Overview of Haematopoeisis Final

HUMAN PHYSIOLOGY

Presented by

Dr. Magdi El Sersi, A/Professor of Physiology, SEGi University

BLOOD

Overview of Haematopoeisis

Objectives

• Composition of Blood

• Plasma make up and roles

• Various cell types, origin and roles

References

• Guyton, Arthur C. Textbook of medical physiology

• Ganong's Review of Medical Physiology .

Blood is a specialized bodily fluid circulating around the body

through blood vessels by the pumping action of the heart.

Physical Characteristics

•Blood is a sticky, opaque fluid

•Color varies from scarlet (oxygen-rich) to dark red (oxygen-poor)

•The pH of blood is 7.35–7.45

•Osmolarity = 300 mOsmThis value reflects the concentration of solutes in the plasma

•Salinity = 0.85%•Reflects the concentration of NaCl in the blood

•Blood accounts for approximately 8% of body weight

•Average volume of blood is 5–6 L for males, and 4–5 L for females

Blood

Figure 1: Systemic &

Pulmonary Circulations

Functions of Blood

• Blood performs a number of functions dealing with:

1. Transport and distribution

2. Regulation of blood levels of particular substances

3. Body protection

Transport and Distribution

• Blood transports:• Oxygen from the lungs

and nutrients from the digestive tract

• Metabolic wastes from cells to the lungs and kidneys for elimination

• Hormones from endocrine glands to target organs

Regulation

• Blood maintains:

• Appropriate body temperature by absorbing and distributing heat

• Normal pH in body tissues using buffer systems

• Adequate fluid volume in the circulatory system

Protection

• Hemostasis :Blood prevents blood loss by:

• Activating plasma proteins and platelets

• Initiating clot formation when a vessel is broken

• Blood prevents infection by:

• Synthesizing and utilizing antibodies

• Activating WBCs to defend the body against foreign invaders

Blood Plasma

• 98% Water,

• Solutes, including:

• Proteins – albumin, globulins, clotting proteins, and others

• Non-protein nitrogenous substances – lactic acid, urea, creatinine

• Organic nutrients – glucose, carbohydrates, amino acids

• Electrolytes – Na⁺, K ⁺, Ca ⁺ ⁺, Clˉ, HCO3ˉ

• Respiratory gases – O2 and CO2

• Trace elements and vitamines

Plasma proteins and functions

• Albumin-3.5-5 gm/dl

• Maintain blood osmotic pressure

• Transport of hormones, FFA, Ca++ etc

• Globulins-1.5-2.5gm/dl

• α & β globulins transport hormones and other substances

• γ globulins-immunoglobulins form antibodies

• Fibrinogen- 0.2-0.4gm/dl

• Formation of clot• Serum; is plasma without clotting proteins

Blood Components: Plasma Transports Solutes

• Water, ions, trace elements

• Gasses: O2 & CO2

• Organic Molecules

• Glucose

• N–wastes

• Proteins

• Antibodies

• Hormones

Blood Components: Plasma Transports Solutes

Figure 2: Composition of blood

Composition of Blood

• Blood is the body’s only fluid tissue (a connective tissue)

• 2 major components

• Liquid = plasma (55%) Formed elements (45%)

1. Erythrocytes (red blood cells)

2. Leukocytes (white blood cells )

3. Platelets

Figure 3: Composition of blood


Figure 2 (1 of 2)

BLOOD

Gases such as

such asPlasma

Ions

Trace elements

and vitamins

O2

CO2

Proteins

Glucose

Lipids

Nitrogenous

waste

Globulins

Fibrinogen

Amino acids Albumins

Organic

molecules

Water

is

composed

of

Blood Components: "Blood Count" – % of Each Component

Figure 4: The blood count

Blood Components: Cells

• Erythrocytes

• Red Blood Cells (RBC)

• O2 & CO2 transport

• White Blood Cells (WBC)

