The Blood VesselsThe Blood Vessels~The Vascular System~The Vascular System

Ch 20Ch 20

Human AnatomyHuman Anatomy

Sonya Schuh-Huerta, Ph.D.Sonya Schuh-Huerta, Ph.D.

Leonardo Da Vinci

Types of Blood Vessels

• Arteries carry blood Away from the heart

• Capillaries smallest blood vessels– The site of exchange of molecules between

blood & tissue fluid

• Veins carry blood toward the heart

Structure of Blood Vessels

• Composed of 3 layers (= tunics)– Tunica intima endothelium; composed of

simple squamous epithelium– Tunica media sheets of smooth muscle

• Contraction = vasoconstriction• Relaxation = vasodilation

– Tunica externa composed of C.T.

• Lumen– Central blood-filled space of a vessel

Structure of Blood Vessels

Tunica media(smooth muscle and elastic fibers)

Tunica externa(collagen fibers)

Artery Vein

Lumen Lumen

Internal elastic membrane

External elastic membrane

Valve

(b)

Endothelial cellsBasement membrane

Capillarynetwork

Capillary

Tunica intima

Subendothelial layerEndothelium

Structure of Arteries, Veins, & Capillaries

Artery

Vein

(a)

Structure of Arteries, Veins, & CapillariesLab iScopy Pix

Types of Arteries

• 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 BP

Vasavasorum Elastin Lumen

Tunicaexterna

Tunicamedia

Tunicaintima

(a) Elastic artery (aorta, 12)

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 feature • Internal & external

elastic laminae

Externalelasticmembrane

Internalelasticmembrane

Lumen

Tunicaexterna

Tunicamedia

(b) Muscular artery (40)

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

Lumen

Tunica media

Endothelium

(c) Small arteriole (285)

Capillaries

• Smallest blood vessels– Diameter from 8–10 µm

• RBCs pass through single file!!!

– Site-specific functions of capillaries• Lungs oxygen enters blood, carbon dioxide

leaves• Small intestines receive digested nutrients• Endocrine glands pick up/release hormones• Kidneys removal of nitrogenous wastes

RBCs in a Capillary – Single File

Capillary Beds

• Network of capillaries running through tissues

• Precapillary sphincters– Regulate the flow of blood to tissues

• Tendons & ligaments poorly vascularized

• Epithelia & cartilage avascular– Receive nutrients from nearby CT

Capillary Beds

(a) Sphincters open—blood flows throughtrue capillaries.

Precapillarysphincters Metarteriole

Vascular shunt

Terminal arteriole Postcapillary venule

Thoroughfarechannel

Truecapillaries

Capillary Beds

(b) Sphincters closed—blood flows through metarteriole—thoroughfare channel & bypasses true capillaries (no blood/O2 to tissue)

Terminal arteriole Postcapillary venule

Capillary Permeability

• Endothelial cells held together by tight junctions & desmosomes

• Intercellular clefts gaps of unjoined membrane – Small molecules can enter & exit

• 2 types of capillary– Continuous most common– Fenestrated have pores; least common

Continuous Capillary

Red bloodcell in lumen

Intercellularcleft

Endothelialcell

Endothelialnucleus

Tight junction Pinocytoticvesicles

Pericyte

Basementmembrane

(a) Continuous capillary. Least permeable and mostcommon (e.g., skin, muscle).

Red bloodcell in lumen

Intercellularcleft

Fenestrations(pores)

Endothelialcell

EndothelialnucleusBasement membrane

Tight junction

Pinocytoticvesicles

(b) Fenestrated capillary. Large fenestrations (pores)increase permeability. Occurs in special locations(e.g., kidney, small intestine).

