Transcript Bio 122: Anatomy and Physiology II

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
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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
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Lymphatic System
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Fig. 20.1
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
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Lymphatic System
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Fig. 20.2
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 minivalves)
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
3/3/08♦ Contain protrusions on the vessel walls = lymph nodes
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)
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Lymphatic System
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Fig. 20.3
Lymphatic System
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Fig. 20.4
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)
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Lymphatic System
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Fig. 20.5
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
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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
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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
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Lymphatic System
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Fig. 20.7
Spleen
 Largest lymphoid organ
♦ 12 cm long (left side between 9th & 11th 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)
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Tonsils
Simplest lymphoid organ
Name based on location
♦ Palatine tonsils
♦ Lingual tonsils
♦ Pharyngeal tonsils
♦ Tubal tonsils
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Fig. 20.6
Thymus
The site of T-cell maturation
Most active in younger children – atrophies with age
Does not contain reticular fibers
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Thymus
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Fig. 20.8
Lymphatic System
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Fig. 20.9
Lymphatic System
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Fig. 20.6
Lymphatic System
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Fig. 20.10
Lymphatic System
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Fig. 20.10
Lymphatic System
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Fig. 20.11
Lymphatic System
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Fig. 20.12
Lymphatic System
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Fig. 20.13
Lymphatic System
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Fig. 20.14
Lymphatic System
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Fig. 20.5
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
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Blood Vessel Structure
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Fig. 19.1
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)
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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
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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. 19.2
Be able to work though these – know order and
characteristics
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Blood Vessel Hierarchy
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Fig. 19.2
Capillaries
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Fig. 19.5
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
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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
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Fig. 19.6
Blood vessel function
Ultimately blood delivers O2 & 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
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O2, 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)
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Fig. 19.4
O2, 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
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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)
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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
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Fig. 19.11
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)
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 Pressures have to be balanced so that fluid in and
out can be coordinated – refer to handout (review!!)
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Fig. 19.11
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
pressure
pressure
osmotic pressure
 If positive fluid moves OUT of capillary
 If negative fluid moves INTO capillary
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Equilibrium
 Analogy to filtration experiment
♦ Charcoal = cells & proteins
♦ CuSO4 = nutrients & O2
 Cells & Proteins remain in blood vessel
 H2O, 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
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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
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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 CO2, O2, H+ (pH),
♦ Can adjust constriction based on the concentration of these
chemicals
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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
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Blood Vessels
Chapter 19 – Day 3
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Hypertension
 Abnormally high BP levels (>150/90)
♦ Approximately 25% of the population suffers from
hypertension
 Cause & Effects
♦ uncertain
♦ Heart works harder – O2 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)
♦ CA2+ blockers: reduce cardiac output
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Other Vessel Disorders
 Varicose veins
♦ Result of failure of valve function –
♦ Treatments:
♦ Hemorrhoids =
♦ Treatment
 Circulatory Shock
♦ Hematogenic Shock
♦ Cardiogenic Shock
♦ Neurogenic Shock
♦ Septic Shock
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Blood distrubution & Vessel Disorders
 Blood distribution
 ___% in veins
 Why?
 What happens
during
hemorrhaging?
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Fig. 19.7
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 (O2)
 Symptoms/Signs
♦ Hypotension =
♦ Vasoconstriction =
♦ Sympathetic stimulation =
♦ Pulse becomes
♦ Arrythmia in the form of
♦ Cardiac output is
♦ Venous return is
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Fig. 19.7
Circulatory Shock
 Shock can be caused by different conditions
 Hematogenic Shock
 Cardiogenic Shock
 Neurogenic Shock
 Septic Shock
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Fig. 19.7
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
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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 levels @ 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
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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
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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
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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
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Important Homeostasis Figures
 Know the following:
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