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Exam 2 Objectives
Chapter 19: Blood Vessels
-Be able to describe the properties of major components of vasculature
• Arteries—carry blood away from heart and are divided into three groups, based on size and
function
• Elastic arteries
• thick-walled with large, low-resistance lumen
• Aorta and its major branches: also called conducting arteries because they conduct blood
from heart to medium sized vessels
• Contain substantial smooth muscle, but inactive in vasoconstriction
• Muscular arteries
• deliver blood to body organs
• Diameters range from pinky-finger size to pencil-lead size
• Active in vasoconstriction
• Arterioles
• smallest of all arteries
• Also called resistance arteries because changing diameters change resistance to blood
flow
• Control flow into capillary beds via vasodilation and vasoconstriction of smooth muscle
• Veins—return blood to heart and their formation begins when capillary beds unite in
postcapillary venules and merge into larger and larger veins
• Venous valves
• Prevent backflow of blood
• Most abundant in veins of limbs
• Venous sinuses
• Flattened veins with extremely thin walls
• Composed only of endothelium
• Examples: coronary sinus of the heart and dural sinuses of the brain
• Microcirculation and microscopic vessels; diameters so small only single RBC can pass
through at a time
• Walls just thin tunica intima
• in smallest vessels, one cell forms entire circumference
• Arterioles
• Capillaries—site of exchange
• Precapillary sphincters regulate blood flow into true capillaries

• Venules
-Know the factors that affect physiology of circulation
• Blood flow: volume of blood flowing through vessel, organ, or entire circulation in given
period
• Measured in ml/min
• Blood pressure (BP): force per unit area exerted on wall of blood vessel by blood
• Expressed in mm Hg
• Resistance (peripheral resistance): opposition to flow
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• Increased viscosity equals increased resistance
Total blood vessel length
• The longer the vessel, the greater the resistance encountered

3
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Network of lymphatic vessels (lymphatics)
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Lymph nodes: cleanse lymph
• Lymphoid organs and tissues provide structural basis of immune system by housing phagocytic
cells and lymphocytes
• spleen, thymus, tonsils, lymph nodes, other lymphoid tissues
-Know Lymphatic cells, tissues, and organs
• Lymphoid Cells
• Immune system cells (functional)
• T cells: manage immune response, and some also attack and destroy infected cells
• B cells: produce plasma cells, which secrete antibodies
• Supporting lymphoid cell (structural)
• Reticular cells produce reticular fibers called stroma in lymphoid organs
• Lymphoid Tissues
• Largely composed of reticular connective tissue, a type of loose connective tissue
• Diffuse lymphoid tissue: loose arrangement of lymphoid cells and some reticular fibers
• Found in virtually every body organ
• Lymphoid follicles (nodules): solid, spherical bodies consisting of tightly packed lymphoid
cells and reticular fibers
• Lymphoid Organs
• Thymus (Primary)
• bilobed lymphoid organ found in inferior neck
• Functions as lymphoid organ where T-cells mature
• Divided into:
• Cortex – rapidly dividing lymphocytes
• Medulla – thymic corpuscles (regulatory T-cells develop)

• Spleen (Secondary)
• Largest lymphoid organ
• Served by splenic artery
and vein which enter and exit at hilum
• Histology
• White pulp: site of immune response
• Red pulp: site of RBC breakdown
• Functions:
• Site of lymphocyte proliferation and immune response
• Cleanses blood of aged blood cells and platelets
• Stores breakdown products of RBC (iron) and platelets for later reuse
• MALT - Mucosa Associated Lymphoid Tissue (Secondary)
• Lymphoid tissues in mucous membranes throughout body
• Tonsils
• Palatine
• Lingual
• Pharyngeal (adenoids)
• Tubal
• Peyer’s patches
• In small intestine
• Appendix
• Offshoot of first part of large intestine
-Know the Lymphatic pathway
• Lymphatic capillaries-> Larger lymphatic vessels-> Collecting lymphatic vessels->
Lymphatic trunks-> Lymphatic ducts-> Right Lymphatic duct-> Thoracic duct->Venous
circulation

-Be able to compare and contrast the circulatory system and the lymphatic system
-Be familiar with the structure and lymphatic transport in lymph nodes
• Lymph Circulation: afferent lymphatic vessels -> subcapsular sinus -> medullary sinuses ->
hilum via efferent lymphatic vessels
• Structure
• Lymph nodes
• Bean shaped
• Fibrous capsule
• Trabaculae – invaginations of capsule
• Histologically distinct regions
• Cortex
• Medulla
• Contain T-cells and B-cells
• Lymphoid sinuses
• Contain capillaries, macrophages

-Differentiate between primary and secondary lymph organs

• Primary lymphoid organs: areas where T and B cells mature
• red bone marrow and thymus

• Secondary lymphoid organs: areas where mature lymphocytes first encounter their antigen and
become activated
• Nodes, spleen, MALT (mucosa-associated lymphoid tissue) and diffuse lymphoid tissues
-Know general purpose of Lymphatic system and transport
• Lymphatic system returns interstitial fluid and leaked plasma proteins back to blood via:
• Lymphatic vessels (lymphatics): elaborate network of drainage vessels
• Circulates ~ 3L interstitial fluid per day
• Once interstitial fluid enters lymphatics, it is called lymph
• Lymph system is a low-pressure system - like venous system
• Lymph is propelled by same mechanisms:
• Milking action of skeletal muscle
• Pressure changes in thorax during breathing
• Valves to prevent backflow
• Pulsations of nearby arteries
• Contractions of smooth muscle in walls of lymphatics

