Test 1 (Part 1) Flashcards
The Muscle of the Gut, Vasculature, and Respiratory Tract must be able to:
1) Contract and maintain that contraction for a long period of time (ENERGY EFFICIENT)
2) Contract periodically to mix contents of Organ
3) Maintain SHAPE of Organ
4) Continue to GENERATE ACTIVE TENSION even when STRETCHED
5) Use relatively LITTLE ATP!!!!
Where is Smooth Muscle Found?
1) Vasculature (Arteries in Particular)
2) GI Tract
3) Urogenital Tract
4) Respiratory Tract
5) Eye
Innervation of Skeletal Muscle
- Skeletal muscle is innervated by an ALPHA- MOTONEURON arising from the Spinal Cord
Innervation of Smooth Muscle
1) INTRINSIC INNERVATION:
- Gut, Trachea
- Neurons (Sensory and Motor)
- INDEPENDENT of CNS and PNS!!!!!!!
2) EXTRINSIC INNERVATION:
- the AUTONOMIC NERVOUS SYSTEM
- Allows CNS to Control Viscera
Neurotransmitters in Skeletal Muscle
- Skeletal Muscle is activated by ACETYLCHOLINE, the only Neurotransmitter released at the NMJ!!!!
Neurotransmitters in Smooth Muscle
1) ACETYLCHOLINE:
- Excites Smooth Muscle (Gut)
- May INHIBIT other (Cause Relaxation)
2) NOREPINEPHRINE or EPINEPHRINE:
- Cause Contration of Vascular Smooth Muscle
- INHIBITS Gut Smooth Muscle
3) NITRIC OXIDE (NO)
- MAJOR INHIBITORY Influence on Smooth Muscle
- Don’t know any Smooth Muscle where a positive influence has been shown
- Acts vis cGMP Mechanism!!!!!
Major Difference between Skeletal Muscle and Smooth Muscle
- Smooth Muscle can be DIRECTLY INHIBITED (Caused to RELAX)!!!!!!!!
Neuromuscular Contact in Skeletal Muscle
Motor End-Plate:
- Where we find the each Receptors
Presynaptic Terminal of Alpha Motor:
- Part that releases the Neurotransmitter!!!
Neuromuscular Contact in Smooth Muscle
VARICOSITIES: Swellings in Axons. Neurotransmitter is released from the VARICOSITY!!!!!!!!!!!!
** Varicosities are like the Pre-Synaptic Terminals!!!!
Neurotransmitter Receptors of Skeletal Muscle
- Skeletal Muscle only has ACh Receptors!!!!!
Neurotransmitter Receptors of Smooth Muscle
1) MUSCARINIC Cholinergic
2) ADRENERGIC (Alpha and Beta)
**It is currently believed that NO does not require a membrane-bound receptor because it is extremely lipid soluble. It is believed that it diffuses through the cell membrane and has its action of the cGMP System
Compare and Contrast Activation/ Inhibition of Smooth Muscle with that in Skeletal Muscle
SKELETAL MUSCLE:
1) Alpha- MotorNeuron
2) Acetylcholine
3) Exclusively Positive
4) Specialized NMJ
5) ACh Receptors located at the Motor End-Plate
6) Only ACTIVATED vis NMJ!!!
SMOOTH MUSCLE:
1) Multiple Sources- Intrinsic, ANS, Sensory
2) ACh, Epinephrine/ Norepinephrine, Nitric Oxide, Others
3) May be Positive or Negative
4) VARICOSITIES, no Motor- End Plate
5) Multiple Receptor types located over Cell Membrane
6) May be activated by Blood-Borne Substances!!!!!!!
Hormonal Control of Smooth Muscle Contraction
- Hormone Receptors are on the side of the Smooth Muscle cell that faces the Blood!!!!!
- The Receptors for the Neurotransmitters are on the side of the cell closest to the Neurons!!!!!!
***Can have Hormones and Paracrine agents acting on the Smooth Muscle Cells as well
Examples of Hormones that can Elicit Smooth Muscle Contraction:!!!!!!!!!!!!!!!!!!