• Immune defense

• Phagocytosis

• Platelets: clotting

Cellular Elements

• Three main cellular elements

• Red blood cells – also called erythrocytes

• Platelets – split off from megakaryocytes

• White blood cells – also called leukocytes

• Lymphocytes – are also called immunocytes

• Monocytes – develop into macrophages

• Neutrophils – neutrophils along with monocytes and macrophages are known as phagocytes

• Eosinophils – eosinophils along with neutrophils and basophils are also called granulocytes

• Basophils – tissue basophils are called mast cells


Figure 2 (2 of 2)Cellular

elements

Red blood

cells

White

blood cells

Platelets

Lymphocytes

Monocytes

Neutrophils

Eosinophils

Basophils

include

m 0

5

10

15

BLOOD

is

composed

of

Plasma Proteins

Table 1

Clinical Tests

• Hematocrit: ratio of red blood cells to plasma

Figure 16-3

100%

•58%

plasma

volume

42%

packed

red cell

volume

<1%

white

cells

MALES FEMALES

Hematocrit 40%–54% 37%–47%

Hemoglobin (g Hb/dL* blood) 14–17 12–16

Red cell count (cells/µL) 4.5–6.5 x 106 3.9–5.6 x 106

Total white cell count (cells/µL) 4–11 x 103 4–11 x 103

Differential white cell count

Neutrophils 50%–70% 50%–70%

Eosinophils 1%–4% 1%–4%

Basophils <1% <1%

Lymphocytes 20%–40% 20%–40%

Monocytes 2%–8% 2%–8%

Platelets (per µL) 150–450 x 103 150–450 x 103

*1 deciliter (dL) = 100 mL

Hematopoiesis: Blood Cell Formation

• Mostly in bone marrow from stem cells

• Rate regulated by cytokines & growth factors

Blood Cells

Table 2

Stem Cells ……………….!! What is a stem cell?

A cell that has the ability to:

continuously divide and

differentiate (develop) into various

other kind(s) of cells/tissues

Stem Cells

Hematopoiesis

Figure 5 (1 of 2)

Uncommitted

stem cells

Pluripotent hematopoietic stem cell

Committed

progenitor cells

Erythroblast

Megakaryocyte

Lymphocyte

stem cells

BO

NE

M

AR

RO

W

Hematopoiesis

Figure 5 (2 of 2)

Erythroblast

Megakaryocyte

Reticulocyte

Erythrocyte Platelets Basophil EosinophilNeutrophil Monocyte Lymphocyte

BO

NE

M

AR

RO

WC

IR

CU

LA

TIO

N

Focus on … Bone Marrow

Figure 6-a

(a)

Bone

marrow


Figure 6-b

Bone

cortexCentral sinus

Venous

sinuses

Stroma of

marrow

(b)

Nutrient

artery

Radial

artery


Figure 6-c

Platelets

Reticular cell

Stem cell

Mature blood cells squeeze

through the endothelium to

reach the circulation.

Fragments of megakaryocyte

break off to become platelets.

The stroma is composed of

fibroblast-like reticular cells,

collagenous fibers, and

extracellular matrix.

Reticulocyte

expelling

nucleus

Stem cell

Monocyte

(c)

Lymphocyte

Macrophage

Venous sinus

Mature

neutrophil

Reticular

fiber


Figure 6-c (1 of 11)

Platelets

Reticular cell

Stem cell







Stem cell

Monocyte

(c)

Lymphocyte

Macrophage

Venous sinusReticular

fiber



Platelets

Reticular cell

Stem cell







Stem cell

Monocyte

(c)

Lymphocyte

Macrophage


fiber



Platelets

Reticular cell

Stem cell







Reticulocyte

expelling

nucleus

Stem cell

Monocyte

(c)

Lymphocyte

Macrophage


fiber



Platelets

Reticular cell

Stem cell










Reticulocyte

expelling

nucleus

Stem cell

Monocyte

(c)

Lymphocyte

Macrophage


fiber



Platelets

Reticular cell

Stem cell










Reticulocyte

expelling

nucleus

Stem cell

Monocyte

(c)

Lymphocyte

Macrophage

Venous sinus

Mature

neutrophil

Reticular

fiber

Overview of Haematopoeisis Final

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