Introduction to Arteries, Veins and Lymphatics

7/28/2019 Introduction to Arteries, Veins and Lymphatics

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} The student should be able to describe: Circulation (pulmonary/systemic, arteries, veins, capillaries, lymphatics,

pressure differences)

Arteries (definition, branches, elastic, muscular, arterioles, anastomoses,end arteries, major arteries of body, avascular structures)

Veins (definition, tributaries, portal system, venous sinuses, venousplexus, anastomoses, valves, venae comitantes, superficial/deep veins,

flow, venous pathologies)

Lymphatics (function, vessels & organs, afferent & efferent vessels,superficial & deep lymph vessels, flow, regions of drainage of thoracic

duct & right lymphatic duct)

Neurovascular pathways (neurovascular bundles, pulses, arterialpuncture, venepuncture, intravenous cannulation, nerve blocks)


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} Cardiovascular system Functions:

- Transport System of Body

- Supplies Nutrients to all Tissues

- Carry Metabolites to Excretory Organs

Features :- Closed System of Tubes- Lined from Inside byENDOTHELIUM

Components :- Heart

- Arteries

- Veins

- Capillaries

} Lymphatic vascular system- Drainage System for Extracellular Fluid

( Lymph )


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} PULMONARY CIRCULATION : Blood flowsfrom Right Ventricle through Lungs to Left

Atrium} SYSTEMIC CIRCULATION : Blood flows

from Left Ventricle through various parts of

body to the Right Atrium

PORTAL CIRCULATION: Part of SystemicCharacteristics:1. Blood Passes Through 2 Sets of

Capillaries Before Draining into a

Systemic Vein

2. The Vein Draining the First Capillary

Network is known as PORTAL VEIN

which Branches like an Artery to form

the Second Set of Capillaries or Sinusoids

- Example : Hepatic Portal Circulations


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} FEATURES:1. Carry Oxygenated Blood Away From

Heart (ExceptPulmonary Artery )2. Show Branching Like a TREE

} FUNCTION:Distribute Blood from Heart to CapillaryBeds through out Body

} TYPES:- Three Main Types of Vessel

- Based on theiroverall size, relativeamounts of elastic tissue or muscle in thetunica media, the thickness of the wallrelative to the lumen, and function.

1. Elastic / Conducting / Large Vessels

2. Muscular/ Distributing / MediumVessels

3.Small arteries and Arterioles /Resistance vessels


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} ELASTIC ARTERIES :- Largest of the arteries (Diameter > 1 cm)

- Receive blood directly from heart

- Contain substantial amount of elastic

fibres in tunica media

- Elastic Fibres : Allows Expansion & Recoil

During Normal Cardiac Cycle & Helps MaintainsConstant Flow

of Blood During Diastole .

v Thus maintain BP between contractions andensure continous blood flow

- ExampleAorta

Brachiocephalic Artery

Left Subclavian Artery

Left Common Carotid Artery

Pulmonary Trunk and arteries


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} MUSCULAR ARTERY- is also called medium artery- Distribute Blood to Various Organs

- Account for Most of the Named Arteries

Studied in the Anatomy Laboratory

- Range of Internal Diameter From 1 - 0.3 cm- Regulate s the flow of blood to parts in term

of amount and distribution (as their walls

consist chiefly of circularly disposed smooth

muscle fibers- Example

Radial , Femoral , Coronary , Cerebral


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} SMALL ARTERIES AND ARTERIOLES- Have Relative Narrow Lumen And ThickMuscular Coat

- Usually not named

} ARTERIOLES- Terminal Branches of the Arterial Tree

- Supply the Capillary Bed

- Regulate Blood Pressure of Vessel Wall

through Vasoconstriction & Vasodilatation

- Regulate Degree Of Filling Of The Capillary

Beds- Diameter < 0.1 mm


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} ANASTOMOSIS- Communication Between Neighboring Vessels allows

alternative pathways in case of block due to obstructed bycompression, position of a joint, pathology, or surgical ligation

- Circulation Through them is Called Collateral Circulation

- Collateral Circulation Functionality Depend on Place and

Time (Sudden or Gradual)

- TYPES OF ANASTOMOSIS1. End To- End Anastomosis

2. Convergence

3. Transversal

} END ARTERIES: Two Types- True terminal Arteries which do not Anastomose with their

Neighbours e.g., Central Artery of Retina

- Functional Terminal Arteries (Arteries with Ineffectual

Anastomoses) Supply Segments of the Brain, Liver, Kidneys,

Spleen, and Intestines; They may also Exist in the Heart


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} Pulse can be felt in any artery lyingclose to the body surface bycompressing the artery against firm

tissue.

Because it is so accessible, the pointwhere the radial artery surfaces at the

wrist is routinely used to take a pulse(the radial pulse).

} Several other clinically importantarterial pulse points shown here.

Because these same points arecompressed to stop blood flow into

distal tissues during hemorage, they

are also called pressure points.