1) EPINEPHRINE
2) CHOLECYSTOKININ
Activation of Paracrine Agents in Control of Smooth Muscle Contraction
- Endothelial Cells Secrete EDRF (Endothelium-derived Relaxing Factor) now know to be NITRIC OXIDE!!!!!!
**NO is produced by the Endothelial Cells and diffuses over to the Smooth Muscle cells and causes RELAXATION!
**Paracrine Agents can also ACTIVATE Smooth Muscle
Other Forms of Activation in Control of Smooth Muscle Contraction
- Some smooth muscle cells can be activated by STRETCH!!!!!!!
- Some of the Smooth Muscle in the VASCULATURE can be activated this way!!!!!
Compare and Contrast Activation/ Inhibition of Smooth Muscle with that in Skeletal Muscle
SKELETAL MUSCLE:
1) Innervation: Alpha- Motorneuron
2) Neurotransmitters: Acetylcholine
3) Action of NT: Exclusively EXCITATORY
4) Transmission Specializations: NMJ (Presynaptic terminal and specialized Motor End Plate)
5) NT Receptors: NICOTONIC CHOLINERGIC
6) Other forms of Activation: None
SMOOTH MUSCLE:
1) Innervation: Multiple- Including INTRINSIC and ANS
2) Neurotransmitters: Many- ACh, Norepo, NO, Others
3) Action of NT: May be Positive or Negative
4) Transmission Specializations: VARICOSITIES (presynaptic Swelling) with No end ORGAN SPECIALIZATIONS
5) NT Receptors: MUSCARINIC Cholinergic; Adrenergic, Others
6) Other forms of Activation: Blood-borne (Hormones). Paracrine (Ex: Nitric Oxide), and Intrinsic Mechanisms
Smooth Muscle Contraction Relaxation
- The Pi can be REMOVED rom the Myosin Light Chain at any point in the Cycle. The Cycle will continue bet VERY SLOWLY!!!!!! A new Cycle cannot be started!
- ***THIS IS HOW SM REDUCES Energy Consumption!!!
**Two ATPs are consumed in a cross bridge cycle for Smooth Muscle. With every cycle of a cross bridge of Smooth Muscle, it comes close to a 2nd ATP being consumed.
Smooth Muscle Contraction: the LATCH MECHANISM
1) Dephosphorylation of the Light Chain
2) Cycle preceding very SLOWLY
3) Any attached CROSSBRIDGES are still GENERATING TENSION!!!!
4) Way of INCREASING TENSION and DECREASING ATP Usage!!!!!
**Decreases ATP use because ATP cant get to the Myosin Head (Incredibly Slow) and when the Myosin head is Dephosphorylated, it will stay BOUND to the ACTIN (Generates TENSION) until the Myosin Head attaches to ATP again!!!
Energy Utilization of Skeletal Muscle vs Smooth Muscle
SKELETAL MUSCLE:
1) ATP Binding to Actomyosin Complex (To Separate): 1 ATP/ Cycle
2) Ion ATPases: Na/K; Ca2+ (SR); Other Membrane Bound
3) Addition During Cycle: None
4) ATP Savings: None
SMOOTH MUSCLE:
1) ATP Binding to Actomyosin Complex (To Separate): 1 ATP/Cycle
2) Ion ATPases: Na/K; Ca2+ (SR and Membrane); Others
3) Addition During Cycle: 1 ATP/ Cycle by MLCK
4) ATP Savings: Latch Mechanism and Slow Myosin ATPase
- These two mechanisms more than make up for the additional ATP used to Phosphorylate the Light Chain in each cycle of the Smooth Muscle Contraction
Length-Tension Relationship in Skeletal Muscle
ACTIVE TENSION:
- What the Cross Bridges do
PASSIVE TENSION:
- Comes from stretching the membranes (think of a rubber band)
Length-Tension Relationship in Smooth Muscle
- So with EVERY STRETCH of the Muscle Cell, Passive Tension INCREASES a LITTLE, but as the Actin and Myosin REARRANGE, the Passive Tension DECREASES AGAIN!!!!!
