3/3/08 Lymphatic System Chapter 20 – Day 1

3/3/08 Lymphatic system Intro  Closely connected to the cardiovascular system is the lymphatic system  Interstitial fluid circulates through lymph system ♦It is monitored for presence of pathogens  The lymph system is responsible for the body’s IMMUNE RESPONSE  It also absorbs fats (and other substances) and transfers them to the blood  It helps with the circulation of hormones, nutrients, and waste products not picked up by the blood as well as returning fluid and solutes

3/3/08 Components of the Lymph System  Lymph Vessels  Lymph Nodes ♦Both lymph vessels & nodes carry lymph  Tonsils  Spleen  Thymus  Lymphocytes  Lymph = the fluid that circulated between cells & the bloodstream ♦Lymph resembles plasma, but has less (fewer) protein ♦Lymph contains lymphocytes

3/3/08 Lymphatic System Fig. 20.1

3/3/08 Lymphatic Vessels  Start out as blind-ended capillaries in tissues ♦In the interstitial spaces  Lymphatic vessels travel alongside blood vessels  Located in all tissues except the CNS, bone marrow & epidermis

3/3/08 Lymphatic System Fig. 20.2

3/3/08 Lymphatic Vessels  Lymph capillaries are attached to the surrounding tissue via anchoring filament  Lymph capillary lined with endothelial cells ♦These special cells – allow fluid in but not out  Have UNIDIRECTIONAL circulation (due to mini- valves)  Lymph capillary carries fluid through lymph vessels and back to the blood stream  Lymph vessels ♦Are similar to veins – they are thin walled ♦Are extremely permeable – endothelial cells are not tightly joined (they form mini-valves) ♦Proteins and other large particles are able to enter lymphatic vessels ♦Contain protrusions on the vessel walls = lymph nodes

3/3/08 Lymphatic Vessels  Lymphatic circulation lacks a pumping organ, so ♦Must utilize the valves, respiratory pumps and muscular pumps to move lymph toward heart (same “pumps” as veins)  Lymphatic capillaries converge into larger vessels  At specific locations the lymph system connects with the blood circulation ♦Right Lymphatic duct Receives lymph from right side (R upper arm & R side of head and thorax) Empties into right subclavian & right jugular ♦Thoracic duct – receives lymph from the rest of the body) Has enlarged sac-like structure (cisternae chyli)

3/3/08 Lymphatic System Fig. 20.3

3/3/08 Lymphatic System Fig. 20.4

3/3/08 Lymphoid Cells and Tissues Cells  Lymphocytes ♦Arise in the red bone marrow ♦Protect the body against antigens ♦Circulate in blood, bone marrow, lymph nodes, spleen & thymus ♦There are 2 types T-lymphocytes (T-cells) ◦Mature in the thymus ◦Directly attack and destroy foreign cells B-lymphocytes (B-cells) ◦Mature in the bone marrow ◦Produce plasma cells that manufacture antibodies Natural Killer cells (NK cells)

3/3/08 Lymphatic System Fig. 20.5

3/3/08 Lymphoid Cells and Tissues Cells  Macrophages ♦Phagocytize foreign substances and activate the T-cell response  Dendritic cells ♦Initiate the immune response  Reticular cells ♦Produce the reticular fibers that form the soft skeletal structure of lymphoid organs

3/3/08 Lymphoid Cells and Tissues Tissues  Function of Lymphatic Tissues ♦House and provide a site of proliferation for lymphocytes ♦Surveillance site for lymphocytes and macrophages  Composition ♦Primarily reticular connective tissue (except thymus) ♦Macrophages reside on reticular fibers, lymphocytes temporarily reside in spaces of the reticular fiber network before leaving to “patrol” the body  Types ♦Diffuse = scatter reticular tissue (& cells) – found in every body organ ♦Follicles (nodules) – solid spherical bodies of tightly packed reticular elements and cells

3/3/08 Lymph Nodes  Lymph nodes = aggregates of lymphatic tissue in the body ♦Cluster along the lymphatic vessels of the body ♦Lymph is filtered through the lymph nodes before it is returned to the blood stream ♦Large clusters of lymph nodes appear near the body surface in the inguinal, axillary, and cervical regions  Form ♦Bean shaped, surrounded by a fibrous capsule  Function ♦Filters lymph (only done in lymph nodes) ♦Assist in activating immune system

