Lecture 11 - Blood cells Flashcards Preview

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Flashcards in Lecture 11 - Blood cells Deck (48):

What is blood?


Blood is a mixture of cells, fluid, protein and metabolites within a closed circulatory system.



What are the major elements of blood



Erythrocytes(red blood cells) used to transport oxygen

Leukocytes (white blood cells) which have a defensive role, destroying infecting organisms such as bacteria and viruses as well as the removal of dead or damaged tissue.

Platelets which are the first line of defence against, damage to blood vessels, adhering to defects and participating in the blood clotting system.




What is plasma?


Plasma is the proteinaceous solution in which the cells circulate, and carries nutrients, metabolites, blood clotting systems and other molecules throughout the body.


• An aqueous solution containing: 7% protein,

0.9% inorganic salts, and 2.1% consisting of amino acids, vitamins, hormones & lipoproteins.

• The main protein is albumin which is fundamental to maintaining the osmotic pressure of the blood.

• Coagulant proteins such as fibrinogen are present

as are other proteins of the immune system.




What is the size of the nucleus in a erythrocyte?


They don't have a nucleus



What is the size and shape of the red blood cell?


RBC’s are biconcave in shape and between 6 & 9μm in diameter (average 7μm), 2.6μm thick at the rim and 0.8 μm at the centre. Their shape gives them a large surface to volume ratio which facilitates gaseous exchange. 



What is the normal concentration of RBD's in blood in males and females?


The normal concentration in blood is 3.9-5.5 million/μl
in the female and 4.1- 6.0 million/μl in the male.

Their flexibility permits them to adapt to the small diameter of some capillaries. 



What permits RBC's to adapt to the small diameter of some capillaries?


Their flexibility



List all the leukocytes









What is the most common WBC?


Neutrophils (60-70%)



Neutrophil diameter?





What are the neutrophil granules?


• primary granules(azurophilic granules)-contain microbicidal agents such as myeloperoxidase to kill engulfed bacteria.

secondary granules (specific granules)- most numerous in the cell. Also contains antimicrobial substances as well as a few enzymes to degrade the extracellular matrix.

tertiary granules (gelatinase granules)- mainly secrete enzymes to degrade tissues.




How many of the leukocytes in normal blood are Eosinophils(%)?





Diameter of leukocytes?


12 - 17µm



What are the least common leukocytes?


Basophils. They make up about 1% of the leukocytes in normal circulation



Diameter of basophils?


14 - 16 µm



Diameter of monocytes?


15-20µm - they are the largest WBC



How much % of leukocytes are monocytes?


2-8 %



Diameter of lymphocytes


7 - 12 µm



20 -40 % of leukocytes are _________?





Diameter of Platelets?





6 steps of haemostasis?


1)   Starts with vessel damage

2)   Platelet adhesion

3)   Activated platelets release factors such as ADP and thromboxane to recruit more platelets

4)   Clot formation: clotting factors in plasma induce formation of thrombin, which converts fibrinogen to fibrin

5)   Thrombin triggers further platelet activation

6)   During repair, the clot is dissolved by factors such as plasmin






process by which blood cells are formed



How many new blood cells are formed each day?


100 billion



What is an Erythrocytes?

Red blood cells are anucleate and highly deformable cells packed with O2 and under normal circumstances never leave the circulatory system. 


Structure of erythrocytes??

The cell membrane surrounds the cytoplasm which has no discernable organelles.

Cytoskeletal proteins such as actin & spectrin help to maintain its shape.

Without organelles an RBC cannot synthesise proteins lost during normal metabolism. Thus their lifespan is limited to approx. 120 days. 


lifespan of erythrocytes??

Without organelles an RBC cannot synthesise proteins lost during normal metabolism. Thus their lifespan is limited to approx. 120 days. 


Innate Immunity ??

Non specific.
Response to infections (non-self).

Response to altered self.
Can be humoral
or cell mediated. 


Adaptive Immunity ??

Slower to develop.
Response to infections (non-self). • Response to altered self.
Can be humoral
or cell mediated.
Has memory. 


Leukocytes ??

Use the circulatory system as a highway to reach their required destinations.

The concentration in the blood is 4-11 x 109/l but as they are involved in the defence against foreign material their numbers increase in response to infections.

Grouped on the basis of the granules in their cytoplasm and the shape of their nucleus they are divided into two groups:

1. Granulocytes- polymorphonuclear leukocytes: neutrophils, basophils & eosinophils.

2. Agranulocytes- mononuclear leukocytes: lymphocytes & monocytes. 


what is this?




Neutrophil function'?