***With time (even though the muscle is at the same length) the PASSIVE TENSION still goes back down to zero after the INITIAL STRETCH!!
***Passive Tension dissipates at any given length of the Smooth Muscle Cell. The reason it dissipates like this is because the Thick and Thin Filaments of the Smooth Muscle cell are NOT ARRANGED like in the Sarcomere!!!
Length-Tension Relationships in Smooth Muscle Cont.
- REMEMBER that the Thick and Thin Filaments are not arranged in such a neat and organized manner like in the Skeletal Muscle
- Instead the Thick and Thin Filaments are MUCH MORE “RANDOMLY” Arranged
- As Smooth Muscle is Stretched, the Myosin Heads, once free from the Actin, will INTERACT with a DIFFERENT THIN FILAMENT!!!!!!!!
* **Since the Thin Filaments are anchored and the Thick filaments are free to move around, the Myosin heads on the Thick Filaments can attach to different Thin Filaments. THIS EXPLAINS WHY THE PASSIVE TENSION DECREASES AFTER THE MYOSIN AND ACTIN ARE RELEASED FROM EACH OTHER!!!!!!
**Thin Filaments are Anchored to the Sarcoplasmic Reticulum of the Smooth Muscle Cell
**Thick Filaments are free to move around
Myosin interacting with different Actin Heads does two things:
1) It REDUCES the Passive Tension by Reducing the STRAIN on the points of attachment to the Membrane
2) It allows the Smooth Muscle cell to continue to GENERATE ACTIVE TENSION over a wide range of length. There is alway an ACTIN available for the Myosin Head
- The Active Tension in Smooth Muscle is maintained over a longer MUSCLE LENGTH compared to Smooth Muscle!!!!!!
General Purpose of the Cardiovascular System
- The perfusion of capillary beds permeating all Organs with fresh blood over a narrow range of HYDROSTATIC Pressures
- Local functional demands determine the structural nature of the wall surrounding the endothelial tubes
- Divided into Systemic/ Peripheral Circulation and Pulmonary Circulation
Vascular Development
Blood Vessels for in two ways:
1) VASCULOGENESIS: blood vessels arise from Coalescence of HEMANGIOBLASTS, which arise from Blood Islands
- How we make most of the Blood Vessels in the Body
2) ANGIONGENESIS: Vessel formation via branches arising from existing vessels
- Major Vessels from VASCULOGENESIS
- An understanding of these processes is relevant to developing therapeutic strategies to produce revascularization of Ischemic Tissues or Inhibit Angiogenesis in Cancer and other disorders
Early Vasculogenesis
- Begins is the XE SPLANCHNIC MESODERM surrounding the YOLK SAC (Week 3)
- Formation then moves to LATERAL PLATE MESODERM
- Yolk Sac is first see for formation of BLOOD ISLANDS
- ISLANDS arise from MESODERM Cells that INDUCED to for HEMANGIOBLASTS, a common precursor for vessel and blood cell formation
Blood Islands
- Blood Islands contain cells (Hemangioblasts) which are capable of DIFFERENTIATING into 2 Populations of Cells:
1) ANGIONBLASTS (Vascular precursors)- form the ENDOTHELIAL CELLS aka the Tubing
2) HEMATOPOIETIC STEM CELLS- made from the remaining Hemangioblasts
Molecular Regulation of Development
- FGF2 binds to MESENCHYMAL CELLS (Mitogen)—> Hemangioblasts
- Vascular Endothelial Growth Factor (VEGF) elicits regional change in Blood Islands (2 Receptors)
a) Once Receptor makes tubing and the other makes the Hemangionblasts which make the Stem Cells - Signal to express VEGF may involve HOXB5, which up regulates the VEGF receptor FLK1!!!!!!!
- CENTRAL CELLS become HEMATOPOIETIC STEM CELLS
- PERIPHERAL CELLS differentiate into Angioblasts —> Endothelium of Blood Vessels!!!!!!
