The Blood and Blood Vessels Dr.Mohammed Sharique Ahmed Quadri Assistant 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. 3

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 5

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] – /mm3 –Platelet – 150, ,000 /mm3

Blood Composition Hematocrit 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 O 2 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 +, HCO 3 -, Ca 2+  Plasma protein [6-8%]  Organic Substances - Glucose, Amino acids, Lipids, Vitamins  Waste products – urea, creatinine  Dissolved gases – O 2 and CO 2  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.

Plasma ConstituentFunctions Water (makes up 90% of plasma) Transport medium, carries heat ElectrolytesMembrane excitability; osmotic distribution of fluid between ECF and ICF; buffer pH changes Nutrients, wastes, gases, hormones Transported in blood; blood gas CO 2 plays role in acid- base balance Plasma proteinsIn general, exert an osmotic effect important in distribution of ECF between vascular and interstitial compartments; buffer pH changes AlbuminsTransport many substances; contribute most to colloid osmotic pressure Alpha and beta globulins Transport many water-insoluble substances; clotting factors; inactive precursor molecules Gamma globulinsAntibodies FibrinogenInactive 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 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. 15

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 beats/min) Normal Blood Pressure (BP) – 120/80 mmHg (range for systolic BP – mmHg) (range for diastolic BP – mmHg) Hypertension (high blood pressure) – when BP is above 140/90 mmHg. Hypotension (low blood pressure) – when BP is below 100/60 mmHg. 29

References Human physiology by Lauralee Sherwood, seventh edition Text book physiology by Guyton &Hall,11 th edition Text book of physiology by Linda.s contanzo,third edition 30