, - . -- * - I

r . '- -. -. Vein WW J; '; O b j e c t i v e 2 : Recognizeamm-&andvim I 1 ofanartnytmdaveia

Figure 21.1 Structure of rrtdes, wins, and - caplllariar. (a) Diagrammatic view. (b) Line drawing of r $mall artery and win, crass-w'bisnrl dew. See also Plate I f in the Histology Atlas.

- - .. . - .

A c t i v i t y 1 : - 2.: - - !.- ,

Examining the Microscopic Itructuit! of Arteries and Veins 1. GQ to the Dtrnmstration area to examine a glide show- ing a cross-sectisnd view of blood vessels. 2 Using Figure 2 1.1 b rs a guide, scan the section to iden- tify a thick-wallad artery. Often, but not always, in lumen will appear fcallopcd due to the emstriction of its walls by the elmtic tim of tht media 3. Identify r vein. Its lumen may be elongated cir inegulmly duped and collapsed, and its walls will be considerably thin- ner. Also, notict the thinness of the intema laytr. .

Anatclmy of Blood Veuclr 181

O b / a t t l v e 3 : Identlfythemajorarteriesarising from the acwta, and name the body region supplied by

Major Systemic Arteries of the Body

The aorta is the largest artery of the body. Extending up w d s~ the asctmliq aorta from the left ventricle, it arches p0stetiotl.y and to the left at the mrtkc arcb and then cwrses downward as the tharacie aorta tbsough the t hmic cavity. It to enter thir abdomhd w i t y as ust antetior to ftLe vertebral column,

Rpn: 21.2 depicts thc relationship of ttbe aorta and its major branches in shcmatic form. As you locate the armies on this figure and the ones ttr;rt follow, k aware s f ways to make your memoriz~tibn task easier. In many cases the name of the army nflm the body region mveled through (axil- lay, rubclavir- brachial, popliteal), thc served (nnd, hepatic). or tF ~ n e followed (tibial, fcmxd, radial, h).

The only braaches of tfio asconding mzta am the right and Phe I& coronary arteries, which supply the myacardium. T h e c o m n a r y a r t e t i e s a r e ~ b c d i n E x e r c i ~ 2 2 0 i n - junction with anatomy.

~ ] ~ q y G p T z z J carotid artery carotfd art@wy world artery carrotkl artery

I R. Mvtebral I I R, common carotid - riaht Me of head and neck

I R. upper limb] 1 R. upper limb 1 A A. subclanan .. subclavfan - neck and fi- - - " - neck and L.

u r n limb

- L. wantrick to sternal ewlo

L end R. coronary

I L. ventricle of heart

ParietaJ bremha

/ M~;;;I 1 I I"" int*rwtab 1 1 hdtra;;mim 1 - pastsrbr - esophagus - lung@ and - pmicardium - imtwcostal rnwlw, spinal - poeterior and superb

cord, verrcabrae, pkm$b, skin

Gonadal - kstm or

warice

Suprarenal - &mal gland$ and

Renal - kidneyti

Superior culd inferior mw - small

intesthe - colon

Cellae t ~ k - liver - @lbhdde~ - splm - t m - g'Js

R. c m iliac - oelvis and R. lower limb - Deivlrs and L. lOwtK limb

Flgura 21.2 khemittk of tha qtmk arterial dnuktlon. (Notice that a few of the arterfer h-td hem are not di~~.u& in the exercise; L. P left, R. = right.)

Anatomy of M o d MS& 191

Arterial Supply of the Brain and the Circle of Willir A continuous blood supply to the brain k csmtial because oxygen deprivation for evm sr few minutes m u m the &li- catc brain tissue t~ die. The b& is supplied by two p& of artcries arising from the ~ g i o n of the aortic arch-the inter- rtal carcltid arteries and the vertebral arteries. Figure 21.13 is (1 diagram of the brain% arterial supply.

A c t i v i t y 7 :

Tracing the Arterial Supply of the Brain fi intemd carotid and vtrtcbml arteries arc labelcd in Fig- ure 21.13. As yw read the description of the brain's blood supply below, complete the labeling oft& diagram. .

T?E intertuPl carotid rrtsrk, bmchee of h e common carotid arteries, rake a deep cwrw through the neck, entering the &ull through the carotid canals of the temporal bone. Within the cranium, w h divides into snterlor and middle

cerebral arteries, which supply dK: bulk of the cerebrum. The internal carotid arteries also contribute to the drcte sl WIIILP, an evtcrid mtwo~k iu tb base of the brrmin sum&- ing the pituitary gland and the optic c-a, by helping to form a pmtcdor communicating artery on each side. The circle is completed by the anterior communlcntlng artery, s short shunt eomting tho right and left anterior censbrill b?iteTia.

parnd vertebral arterks brshch fmm thc subcla- vian aer ies and pass superiorly through the tflifljverw processes of the m i c a 1 vertebrae to enter the skull through t,he foramen magnum. Within thc skull, the vertebral artcries unik to fom thc oingk lrasilar artery* which runs superiorly along tfic ventral brain stern, giving off branches to the pons and cercbelIum. At the base of the cerebrum, the bsrsilar rrttefy divides to form t h ~ pmterior cerebral arteria, which supply t4-s posterior paa of the cerebrum and lxmme pm of the circle of Willis by joining with tfie pxterior cornmunicat- ing arteries.