Angiogenesis
- Once the Vascular Bed is established, VEGF their regulates formation of Additional Vasculature via Angiogenesis
1) Angiopoietin 1 (ANG1(: Signals to other Pericytes to come into this newly forming vessels and form new SMOOTH MUSCLE CELLS
2) Angiopoietin 2 (ANG2): Causes the loss of Endothelium cells and then allow the Branch to BUD OFF!!!!!!
Blood Circulation
- Blood Circulation is established and Primary Plexi are remodeled into hierarchical network of Arterioles and Arteries (red), Capillaries (Grey), and Venues and Veins (Blue)
1) Aorta
2) Arteries
3) Arterioles
4) Capillaries
5) Venules
6) Veins
7) Vena Cava
Maturation and Remodeling of Vasculature
- In addition to VEGF, regulated by Platelet-derived Growth Factor (PDGF) and TGF-Beta
- Specification of occurs soon after ANGIOBLAST Induction
- SHH from Notochord INDUCES Expression go VEGF (Mesoderm)
- VEGF INDUCES Notch Pathway which specifies ARTERIAL DEVELOPMENT through expression of EphrinB2 (Ligand)!!!!!!
- VEIN SPECIFIC Genes controlling Venous Development EphrinB4!!!!!!!!
***MASTER Gene for Lymphatic Vessel Differentiation is PROX1!!!!!!!!!!
Definitive Hematopoietic Stem Cells- AGM (Aorta-Gonad- Mesonephros Region)
- In the fetus are derived from Mesoderm surrounding the AORTA in a site near the Developing Mesonephric KIDNEY
- Called the AORT-GONAD-MESONEPHROS REGION (AGM)
- These cells eventually colonize the LIVER, which becomes the MAJOR HEMATOPOIETIC ORGAN of the Embryo (2-7 Months)
- HEMATOPOIESIS moves from LIVER to BONE MARROW (Month 7)
Hemangioma
- ABNORMALLY DENSE collection of Capillary Vessels
- Common TUMORS of Infancy (10%)
- Focal or diffuse, more secondary complications
**Laser or surgical treatments available!!!!
Port Wine Stain
***NAEVUS FLAMMEUS
- Superficial and Deep Dilated Capillaries in the Skin!!!!
***Some laser treatments have been Successful
Tumor Angiogenesis
- There are today HUNDREDS of molecules know to Mediate or Regulate ANGIOGENESIS
- Progressive Tumro Growth is DEPENDENT on Angiogenesis
Tumor Angiogenesis
- When some of the Tumor Cells switch to an Angiogenic Phenotype, the local equilibrium between Positive and Negative ANGIOGENIC Regulators Changes
- Tumor Growth begins, OFTEN RAPIDLY
- Many molecules have been considered as POTENTIAL THERAPEUTIC targets or tools to inhibit Pathological Angiogenesis, in particular tumors!!!!!
***Tumors switch from a positive/ negative balance of VEGF, and then this causes for the tumors to produce NEW BLOOD VESSELS (Angiogenesis)
The Heart
- The Heart is a folded Endothelial tube whose wall is thickened to act as a REGULATED PUMP
3 Cardiac Layers:
1) ENDOCARDIUM: Consisting of an Endothelial lining and sub endothelial Connective Tissue
2) MYOCARDIUM: a functional SYNCYTIUM of Striated Cardiac Muscle fibers forming three Major Types of Cardiac Muscle:
1) Atrial Muscle
2) Ventricular Muscle
3) Specialized Excitatory and Conductive Muscle Fibers
3) EPICARDIUM, the Visceral layer of the PERICARDIUM, is a LOW-FRICTION SURFACE lined by a MESOTHELIUM in contact with the PARIETAL PERICARDIAL SPACE!!!
