Lecture 15

The Circulatory System – Blood and the Heart

Introduction

  • Functions of the Circulatory System
  • Transport
  • Blood carries oxygen from the ______ to all of the body’s tissues.
  • Blood carries carbon dioxide from the body’s tissues and carries it to the lungs to be removed from the body
  • Blood picks up ______ from the digestive system and delivers them to all of the body’s tissues
  • Blood carries metabolic wastes to the kidneys for removal
  • Blood helps to regulate body temperature by carrying heat to the ______ surface for removal
  • Protection
  • Blood plays several roles in inflammation, a mechanism for limiting the spread of infection
  • White blood cells destroy microorganisms and ______ cells
  • Antibodies and other blood proteins neutralize toxins and help to destroy pathogens
  • Platelets secrete factors that initiate blood ______ and other processes for minimizing blood loss
  • Regulation
  • By absorbing or giving off fluid under different conditions, the blood capillaries help to stabilize ______ distribution in the body
  • By buffering acids and bases, blood proteins help to stabilize the pH of the extracellular fluids
  • Formed elements:
  • Erythrocytes
  • Red blood cells
  • Have two functions
  • Pick up ______ from the lungs and deliver it to tissues in other parts of the body
  • Pick up carbon dioxide from tissues and unload it in the ______
  • Most abundant formed elements in the blood
  • Leukocytes
  • ______ blood cells
  • Least abundant, but provide protection against infectious microorganisms and other pathogens
  • Platelets
  • Cell fragments
  • Used primarily to form clots

