Cellular Components Flashcards
What are the 2 main components of blood?
- Formed elements
2. Plasma
Blood is a special type of connective tissue. What is the matrix of this tissue known as?
Plasma
The formed elements are classified into 3 main categories. What are they?
- Erythrocytes
- Leukocytes
- Platelets
Mention the relative amounts of formed elements and plasma.
45% and 55%
What are the characteristics of plasma?
Yellow color
Homogeneous
What is the major component of plasma? What is the composition?
Water
90%
Besides the 90% of water in the plasma, what occupies the remaining 10%?
Various solutes dissolved in the water component of plasma
What percentage of these solutes do proteins bear?
80%
Name 3 main plasma proteins.
Albumin
Globulins
Fibrinogen
When proteins are excluded, the plasma is occupied by several other types of solutes. What is their percentage? What are they?
20%
Various nutrients Inorganic salts Electrolytes Nitrogenous compounds Hormones Enzymes Dissolved gases
What are some nutrients found in plasma?
Glucose
Amino acids
Lipids
What are the dissolved gases in plasma?
Oxygen
Nitrogen
Carbon dioxide
What are the nitrogenous compounds found in plasma?
Urea
Creatinine
What are the most numerous cells in blood?
Erythrocytes
Describe the structure of a mature RBC.
Circular, biconcave disc shaped.
Does not have a nucleus.
Cytoplasm has no cellular organelles.
What is the diameter of a living erythrocyte?
7.5 μm
What is the thickness of an erythrocyte?
- 6 μm at the periphery (rim)
0. 8 μm at the central region
How are erythrocytes seen in blood smears stained by the Wright stain?
Circular bodies which stain pinkish color
In which part of the body do RBCs develop as true cells?
Bone marrow
What modifications are made to RBCs in bone marrow, before they enter the blood?
Extrude their nucleus and lose various cellular organelles (including the mitochondria).
How do erythrocytes generate energy?
By anaerobic glycolysis
What is the main content of the cytoplasm of an erythrocyte?
Iron-containing metalloprotein Hemoglobin
Hemoglobin binds reversibly with oxygen and carbon dioxide separately to form;
Oxyhemoglobin and Carbaminohemoglobin
Why do RBCs give a reddish tinge to circulating blood?
Because the hemoglobin in the cytoplasm of the erythrocyte turns red when it binds to oxygen.
How does the biconcave shape of erythrocytes facilitate the gaseous exchange?
By increasing the surface area of the cells and by bringing the plasma membrane of the cell close to the hemoglobin molecules present in the cytoplasm
How are erythrocytes capable of considerable distortion in shape?
They have a very pliable and elastic body due to which they have the capability to fold themselves to pass through the small capillaries that have lesser calíber than their own diameter.
The RBCs are enveloped by a specialized cell membrane. State its functions.
- imparts flexibility to the cells
- prevents adhesion of erythrocytes to the endothelium of blood vessels and to other cells.
- determines the antigenic properties of the erythrocytes (forms the basis of blood grouping)
What is the average life span of erythrocytes?
120 days
What happens after 120 days?
The erythrocytes are trapped, engulfed and degraded mainly by the phagocytic cells of the spleen and liver.
Where are new erythrocytes produced in the body? What is the rate of production?
Red bone marrow
2 million RBC per second
Average count of RBC in healthy adult human male and female are?
5,200,000 per cubic millimetre
4,700,000 per cubic millimetre
What is the percentage volume of blood occupied erythrocytes called?
Hematocrit
What is the normal value of hematocrit? What does low hematocrit indicate?
45%
Anemia
What is a special type of movement seen in some leukocytes?
Ameboid movement
Describe their structure.
Nucleated cells
Generally larger than erythrocytes
Cytoplasm does not have hemoglobin
What is the primary function of leukocytes?
Defense of the body against bacteria, viruses, parasites and foreign proteins
Where do leukocytes carry out their functions?
In the connective tissues.
What is the place of origin of leukocytes?
Bone marrow
How do leukocytes travel to the connective tissues from the bone marrow?
Through the bloodstream
because they use the blood circulation merely as means of transportation
What is the normal total leukocyte count (TLC) of an adult and in children?
4,000 to 11,000 cells per microliter of blood.
Higher in children
What are the 2 ways in which leukocytes work together to prevent disease?
- Actually destroying invading bacteria or viruses by phagocytosis
- By forming antibodies and sensitized lymphocytes that may destroy or inactivate the invader.
What are the two categories into which WBC are divided?
On what basis has it been done?
Granulocytes and Agranulocytes
Granulocytes have a granular appearance and are called polymorphonuclear cells, unlike agranulocytes.
What are the type of Granulocytes and Agranulocytes?
Granulocytes- Neutrophils, Eosinophils, Basophils
Agranulocytes - Monocytes, Lymphocytes
The ‘platelets’ seen in WBC are found in the bone marrow. They are fragments of another type of cell similar to the WBCs. What is this type of cell called?