3/3/08 Lymphatic System Fig. 20.7

3/3/08 Spleen  Largest lymphoid organ ♦12 cm long (left side between 9 th & 11 th ribs) ♦Site of lymphocyte proliferation & immune surveillance & response  Function ♦Cleanses the blood by removing old RBCs, platelets & debris from the blood ♦Stores the breakdown products of RBCs ♦Site of RBC production in fetus and extreme cases  Anatomy ♦Surrounded by fibrous capsule ♦Contains T-cells, B-cells, RBCs and macrophages ♦Divided into 2 regions Red pulp = lymphocytes & reticular fibers (RBC disposal/recycle) White pulp = rich in macrophages and reticular fibers (immune function)

3/3/08 Tonsils  Simplest lymphoid organ  Name based on location ♦Palatine tonsils ♦Lingual tonsils ♦Pharyngeal tonsils ♦Tubal tonsils Fig. 20.6

3/3/08 Thymus  The site of T-cell maturation  Most active in younger children – atrophies with age  Does not contain reticular fibers

3/3/08 Thymus Fig. 20.8

3/3/08 Lymphatic System Fig. 20.9

3/3/08 Lymphatic System Fig. 20.6

3/3/08 Lymphatic System Fig

3/3/08 Lymphatic System Fig

3/3/08 Lymphatic System Fig

3/3/08 Lymphatic System Fig

3/3/08 Lymphatic System Fig

3/3/08 Lymphatic System Fig

3/3/08 Lymphatic System Fig. 20.5

3/3/08 Blood Vessels - Intro  Veins = mostly deoxygenated – except pulmonary vein & umbilical vein  Arteries = mostly oxygenated – except pulmonary artery & umbilical artery  Capillaries = interconnecting vessels ♦Enable gas exchange, etc.  Blood vessel structure and comparison activity in lab

3/3/08 Blood Vessel Structure Fig. 19.1

3/3/08 Arteries vs. Veins - Similarities 3 Layers  Tunica Externa ♦Connective Tissue  Tunica Media ♦Smooth muscle cells ♦Elastic fibers (arteries) ♦Collagen fibers  Tunica Interna ♦Elastic layer ♦Endothelial cells & connective tissue with elastic fibers (arteries)

3/3/08 Arteries vs. Veins  Arteries are thick walled  Larger arteries have more elastic fibers ♦Tunica media – thicker, concentric & longitudinal ♦Tunica interna – internal elastic membrane  ARTERIES ♦Elasticity Ability to stretch when full = high pressure Return to their original state when relaxed ♦Contractability More smooth muscle (than veins) Vasodilation, Vasoconstriction  Both veins & large arteries need O2 – supplied by vaso vasorum

3/3/08 Arteries vs. Veins  Hierarchy of organization ♦(learn examples from text)  Largest vessels coming out of heart or to heart  These carry the most volume ♦If arteries – they have the highest pressure  Diagram on board and Fig  Be able to work though these – know order and characteristics

3/3/08 Blood Vessel Hierarchy Fig. 19.2

3/3/08 Capillaries Fig. 19.5

3/3/08 Arteries vs. Veins  Different jobs and different driving forces  Arteries ♦Force of contraction pushes blood forward ♦Blood pressure = driving force ♦Moves downhill to lower extremities - gravity  Veins ♦Lower extremities to heart = against gravity ♦Low pressure ♦Relies on other driving forces

3/3/08 Veins  Two features help to push blood forward: ♦Valves – keep blood from flowing backward (flow is possible in 1 direction only) ♦Skeletal muscle contraction Helps to push blood forward ♦Breathing action Pressure in chest helps venous flow ♦All contribute to venous return Fig. 19.6

3/3/08 Blood vessel function  Ultimately blood delivers O 2 & nutrients to tissues as well as removing wastes  How does this happen?  Any organ: ♦Blood vessels (in & out): arteries – smallest branch = capillary ♦The organ is infused with capillaries ♦Nutrient exchange occurs at this level  In the capillaries – only the endothelial layer is present  Substances in the capillaries move to the Interstitial Fluid → then into cells