Fenestrated Capillary

Routes of Capillary Permeability

• 4 routes into & out of capillaries– Direct diffusion– Through intercellular clefts– Through cytoplasmic vesicles– Through fenestrations (= pores)

Low Permeability Capillaries

• Blood-Brain Barrier – Capillaries have complete

tight junctions– No intercellular clefts present– Vital molecules pass through

• Highly selective transport mechanisms– Not a barrier against:

• Oxygen, carbon dioxide, & some anesthetics (ie. many drugs)

Sinusoids

• Wide, leaky capillaries found in some organs– Usually fenestrated– Intercellular clefts are wide open

• Occur in bone marrow, spleen, & liver– Sinusoids have large diameter & twisted course

Sinusoids

Nucleus ofendothelialcell

Red bloodcell in lumen

Endothelialcell

Tight junction

Incompletebasementmembrane

Largeintercellularcleft

(c) Sinusoidal capillary. Most permeable. Occurs in speciallocations (e.g., liver, bone marrow, spleen).

Veins

• Conduct blood from capillaries toward the heart• Blood pressure is much lower than in arteries• Smallest veins called venules

– Diameters from 8–100 m – Smallest venules called postcapillary

venules• Venules join to form veins• Tunica externa is the thickest tunic in veins (not

the tunica media)

Mechanisms to Counteract Low Venous Pressure

• Valves in some veins!– Particularly in limbs

• Skeletal muscle pump– Muscles press against

thin-walled veins– Helps return blood to

heart & prevent pooling

Valve (open)

Contractedskeletalmuscle

Valve (closed)

Vein

Direction ofblood flow

Summary of Blood Vessel Anatomy

Vascular Anastomoses

• Vessels interconnect to form vascular anastomoses– Organs receive blood from more than one

arterial source

• Neighboring arteries form arterial anastomoses – Provide collateral channels

• Veins anastomose more frequently than arteries

Vasa Vasorum

• Tunica externa of large vessels have– Tiny arteries, capillaries, & veins

• Vasa vasorum “vessels of vessels”– Nourish outer region of large vessels

• Inner half of large vessels receive nutrients from luminal blood

Pulmonary Circulation

• Pulmonary trunk leaves the right ventricle– Divides into right & left pulmonary arteries

• Superior & inferior pulmonary veins– Carry oxygenated blood into the left atrium

Pulmonary CirculationLeft pulmonaryartery Air-filled

alveolusof lung

Pulmonarycapillary

Two lobar arteriesto left lung

CO2

O2Right pulmonaryartery

Three lobararteries toright lung

PulmonaryveinsRightatrium

Aortic arch

Pulmonary trunk

Rightventricle

Leftventricle

Pulmonaryveins

Left atrium

Gas exchange

Blood Vessels Throughout Life

• Fetal circulation– All major vessels in place

by month 3 of development– Differences between fetal & postnatal

circulation• Fetus must supply blood to the placenta• Very little blood is sent through the pulmonary

circuit (lungs not doing gas exchange yet; no breathing until born)

Shunts Away from the Pulmonary Circuit

• Foramen ovale

• Ductus arteriosus

Vessels to & from the Placenta

• Umbilical vessels run in the umbilical cord– Paired umbilical arteries– Unpaired umbilical vein

• Fetal vessels & structures– Ductus venosus – Ligamentum teres– Ligamentum venosum

Fetal & Newborn Circulation ComparedAortic arch

Fetus

Superior vena cavaDuctus arteriosus

Lung

Pulmonary arteryPulmonary veins

Heart

Foramen ovale

LiverDuctus venosus

Umbilical vein

Inferior vena cava

Hepatic portal vein

Umbilicus

Abdominal aorta

Common iliac artery

Umbilical arteries

Urinary bladderUmbilical cord

(a)

Placenta

High oxygenationModerate oxygenationLow oxygenationVery low oxygenation

Ligamentum arteriosum

Fossa ovalis

Ligamentum venosum

Ligamentum teres

Medial umbilical ligaments

Disorders of the Blood Vessels

• Aneurysm

• Deep vein thrombosis of the lower limb

• Venous disease

• Microangiopathy of diabetes

• Arteriovenous malformation

• Varicose veins

Abdominal Aneurysm

Aortic aneurysm

• Atherosclerosis begins in youth

• Often related to fatty diet, little exercise, etc.– Consequences evident in middle – old age– Males (ages 45–65)

• More common than in females

– Females• Experience heart disease & atherosclerosis later in

life than males

Disorders of the Blood Vessels

Atherosclerosis

What is one of the best ways to maintainvascular health…?

