Blood and Blood forming organs introduction

OPTOMETRY · SEMESTER 1

Blood and Blood forming organs introduction

Human Anatomy and Physiology

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Mention constituent of blood

Classify blood cells
Outline sites for the synthesis of blood cells
Describe requirements for production of blood cells
Describe functions of blood cells
Describe metabolism of haemoglobin
Describe blood typing and transfusion
Describe mechanism of blood coagulation(haemostasis)

Blood and blood forming organs

Blood is the body’s only fluid tissue, It is composed of liquid plasma and formed elements

Formed elements include:
Erythrocytes(RBCs), Leukocytes(WBCs), Platelets

Blood and blood forming organs

The blood components.

Blood and blood forming organs

The liquid component of blood is called plasma, a mixture of water, sugar, fat, protein, and salts.

It makes up about 55% of total blood volume

Blood and blood forming organs

Constituents of plasma:

It is mostly water – 92% by volume
Dissolved proteins (plasma proteins)

Albumin (60%)

Globulin (36%)

Fibrinogen (4%)

Nutrients (glucose, amino acids, fats, salts, minerals, etc.)

Blood and blood forming organs

Clotting factors

Electrolytes (Na+, Ca2+, Mg2+, HCO3-, Cl- etc.)
Hormones
Antibodies

Waste products of metabolism (CO2, lactic acid, urea, uric acid, creatinine, etc.)

If whole blood is allowed to clot and the clot is removed, the remaining fluid is called serum

Blood and blood forming organs
serum

clot

Plasma Proteins – constitute 7-9% of the plasma

Albumins (60% – 80%)

Produced by the liver, Provide the osmotic pressure which is necessary to maintain blood volume and pressure.

Blood and blood forming organs

Plasma Proteins

Globulins, divided into three types:

Alpha and beta globulin, produced by the liver and function to transport lipids and fat soluble vitamins in the blood.

Gamma globulins are antibodies produced by lymphocytes and function in immunity.

Blood and blood forming organs

Most of Gamma globulins are immunoglobulins;

IgA
IgD
IgE
IgG- 3/4 of all immunoglobulins
IgM

Blood and blood forming organs

Functions of Plasma

Serves as the protein reserve of the human body Albumin maintains the colloid osmotic pressure, which regulates the movement of water between blood and tissue Albumin transports bilirubin, fatty acids and some drugs Protects the body from infection and other blood disorders

Clotting factor (fibrinogen) plays a key role in the clotting of blood

Transports nutrients and gases
Transports metabolic waste products

Blood and blood forming organs

Blood Cells.

Red blood cells (RBC) a.k.a erythrocytes)
White blood cells (WBC), leucocytes
Platelets (thrombocytes).

Blood and blood forming organs

Blood cells.. Formed elements

Erythrocytes, leukocytes, and platelets make up the formed elements Only WBCs are complete cells, RBCs have no nuclei or organelles, and platelets are just cell fragments Most formed elements survive in the bloodstream for only a few days, Most blood cells do not divide but are renewed by cells in bone marrow Blood and blood forming organs

Production of Red Blood Cells

Areas of the Body That Produce Red Blood Cells.

In the early weeks of embryonic life, primitive, nucleated RBC are produced in the yolk sac.

During the middle trimester of gestation, the liver is the main organ for production of RBC but reasonable numbers are also produced in the spleen and lymph nodes.

Blood and blood forming organs

Production of Red Blood Cells

Then, during the last month or so of gestation and after birth, red blood cells are produced exclusively in the bone marrow.

Blood and blood forming organs

Erythrocytes (RBCs)

Biconcave discs, anucleate, essentially no organelles
Filled with hemoglobin (Hb), a protein that functions in gas transport.
Contain the plasma membrane protein spectrin and other proteins that:
Give erythrocytes their flexibility
Allow them to change shape as necessary

Blood and blood forming organs

RBCs

Biconcave disk shape of the RBC

Blood and blood forming organs

Is the process of red blood cell formation

Blood and blood forming organs

Red Blood Cells (3)

Synthesis of RBC needs iron, folic acid, vitamin B12, manganese, iodine, erythropoietin and protein Erythropoietin hormone (EPO) secreted by kidneys, is a glycoprotein that serves as the primary regulator of red blood cells Blood and blood forming organs

FACTORS NECESSARY FORERYTHROPOIESIS

Development and maturation of erythrocytes require variety of factors, which are classified into three categories:

1. General factors
2. Maturation factors
3. Factors necessary for hemoglobin formation.

Blood and blood forming organs

GENERAL FACTORS

General factors necessary for erythropoiesis are:
i. Erythropoietin hormone
ii. Thyroxine
iii. Hemopoietic growth factors
iv. Vitamins.

Blood and blood forming organs

MATURATION FACTORS

Vitamin B12,

intrinsic factor and
folic acid are
necessary
for the maturation of RBCs.

