Module 5. Cardiovascular System and Blood

Cardiovascular System/ Haematology

What are the components of the cardiovascular system, and their major functions?

Heart Hollow muscular organ providing the force for flow of Overviewblood throughout human body Pathways of blood flow in human body, hollow tubes, of 3 types Arteries Carry blood away from heart to other body parts, very muscular and elastic Blood Microscopic blood vessels where Vessels Capillaries exchange of nutrients with tissues take place Components Carry blood towards the heart from other body parts, their walls are thinner as Veins compared to corresponding arteries. Special type of body tissue that is in fluid form, consists of the following components; Blood Blood cells Plasma White Blood Red Blood Platelets Cells Cells Functions Provide nutrients to body parts, Remove excretory Products from body parts, Protects body against infection, Distribution of heat.

Recap of the CVS

What are the important components and major functions of blood?

Define blood • A living life maintaining tissue that circulates through the body • Carries nourishment, electrolytes, hormones, vitamins, antibodies, heat and oxygen to body tissues • Carries waste and carbon dioxide away from body tissues

5 Functions of Blood 1. Transport of dissolved substances 2. Regulation of pH and ions 3. Restriction of fluid losses at injury sites 4. Defense against toxins and pathogens 5. Stabilization of body temperature How does a Therapeutic Apheresis procedure affect these functions?

3 General Characteristics of Blood • 38°C is normal temperature • High viscosity • Slightly alkaline pH (7.35–7.45)

Blood Volume • Blood volume (liters) = 7% of body weight (kilograms): – adult male: 5 to 6 liters – adult female: 4 to 5 liters





Haematology and Coagulation Haematopoiesis Greek meaning to make blood



What is the composition and function of plasma?

Haematology and Coagulation Plasma Proteins – albumin, globulins, fibrinogen Small nutrients – glucose, lipids, amino acids Gases – O₂, CO₂, nitrogen Metabolic waste products – urea, lactic acid Electrolytes – Na, K, Cl

Plasma Figure 19–1b

3 Classes of Plasma Proteins • Albumins (60%) • Globulins (35%) • Fibrinogen (4%)

Albumins • Transport substances: – fatty acids – thyroid hormones – steroid hormones

Globulins 1. Antibodies, also called immunoglobulins 2. Transport globulins (small molecules): – hormone-binding proteins – metalloproteins – apolipoproteins (lipoproteins) – steroid-binding proteins

Fibrinogen • Molecules form clots • Produce long, insoluble strands of fibrin

Serum • Liquid part of a blood sample: – in which dissolved fibrinogen has converted to solid fibrin

Other Plasma Proteins • 1% of plasma: – changing quantities of specialized plasma proteins – enzymes, hormones, and prohormones

Origins of Plasma Proteins • 90% made in liver • Antibodies made by plasma cells • Peptide hormones made by endocrine organs

Key Concepts • Total blood volume (liters) = 7% of body weight (kilograms) • About 1/2 the volume of whole blood is cells and cell products • Plasma resembles interstitial fluid, but contains a unique mixture of proteins not found in other extracellular fluids

Blood clotting cascade

What are the characteristics and functions of red blood cells?

Red Blood Cells • Red blood cells (RBCs) make up 99.9% of blood’s formed elements

Measuring RBCs • Red blood cell count: – reports the number of RBCs in 1 microliter whole blood • Haematocrit (packed cell volume, PCV): – percentage of RBCs in centrifuged whole blood

RBC Structure • Small and highly specialized disc • Thin in middle and thicker at edge Figure 19–2d

Importance of RBC Shape and Size 1. High surface-to-volume ratio: – quickly absorbs and releases oxygen 2. Discs form stacks: – smoothes flow through narrow blood vessels 3. Discs bend and flex entering small capillaries: – 7.8 µm RBC passes through 4 µm capillary

Lifespan of RBCs • Lack nuclei, mitochondria, and ribosomes • Live about 120 days

Erythropoiesis • Production of red blood cells – Stem cells proerythroblasts early erythroblasts intermediate late reticulocytes • Erythropoietin: Hormone to stimulate RBC production 19-32

How are the components of old or damaged red blood cells recycled?

Recycling RBCs Figure 19–4

Recycling RBCs • 1% of circulating RBCs wear out per day: – about 3 million RBCs per second • Macrophages of liver, spleen, and bone marrow: – monitor RBCs – engulf RBCs before membranes rupture (hemolyze)

What are the RBC tests that are performed and what do they indicate?



Haematocrit • Measures the amount of RBC in blood • Expressed as a fraction or % • Increases when RBC increase or plasma decrease • Decreases when RBC production decrease / blood loss / RBC destruction Females 37 – 49% Males 43 – 55%

Haemoglobin • 1gram of haemoglobin can carry up to 1.34ml oxygen • Used to screen for anaemia Adult Males 14.0 – 17.5 g/dl Adult Females 12.0 – 16.0 g/dl SANBS 12.5-18 g/dl

Mean Corpuscle Volume • MCV = Hct / total RBC count • Measures the average size of RBC Adult Male 84 – 96 fL Adult Female 76 – 96 fL

Mean Corpuscle Volume • Microcytic – small RBC (iron deficiency anaemia, folate anaemia, lead poisoning + Thalassemia • Macrocytic – large RBC (folic acid deficiency, alcoholism, hepatic disease) • Normocytic – within normal ranges

Mean Corpuscle Haemoglobin • Measures the amount of Hb present on average in one RBC • MCH = Hgb / total RBC count Adult Male 27 – 32 Adult Female 27 – 32

Mean Corpuscle Haemoglobin • Hypochromic (pale) – microcytic anaemia • Hyperchromic – macrocytic anaemia • Normochromic

Mean Corpuscle Haemoglobin concentration • Also used to determine if RBCs are Hypochromic (pale), Hyperchromic or Normochromic • MCHC = (Hgb / Hct)x100 Adults 30 – 35g/dL

Red Blood Cell Distribution width • RDW measures variation in RBC size and is based on MCV • Values may increase with various types of anaemia (megaloblastic, haemolytic, sickle cell), liver disease, alcoholism, folate deficiency. 12.8 – 15.2%

Erythrocyte Sedimentation rate (ESR) • It measures the rate at which RBCs in anticoagulated blood precipitate after an hr in an upright test tube

Erythrocyte Sedimentation rate (ESR) • Indicates inflammation associated with infections, cancers and auto immune disease • Inflammation increases clotting factors such as fibrinogen and globulin • Fibrinogen causes red cells to clump, the clump settles faster which indicated inflammation

Reticulocyte 0.5-1.5% Anaemia Bone Marrow RET RET Bone marrow activity Other causes of RET – chemo, bone marrow malignancies, vit+mineral deficiency, aplastic anaemia



Red Blood Cell Turnover (recycling)