Blood Vessels Dr. Emad Abu Alrub AAUJ
Jan 03, 2016
Three basic components:• Heart - serves as pump that establishes the
pressure gradient needed for blood to flow to tissues
• Blood - transport medium within which materials being transported are dissolved or suspended
• Blood vessels - passageways through which blood is distributed from heart to all parts of body and back to heart
Circulatory System
Arteries – carry blood away from the heart Capillaries – smallest blood vessels
◦ The site of exchange of molecules between blood and tissue fluid
Veins – carry blood toward the heartarteries → arterioles → capillaries → venules → veins
Types Of Blood Vessels
Arteries - carry blood away from heart Arterioles - small arteries that deliver
blood to capillaries Capillaries – thin walled vessels allow
for exchange between blood and tissue cells
Venules - collect and drain blood into veins
Veins - return blood to heart
Functions Of Blood Vessels
Composed of three layers (tunics)◦ Tunica intima – composed of simple squamous
epithelium◦ Tunica media – sheets of smooth muscle
Contraction – vasoconstriction Relaxation – vasodilation
◦ Tunica externa – composed of connective tissue Lumen - central blood-filled space of a vessel
Structure Of Blood Vessels
• Arteries have thicker tunica media and narrower lumens• Veins have thicker tunica externa• Arteries have more elastic and collagen fibers• Veins have larger lumens and valves
Structural Differences
Elastic arteries – the largest arteries ◦ Diameters range from 2.5 cm to 1 cm◦ Includes the aorta and its major branches◦ Sometimes called conducting arteries◦ High elastin content dampens surge of blood
pressure
Types Of Arteries
Muscular (distributing) arteries◦Lie distal to elastic arteries◦Diameters range from 1 cm to 0.3 mm◦ Includes most named arteries◦Tunica media is thick◦Unique features Internal and external elastic laminae
Types Of Arteries
Arterioles◦ Smallest arteries◦ Diameters range from 0.3 mm to 10 µm ◦ Larger arterioles possess all three tunics◦ Diameter of arterioles controlled by:
Local factors in the tissues Sympathetic nervous system
Types Of Arteries
Smallest blood vessels◦ Diameter from 8–10 µm◦ Red blood cells pass through single file
Endothelial cells – held together by tight junctions and desmosomes
Routes into and out of capillaries◦ Direct diffusion◦ Through intercellular clefts - gaps of unjoined
membrane where small molecules can enter and exit
◦ Through fenestrations - pores
Capillaries
Site-specific functions of capillaries Lungs – oxygen enters blood, carbon dioxide leaves Small intestines – receive digested nutrients Endocrine glands – pick up hormones Kidneys – removal of nitrogenous wastes
Tendons and ligaments – poorly vascularized
Epithelia and cartilage – avascular, receive nutrients from nearby CT
Capillaries
Wide, leaky capillaries found in some organs Usually fenestrated Have large diameters Intercellular clefts are wide open Occur in bone marrow, liver, spleen and
lymphoid tissue
Sinusoids
An interconnected network of vessels running through tissues
Consists of: • Collateral arteries feeding an arteriole• Metarterioles• Arteriovenous anastomoses• Capillaries• Venules
Capillary Beds
Conduct blood from capillaries toward the heart
Blood pressure is much lower than in arteries
Smallest veins – called venules◦ Diameters from 8 – 100 µm ◦ Smallest venules – called
postcapillary venules Venules join to form veins
Veins
Role Of Veins To return blood to the heart, veins have special adaptations
◦ Large-diameter lumens, which offer little resistance to flow
◦ Valves (resembling semilunar heart valves), which prevent backflow of blood
◦ Skeletal muscle pump - muscles press against thin-walled veins