***LARGE Vessels in the Heart have their own Blood Supply and Nerves!!!!!
Cardio (myo) cytes
1) CONTRACTILE: Contract to Move Blood
2) MYOENDOCRINE: Produce ATRIAL NATRIURETIC FACTOR that stimulates for DIURESIS and EXCRETION of SODIUM in Urine by Increasing the GLOMERULAR Filtration rate, Reduces Blood Volume!!!!!!!!!!
3) NODAL: Specialized to Regulate CONTRACTION of the Heart (Sinoatrial node and Atrioventricular Node)
Arteries
- Arteries conduct blood from the heart to the Capillaries
- They store some of the pumped blood during each CARDIAC SYSTOLE to ensure continued flow through the capillaries during CARDIAC DIASTOLE
Arteries are organized in three Major TUNICS or LAYERS:
1) TUNICA INTIMA
2) TUNICA MEDIA
3) TUNICA EXTERNA
Blood Bessel Tunics
1) TUNICA EXTERNA/ ADVENTITIA
- Outermost layer of the Blood Vessel Wall
- Composed of a LOOSE CT that contains ELASTIC and COLLAGEN FIBERS
- Helps ANCHOR the vessel to other tissues
- An EXTERNAL ELASTIC LAMINA can be seen separating the Tunica Media from the ADVENTITIA
- VASA VASORUM
2) TUNICA MEDIA
- Middel Layer of the Vessel Wall
- Composed of CIRCULARLY ARRANGED layers of Smooth Muscle Cells
- VASOCONTRICTION (Narrowing of the Blood Vessel Lumen)
- VASODILATION (Widening of the Blood Vessel Lumen)
3) TUNICA INTIMA/ INTERNA
- Innermost Lyare of Blood Vessel Wall
- Composed of an Endothelium and a Subendothelial layer
- External layer of ELASTIC FIBERS, the INTERNAL ELASTIC LAMINA
Arteries
From the Heart to the Capillaries, Arteries can be classified into three major Groups:
1) LARGE Elastic Arteries
2) MEDIUM-SIZED Muscular Arteries
3) SMALL Arteries and Arterioles
Large Elastic (Conducting) Arteries
Two Major Characteristics:
1) RECEIVE Blood from the HEART under HIGH PRESSURE
2) Keep Blood circulating continuously while the heart is PUMPING INTERMITTENTLY
- DISTEND (Swell) during SYSTOLE and RECOIL during DIASTOLE
- Tunica Intima consists of the Endothelium and the Subendothelial Connective Tissue
- LARGE AMOUNTS of Fenestrated ELASTIC SHEATHS are found in the TUNICA MEDIA, with bundles of Smooth Muscle cells PERMEATING the Narrow Gaps between the ELASTIC LAMELLAE!!!
Large Elastic (Conducting) Arteries
- BLOOD VESSELS (Vasa Vasorum), NERVES (Nervi Vasorum), and LYMPHATICS can be recognized in the TUNICA ADVENTITIA of Large Elastic Arteries
- AORTA and its largest branches (the Brachiocephalic, Common Carotid, Subclavian, and Common Iliac Arteries)
Musculature or Distributing Arteries
- Allow a Selective Distribution of Blood to Different organs in response to FUNCTIONAL NEEDS. Diameter about 3 mm or Greater
- Tunica Intima consists of Three Layers:
1) The Endothelium
2) The Subendothelium
3) The Internal Elastic Lamina (IEL) - In the larger vessels of this group, a fenestrated EXTERNAL ELASTIC LAMINA can be seen at the junction of the Tunica Media and the Adventitia.
Muscular or Distributing Arteries Cont.
- The TUNICA MEDIA shows a SIGNIFICANT REDUCTION in Elastic Components and an INCREASE in Smooth Muscle Fibers
- Examples of Medium sized Arteries include the Radial, Tibial, Popliteal, Axillary, Splenic, Mesenteric, and Intercostal Arteries
Arterioles or Resistance Vessels
- Final Branches of the Arterial System
- Regulate the DISTRIBUTION of Blood to different capillary beds by Vasoconstriction/ Vasodilation
- Structural adaption is walls with Circularly arranged Smooth Muscle
- PARTIAL CONTRACTION (known as Tone) of the Vascular Smooth Muscle exists in ARTERIOLES!!!
