Blood and The Cardiovascular System Volume and Composition

Blood and The Cardiovascular System

Volume and Composition v. Average human adult has a blood volume of about 5. 3 liters. v. Sample of blood = v 45% cells by volume – called Hematocrit (HCT) or Packed Cell Volume (PCV) v. Types of Cellsv. Red Blood Cells v. White Blood Cells v. Platelets

Volume and Composition v. Other 55% is a clear, straw colored liquid called plasma. v. Plasma components: v Water v Proteins v Amino Acids v Nutrients v Electrolytes v Wastes

Red Blood Cells v Also called Erythrocytes v Biconcave Shape –Thin in the middle and thick on the outside. v Why might these be shaped in this way? v Reason #1 – Increases surface area, assisting in transportation of gases v Reason #2 - places the membrane closer to oxygen-carrying hemoglobin in the cell. v Reason #3 – Shape allows it to squeeze through the tiny capillaries.

Red Blood Cells v. What is hemoglobin? v. A molecule in red blood cells that transports oxygen. v It is responsible for the red color of red blood cells v Equals about 1/3 of each RBC by volume v With Oxygen it is oxyhemoglobin and a very bright red. v Without Oxygen it is deoxyhemoglobin and a darker red

White Blood Cells • Also known as Leukocytes • Primary Function = fight disease and infection • Two groups – Granulocytes – granules in cytoplasm • Short life spans, mainly in blood – Agranulocytes – no granules in cytoplasm • Longer life spans, can leave bloodstream

Platelets • Also called Thrombocytes – Not necessarily Red Blood Cell fragments – Arise from Megakaryocytes • These fragment, releasing small sections into cytoplasm – Each platelet: • Half the size of a RBC • Lack a nucleus • Function in the formation of blood clots • Break up and review three types of cells and their functions.

Plasma • • • 92% Water Functions 1. Transport materials 2. Regulate Fluid and electrolyte levels 3. Regulate p. H Components – Plasma proteins – Nutrients and Gases – Plasma Electrolytes

Plasma Proteins • 3 Types • Albumins – Smallest in Size, make up 60% of volume – Function – Osmotic Pressure – Why are so many needed? • Globulins – Alpha and Beta – transport lipids and vitamins – Gamma – are a type of antibody • Fibrinogen – Least common plasma protein (4%) – Function – Blood Coagulation

Nutrients and Gases • • Includes amino acids, simple sugars, and lipids Where do these nutrients come from? How are lipids able to be in the plasma? Lipoproteins – Low density Lipoproteins • Bad Cholesterol (LDL) • Why bad? – High Density Lipoproteins • Good Cholesterol (HDL) • Why good? • How do they have different densities?

Plasma Electrolytes • Include: Sodium, Potassium, Calcium, Chloride, and others • Where do they come from? • Purposes: • 1. Maintain Osmotic Pressure • 2. Supply tissues with electrolytes when needed • 3. Regulate p. H

Production of a Blood Cell • • • Occurs in the red bone marrow All types start out as a Hemocytoblast Platelets then become what? Megakaryocytes, which break apart WBCs become leukocytes, many diff. types RBCs • Use a negative feedback system – means what? • Low oxygen = more erythropoietin – More oxygen = less erythropoietin • Become erythrocytes

Blood Clotting • Hemostasis – stoppage of bleeding • Done in three ways • 1. Vasospasm – What is this? • Muscular layers in the walls of the vessel contract – Can sometimes close the vessel completely – May only last for a few minutes

Hemostasis • 2. Platelet plug – What is this? • Platelets stick to any rough surface, to collagen, and to eachother • When a break occurs, they stick to the vessel, then to each other – This keeps building, creates a dam. – Fig. 12 on page 333

Hemostasis • • 3. Blood Coagulation What is this? Formation of a blood clot This is the most effective, but also most complex way • Many things must occur for this to happen – Prothrombin to thrombin – Fibrinogen to Fibrin – Positive feedback system

Blood Coagulation • What must happen?

Parts of the heart • External Anatomy • Covered with the Pericardium – A sac like structure filled with fluid surrounding the heart. – Why would this be here? • Used mainly for protection • Walls of the heart are thick and muscular – Why would this be?

Parts of the heart • • Internal Anatomy 4 Chambers Atria – Blood enters heart here – From where? • Body or the lungs • Ventricles – Blood leaves heart from here – The walls are much thicker around the ventricles, why?

Parts of the heart • Atria and Ventricles separated by valves. • What are they going to do? • They prevent blood from flowing the wrong direction • Tricuspid valve – between right atrium and right ventricle • Bicuspid valve – between left atrium and left ventricle • Also valves at the beginning of pulmonary veins and aorta

Path of Blood • Right atrium Right ventricle pulmonary artery lungs pulmonary vein left atrium left ventricle aorta body vena cava right atrium

Blood Vessels • • • 3 types Arteries Veins Capillaries All of these provide a closed system for blood to continuously flow through – But each are structurally and functionally different.

Blood Vessels • Arteries • Carry blood away from the heart at high pressures • Characteristics of the walls: – Strong – Thick – Elastic • Why would the walls have these characteristics?

Blood Vessels • • Veins Designed to carry blood back to the heart. Run parallel to arteries Wall is similar in structure to arteries, but muscular layer is less developed. – Wall is thinner, weaker, and less elastic

Blood Vessels • Capillaries • Smallest of blood vessels – Some are so small that only a single RBC can make it through at a time • Have extremely thin walls • Why would they have such thin walls? • This is the point where gases and nutrients are exchanged.

Not sure what this is !? ! Red Blood Cells v. Erythrocytes v. Have v. Sample of blood = v 45% cells by volume – called Hematocrit (HCT) v. Types of Cellsv. Red Blood Cells v. White Blood Cells v. Platelets