolling- weak interaction with the endothelium
Adhesion- strong activation

4- Diapedesis
Podocyte extensions squeeze between two adjacent endothelial cells.
Neutrophils secrete collagenase to break down basement membrane.

5- Recognition-Attachment- phagocyte to pathogen

6- Ingestion

7- Pathogen killing and degradation

Question 15

Describe features of neutrophils

Answer 15

-Nucleus has 2-5 lobes
Numerous cytoplasmic granules
Life span 1-2 days
Chemotaxis

Question 16

Describe features of eosinophils.

Answer 16

-Bilobed nucleus
-Large refractile granules (lysosomes)
Chemotaxis
Phagocytic
Degranulation releases toxic substances aiding defence against larger parasites
Prolonged elevation leads to tissue damage

Question 17

Functions of eosinophils

Answer 17

Eosinophils regulate local inflammatory responses due to allergic or parasitic action
Levels increase in allergic disease eg asthma and hay fever

Question 18

Describe features of basophils.

Answer 18

-Irregularly-lobed nucleus
-Numerous large overlying granules which often obscure nucleus
-Granules contain heparin and histamine
-Chemotaxis

Question 19

What do the granules in a basophil contain?

Answer 19

Heparin- anti-coagulant
Histamine- vasodilator

Question 20

Describe functions of basophils

Answer 20

Associated with systemic inflammation and allergies.
When stimulated- eject chemicals from granules (non-phagocytic)
Attract other WBC

Question 21

Describe features of lymphocytes.

Answer 21

Agranulocyte
-Spherical and densely stained nucleus
-Usually present in tissues and lymphatic system
-Non-phagocytic

Question 22

Describe functions of lymphocytes.

Answer 22

Involved in adaptive immune response
B-lymphocytes-> plasma cells - produce antibodies (attacks invaders outside cells)
T-lymphocytes -> cell mediated response (attacks infected cells)
Natural killer cells- innate immune response

Question 23

Describe features of monocytes.

Answer 23

-Agranulocyte
-Kidney/U shaped nucleus
-Largest WBC
-Phagocytic
- Attracts other WBCs and fibroblasts (cells that contribute to formation of connective tissue)
-Transform into macrophage in tissues and organs eg
Osteoclasts- degrade bones
Kuppfer cells- breakdown of RBC in liver
Alveolar macrophages- lung

Question 24

What is haemopoiesis?

Answer 24

Blood cell formation

Question 25

Describe haemopoeisis

Answer 25

Occurs in the bone marrow.
All blood cells develop from a pluripotential haemopoietic stem cell–> haemocytoblasts, which are found in the marrow.

Pluripotent stem cells give rise to multipotent haemopoeitic progenitors. These are split into:

Lymphoid progenitors-> B and T lymphocyte AND NK
Myeloid progenitors-> RBC, Granulocytes, monocytes and megakaryocytes

Question 26

What the composition of plasma.

Answer 26

Water 92%- transports organic and inorganic molecules, formed elements and heat

Plasma proteins 7%

Other solutes 1%-
Electrolytes- extracellular fluid ion composition which is essential for cellular activity
Organic nutrients- used for ATP production
Organic wastes- carried to sites of break down and excretion

Serum= blood plasma without clotting factors

Question 27

List the types of proteins in plasma and describe their functions

Answer 27

1- Albumin
60% of total plasma proteins
-transport fats amino acids, enzymes and drugs eg Warfarin
Exert plasma oncotic pressure

2- Globulin
35%
-Transport ions, hormones and vitamins (diff classes carry diff substances)
Gamma Globulins are antibodies

3-Fibrinogen
4%
-Functions in blood clotting

All proteins in plasma have negative charge

Question 28

Describe morphological features of erythrocytes.

Answer 28

-Biconcave discs
-Anucleate and lack major organelles
-Contain haemoglobin
-Life span- 120 days
-Produce ATP through glycoysis
aka red blood corpuscles

Question 29

Where are erythrocytes formed? where are they broken down?

Answer 29

Formed in bone marrow
Broken down in spleen and liver

Question 30

Why are erythrocytes concave?

Answer 30

Increased surface area so more haemoglobin molecules are closer to plasma membrane.

Less distance for oxygen and carbon dioxide to diffuse.

Extremely deformable- able to squeeze through capillaries
Less likely to rupture.