The uniting of tbe anterior and posterior b l d supplj via the circle of Willis is a protective &vim that providedl alternate set of pathways for b l d to nach the brain tissue in the case of irnpaind blood flow mywhcn in the system.

n

Left heart

Figure 22.1 Summrr)t of wants occurring In the hsart dudw thr cadlac cyck, (a ) Events in the Ccft s k l e of tht heart. An electrocardiogram tracing is suptrimposed an the graph (top) x, that pressure and volume changer cjrn be related to electrical events occurring at any point. The P wwe indicate dcpolarizatlon of the atria; the QRS wave is depohrbtian of the ws~~tticles (which hkles the repdadration wave of tho atria); the T wave Lf rqdariratian of the vsntrlcks. Time ocnrtrmc of heaft swnds, due ta valve dmrcs, is alm indicated. @) Evcntr of phases 1 th~ough 3 of €he cardiac cyck are depicted in diagrammatic views af the heart.

Humn g r d i w g ~ u l a r Ph)csfdlqy-Bid P w u m and Pulse Determinations 193

A c t i v l t y 1 : , .

Auscultsting Heart Sounds In the following pmcdure, you will auscultate (listen to) ywr partner's heart sounds with an ordinary

1. Obtain a stethoscope and w n e alcohol swabs. Heart s o d s busst ewgcultateci if the subject's outer clothing is removed, so a mile subject is preferable.

2. Clean the e a r p h of the stethoscope with an alcohol swab. Mow the alcohol to dry, Notice that the earpieces are &cd. For comfort, ;the earpieces h u l d be angled in afor- ward direction vvhert you place thcm into your e m .

3. Don the s t e w - . P l m the diaphragm of the gtetb-

scope on y w partner's thorn, just medial to the left nipple at the fifth inttm~tal space. Listen carefully for hcm sounds. The first sound will be a longer, louder (more boom- ing) sound than the s e c d , which is short and sharp, After listening for a couple minutes, try to dme the pusc. between the second sound of one lwdxat and tfit first smmd of the subsequent heartbeat.

How long is this interval? sec

How dc#s it canpare to the intervd between the fwt and sec- ond of a 9ingle heartbeat?

The Pulse 0 b j e c t i r e 3 : Dtfmtpu1~Bnd~ccuratciydetcr- mim a subject's d i a l and apical pulse,

The tenn pulse refem ta the dtt&ng surges of pres- sure (expansion and then rewill irn an artery that occur with each beat of the left ventricle. Normally the pulse rate equals the heart rate, and the pulse averages 70 to 76 beats per minute in ttLG resting s tab

Conditions other than pulse rare are also useful clini- cally. Can you feel it strongly-does the blood vessel expand ad moil (sometimes visibly) with the pressure waves-or is it difficult to detect? Is it regular like the ticking of r clock, or d m it seem to skip beats? Record your observdaas.

Posterior tibia1 artery

Dorsalis pedis artery

Flgura 22.2 eody s f m where Phs pulse & mast ewly palpated.

A c t l v i t y 2 :

Palpating Superficial Pulrc Points The pulse m y be felt easily on my artery cbw ta trr M y surfact w h the artery is compressed o m a bone m &in tis- sue. Palpate the following pulse ar ~~ points m your partner by placing the fingertips of the f i s t two or thee fin- gers of one hand over the artery. It help to c q p n & s thc artery f i y as y w begin your palpation and then itwnedi- ately eazw up on thc pressure slightly. In each case, ~ M i e e tbc regularity of tkt pulse, eurd asma it8 force. Figure 22.2 illus- trates the sruwcierl pulw point8 to be palpated.

Common carotid articry: At the sick of the neck

Temporal artery: Anterior to h w, in the temple region Facial artery: Clench the teeth, aad pillpate the pulse just an- terior to the maosetcr muscle in iim with the corner of the mouth.

Brachial artery: In the antecubitd f m a , at the p i n t when it splits into the radial and u l m mtmiest

Radhl artery: At fhe lateral aspciet of h wrist, just above the thumb Femml artery: In the groin Papliteal artery: At tfx: back of the Lnw Pssttrior t3blrl artery: Just above the medial malleolug

pedb artwy: On the dorsum of the foot