**Arterioles are regarded as RESISTANCE VESSELS and are the MAJOR Determinants of SYSTEMIC BLOOD PRESSURE
***Lined by SQUAMOUS ENDOTHELIAL CELLS with SMOOTH MUSCLE CELLS in the Wall
Microcirculation
- The Microvascular bed, the sire of the Microcirculation, is composed of the TERMINAL ARTERIOLE (An Metarteriole), the Capillary Bed, and the Postcapillary Venues
- The capillary bed consists of slightly large capillaries (Called Preferential or THOROUGHFARE CHANNELS), where Blood Flow is CONTINUOUS, and the Small Capillaries, called the TRUE CAPILLARIES, where Blood Flow is INTERMITTENT!!!!!!
Capillaries
***The FUNCTION UNITS of the CARDIOVASCULAR SYSTEM!!!!!!
- Small Blood Vessels, CONNECT Arterioles to Venues
- The diameter range of a capillary is about 5 to 10 micrometers, large enough to accommodate ONE RED BLOOD CELL, and thin enough (0.5 micrometers) for GAS DIFFUSION
- Contain only the TUNICA INTIMA, but this layer consists of a Basement Membrane and Endothelium ONLY!!!!!
- CAPILLARY BED: group of capillaries (10-100) FUNCTION TOGETHER!!!
3 Kinds of Capillaries
1) CONTINUOUS Capillaries: lined by Endothelium with TIGHT JUNCTIONS and a Basal Lamina with PERICYTES (Contractile Cells)
2) FENESTRATED Capillaries: have PORES or Fenestrae (GI and Kidney)
3) SINUSOIDS, or Discontinuous Capillaries, are characterized by an Incomplete Endothelial Lining and Basal Lamina, with Gaps or Holes between and WITHIN ENDOTHELIAL CELLS (Liver and Spleen)
* **Designed to facilitate something going forma he Capillary to the tissue or picking something from the tissue to the Capillary
Veins are Capacitance (Reservoir) Vessels
- The Venous system starts at the end of the Capillary bed with a Postcapilary Venule that structurally resembles Continuous Capillaries but with a WIDER LUMEN
- POSTCAPILLARY VENUES are the preferred site of Migration of Blood Cells into Tissues (DIAPEDESIS!!!!!)
Venous System
- Postcapillar venues converge to form muscular Venues, which converge and lead to a series of Veins of Progressively Larger diameter
- Veins have a relatively thin wall in comparison with Arteries of the same size
- The high CAPACITANCE of veins is attributable to the distensibility of their wall (Compliance Vessels) and, therefore, the content of Blood is LARGE relative to the VOLUME of the Veins
Venous System Cont.
- Similar to Arteries, Veins consist of TUNICS
- However, the DISTINCTION of TM from a TA is OFTEN NOT CLEAR
- A distinct INTERNAL ELASTIC LAMIN is NOT SEEN!!!!!!
- the Muscular Tunica Media is THINNER than in Arteries and Smooth Muscle cells have an IRREGULAR ORIENTATION Approximately Circular
- a typical characteristic of veins is the presence of VALVES to PREVENT REFLUX of BLOOD!!!
Large Veins
- A typical characteristic of veins is the presence of VALVES to PREVENT REFLUX OF BLOOD
- You get VARICOSE VEINS when the VALVES IN YOUR VEINS DO NOT CLOSE PROPERLY
- HEMORRHOIDS are dilations of the Internal or External Rectal Venous Plexuses
Vasculities
- Vasculitis is an INFLAMMATION of you Blood Vessels
- Causes changes in the walls of Blood Vessels, including THICKENING, WEAKENING, NARROWING, and SCARRING!!!!