Lab Guide to the Vessels

Systemic Circulation

• Systemic arteries– Carry oxygenated blood away from the heart– Aorta largest artery in the body!!!

Major Arteries

Internal carotid artery

Common carotid arteries

Subclavian artery Subclavian artery

Aortic archAscending aortaCoronary arteryThoracic aorta (above diaphragm)

Renal artery

Superficial palmar arch

Radial arteryUlnar artery

Internal iliac artery

Deep palmar arch

Vertebral artery

Brachiocephalic trunk Axillary artery

Brachial artery

Abdominal aortaSuperior mesenteric artery

Gonadal artery

Common iliac artery

External iliac artery

Digital arteries

Femoral arteryPopliteal arteryAnterior tibial arteryPosterior tibial artery

Arcuate artery

(a) Anterior view

Inferior mesenteric artery

Celiac trunk

External carotid artery

Arteries of the head and trunk

Arteries that supply theupper limb

Arteries that supply thelower limb

Major Arteries – Pulse Points

Common carotid artery

Brachial artery

Radial artery

Femoral artery

Popliteal artery

Posterior tibialartery

Dorsalis pedisartery

Superficial temporal artery

Facial artery

The Aorta

• Ascending aorta arises from the left ventricle– Branches coronary arteries

• Aortic arch lies posterior to the manubrium– Branches

• Brachiocephalic trunk• Left common carotid• Left subclavian arteries

The AortaRight common carotidartery

Right subclavian artery

Right internaljugular vein

Right subclavian vein

Right brachiocephalicvein

Left internaljugular vein

Left subclavianartery

Left subclavian vein

Left brachiocephalicveinLeft common carotidartery

Brachiocephalic trunk

Right pulmonary artery

Superior vena cava

Ascending aorta

Right atrium

Right ventricle

Inferior vena cava

Aortic arch

Left pulmonary artery

Ligamentum arteriosum

Thoracic aorta

Pulmonary trunk

Left atrium

Left ventricle

The Aorta

• Descending aorta continues from the aortic arch– Thoracic aorta in the region of ~T5–T12

– Abdominal aorta ends at L4

• Divides into right & left common iliac arteries

Common Carotid Arteries

• Located in the anterior triangle of the neck

• 2 branches of the common carotid artery:– External carotid artery– Internal carotid artery

Common Carotid Arteries

• External carotid artery branches:– Superior thyroid artery– Lingual artery– Facial artery– Occipital artery– Posterior auricular artery– Superficial temporal artery– Maxillary artery

Common Carotid Arteries

• Internal carotid artery branches:– Optithalmic artery– Anterior cerebral artery– Anterior communicating artery

• Forms part of the cerebral arterial circle

– Middle cerebral artery

Arteries of the Head & Neck

Superficial temporal artery

Ophthalmic artery

Maxillary arteryOccipital arteryFacial artery

Lingual arterySuperior thyroid artery

LarynxThyroid gland(overlying trachea)

Clavicle (cut)Brachiocephalic trunkInternal thoracic artery

Basilar artery

Vertebral artery

Internal carotid artery

Subclavian artery

Axillary artery

(a) Arteries of the head and neck, right aspect

External carotid artery

Commoncarotid artery

Thyrocervical trunk

Costocervical trunk

Branches of the external carotid artery

Vertebral Arteries

• Supply the posterior brain

• Join to form the basilar artery– Basilar artery divides into 2 posterior cerebral

arteries• Posterior cerebral arteries connect to the posterior

communicating arteries

Cerebral Arterial Circle• 2 posterior communicating arteries join the

anterior communicating artery

Frontal lobe

Optic chiasma

Middle cerebral artery

Internal carotid artery

Mammillarybody

Temporal lobe

Occipital lobe

Cerebral arterial circle (circle of Willis)

Posterior cerebral artery

Basilar artery

Vertebral artery

Cerebellum

Posterior communicating artery

(c) Major arteries serving the brain (inferior view, right side of cerebellum and part of right temporal lobe removed)