Neutrophils leave the circulation and quickly travel to areas of damage.

First to arrive on the scene.

They live for only a few days outside the circulatory system.

When they die their lysosomes are released and cause liquefaction of the surrounding material (pus). 


Eosinophils ??

Constitute 2-4% of leukocytes in normal blood.
Have a bilobed nucleus and acidophilic (pink) granules.

Larger than neutrophils at 12-17um in diameter. Granules are pink in color.

They are phagocytic but not as active as neutrophils. 


Eosinophil numbers are increased in parasitic infestations & asthma.

Play a major role modulating inflammatory reactions.

Contain oval granules (specific granules) that contain major basic protein, eosinophil peroxidase, and other lysosomal enzymes. 


What is this??



Basophils ??

Least common of the granular leukocytes (1% normal circulation).

Have large basophilic granules.

May be precursors of mast cells.

The granules are exocytosed in the presence of allergens.

14-16μm in diameter and usually have a bilobed nucleus which is obscured by the granules. 


The granules contain sulphated proteoglycans, heparin and chondroitin sulphate along with histamine. 


what is this?



Monocytes ?

Monocytes (2-8% of leukocytes) are the largest WBC being between 15-20μm in diameter.

The nucleus is eccentrically placed and often kidney shaped.

Monocytes travel in the blood stream before entering the peripheral tissues to become macrophages.


Precursors of macrophage lineage cells.
Many macrophages are found resident in many tissues throughout the body

In some organs they are given specific names e.g. Kupffer cells in the liver and microglia in the CN



What is this??




A family of spherical cells with similar morphological characteristics.

Their nuclei are oval in shape with dense chromatin.

There are two main types of lymphocyte termed B & T cells, which perform different but linked roles in generation of adaptive immune responses. 

Account for 20-40% of total leukocytes

Range from 7-12μm in diameter. 


Platelets ??

Small (2-4μm) cell fragments derived from megakaryocytes and are important in haemostasis.

Contain cell organelles and granules.

Adhere to collagen and release their granules when needed to activate the blood clotting cascade. 


How does Haemostasis (the stopping of blood flow) work??

1)  Starts with vessel damage

2)  Platelet adhesion

3)  Activated platelets release factors such as ADP and

thromboxane to recruit more platelets

4)  Clot formation: clotting factors in plasma induce formation of

thrombin, which converts fibrinogen to fibrin

5)  Thrombin triggers further platelet activation

6)  During repair, the clot is dissolved by factors such as plasmin 



Blood Cell Formation ??

Hematopoiesis – process by which blood cells are formed

100 billion new blood cells formed each day

In the earliest stages of embryogenesis, blood cells arise from the yolk sac. Later, the spleen, liver, and bone marrow take over. After birth only red bone marrow is the source of blood cells.

In adults it takes place in the red bone marrow of the head of the humerus and femur, sternum, ribs, vertebra and pelvis

Bone marrow consists of spicules of bone with haematopoiesis occurring in the spaces between. There are many vascular sinuses amongst the haematopoietic cells. 


The Tissues of the Immune System ??

Primary Lymphoid Tissues - where immature lymphocytes acquire the capacity for antigen recognition.

Bone marrow- T cell development, and B cell development and maturation

Thymus- T cell maturation


Secondary Lymphoid Tissues- Sites of lymphocyte

Lymph nodes- Screens lymph
Spleen- Screens blood borne antigens
Mucosa Associated Lymphoid Tissue (MALT)- Screens mucosa 


Haematopoiesis ?

All blood cells originate in bone marrow

All originate from one cell type Blood stem cell (pluripotential hematopoeitic stem cell)

-Lymphoid stem cells - give rise to lymphocytes

-Myeloid stem cells - give rise to all other blood cells 


Erythropoiesis ?

Proerythroblast is the earliest recognisable precursor. The cell is large, intensely stained with sparse cytoplasm. There is no haemoglobin.

Next are the normoblast stages. Haemoglobin content rises and the nucleus becomes more condensed before being extruded from the cell. 


Megakaryocyte ??

Huge polyploid cells 30-100um in diameter.

Reside in the bone marrow.

Platelets are formed by fragmentation of the megakaryocyte pseudopodia. 



RBC life span and circulation ?

Replaced at a rate of approximately 3 million new blood cells entering the circulation per second

Damaged or dead RBCs are recycled by phagocytes

Components of hemoglobin individually recycled

– Heme stripped of iron and converted to

biliverdin, then bilirubin

Iron is recycled by being stored in phagocytes, or transported throughout the blood stream bound to transferrin