Blood and Circulation PDF

8.2 - Blood and Circulation Blood Blood: Considered to be a connective tissue because it links all cells and organs in the body ○ Connective tissue: Supports and connects different parts of the body (Ex. blood, bones) Plasma Plasma: Liquid component of blood 55% of blood...

8.2 - Blood and Circulation Blood Blood: Considered to be a connective tissue because it links all cells and organs in the body ○ Connective tissue: Supports and connects different parts of the body (Ex. blood, bones) Plasma Plasma: Liquid component of blood 55% of blood volume is plasma (fluids, proteins, glucose, gases, wastes, vitamins, and minerals) Carries all blood cells Role: Helps transport CO2 in blood Remaining Blood Volume The remaining 45% of blood volume is made up of the following cells: ○ Erythrocytes: Red blood cells ○ Leukocytes: White blood cells ○ Platelets: Involved in blood clotting Erythrocytes Erythrocytes are also known as red blood cells ○ Makes up 44% of blood volume Specially designed to carry oxygen Lacks a nucleus ○ Because of this, erythrocytes cannot divide “Folded disk” shape allows them to have much greater surface area than a spherical cell - can carry more oxygen Packed with an iron containing molecule called hemoglobin ○ Hemoglobin: Allows large quantities of oxygen to be transported in blood ○ Anemia: When a person has too few blood cells or too little hemoglobin inside red blood cells Reduces the amount of oxygen flowing through the body Leukocytes Leukocytes are also known as white blood cells ○ Make up 1% of blood volume Responsible for immune system responses Contains nuclei Three different types: ○ Granulocytes: Consists of neutrophils, basophils, eosinophils ○ Monocytes: Can leave bloodstream to destroy bacteria Leucocyte attacking E. coli bacteria ○ Lymphocytes: Produce special proteins called antibodies that incapacitate pathogens for detection and destruction Platelets Platelets are formed when larger cells in bone marrow break apart ○ Do not contain a nucleus ○ Break down quickly in blood Play a key role in blood clotting (prevents excessive blood loss) Functions of Blood 1. Transport: Transports cells and other materials present in plasma (nutrients, waste, hormones, etc.) 2. Homeostatic regulation: Maintain temperature by balancing heat production and heat loss Vasodilation: Body’s internal temperature becomes too warm ○ Blood transports heat from where it’s formed by cellular respiration and muscular activity to blood vessels in skin ○ Nervous system causes vessels to dilate to increase amount of heat that can be lost from skin ○ Perspiration (sweat) can help body rid itself of excessive heat Vasoconstriction: Body’s internal temperature becomes too cold ○ Blood vessels near surface of skin are constricted in order to reduce amount of heat that is lost from skin ○ Shivering increases the production of heat by cellular metabolism Circulation and Action of Capillaries Combined surface area of capillaries covers about 6300 m2 Exchange materials between blood and cells Capillary Exchange When certain cells don’t need servicing and others do, sphincters at branching points of capillaries can close off blood supply and send blood down an arteriovenous shunt ○ Prevents waste of resources Cells are surrounded by interstitial fluid, also known as extracellular fluid or tissue fluid Blood moves slowly through capillaries - increases the time over which diffusion may occur Capillary Exchange Capillaries have: Arterial end: Blood is bright red because it is oxygenated (due to hemoglobin in red blood cell ) Midsection: Responsible for diffusion of materials ○ Oxygen and nutrients have low concentration in interstitial fluid, but high concentration in blood Venous end Capillary Exchange Blood Disorders - Hemophilia Inherited Result of insufficient clotting protein in blood Those who have severe hemophilia have less than 1% of clotting protein in blood Danger of bleeding to death Can be treated by injecting with substance called “Factor VIII” (protein involved in coagulation) ○ Coagulation: Blood changing to a semi-solid/solid state Blood Disorders - Leukemia Cancer of white blood cells Two main types: ○ Myeloid: Characterized by presence of too many leukocytes Leukocytes are immature and unable to fight infection Crowd out red blood cells causing anemia and fatigue ○ Lymphoid: Cancer of lymphocytes Both can be acute (appear suddenly and die quickly) or chronic (go undetected for a long time) Treatments: Blood transfusions, chemotherapy, bone marrow transplants Blood Disorders - Leukemia