Pons

Anterior cerebral artery

Anterior communicating artery

Anterior

Posterior

Arteries of the Upper Limb

• Subclavian artery enters the axilla as the axillary artery

• Axillary artery becomes the brachial artery at the inferior border of teres major

• Brachial artery divides into Radial artery & ulnar artery

Arteries of the Upper Limb & ThoraxVertebral artery

Costocervical trunk

Thoracoacromial artery

Axillary artery

Subscapular artery

Radial artery

Ulnar artery

Deep palmar arch

Superficial palmar arch

Digital arteries

Brachial artery

Suprascapular artery

Thyrocervical trunk

Posterior circumflexhumeral artery

Anterior circumflexhumeral artery

Deep artery of arm

Common interosseousartery

Common carotid arteriesRight subclavian artery

Left subclavian artery

Brachiocephalic trunk

Posterior intercostal arteries

Anterior intercostal artery

Internal thoracic artery

Lateral thoracic artery

Descending aorta

Arteries of the Abdominal Aorta

• Inferior phrenic arteries

• Celiac trunk

• Superior mesenteric artery

• Suprarenal arteries

• Renal arteries

• Gonadal (testicular or ovarian) arteries

• Inferior mesenteric artery

• Common iliac arteries

Arteries of the Abdominal Aorta

Hiatus (opening)for inferior vena cava

Diaphragm

Inferior phrenic artery

Middle suprarenal artery

Renal artery

Superior mesentericartery

Inferior mesentericartery

Median sacralartery Common iliac artery

Ureter

Gonadal (testicularor ovarian) artery

Hiatus (opening)for esophagus

Celiac trunk

Adrenal (suprarenal)gland

Kidney

Abdominal aorta

Lumbar arteries

The Celiac Trunk & Main Branches

(a) The celiac trunk and its major branches. The left half of the liver has been removed.

Liver (cut) Diaphragm

Esophagus

Left gastric artery

Superior mesentericartery

Left gastroepiploicartery

Spleen

Stomach

Pancreas(major portion liesposterior to stomach)

Splenic artery

Inferior vena cava

Celiac trunk

Hepatic artery proper

Common hepaticartery

Gastroduodenalartery

Right gastric artery

Gallbladder

Abdominal aorta

Right gastroepiploicartery

Duodenum

Arteries of Pelvis & Lower Limbs

• Internal iliac arteries

• External iliac artery

• Femoral artery

• Popliteal artery

• Anterior tibial artery

• Posterior tibial artery

Arteries of the Pelvis

Common iliac artery

Aorta

(a) Anterior view

Internal iliac artery

External iliac artery

Arteries of the Pelvis & Lower LimbsCommon iliac artery

Deep artery of thigh

Obturator artery

Descending branch

Femoral artery

Adductor hiatus

Popliteal artery

Genicular artery

Anterior tibial artery

Posterior tibial artery

Fibular artery

Dorsalis pedis arteryArcuate artery

Dorsal metatarsal arteries

(a) Anterior view

Internal iliac artery

Superior gluteal artery

External iliac artery

Lateral circumflex femoral artery

Medial circumflex femoral artery

Arteries of the Pelvis & Lower Limbs

(b) Posterior view of leg

Popliteal artery

Anterior tibial artery

Dorsalis pedisartery (from top offoot)

Posteriortibialartery

Fibular artery

Lateral plantarartery

Medial plantarartery Plantar arch

Systemic Veins

• 3 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

Venae Cavae & Tributaries

• 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

Major Veins of the Systemic Circulation

Renal vein

Splenic vein

Basilic veinBrachial veinCephalic vein

Dural venous sinuses

External jugular vein

Vertebral vein

Internal jugular vein

Superior vena cava

Right and leftbrachiocephalic veins

Axillary vein

Great cardiac vein

Hepatic veins

Hepatic portal vein

Superior mesenteric vein

Inferior vena cava

Ulnar veinRadial vein

Common iliac vein

External iliac vein

Internal iliac vein

Digital veins

Femoral veinGreat saphenous veinPopliteal vein

Posterior tibial veinAnterior tibial veinSmall saphenous veinDorsal venous archDorsal metatarsal veins