Question 31

Function of erythrocytes

Answer 31

Carry oxygen from lungs and deliver it throughout the body

Question 32

Describe morphological features of Thrombocytes

Answer 32

-Platelets are packets of cytoplasm that budded off a megakaryocyte
-Anucleate but have granules containing growth factors
Life span- 10 days

Question 33

Function of thrombocytes

Answer 33

Involved in haemostasis- clot (thrombus) formation

Question 34

Describe structure of haemoglobin

Answer 34

4 peptide chains-> 2 alpha and 2 beta
Each have a Porphyrin ring which iron binds to center of ->heme group
Tetrahedral shape.
Iron is vital component of haemoglobin
Oxygen binds to iron in heme group

Question 35

What are some other functions of erythrocytes?

Answer 35

-Facilitates carbon dioxide transport
-Controls acid-base equilibrium in blood

HCO3- + H+ <———> H2CO3 <———> CO2 +H2O
(bicarbonate ion) (carbonic acid)

Erythrocytes contain carbonic anhydrase ->enzyme that catalyses hydration of carbon dioxide

Question 36

What is erythropoiesis? Where does it occur?

Answer 36

Formation of RBCs.
In fetus occurs in liver and bone marrow.
After birth occurs in bone marrow
In adult- marrow of membranous bones eg verterbrae, ribs and pelvis

Question 37

Describe process of erythropoiesis

Answer 37

Myeloid stem cell becomes a committed cell called a Proerythroblast and undergoes developmental pathway.

Phase 1: Ribosomes synthesis
Early erythroblast becomes late erythroblast

Phase 2: Haemoglobin accumulation
Late erythroblast becomes normoblast

Phase 3: Ejection of nucleus
Once ejected, normoblast becomes reticulocyte

Reticulocyte is a baby erythrocyte

During this process;
cell size is reduced
nucleus size decreases then is ejected
haemoglobin is produced during erythroblast stage

Question 38

How does a Vit B12 and folate deficiency affect erythropoiesis?

Answer 38

Inhibits DNA synthesis (cell multiplication)
Causes very few but large haemoglobin-rich erythrocytes

Question 39

How does Iron deficiency affect erythropoiesis.

Answer 39

Inhibits haemoglobin synthesis .
Causes few and small haemoglobin-poor erythrocytes

Question 40

Can reticulocytes be seen in normal blood smear?

Answer 40

Yes, typically.

Question 41

Describe regulation of erythropoiesis via arterial blood oxygen content.

Answer 41

Stimulus- Hypoxia ( state in which oxygen is not available to tissues in sufficient amount to maintain homeostasis.

Kidney cells detect low oxygen level and increase erythropoietin (EPO) secretion into blood.

Proerythroblasts in bone marrow mature more quickly into reticulocytes

Increased number of RBCs-> increased oxygen delivery to tissues

Question 42

What is erythropoietin (EPO)

Answer 42

A glycoprotein hormone that is produced by peritubular cells of kidney which stimulates red blood cell production

Question 43

What is polycythaemia?

Answer 43

Excess red blood cells in the blood

Question 44

Briefly name the different causes of anemia.

Answer 44

1- Iron, B12, Folic acid deficiency
Reduction in EPO or bone marrow disorder/aplasia

2- Hemolysis- destruction of RBCs

3- Blood loss

4- Hypersplenism- overactive spleen

Question 45

What is MCV, MCH, MCHC?

Answer 45

MCV- mean cell volume
Hct/RBC count
Haematocrit ie % of red cells in blood, divided by red blood cell count

MCHC- mean cell Hb concentration- haemoglobin per unit volume
Hb/Hct
Haemoglobin level divided by % of red cells in blood

MCH- mean cell Hb- haemoglobin per cell
Hb/RBC count
Haemoglobin levels divided by number of red cells

Question 46

The erythrocytes in iron deficiency anaemia are…?

Answer 46

Hypochromic- light and Microcytic- small

Decreased MCV (mean cell volume) and decreased MCH (mean cell haemoglobin)

Question 47

The erythrocytes in Vit B12 or Folate deficiency anemia are…?

Answer 47

Hyperchromic- dark and macrocytic- large
Known as megaloblastic anaemia.
Increased MCV (mean cell volume) and increased MCH (mean cell haemoglobin)

Question 48

The erythrocytes in haemolysis or acute blood loss are…?

Answer 48

Normochromic and normocytic
MCV=MCH

Question 49

What are the tests that can conform iron deficiency?

Answer 49

1- Serum iron- the level of iron in your blood. Patient must fast before. Results may vary throughout day and during acute illness.

2- Total iron-binding capacity (TIBC) or Unbound iron-binding capacity (UIBC)- measures the amount of proteins transferrin that carries iron through the blood.

3- Ferritin- reflects amount of stored iron in your body and is usually low in anaemia. Considered most specific for identifying iron deficiency anaemia unless infection or inflammation are present.