Blood and blood forming organs

FACTORS NECESSARY FOR HEMOGLOBIN FORMATION

First class proteins and amino acids
Iron
Copper
Cobalt and nickel
Vitamins

Blood and blood forming organs

Haemoglobin (1)

Haemoglobin (Hb or Hgb) is the iron-containing oxygen-transport substance in the red blood cells The adult haemoglobin (HbA) molecule is made up of four chains 2 alpha chains and 2 beta chains (α2 β2) The fetal haemoglobin (HbF) contains alpha chains and gamma chains (α2γ2) Blood and blood forming organs

ANAEMIA

Anaemia is a decrease of haemoglobin or number of RBC for age and sex of an individual
Anaemia is a sign of a disease process
Causes:

Haemorrhage – Bleeding

Haemolytic – Excessive breakdown of RBC
Nutritional – Deficiency of iron, folic acid,
vitamin B12, protein
Disorders in the bone marrow (aplastic anaemia)

Blood and blood forming organs

They are also known as leukocytes or leucocytes

leuko is derived from Greek word leukos = white.
Are the colorless and nucleated formed elements of blood

Blood and blood forming organs

White Blood Cells (1)

White blood cells (leucocytes/leukocytes), are cells of the immune system defending the body against both infectious disease and foreign materials They are formed in the bone marrow (granulocytes and monocytes and some lymphocytes) and in the lymph tissue (lymphocytes and plasma cells).

After formation, they are transported in the blood to different parts of the body where they are needed.

White Blood Cells (2)

Leucocytes are found throughout the body, including the blood and lymphatic system.

There are normally between 4×109 and 11×109 white blood cells in a litre of blood, approximately 1% of blood in a healthy adult

Classification of Leucocytes

Leucocytes are classified as
Granulocytes (polymorph nuclear leucocytes [PMN]):
Characterized by the presence of differently
staining granules in their cytoplasm
There are three types of granulocytes
Neutrophils
Basophils
Eosinophils

Blood and blood forming organs

Classification of Leucocytes (2)

Agranulocytes (mononuclear leucocytes):
Characterized by the apparent absence of granules in their cytoplasm
There are two types of agranulocytes
Lymphocytes
Monocytes

Blood and blood forming organs

Neutrophils (2)

Neutrophils are very active in phagocytosis of bacteria
It is the common cell type seen in the early stages of acute inflammation

Have the ability to cross from blood capillaries into tissue The life span of a human neutrophil is about 4-8 hours in circulation and about 5 days in tissue Blood and blood forming organs

Eosinophils

Eosinophils nucleus is bi-lobed. The cytoplasm is full of granules that assume a characteristic pink-orange colour with eosin stain Eosinophils produce chemicals that weaken or destroy parasites e.g. worms Phagocytize inflammatory chemicals, allergens and antigen-antibody complexes Eosinophilia is increased eosinophils count in blood

Basophils

Basophils nucleus is bi- or tri-lobed

Cytoplasm has large blue granules

Basophils are responsible for allergic and antigen response by releasing the chemical histamine, which causes vasodilatation Blood and blood forming

Macrophages (1)

Macrophages are phagocytic cells which remove dead cell debris, microorganisms and other foreign matter

Macrophages (2)

Macrophages are abundant in lymph nodes, spleen and bone marrow
Macrophages are found in different tissue where they are assigned various names
Dendritic cells (epidermis, mucous membranes)
Microglia (CNS)
Alveolar macrophages (alveoli of lung)
Kupffer cells (liver sinusoids)

Blood and blood forming organs

Lymphocyte

Lymphocytes are synthesized in the lymphoid tissue system e.g. lymph nodes, spleen, tonsils and bone marrow Lymphocytes have deeply staining nucleus with a relatively small amount of cytoplasm.

Blood has three types of lymphocytes:
B- lymphocytes
T- lymphocytes

Natural killer cells (NK)

Lymphocyte

Agranular Leukocytes- Lymphocytes, 20% – 40%

T (thymus dependent) lymphocytes, responsible for the cellular immunity

B lymphocytes, responsible for the humoral immunity.

B-lymphocytes (B cells)

B cells differentiate into plasma cells, which make antibodies that bind to pathogens to enable their destruction 5 types of antibodies are synthesized by B cells IgM

IgE

Platelets (thrombocyte)

Have an average life span of 7 to 14 days and
Are removed and destroyed by reticuloendothelial cells in the liver and spleen.

Blood and blood forming organs

Production of Platelets

Produced in the bone marrow

Blood and blood forming organs

Platelets (Thrombocytes) (3)

Function of platelets:
Secrete clotting factor (Factor XII)
Haemostasis by causing vasoconstriction
Stick together to form a platelet plug
Help in repair of blood vessels by secreting growth factors
Repair of capillary endothelium
Phagocytosis of bacteria
Secrete enzymes which attract neutrophils to site of inflammation

Blood and blood forming

Functions of blood…

Supply of oxygen to tissues (bound to haemoglobin which is carried in red cells).

Supply of nutrients such as glucose, amino acids and fatty acids (dissolved in the blood or bound to plasma proteins (e.g. blood lipids).

Removal of waste such as carbon dioxide, urea and lactic acid.

Functions of blood.

Immunological functions, including circulation of white cells, and detection of foreign material by antibodies.

Coagulation, which is one part of the body's self-repair mechanism.

Messenger functions, including the transport of hormones and the signalling of tissue damage.

Blood and blood forming organs

Functions of blood..

Regulation of body pH (the normal pH of blood is in the range of 7.35 – 7.45).
Regulation of core body temperature.

Blood and blood forming organs

References.

Hall, J. E. (2010). Guyton and Hall Textbook of Medical Physiology. Elsevier Health Sciences.

Scanlon, V. C., & Sanders, T. (2014). Essentials of Anatomy and Physiology. FA Davis.

Blood and blood forming organs CMT04209