Chapter 21: Immune System

-Be able to describe Nonspecific (Innate) defenses in fighting infection
• Surface barriers are skin and mucous membranes, along with their secretions – First line of
defense
• Acid: acid mantle of skin
• Enzymes: in saliva, stomach, and respiratory
• Mucin: sticky mucus in GI and respiratory tract
• Defensins: antimicrobial peptides
• Other chemicals: lipids in sebum and dermicidin in sweat-Be familiar with the types of
Specific (Adaptive) immune responses
• Cells and Chemicals – Second line of defense
• Phagocytes: white blood cells that ingest and digest (eat) foreign invaders
• Neutrophils
• Macrophages

• Natural killer (NK) cells: Non-phagocytic, large granular lymphocytes that police blood and
lymph
• Can kill cancer and virus-infected cells before adaptive immune system is activated
• Kill by inducing apoptosis in cancer cells and virus-infected cells
• Inflammatory response (macrophages, mast cells, WBCs, and inflammatory chemicals):
triggered whenever body tissues are injured
• Injuries can be due to trauma, heat, irritating chemicals, or infections by microorganisms
• Stages of inflammation:
• Inflammatory chemical release
• Into ECF by injured tissue
• Vasodilation and increased vascular permeability
• Vasodilation causes hyperemia—congestion with blood—which leads to redness
and heat
• Increased capillary permeability causes 

exudate—fluid containing clotting factors and antibodies—to leak into tissue
• Phagocyte mobilization
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Margination: endothelial cells of capillaries in inflamed area project cell adhesion
molecules (CAMs) into vessel lumen
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Chemotaxis: inflammatory chemicals act as chemotactic agents that promote
positive chemotaxis of neutrophils toward injured area
• Four cardinal signs of acute inflammation:
• Redness

• Heat
• Swelling
• Pain

• Antimicrobial proteins (interferons and complement proteins): attack microorganisms
directly, or hinder microorganisms’ ability to reproduce
• Most important antimicrobial proteins
• Interferons: family of immune modulating proteins
• Proteins secreted by leukocytes and virus-infected cells
• Viral nucleic acid stimulates host cell to secrete interferon-α and interferon-β
• Kills host cells
• Induces neighboring cells to resist viral infection
• Interferon-γ
• Is secreted by lymphocytes
• Has widespread immune mobilizing effects
• Activates macrophages

• Complement proteins: components of the complement pathways: consists of ~20 blood
proteins that circulate in blood in inactive form
• Activation enhances inflammation and also directly destroys bacteria
• 3 pathways of activation
• Classical pathway: Antibodies first bind to invading organisms and then bind to
complement components, activating them
• Lectin pathway: When lectin is bound to specific sugars on foreign invaders, it
can also bind and activate complement
• Alternative pathway: Complement cascade is activated spontaneously when
certain complement factors bind directly to foreign invader

• Fever: Abnormally high body temperature that is systemic response to invading
microorganisms
• Leukocytes and macrophages exposed to foreign substances secrete pyrogens
• Pyrogens act on body’s thermostat in hypothalamus, raising body temperature
-Be familiar with the types of adaptive immune responses
• Humoral immunity
• Antibodies, produced by lymphocytes, circulate freely in body fluids
• Humoral immunity has extracellular targets
• Cellular Immunity
• Lymphocytes act against target cell
• Cellular immunity has cellular targets
• Antigens: substances that can mobilize adaptive defenses and provoke an immune response
• Characteristics of antigens
• Can be a complete antigen or hapten (incomplete)
• Complete antigen - foreign proteins, polysaccharides, lipids, and nucleic acids
• Hapten: binds to body’s own proteins and together gets recognized as foreign substance
• Contain antigenic determinants: parts of antigen that antibodies or lymphocyte receptors bind
to

• Can be a self-antigen: cell surface proteins that are antigenic to other cells (transfusion/
grafts)
• Antigens: substances that can mobilize adaptive defenses and provoke an immune response
• Characteristics of antigens
• Can be a complete antigen or hapten (incomplete)
• Complete antigen - foreign proteins, polysaccharides, lipids, and nucleic acids
• Hapten: binds to body’s own proteins and together gets recognized as foreign
substance
• Contain antigenic determinants: parts of antigen that antibodies or lymphocyte
receptors bind to
• Can be a self-antigen: cell surface proteins that are antigenic to other cells (transfusion/
grafts)
-Know cell types of the adaptive immune system
• Adaptive immune system involves three crucial types of cells
• Two types of lymphocytes
• B lymphocytes (B cells)—humoral immunity
• T lymphocytes (T cells)—cellular immunity
• Origin-> red bone marrow
• Maturation ->
• T cells in Thymus
• B cells in red Bone marrow
• Activation ->
• Upon binding to antigen
• Proliferate and differentiate into
• Effector cells
• Memory cells

• Antigen-presenting cells (APCs)
• Dendritic cells
• Macrophages
• B cells
• Engulf antigens and present fragments of antigens to T cells for recognition
• Do not respond to specific antigens
• Play essential auxiliary roles in immunity
-Be able to differentiate between cellular and humoral immunity
• Humoral Immunity: When B cell encounters target antigen, it provokes humoral immune
response
• Antibodies specific for that particular antigen are then produced
• Cellular Immunity: T cells defend against foreign or abnormal matter through direct contact
• Helper T cells (CD4 when naïve)
• Secrete cytokines that enhance activity of B cells and other T cells
• Enhance activity of macrophages and NK cells
• Cytotoxic T cells (CD8 when naïve)
• Kill virus-infected cells, abnormal cells, and bacteria
• Require Helper T cells for activation
-Know the activation and function of Helper T cells
-Know the activation and function of Cytotoxic T cells
-Be able to explain the mechanism of infection and target cell killing



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