Consists of blood vessels that take the blood to and from the lungs for the purpose of gas exchange◦ Pulmonary Trunk: oxygen-poor blood leaves the right
ventricle via the pulmonary trunk; large artery that branches to left and right pulmonary arteries
◦ Pulmonary Arteries : take the blood to the lung where oxygen is picked up and CO2 is left off
◦ Pulmonary Veins: blood returns to the heart via four pulmonary veins that go to the left atrium
Pulmonary Circulation
Consists of blood vessels that extend to and from the heart delivers oxygen and nutrients to body tissues picks up CO2 and waste products
Systemic Circulation
Ascending aorta – arises from the left ventricle branches to form coronary arteries
Aortic arch – lies posterior to the manubrium branches to form ◦ Brachiocephalic trunk◦ Left common carotid◦ Left subclavian arteries
Descending aorta – continues from the aortic arch ◦ Thoracic aorta – in the
region of T5–T12
◦ Abdominal aorta – ends at L4
◦ Divides into right and left common iliac arteries
Superior/Inferior vena cava returns blood from the systemic veins to the heart
The Aorta And Vena Cava
A specialized part of the vascular circuit Picks up digested nutrients Delivers nutrients to the liver for processing
The Hepatic Portal System
Veins Of The Hepatic Portal System
Hepatic veins
LiverSpleenGastric veins
Inferior vena cavaSplenic vein
Inferiormesenteric vein
Superiormesenteric vein
Large intestine
Hepatic portal vein
Small intestine
Rectum
“Circle” equalizes blood pressure in the brain and can provide alternative channels if one vessel becomes blocked
The circle is formed from : posterior cerebral arteries, posterior communicating arteries, internal carotid arteries, anterior cerebral arteries, and anterior communicating arteries
Cerebral Arterial Circle (Circle Of Willis)
(c)
Middle cerebralartery
Internalcarotidartery
Cerebral arterial circle (circle of Willis)
Anterior
Posterior
• Posterior cerebral arteryBasilar artery
Vertebral artery
• Posterior communicating artery
• Anterior cerebral artery
• Anterior communicating artery
Arteries Of The Right Upper Limb And Thorax
(b)
Vertebral arteryCommon carotidarteries
Left axillaryartery
Right subclavianarteryLeft subclavianartery
Anterior intercostalartery
Descending aorta
Brachiocephalictrunk
Axillary artery
Radial arteryUlnar artery
Brachial artery
Suprascapular artery
Arteries Of The Head And Neck/ Right Aspect
BrachiocephalictrunkInternal thoracicartery
Internalcarotid artery
Subclavianartery
(a)
Axillaryartery
Externalcarotid artery
Commoncarotid artery
Major Branches Of The Abdominal Aorta
Adrenalgland
Celiac trunk
Kidney
Abdominal aorta
Diaphragm
Suprarenal artery
Renal arterySuperiormesenteric artery
Gonadalartery
Inferiormesenteric artery
Common iliacartery
The Celiac Trunk And Its Main Branches
(b)
Liver
Left gastric artery
Superior mesentericartery
SpleenSplenic artery
Inferior vena cava
Celiac trunk
Common hepatic arteryRight gastric artery
Abdominal aorta
Arteries Of The Right Pelvis And Lower Limb
(a)
(b)
Common iliac artery
Femoral artery
Popliteal artery
Anterior tibial arteryPosterior tibial artery
Fibular artery
Internal iliac artery
External iliac arteryPopliteal artery
Anterior tibial artery
Fibular arteryPosterior tibial artery
Anterior view
Posterior view
Three major veins enter the right atrium
Superficial veins lie just beneath the skin
Multivein bundles – venous plexuses Unusual patterns of venous drainage
◦Dural sinuses◦Hepatic portal system
Systemic Veins
Superior vena cava ◦ Returns blood from body regions superior to the
diaphragm Inferior vena cava
◦ Returns blood from body regions inferior to the diaphragm
Superior and inferior vena cava◦ Join the right atrium
Venae Cavae and Tributaries
Major veins of the systemic circulation.
