vessels.ppt

8/18/2019 Vessels.ppt

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Blood Vessels: The Vascular

System• Taking blood to the tissues and back• Arteries

• Arterioles

• Capillaries

• Venules

• Veins


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The Vascular System


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Blood Vessels: Anatomy

• Three layers (tunics)

• Tunic intima

• Endothelium

• Tunic media

• Smooth muscle

• Controlled by sympathetic nerous system

• Tunic e!terna• "ostly #ibrous connectie tissue


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Arteries• Elastic

• "uscular

• Arterioles

Veins

• Venules• Veins


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$


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Capillaries

Structurally three types

%&Continuous

'&enestrated

&Sinusoids


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Capillary Beds• Capillary beds consist o#

t*o types o# essels• Vascular shunt + directly

connects an arteriole to a

enule

Figure 11.10


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"oement o# Blood Through

Vessels• "ost arterial blood ispumped by the heart• Veins use the milking

action o# muscles to help

moe blood


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"a,or Arteries o# Systemic

Circulation


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"a,or Veins o# Systemic Circulation


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Circulation o# the blood

o describe the circulation o# the blood through thelungs- naming the main essels inoled

o list the arteries supplying blood to all ma,or body

structureso describe the enous drainage inoled in

returning blood to the heart #rom the body

o

describe the arrangement o# blood esselsrelating to the portal circulation&


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Although circulation o# blood round the body

is continuous it is conenient to describe it in

t*o parts:

opulmonary circulation

o

systemic or general circulation


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.ulmonary Circulation

#rom the right entricle o# the heart to the lungs and back

to the le#t atrium

/n the lungs- carbon dio!ide is e!creted and o!ygen is

absorbed

The pulmonary artery or trunk- carrying deoxygenated

blood - leaes the upper part o# the right entricle o# the

heart

.asses up*ards and diides into le#t and right pulmonary

arteries at the leel o# the 0th thoracic ertebra&


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.ulmonary Arteries

o The left pulmonary artery runs to the root o# the

le#t lung *here it diides into t*o branches- one

passing into each lobe&

oThe right pulmonary artery passes to the root o#

the right lung and diides into t*o branches& The

larger branch carries blood to the middle and

lo*er lobes- and the smaller branch to the upper

lobe&


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o1ithin the lung these arteries diide and

subdiide into smaller arteries- arterioles and

capillaries&

oThe e!change o# gases takes place bet*eencapillary blood and air in the aleoli o# the lungs&

o/n each lung the capillaries containing

o!ygenated blood ,oin up and eentually #orm t*o

pulmonary eins&


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.ulmonary Veins

oTwo pulmonary veins leae each lung-

returning o!ygenated blood to the le#t

atrium o# the heart&

o2uring atrial systole this blood is pumped

into the le#t entricle- and during entricular

systole it is #orced into the aorta- the #irst

artery o# the general circulation&


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Systemic or general circulation

• The blood pumped out #rom the le#t

entricle carried by the branches o# the

aorta around the body superior and

inferior venae cavae right atrium o# theheart


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AortaoThe aorta begins at the upper part o# the le#t entricle

oa#ter passing up*ards #or a short *ay- it arches

back*ards and to the le#t

odescends behind the heart through the thoraciccaity a little to the le#t o# the thoracic ertebrae&

o At the leel o# the %'th thoracic ertebra it passes

behind the diaphragm then do*n*ards in the

abdominal caityo At the leel o# the 3th lumbar ertebra- it diides into

the right and left common iliac arteries&


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Branches o# Aorta

oThroughout its length the aorta gies o##

numerous branches&

oSome o# the branches are paired - i&e& there

is a right and le#t branch o# the same name-

#or instance- the right and le#t renal arteries

supplying the kidneys

osome are single or unpaired - e&g& the

coeliac artery&


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•The aorta *ill be described here

according to its location:

othoracic aorta

oabdominal aorta


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Thoracic aorta

• This part o# the aorta lies aboe the diaphragm and is

described in three parts:

%& ascending aorta'& arch o# the aorta

& descending aorta in the thora!