Components and General Properties of Blood

  • Blood ______ – clear extracellular marix
  • Has no anatomy that we can study visually
  • It’s a complex mixture of water, proteins, nutrients, electrolytes, nitrogenous wastes, hormones, and gases
  • ______ are the most abundant plasma solutes by weight and play a variety of roles
  • Albumin
  • Smallest and most abundant plasma protein
  • Transports various ______ solutes and buffer the pH of the blood plasma
  • Contributes to viscosity and osmolarity of blood to affect blood volume, blood pressure, and blood flow
  • ______ – thickness, or resistance to flow
  • Osmolarity – concentration of particles that cannot pass through the walls of blood vessels
  • Globulins
  • Alpha Globulins
  • Transport hemoglobin released by dead erythrocytes
  • Transport ______, lipids, fat soluble vitamins, and hormones
  • Beta Globulins
  • Transport iron and lipids
  • Aid in destruction of ______ and microorganisms
  • Gamma Globulins
  • Consists of antibodies that combat pathogens
  • Fibrinogen
  • Soluble precursor of fibrin, which forms the framework of a blood ______
  • Erythrocytes
  • Form and Function
  • ______ cells with thick rim and thin sunken center
  • Lose nearly all of their organelles during their development
  • They lack mitochondria, and rely on anaerobic fermentation to produce ATP
  • They have no nucleus, so they cannot produce proteins or undergo ______
  • They have glycoproteins on their outer surface that determine blood type
  • The cytoplasm of erythrocytes consists of a 33% solution of ______
  • Hemoglobin is best known for oxygen transport
  • It also transports carbon dioxide and buffers blood _____
  • The bioconcave shape increases surface area to volume ratio which enables oxygen and carbon dioxide to diffuse quickly to and from the ______
  • Quantity of Erythrocytes
  • Quantity determines the amount of oxygen the blood can carry
  • The RBC (red blood count) is normally 4.6 to 6.2 million RBCs/microliter in men and 4.2 to 5.4 million in women
  • Hematocrit is the percentage of blood ______ composed of RBCs
  • It normally ranges from 42% and 52% in men
  • It’s usually between 37% and 48% in women
  • Hemoglobin
  • This is an iron-containing gas-transport protein normally found only in RBCs
  • It consists of four protein chains called globins and non-protein ______ groups bound to each protein chain
  • Attached to each heme is a ferrous iron, which is the binding site for oxygen
  • Carbon dioxide that is transported by hemoglobin attaches to the ______, rather than the heme
  • The Erythrocyte Life Cycle
  • Erythropoiesis is the formation of new red blood cells.
  • Hemopoiesis is the formation of all formed elements in the blood
  • In the embryo, the yolk sac produces blood cells
  • In the fetus, blood cells are produced by the bone marrow, ______, spleen, and thymus
  • In an adult, the bone marrow and thymus continue to produce blood cells
  • The spleen continues to produce lymphocytes
  • Red blood cells, originate as bone marrow stem cells called pluripotent stem cells (which have the potential to develop into multiple mature cell types)
  • The cells pass through several stages of transformation over 3-5 days
  • Reduction in ______
  • Increase in cell number
  • Synthesis of hemoglobin
  • Loss of ______ and other organelles
  • Erythrocytes live for about 120 days and then become trapped in (and destroyed by) the spleen
  • Blood Types
  • Blood types differ because different glycoproteins and glycolipids may be found on the surface of the erythrocyte
  • The molecules act as ______
  • Antigens are substances capable of evoking an immune reaction
  • The blood plasma contains antibodies that react against incompatible antigens on foreign RBCs, so some blood types are incompatible for blood transfusions
  • Leukocytes
  • Form and Function –
  • Protect against ______
  • Retain their organelles throughout life
  • Types of Leukocytes
  • Granulocytes – have cytoplasm that contains lysosomes and other organelles that appear as conspicuous colored granules in stained blood films
  • Neutrophils –
  • have granules that stain a very light lilac color at a neutral pH (don’t stain a dark pink or a dark blue)
  • Most ______ WBCs
  • Primary job is to destroy bacteria
  • Phagocytize bacteria and digest them
  • Release toxic mix of chemicals that forms a killing zone to kill bacteria (but themselves too in the process)
  • Eosinophils –
  • have rosy to orange-colored granules (“stain pink”)
  • Abundant in ______ membranes
  • Secrete chemicals that weaken or destroy relatively large parasites such as hookworms and tapeworms
  • Phagocytize and dispose of inflammatory chemicals, antigen-antibody complexes, and ______ (foreign antigens that trigger allergies)
  • Basophils –
  • Have dark violet staining granules (“stain blue”)
  • Rarest of the WBCs
  • Secrete chemicals which aid in the body’s defense processes
  • Histamine is a vasodilator that widens the blood vessels
  • This speeds the flow of blood to ______ tissue
  • This makes the blood vessels more permeable, so that components such as neutrophils and clotting proteins can get into the connective tissues more quickly
  • ______ is an anticoagulant
  • In inhibits blood clotting, so it promotes the mobility of WBCs in the area
  • Agranulocytes – white blood cells that lack visible granules in the cytoplasm
  • Monocytes
  • ______ of the WBCs
  • Become macrophages after leaving the blood stream
  • Macrophages are highly phagocytic cells that consume up to 25% of their own volume per hour
  • They destroy dead or dying ______ and foreign cells, pathogenic chemicals and microorganisms, and other foreign matter
  • They can chop up or “process” foreign antigens and display fragments of them on the cell surface to alert the ______ system to the presence of a pathogen
  • Types of macrophages
  • Dendritic cells are in the epidermis and mucous membranes
  • ______ are in the CNS
  • Alveolar macrophages are in the pulmonary alveoli
  • Hepatic macrophages are in the liver sinusoids
  • Lymphocytes
  • Smallest WBCs
  • ______ fills most of the cell
  • Most are involved in specific immunity
  • Immunity is a defense in which the body recognizes a certain antigen it has encountered before and mouse such a quick response that a person notices little or no symptoms of illness
  • Certain T lymphocytes attack foreign cells directly
  • B lymphocytes fight pathogens by differentiating into plasma cells and secreting antibodies
  • Life Cycle of Leukocytes
  • Granulocytes and monocytes stay in red bone marrow until they are needed
  • ______ begin developing in bone marrow, but migrate elsewhere
  • B lymphocytes mature in bone marrow and disperse and colonize the lymph nodes, spleen, tonsils, and mucous membranes
  • T lymphocytes begin development in bone marrow but then migrate to the thymus and mature there.
  • Mature T lymphocytes disperse from the thymus and colonize the same organs as B lymphocytes
  • Natural killer (NK) cells develop in bone marrow
  • Circulating WBCs don’t stay in the blood for long
  • 4 to 20 hours
  • ______ may live in tissue for a few years, however
  • Platelets
  • Platelets are not cells, but small fragments of marrow cells
  • Platelets have a complex internal structure that includes lysosomes, mitochondria, microtubules, and granules
  • Platelets have multiple functions:
  • They secrete vasoconstrictors, which cause blood vessels to ______
  • They stick together to form temporary platelet plugs to seal small breaks in injured blood vessels
  • They secrete procoagulants, or clotting factors, which promote blood clotting
  • They secrete chemicals that attract neutrophils and monocytes to sites of inflammation
  • They secrete growth factors that stimulate ______ in fibroblasts and smooth muscle and thus help to maintain and repair blood vessels