The Blood and Blood Vessels

بسم الله الرحمن الرحيم

Dr.Mohammed Sharique Ahmed QuadriAssistant prof. Physiology

Al Maarefa College

Objectives

By the end of this lecture you should be able to• Describe the composition of Blood• Describe composition of Plasma and Types of Cells

Present [RBC, WBC, Platelets]• List the normal Values for Hb, RBC, WBC, PLT• Define Anemia, Polycythemia, Leukocytosis, Leukopenia,

Thrombocytosis, Thrombocytopenia • List the different types of the blood

Vessels(Arteries ,Arterioles – resistance, Capillaries, Veins)

• Define blood Pressure, Hyper tension, Hypo tension• Define normal Heart rate

BLOOD

• Blood transports O2, nutrients to tissues and CO2 to lungs and other products of metabolism to kidneys.

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Blood

• Represents about 8% of total body weight

• Average volume• 5 liters in women

• 5.5 liters in men

BLOOD COMPOSITION

• Blood consists of – Liquid PLASMA , in which cellular elements

are present.

– Cellular Elements are• Red Blood Cells(RBC) or Erythrocytes• White Blood Cells (WBC) or Leukocytes• Platelets or Thrombocyte

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Normal values • Plasma: fluid part, 55% of total blood volume.• Cellular elements: 45% of total blood volume.

– Red Blood Cell [RBC] – 5 millions / mm3

– Hemoglobin [Hb] – 15 gm / dl

– White Blood Cell [WBC] – 4000-11000/mm3

– Platelet – 150,000-400,000 /mm3

Blood CompositionHematocrit or packed cell volume: % of total blood volume occupied by RBCs.

Blood • Consists of 3 types of specialized cellular elements

suspended in plasma (liquid portion of blood)– Erythrocytes

• Red blood cells ( contains hemoglobin)• Important in O2 transport

– Leukocytes• White blood cells• Immune system’s mobile defense units

– Platelets • Cell fragments• Important in hemostasis(they prevent blood

loose from damaged blood vessels).

DIFFERENT TYPES OF WBC & THEIR FUNCTIONS

WBC FUNCTION

1. Neutrophil (60-70%) Phagocytosis (engulf bacteria)

2. Eosinophil (1-4%) Important in allergic reactions

3. Basophil (0.5-1%) Important in allergic reactions and have heparin

4. Lymphocytes (25-33%) For immunity

5. Monocyte (2-8%) Tissue macrophage

PLASMA• Plasma is transport medium for inorganic and organic

substances.• Plasma Composition: Water – 90% Solids – 10 %

Electrolytes [1%]– mainly Na+, Cl-, K+, HCO3-, Ca2+

Plasma protein [6-8%] Organic Substances - Glucose, Amino acids, Lipids, Vitamins Waste products – urea, creatinine Dissolved gases – O2 and CO2 Hormones

Plasma• Plasma proteins

– Compose 6% to 8% of plasma’s total weight– 3 groups of plasma proteins

• Albumins– Most abundant plasma proteins

• Globulins– 3 subclasses

» Alpha (α)» Beta (β)» Gamma (γ)

• Fibrinogen – Key factor in blood clotting

Most of the plasma protein are synthesized in liver.

PlasmaConstituent Functions

Water (makes up 90% of plasma)

Transport medium, carries heat

Electrolytes Membrane excitability; osmotic distribution of fluid between ECF and ICF; buffer pH changes

Nutrients, wastes, gases, hormones

Transported in blood; blood gas CO2 plays role in acid-base balance

Plasma proteins In general, exert an osmotic effect important in distribution of ECF between vascular and interstitial compartments; buffer pH changes

Albumins Transport many substances; contribute most to colloid osmotic pressure

Alpha and beta globulins

Transport many water-insoluble substances; clotting factors; inactive precursor molecules

Gamma globulins AntibodiesFibrinogen Inactive precursor for the fibrin meshwork of a clot

CLINICAL APPLICATION• Anemia – Decrease in RBC & Hb

• Polycythemia – Increase in RBC & Hb

• Leukocytosis – Increase in WBC count (more than 11,000 /mm3

• Leukopenia – Decrease in WBC count (less than 4000 /mm3)

• Thrombocytosis – Increase in platelet count

• Thrombocytopenia – Decrease in platelet count

BLOOD VESSELS

BLOOD VESSELS

• Blood is transported to all parts of the body through blood vessels to supply O2, nutrition and remove the waste products e.g. CO2, Urea.

• Oxygenated blood is pumped by left ventricle to Aorta and goes to blood vessels to supply oxygen and nutrition to body.

• Blood is returned to right side of the heart as Deoxygenated blood through veins.

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Basic Organization of the Cardiovascular System

Vascular Tree• Consists of

– Arteries• Carry blood away from heart to tissues

– Arterioles• Smaller branches of arteries

– Capillaries• Smaller branches of arterioles• Smallest of vessels across which all exchanges are made

with surrounding cells– Venules

• Formed when capillaries rejoin• Return blood to heart

– Veins • Formed when venules merge• Return blood to heart

Arteries • Specialized to

– Take blood from heart to the organs

– Has large radius

– Large Act as PRESSURE RESERVOIR to provide

driving force for blood when heart is relaxing

– Has thick, highly elastic wall.

– Has elastic fibers in the wall.

Arteries as a Pressure Reservoir

Arterioles

• Arterioles are highly muscular (smooth muscle).

• Have small radius

• Have no elastic fiber.

• Are Major resistance vessels

Arterioles

• Mechanisms involved in adjusting arteriolar resistance– Vasoconstriction

• Refers to narrowing of a vessel– Vasodilation

• Refers to enlargement in circumference and radius of vessel

• Results from relaxation of smooth muscle layer

Arteriolar Vasoconstriction and Vasodilation

Capillaries

• Thin-walled, small-radius, extensively branched

• have endothelial lining only between blood and

tissues.

• Sites of exchange between blood and surrounding

tissue cells (exchange vessels)• Bring blood within reach of every cell.

• 10 billions in number.

Capillaries

Veins– Bring blood to heart.

– Veins are thin walled as compared to arteries

– Large radius

– Also serve as blood reservoir

– serve as a BLOOD RESERVOIR (under resting conditions nearly 65% of blood in located in the veins).

– As they can store blood, they are called they are called ‘CAPACITANCE VESSELS’.

Lymphatic System

• Extensive network of one-way vessels

• Provides accessory route by which fluid can be returned from interstitial to the blood

Percentage of blood volume in different parts of circulatory system

‘USEFUL INFORMATION’

• Normal Pulse Rate – 72 beats/min (range 60-100 beats/min)

• Normal Blood Pressure (BP) – 120/80 mmHg (range for systolic BP – 100-140 mmHg) (range for diastolic BP – 60-90 mmHg)

• Hypertension (high blood pressure) – when BP is above 140/90 mmHg.

• Hypotension (low blood pressure) – when BP is below 100/60 mmHg.

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References

• Human physiology by Lauralee Sherwood, seventh edition

• Text book physiology by Guyton &Hall,11th edition

• Text book of physiology by Linda .s contanzo,third edition

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