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Ascending aorta

• This is the short section o# the aorta that

rises #rom the heart& /t is about 0 cm long

and lies behind the sternum

• The right and left coronary arteries are its

only branches and they arise #rom the aorta

,ust aboe the leel o# the aortic ale&

These important arteries supply the

myocardium&


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Arch o# the aorta

oContinuation o# the ascending aorta

obegins behind the manubrium o# the

sternum and runs up*ards- back*ards and

to the le#t in #ront o# the trachea&

opasses do*n*ards to the le#t o# the

trachea and is continuous *ith the

descending aorta&


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Branches #rom arch or aorta

• Three branches are gien o## #rom its upper aspect:

obrachiocephalic artery or trunk

o le#t common carotid artery

o

le#t subclaian artery&


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Brachiocephalic artery

• The brachiocephalic artery is about 3 to 0

cm long and passes obli4uely up*ards-

back*ards and to the right&

• At the leel o# the sternoclaicular ,oint it

diides into the right common carotid artery

and the right subclavian artery &


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Circulation o# blood to the head and

neck• The paired arteries supplying the head and neck are the

ocommon carotid arteries

o

the ertebral arteries


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Carotid arteries

• The right common carotid artery is a

branch o# the brachiocephalic artery&

• The left common carotid artery arises

directly #rom the arch o# the aorta&

• They pass up*ards on either side o# the

neck and hae the same distribution on

each side

• each diides into an internal carotid artery

and an external carotid artery &


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Carotid sinuses

•slight dilations at the point o# diision

(bi#urcation) o# the common carotid

arteries into their internal and e!ternalbranches&

•contain numerous nere endings o#

the glossopharyngeal neres& Thesenere endings are baroreceptors


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Carotid bodies

• t*o small groups o# specialised cells- called

chemoreceptors- one lying in close

association *ith each common carotid

artery at its bi#urcation&

• They are supplied by the glossopharyngeal

neres and their cells are stimulated by

changes in the carbon dio!ide and o!ygencontent o# blood&


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E!ternal carotid artery

• This artery supplies the super#icial tissues o# the head and

neck- ia a number o# branches:

• The superior thyroid artery supplies the

thyroid gland and ad,acent muscles&• The lingual artery supplies the tongue- the

lining membrane o# the mouth- the

structures in the #loor o# the mouth- thetonsil and the epiglottis&


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• The #acial artery supplies the muscles o#

#acial e!pression and structures in the

mouth&

• The occipital artery supplies the posterior

part o# the scalp&


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• The temporal artery supplies the #rontal-

temporal and parietal parts o# the scalp&

The pulse can be #elt in #ront o# the upper

part o# the ear&

• The ma!illary artery supplies the muscles

o# mastication and a branch o# this artery-

the middle meningeal artery- runs deeply tosupply structures in the interior o# the skull&


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/nternal carotid artery

• This is a ma,or contributor to the circulus

arteriosus (circle o# 1illis)- *hich supplies

the greater part o# the brain&

• /t also has branches that supply the eyes-

#orehead and nose&


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Circulus arteriosus (circle o# 1illis)

• The greater part o# the brain is supplied *ith

arterial blood by an arrangement o# arteries

called the circulus arteriosus or the circle of Willis

• our large arteries contribute to its #ormation:%& the t*o internal carotid arteries

'&t*o vertebral arteries

• The ertebral arteries arise #rom the subclaian

arteries-


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Basilar Artery

• Vertebral arteries enter the skull through

the #oramen magnum- then ,oin to #orm the

basilar artery &


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• Anteriorly- the t*o anterior cerebral arteries arise #rom the

internal carotid arteries and are ,oined by the anterior

communicating artery &

• .osteriorly- the t*o vertebral arteries ,oin to #orm the

basilar artery& A#ter traelling #or a short distance thebasilar artery diides to #orm t*o posterior cerebral

arteries- each o# *hich is ,oined to the corresponding

internal carotid artery by a posterior communicating

artery - completing the circle&


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• The circulus arteriosus is there#ore #ormed by:

• • ' anterior cerebral arteries

• • ' internal carotid arteries

• • % anterior communicating artery• • ' posterior communicating arteries

• • ' posterior cerebral arteries

• • % basilar artery&


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• rom this circle- the anterior cerebral arteries pass

#or*ard to supply the anterior part o# the brain- the middle

cerebral arteries pass laterally to supply the sides o# the

brain- and the posterior cerebral arteries supply the

posterior part o# the brain&• Branches o# the basilar artery supply parts o# the brain

stem&


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