Inferior mesenteric vein

Median cubital vein

Subclavian vein

Veins of the head and trunk

Veins that drainthe upper limb

Veins that drain the lower limb

Veins of the Head & Neck

• Venous drainage– Internal jugular

veins– External jugular

veins– Vertebral veins

(a) Veins of the head and neck, right superficial aspect

Vertebral vein

Ophthalmic veinSuperficial temporal vein

Facial vein

Occipital vein

Superior and middlethyroid veins

Posterior auricular vein

External jugular vein

Internal jugular vein

Brachiocephalic vein

Subclavian vein

Superior vena cava

Veins of the Head & Neck

• Dural sinuses– Superior & inferior

sagittal sinuses– Straight sinus– Transverse

sinuses– Sigmoid sinus

(b) Dural venous sinuses of the brain

Superior sagittal sinusFalx cerebriInferior sagittal sinusStraight sinus

Cavernous sinus

Transverse sinuses

Jugular foramen

Confluence of sinuses

Sigmoid sinus

Right internal jugular vein

Veins of the Thorax

• Azygos vein

• Hemiazygos vein

• Accessory hemiazygos vein

Veins of the Upper Limbs

• Deep veins – Follow the paths of companion arteries– Have the same names as the companion

arteries

• Superficial veins– Visible beneath the skin

• Cephalic vein• Basilic vein• Median cubital vein• Median vein of the forearm

Veins of the Thorax & Right Upper Limb

Right subclavian vein

Brachiocephalic veins

Axillary veinBrachial veinCephalic veinBasilic vein

Median cubitalvein

Median antebrachial vein Basilic vein

Internal jugular veinExternal jugular vein

Left subclavian veinSuperior vena cavaAzygos vein

Inferior vena cavaAscending lumbar vein

Accessory hemiazygosveinHemiazygos vein

Posterior intercostals

Ulnar vein

Deep palmar venous archSuperficial palmar venous arch

Digital veins

Cephalic veinRadial vein

Veins of the Abdomen

• Lumbar veins

• Gonadal (testicular or ovarian) veins

• Renal veins

• Suprarenal veins

• Hepatic veins

Tributaries of the Inferior Vena Cava

Inferior phrenic vein

Left suprarenal vein

Left ascending lumbar vein

Lumbar veins

Left gonadal vein

Common iliac vein

Internal iliac vein

Renal veins

Hepatic veinsInferior vena cavaRight suprarenal vein

Right gonadal vein

External iliac vein

(a) Tributaries of the inferior vena cava; venous drainage of the paired abdominal organs.

Tributaries of the Inferior Vena Cava

(b) Dissection of the posterior abdominal wall illustrating abdominal vessels.

Diaphragm

Right Left

Inferiorvena cava

Hepatic veins

Renal veins

Commoniliac veins

Abdominal aorta

The Hepatic Portal System

• A specialized part of the vascular circuit

• Picks up digested nutrients

• Delivers nutrients to the liver for processing

The Basic Scheme of the Hepatic Portal System

(b) The veins of the hepatic portal system

Hepatic veins

Liver Spleen

Gastric veins

Inferior vena cava

Inferior vena cava(not part of hepaticportal system)

Splenic vein

Rightgastroepiploic vein

Inferiormesenteric vein

Superiormesenteric vein

Large intestine

Hepatic portal vein

Small intestine

Rectum

Veins of the Pelvis & Lower Limbs

• Deep veins– Share the name of the accompanying artery

• Superficial veins– Great saphenous vein empties into the

femoral vein

Veins of the Right Lower Limb & Pelvis

Popliteal vein

Common iliac vein

Fibular vein

Anterior tibial vein

Dorsalis pedis vein

Dorsal venous arch

Dorsal metatarsal veins

(a) Anterior view

Internal iliac vein

External iliac vein

Inguinal ligament

Great saphenous vein (superficial)

Small saphenous vein

Femoral vein

Questions…?

What’s Next?Lab: Blood & Blood VesselsMon Lecture: Finish material & Rev Mon Lab: Lab Exam 4!Wed Lecture: Lecture Exam 4!