Megakaryocytes
What are the normal percentages of different types of WBCs?
Neutrophils : 62% Lymphocytes : 30% Monocytes : 5.3% Eosinophils : 2.3% Basophils : 0.4%
Platelet count of a normal individual is?
300,000 per microliter of blood
What is a temporary increase in the number of leukocytes called?
When the WBC number decreases below the lowest normal range, what is it called?
Leukocytosis
Leukopenia
What is the type of granules that both granulocytes and agranulocytes possess?
Which organelles of the cell do they represent?
Non-specific azurophilic granules
Represent lysosomes of the cell
Why are granulocytes known as polymorphonuclear leukocytes?
Because they have variable appearance of their nuclei.
In blood smears, what is the diameter of neutrophils, eosinophils and basophils?
Neutrophils : 9 - 12 μm
Eosinophils : 10 - 14 μm
Basophils : 8 - 10 μm
Describe the nucleus of a neutrophil.
It shows variety of forms.
Usually appears as 3 to 5 irregularly ovoid masses (lobes) of chromatin.
These lobes are connected to each other by narrow constrictions or fine strands of chromatin.
May be U-shaped, S-shaped or irregular in appearance.
Major part of the cytoplasm of a neutrophil is occupied by 3 types of granules. What are they?
Azurophilic granules (primary) Specific granules (secondary) Tertiary granules
Azurophilic grains stain more deeply than the specific granules. What colour stain does it takes under wright stain?
Reddish purple colour
Azurophilic granules contain some enzymes that enable the neutrophil to digest the phagacytosed bacteria. What are they?
Myeloperoxidases
Various acid hydrolases
Specific granules are The most abundant and have a smaller size than the azurophilic granules. What is their diameter?
0.2 μm
What colour are specific granules when stained?
Faint pinkish-purple
Specific granules contain a number of enzymes and pharmacological agents which aid the neutrophil in killing bacteria. What are they?
Collagenase type IV Phospholipase Lactoferrin Lysozyme Alkaline phosphatase
What do activated neutrophils secrete at the site of an injury?
Cytokines
Chemokines
What do cytokines and chemokines do at a site of injury?
Attract other leukocytes
Direct the leukocytes and local tissue cells to begin the process of repair and restoration of the damaged tissue (to its normal condition)
What do tertiary granules of the neutrophils mainly contain?
What do those enzymes do?
Gelatinases
Collagenases
Degrade the extra cellular matrix of the connective tissue
(so that migration and movement of neutrophils through the connective tissues is facilitated)
In addition to the 3 types of granules what does the cytoplasm of a neutrophil contain?
Few mitochondria
Small Golgi apparatus
Some vesicles of smooth ER
Few ribosomes
What are the sites at which eosinophils are found abundantly?
Loose connective tissue of the mucosa of the digestive, respiratory and lower urinary tracts.
Sites of chronic inflammation. (eg : in lung tissues of patients suffering from asthma)
What are the two principle features by which eosinophils are characterised?
(1) cytoplasm packed by large eosinophilic granules which exhibit a red to orange colour
(2) characteristic bilobed nucleus with 2 large globular lobes connected by a thin intermediate segment.
What are the specific granules of the eosinophils?
Describe their structure.
Large eosinophilic granules
Roughly oval in shape.
Flat, crystal-like core
What do large eosinophilic granules mainly contain?
What is their function?
Give examples.
Four proteins
Strong cytotoxic effect on multicellular parasites like helminths (worms)
- Major basic protein (MBP)
- Eosinophilic cationic protein (ECP)
- Eosinophil-derived neurotoxin (EDN)
- Eosinophil peroxidase (EPO)
Besides proteins what other compounds are secreted by eosinophils? Give examples.
What is their main function?
Enzymes (histaminase and arylsulfatase) Cytokines (interleukins) Lipid mediators (prostaglandins and leukotrienes)
Regulate and modulate the inflammatory response initiated by allergic or hypersensitivity reactions of different types.
Whenever there is an allergic or hypersensitivity reaction to any antigen in the body, what do the mast cells in the local connective tissue release? What does it do?
Eosinophil chemotactic factor (ECF)
Causes eosinophils to leave the blood capillaries and migrate into the connective tissue at the site of allergic reaction.
Describe the nucleus of basophils.
Relatively large in size.
Divided into irregular lobes.
(Not easily seen in stained smears due to the large amount of specific granules in cytoplasm)
Specific granules of basophils are strongly basophilic and are so numerous that they almost fill the entire cytoplasm.
What compounds do these granules contain?
Histamine Heparin Heparan sulfate Interleukin-4 Interleukin-13 Leukotrienes
Eosinophil chemotactic factor
Platelet activating factor
Phospholipase
Why are specific granules of eosinophils strongly basophilic?
Due to presence of sulfated glycosaminoglycans, heparin and heparin sulfate