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} FEATURES :1. Carry Deoxygenated Blood Towards Heart except

Pulmonary Veins2. Have Tributaries like a RIVER

3. Dark Blue Appearance

4. No Pulsations / Do not Squirt or Spurt Blood

when cut

5. More Abundant than Arteries6. Blood Volume : 80 % Veins ; 20 % Arteries

7. Compressible Thinner Walls (low pressure anallow expansion)

8.Larger Diameter Than Corresponding Arteries

9.More Variable than Arteries and VenousAnastamosis is More Often

} TYPES:1. Venules

2. Medium Veins

3. Large Veins


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} VENULES :- Smallest Veins

- Drain Capillary Beds

- Magnification required to Observe

- Join Similar Vessels to Form Small Veins

- Small Veins

Unnamed

Tributaries of Larger Veins that Unite to

form Venous Plexuses e.g., Dorsal Venous Arch ofthe Foot

} MEDIUM VEINS :- Drain Venous Plexuses

- Accompany Medium Arteries

- Have Flap Valves To Ensure UnidirectionalFlow e.g., In Lower Limbs

- Examples : Named Superficial Veins Cephalic & Basilic Veins of Upper Limbs

Great & Small Saphenous Veins of Lower Limb

Name Of Artery They Accompany


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} LARGE VEINS :- Characterized by Wide Bundles of

Longitudinal Smooth Muscle and Well DevelopedTunica Adventitia

- Example: Superior Vena Cava

} VENAE COMITANTES (Accompanying Veins) :- Also Called Satellite Veins

- Accompany Deep Arteries and Tend to be

Double Or Multiple

- Enclosed in a Vascular Sheath with the Artery

accompany , important for Arteriovenous Pump- Surround Arteries in an Irregular Branching

Network

- Serves as a Countercurrent Heat Exchanger


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} Factors important for venousreturn are:

} Competent Valves} Arteriovenous Pump} Thoracic Negative Pressure} Musculofacial Pump} Gravity

} Varicose veins:} Weak Venous Walls Due To Elasticity Loss} Dilate And Swollen} Due to :

Incompitent Valves Degenerated Deep Fascia


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} Simple Endothelial Tubes Connecting The Arteries And Veins} Site of Nutrient and Gas Exchange with tissues} Arranged as network in its bed} Has 3 types: Continuous, Fenestrated And Sinusoids

Sinusoids resemble capillaries in that they are thin-walled blood vessels, buthas irregular cross diameter and are wider found in the bone marrow, the spleen, the liver, and some endocrine glands

} Sometime blood does not go to capillaries but throughArterovenous Anastamoses (AV shunt) Is a direct connections between the small arterioles and venules proximal to

the capillary beds they supply and drain Sites. Skin and the tips of the fingers and toes


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} Their Walls are between theperiosteal and the meningeal layers

of the dura

and Lined with Endothelium

}They Differ from Other BloodVessels in that They Lack a Full Set

of Vessel Layers (e.g. Tunica Media)

Characteristic of Arteries And Veins.

It Also Lacks Valves As Seen In

Veins.

} They receive blood and CSF anddrain into veins. They are collapsed

and response to change in pressure.


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} Always Use Distal then Proximal Veins} Always Remember Veins are Variable} Used for Introducing Medication or

Taking Samples

} Common Veins Used: Median Cubital Vein Cephalic Vein Basilic Vein Great Saphenous Vein Femoral Vein External Jugular Vein


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Observe limb superficial veins tend to

escape pressure sites, and ultimately

drain to deep veins. And deep veins in

trunk are in right side to veins


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A. Anastomosis Between

the Branches of the

Superior Mesenteric

Artery

B. A Capillary Network and

an Arteriovenous

Anastomosis.

C. Anatomic End Artery

And Functional EndArtery.

D. A Portal System

E. Structure of the Bicuspid

Valve In A Vein


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} Essential for life} Constitutes a sort of overflow system} Provides for the drainage of

- Excess of tissue fluid (3L daily)- Plasma proteins- Cellular debris- Whole cells i.e, lymphocytes

- Infection ( Bacteria )} Maintain fluid balance in the internal

environment} Provides immunity} Absorption of fat from GIT ( lacteals )} LYMPHATIC PUMP

Breathing Movements ( Inspiratory Phase ) Skeletal Muscle Contractions Arterial Pulsations Postural Changes Passive Compression ( = Massage ) of the body soft

tissues


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} Lymphatic Plexuses: Network ofBlind - Ended Capillaries Lacking

Basement Membrane and HavingAttenuated Endothelium Act as One-

way Valve

} Lymphatic Vessels ( = Lymphatics ) : A Nearly Body Wide Network ofThin-walled Vessels with Abundant

Lymphatic Valves

Has A Beaded Appearance Due toValves

Occurs Every Where Except inTeeth, Bone, Bone Marrow,

Cartilage and the Entire CNS


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} Lymph (L. Lympha, Clear Water):Similar To Blood. It is Watery SlightlyYellow and Clear

} Lymph Nodes : Filtration SmallMasses, present in aggregates

} Lymphocytes} Lymphoid Tissues Or Organs: Sites

that Produce Lymphocytes and

filtration e.g. Lymph nodes, Tonsils,

Bone Marrow stem cells, Lymphoid

Nodules , Thymus and Spleen.


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Two systems: Superficial lymphatic

vessels, more numerous than veins inthe subcutaneous tissue andanastomosing freely, converge towardand follow the venous drainage the

drain to deep vessels which receivesfrom deep organs and form plexus andusually follow arteries

} Lymphatic capillaries (plexus)Afferent lymphatic vessel

Lymphnode Efferent lymphatic vesselLymphatic Trunklymphatic ducts(right lymphatic duct or the thoracicduct)Veins in neck


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} Trunks: Jugular Subclavian Bronchomediastinal Intestinal Lumbar

} Ducts: Right Lymphatic Duct

Into right subclavian vein/rightinternal jugular junction

Drains Right side of Thorax And HAnd N and right UL

Thoracic Duct: Into left subclavian vein/left

internal jugular junction

Cisterna chyli Drains most of the Body except

those by right duct


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} In the periphery, arteries and veins run together withnerves bound in CT as a neurovascular bundle. In the

brain, arterial and venous distributions are separate

}Nerve Block is an Injection of Anesthetic Agent Arounda Somatic Nerve to Block Sensations eg. Brachial plexus

block, Intercostal nerve block. Pudendal nerve block.


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Introduction to Arteries, Veins and Lymphatics

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