Renal vein
Splenic veinBasilic veinBrachial veinCephalic vein
Dural sinusesExternal jugular veinVertebral veinInternal jugular veinSuperior vena cavaAxillary veinGreat cardiac veinHepatic veinsHepatic portal veinSuperior mesenteric veinInferior vena cava
Ulnar veinRadial vein
Common iliac veinExternal iliac vein
Internal iliac veinDigital veins
Femoral veinGreat saphenous veinPopliteal veinPosterior tibial veinAnterior tibial veinFibular vein
Inferior mesenteric vein
Median cubital vein
Right and leftbrachiocephalic veins
Subclavian vein
Dural Sinuses In The CraniumSuperior sagittalsinusFalx cerebri
Inferior sagittalsinusStraight sinusCavernous sinusJunction of sinusesTransverse sinuses
Jugular foramen
(b)
Right internaljugular vein
Sigmoid sinus
Veins of the head and Neck
Ophthalmic vein
Superficialtemporal vein
Facial vein
Occipital vein
Posteriorauricular vein
Externaljugular veinVertebral vein
Internaljugular veinSuperior and middle thyroid veinsBrachiocephalicveinSubclavianvein
(a)Superiorvena cava
Veins Of The Right Upper Limb And Thorax Wall
Right subclavian vein
Axillary vein
Brachial veinCephalic veinBasilic vein
Median cubital vein
Median vein of the forearmBasilic vein
Internal jugular veinExternal jugular vein
Left subclavian vein
Superior vena cavaAzygos vein
Inferior vena cava
Ascending lumbar vein
Accessory hemiazygos vein
Hemiazygos vein
Posterior intercostals
Brachiocephalic veins
Ulnar vein
Deep palmarvenous archSuperficial palmarvenous arch
(a)
Digital veins
Cephalicvein Radial vein
Form anastomese frequently
Median cubital vein is used to obtain blood or administer IV fluids
Antecubital Fossa
Figure 19.22
Veins Of The Right Upper Limb And Thoracic Wall
Brachiocephalicveins
Left superiorintercostalvein
Azygos vein
Accessoryhemiazygosvein
Hemiazygosvein
Intercostalveins
Ascendinglumbar vein
Renal vein
Superior venacava
Intercostalveins
(b)
Inferior venacava
12
34
5
6
7
8
9
10
11
12
Lumbar veins Gonadal (testicular or ovarian) veins Renal veins Suprarenal veins Hepatic veins
Veins of the Abdomen
Tributaries Of The Inferior Vena Cava
Rightsuprarenal vein
Rightgonadal vein
Hepatic veins
Inferior vena cava
External iliac vein
Inferior phrenicvein
Renal veins
Lumbar veins
Left ascendinglumbar vein
Left gonadal veinCommon iliac vein
Internal iliac vein
Left suprarenal vein
Dissection of the posterior abdominal wall
Diaphragm
Right Left
Inferiorvena cava
Hepaticveins
Renal veins
Commoniliac veins
Abdominalaorta
Deep veins◦Share the name of the accompanying artery
Superficial veins◦Great saphenous vein empties into the femoral vein
◦Small saphenous vein empties into the popliteal vein
Veins of the Pelvis and Lower Limbs
Veins Of The Right Lower Limb And Pelvis
(b)
Popliteal vein
Common iliac vein
Fibular (peroneal)veinAnterior tibial vein
Dorsalis pedis veinDorsal venous archMetatarsal veins
Internal iliac veinExternal iliac veinInguinal ligament
Femoral veinGreat saphenousvein (superficial)
Great saphenous vein
Popliteal veinAnterior tibial veinFibular (peroneal) vein
Small saphenous vein(superficial)Posterior tibial vein
Plantar veins
Plantar archDigital veins
(a)
Flowchart Summarizing The Main VeinsR. External jugular– superficial head and neck
R. vertebral– cervical spinal cord and vertebrae
R. brachiocephalic– R. side of head and R. upper limb
Superior vena cava– runs from union of brachiocephalic veins behind manubrium to R. atrium
Inferior vena cava– runs from junction of common iliac veins at L5 to R. atrium of heart
R. atrium of heart
Diaphragm
L. brachiocephalic– L. side of head and L. upper limb
Intracranialdural sinuses
R. internal jugular– dural sinuses of the brainR. subclavian
– R. head, neck, and upper limb Same as R. brachiocephalic
R. axillary
Azygos system– drains much of thorax
L. and R. hepatic veins– liver
Veins ofL. lower limb
L. and R. renal veins– kidneys
Lumbar veins (several pairs)– posterior abdominal wall
R. suprarenal(L. suprarenal drains into L. renal vein)– adrenal glands
R. gonadal(L. gonadal drains into L. renal vein)– testis or ovary
Veins ofR. lower limb
Veins ofR. upperlimb
R. common iliac– pelvis and R. lower limb
L. common iliac– pelvis and L. lower limb
(a)