- Changes RESTRICT Blood Flow, resulting in ORGAN and TISSUE DAMAGE
Lymphatic Vessels
- Conduct Immune Cells and LYMPH to Lymph Nodes
- Remove EXCESS FLUID accumulated in Interstitial Spaces
- Transport CHYLOMICRONS, LIPID-containing Particles, through LACTEAL Lymphatic Vessels inside the INTERSTINAL VILLI
***Lympahtic Vessels have “FLAPLIKE” Minivalves that allow for the fluid from the Capillaries to flow into the Lymphatic Vessels
Lymphatic Capillaries
- Begin as DILATED TUBES with closed ends in Proximity to Blood Capillaries and Collect Tissue Fluid (LYMPH)
- Wall is an Endothelium Lacking a complete Basal Lamina
- Lymphatic Capillaries can be found in most tissues!!!
- EXCEPTIONS:
1) Cartilage
2) Bone
3) Epithelia
4) CNS
5) Placenta
Lymphatic Drainage
By INTRINSIC CONTRACTION:
- When vessels become expanded by Lymph, the Smooth Muscle of the wall Contracts. Each segment of the Lymphatic vessel between successive valves, called LYMPHANGIONS, behave like an AUTOMATIC PUMP
By EXTRINSIC CONTRACTION:
- External factors such as Contraction of the surrounding muscles during Exercise, Arterial Pulsations, and Compression of tissues by Force OUTSIDE the body, which COMPRESS the Lymph Vessels and cause PUMPING!!!
***When Lymph Drainage is Impaired, excess FLUID accumulated in the Tissue Spaces (EDEMA!!!!!)
Edema
1) LYMPHEDEMA:
- Caused by a DEFECT in the Transport of Lymph because of abnormal vessel development or damaged Lymphatic Vessels
2) FILARIASIS (Elephantiasis):
- A PARASITIC INFECTION of Lymphatic Vessels by WUCHERERIA BANCROFTI or BRUGIA malayo worms, transmitted by Mosquito Bites. This condition causes DAMAGE to the LYMPHATIC VESSELS with CHRONIC LYMPHEDEMA of Legs and Genitals!!!!!
* **Filaris Occurs in TROPICAL COUNTRIES!!!!!
3) CHYLOUS ASCITES and CHYLOTHORAX:
- Caused by the accumulation of HIGH FAT contains Fluid, or Chyle, in the Abdomen or Thorax as a result of TRAUMA, OBSTRUCTION, or ABNORMAL Development of Lymphatic Vessels
Endothelial Cell- Mediated Regulation of Blood Flow
- Endothelial cells produce Vasoactive substances that can induce Contraction and Relaxation of the Smooth Muscle Vascular Wall
- NITRIC OXIDE (NO) and PROSTACYCLIN: Relaxation of Smooth Muscle
- Prostacyclin also PREVENTS Platelet Adhesion and Clumping leading to BLOOD CLOTTING
- ENDOTHELIN 1 is a very Potent VASOCONSTRICTOR Peptide
- The permeability of Capillary Endothelial cells is tissue specific. Also TOPOGRAPHIC PERMEABILITY: the Endothelial cells at the Venous end are MORE PERMEABLE than those at the ARTERIAL END.
- Postcapillaru Venules HAVE THE GREATEST PERMEABILITY to LEUKOCYTES - Endothelial cells also pay a role in the process of cell homie and Inflammation
Artherosclerosis
- The THICKENING and HARDENING of the walls of Arteries caused by ATHEROSCLEROTIC PLAQUES of Lipids, Cells, and Connective Tissue deposited in the TUNICA INTIMA
- Artherosclerosis is frequently seen in arteries sustaining HIGH BLOOD PRESSURE, it does not affect veins and is the cause of MYOCARDIAL INFACTION, Stroke, and Ischemic Gangrene
- Artherosclerosis is now recognized as a CHRONIC INFLAMMATORY DISEASE, characterized by features of Inflammation at all stages of its Development
- Artherosclerosis correlates with the Serum levels of CHOLESTEROL or Low-Desity Lipoprotein (LDL). A genetic defect in Lipoprotein metabolism (Familial Hypercholesterolemia) is associated with Artherosclerosis and Myocardial Infarction before Patients reach 20 years of age!!!