3/3/08 O 2, Nutrient, and Waste Exchange  Waste products are released into the interstitial fluid  Waste products are then taken up by fenestrated capillaries because they are typically large molecules (recall differences between fenestrated & continuous capillaries) Fig. 19.4

3/3/08 O 2, Nutrient, and Waste Exchange  Exchange between blood and interstitial fluid 1.Simple (& Facilitated) Diffusion: ♦In response to a concentration gradient 2.Filtration ♦Force pushes out substances – based on pressure 3.Osmosis ♦Reabsorption of water

3/3/08 Diffusion  Ions and small organic molecules (glucose, amino acids, urea – move through pores in fenestrated capillaries or move via diffusion between endothelial cells of adjacent capillaries  Ions (Na+, K, etc.) diffuse across endothelial cells by passing through channels in cell membranes  Large water-soluble compounds can only work enter or leave blood stream via fenestrated capillaries  Lipids (FAs, steroids) and lipid-soluble compounds (esp. CO2, O2) cross capillary walls by diffusion through endothelial cell membranes  Plasma proteins can only diffuse through in sinusoids (such as those in the liver)

3/3/08 Filtration  Driving force = PRESSURE in capillary = Capillary Hydrostatic Pressure (CHP)  Water is forced across a capillary wall and small solutes travel with the water ♦Through endothelial cells or pores of fenestrated capillaries Fig

3/3/08 Reabsorption  Occurs as a result of osmosis ♦Diffusion of water across selectively permeable membrane Remember, water molecules move toward soln with higher solute concentration  Process by which dissolved solutes is moved  Osmotic pressure = amount of pressure that must be applied to prevent osmotic movement across a membrane (Blood Osmotic Pressure = BOP; IOP=?) ♦BCOP = blood colloid osmotic pressure = osmotic pressure of blood (also BOP)  Remember…hydrostatic pressure forces water OUT of solution, whereas osmotic pressure draws water INTO a solution (BHP vs. IOP; BOP vs. IFHP)

3/3/08  Pressures have to be balanced so that fluid in and out can be coordinated – refer to handout (review!!) Fig

3/3/08 Filtration & Reabsorption  If BHP > BOP in the blood vessel, fluid is pushed out  If BHP < BOP fluid enters in  IFHP & IOP – low & stable because there are fewer proteins in interstitial fluid  Net Filtration Pressure is the difference between the net hydrostatic pressure and the net osmotic pressure: ♦Net filtration = net hydrostatic – net colloid pressurepressure osmotic pressure  If positive fluid moves OUT of capillary  If negative fluid moves INTO capillary

3/3/08 Equilibrium  Analogy to filtration experiment ♦Charcoal = cells & proteins ♦CuSO 4 = nutrients & O 2  Cells & Proteins remain in blood vessel  H 2 O, hormones, other chemicals, nutrients, O2, glucose, ions = pushed out  Equilibrium between arterial & venus ends maintains proper pressure differences (Starling’s Law of Capillaries)  Excess fluid expelled into tissues causes an increase in interstitial fluid – if in excess, causes EDEMA ♦Excess fluid buildup, swollen ankles, etc Read in book and follow handout

3/3/08 Blood Pressure and Blood Vessels  Blood Pressure ♦Pressure within blood vessels ♦Influenced by cardiac output, but other factors are involved as well 1.Vasomotor tone ♦Muscle tone of smooth muscle ♦Resistance against blood ♦This is controlled by the medulla in the brain ♦VASOCONSTRICTION - ↑ sympathetic impulse ♦VASODILATION - ↓ sympathetic impulse ♦THESE CHANGES AFFECT BLOD PRESSURE

3/3/08 Blood Pressure and Blood Vessels  Blood Pressure 1.Vasomotor tone 2.Baroreceptors ♦Monitor the degree of stretch ♦Special receptor nerve cells in specific areas of the body ♦Baroreceptors adjust cardiac output & resistance 3.Chemoreceptors ♦Special nerve cells sensitive to chemical concentrations ♦These sense arterial levels of CO 2, O 2, H + (pH), ♦Can adjust constriction based on the concentration of these chemicals

3/3/08 Blood Pressure and Blood Vessels  Blood Pressure 4.Cerebral Cortex ♦Stress, anger, depression ♦All of these emotions affect the sympathetic division of the nervous system ♦The cerebral cortex alters blood pressure/flow by altering levels of vasoconstriction/vasodilation 5.Local Changes ♦Sphincters near capillaries 6.Chemicals ♦Drugs ♦Alter vasodilation & constriction

3/3/08 Blood Vessels Chapter 19 – Day 3

3/3/08 Hypertension  Abnormally high BP levels (>150/90) ♦Approximately 25% of the population suffers from hypertension  Cause & Effects ♦uncertain ♦Heart works harder – O 2 demand is high ♦Hypertension: accelerates artherosclerosis, increases clot formation, causes kidney damage  Treatment ♦To reduce heart workload ♦Diuretics - ↓ blood volume (increasing urine output) ♦Vasodilators – relax smooth muscle ♦β – blockers: affects sympathetic receptors (reduces cardiac output) ♦CA 2+ blockers: reduce cardiac output

3/3/08 Other Vessel Disorders  Varicose veins ♦Result of failure of valve function – ♦Treatments: ♦Hemorrhoids = ♦Treatment  Circulatory Shock ♦Hematogenic Shock ♦Cardiogenic Shock ♦Neurogenic Shock ♦Septic Shock

3/3/08 Blood distrubution & Vessel Disorders  Blood distribution  ___% in veins  Why?  What happens during hemorrhaging? Fig. 19.7

3/3/08 Other Vessel Disorders  Circulatory Shock  Blood flow restricted =  Problems with blood flow leads to certain symptoms collectively termed shock – usually when tissues are suddenly exposed to prolonged loss of blood (O 2 )  Symptoms/Signs ♦Hypotension = ♦Vasoconstriction = ♦Sympathetic stimulation = ♦Pulse becomes ♦Arrythmia in the form of ♦Cardiac output is ♦Venous return is Fig. 19.7

3/3/08 Circulatory Shock  Shock can be caused by different conditions  Hematogenic Shock  Cardiogenic Shock  Neurogenic Shock  Septic Shock Fig. 19.7

3/3/08 Equilibrium  Equilibrium between arterial & venus ends maintains proper pressure differences  Excess fluid expelled into tissues causes an increase in interstitial fluid – if in excess, causes EDEMA ♦Excess fluid buildup, swollen ankles, etc Read in book and follow handout  Different demands for gas and nutrient exchange  For proper delivery – the cardiovascular system depends on: 1. Cardiac Output 2. Peripheral Resistance 3. Blood Pressure

3/3/08 Equilibrium  Need constant control of these factors to maintain homeostasis = CARDIOVASCULAR REGULATION  Controlled by ♦Autoregulation Mechanisms Local factors change pattern of blood flow w/in capillary beds Response to chemical changes in interstitial fluids ♦Neural Mechanisms Respond to changes in arterial pressure or blood gas a specific site stimulates cardiovascular centers of ANS ♦Endocrine Mechanisms Releases hormones that enhance short-term adjustments and direct long-term changes in cardiovascular performance

3/3/08 Auto Regulation  Local changes ♦Sphincters near capillaries are adjusted ♦Depend on local VASODILATION & VASOCONSTRICTION chemicals (nitrous oxide) – know examples from text (p 547) Vasodilator: factor(s) that promote the dilation of precapillary sphincters Local vasodilators act at the tissue level & accelerate blood flow through the tissue of origin

3/3/08 Neural Mechanisms  Neural Mechanisms ♦Sympathetic division controls… Smooth muscle tone (vasomotor tone) Increased sympathetic impulses (  vasoconstriction) Decreased sympathetic impulses (  vasodilation) ♦Receptors Baroreceptors Chemoreceptors ♦Adjust vasoconstriction to alter cardiac output & blood pressure  CNS – emotional responses control the sympathetic division

3/3/08 Endocrine Mechanisms  Important hormones in control  ADH ♦Blood volume changes  Angiotensin II ♦Synthesized in response to renin in the kidneys ♦Responds to a fall in blood pressure ♦Triggers multiple responses  EPO ♦Erythropoetin raises blood pressure by producing more RBCs  Kidney plays a large role

3/3/08 Important Homeostasis Figures  Know the following: