Cardiovascular System 2 PDF

Preview

Summary

Richard Mynark...

Description

P215 Cardiovascular System Blood Vessels Chapter 14 Introduction

wall and lumen

b lo od ve s s e l

“tubes” for blood flow cros s - s e ct ion conduit lumen - _________ for blood flow smooth wall - connetive tissue and _________ muscle endothelial lining - layer of _________________ cells

blood vessel functions help determine: 1) blood __________ pressure where blood flows in body 2a) _______ how much blood flows to parts of body 2b) __________ Blood Flow Through Blood Vessels la r g e s t v e in s he art v e in s

la r g e s t a r t e r ie s

blood always contained by vessels (and heart chambers) a r t e rie s closed a ____________ circulatory system v e n u le s

c a p illa r ie s

a rt e r io le s

capillaries most important goal: continuous blood flow through __________ exchange between blood and surrounding fluid capillaries: sites of ________ some general characteristics la rg e s t a rt e rie s

a rt e rie s

total number t w o lumen diameter

4 .0 m m

a rt e rio le s

ca p illa rie s

m any b illio n s 0 .0 0 8 m m

v e n ule s

v e in s

la rg e s t v e in s

tw o 5 .0 m m

3000 x

t o t al a re a o f cross-section

30 cm/ sec

spe e d o f blood flow

24 cm/ sec from figure 14.16

b a r e ly a b o v e 0 c m / s e c -slows blood down for gas (faster through big arteries, slower in capillaries exchange

blood vessel anatomy wall

see figure 14.6

co n n e ct iv e t is s u e s m o o t h m u s c le lu m e n e n d o t h e liu m ( lin in g lay e r)

a b a s ic c h a ra c t e r is t ic t h ic k , s t ro n g w a lls

a r t e rie s

lo t s o f s m o o t h m u s c le f o r t h e ir s iz e

a r t e rio le s c a p illa r ie s

t h in w a ll - s in g le e n d o t h e lia l c e ll la y e r

v e n u le s

t h in n e r w a lls le s s s m o o t h m u s c le t h a n c o m p a ra b le a rt e rio le s a n d a r t e rie s

v e in s

blood vessels: blood pressure and blood flow two big factors affect blood flow blood pressure factor #1: ___________________ (actually, difference in bp )

blood pressure (BP) -

BP

a force that pushes against _____________ of blood vessels and pushed blood _______________ of blood vessels declines blood pressure __________ as blood flows through systemic

and pulmonary circuits la rg e s t a rt e rie s

b lo o d p re s s u re

a rte rie s

a rte rio le s

ca p illarie s

v e n u le s

v e in s

la rg e s t v e in s

systemic circuit arterial bp pulmonary circuit

venous bp

from arteries to veins, there’s a difference in blood pressure (BP) that’s important ... difference in BP ( delta BP) between two points drives _______ blood flow low high blood ALW AYS flows from _________ to ______ pressure

look at systemic and pulmonary circuits (blood pressure often measured in millimeters of mercury - mm Hg) 85 mm Hg 0 ___ mm Hg ___ rig h t le f t a t r iu m v e n t ric le

in systemic circuit BP = 85

s y s t e m ic c irc u it

mm Hg

high ______ pressure circuit

in pulmonary circuit BP =

p u lm o n a r y c irc u it rig h t le f t v e n t ric le a t r iu m

low ______ pressure circuit

s y s t e m ic circu la t ion a rt e rie s

mm Hg

2 ___ mm Hg

___ mm Hg 15

pu lm on a ry circu la t io n

13

ca pilla rie s

v e in s

s y s t e m ic circu la t ion

pu lm on a ry circu la t io n rig h t s id e of h e a rt

a rt e rie s

ca pilla rie s

v e ins

why does the systemic circuit require more muscle in the wall of the left ventricle? the blood pressure is way higher blood flow in systemic circuit= CO of left ventricles at rest 5 L/min

le ft s id e of h e a rt

in addition to

BP,

factor #2 also affects blood flow: resistance (R) friction due to __________ as blood flows along blood vessel walls

blood flow = as

BP / R

BP rises, blood flow rises

as R rises, blood flow falls sources of Resistance (R) to blood flow in our cadiovascular system viscosity 1) blood ___________ -affected by number of RBCs in plasma ---------------------------------------polycythemia hemolytic anemia RBC # up viscosity up RBC # down viscosity down -------------------------------------blood doping aplastic anemia total length 2) blood vessels’ _________________ more

adding new blood vessles

adding weight than R of systemic circuit greater ______________ R of pulmonary circuit diameter 3) blood vessel lumen ___________ stressed the most

blood vessel cross-section smooth muscle

smooth muscle

resistance

resistance

contracts less falls

contracts more rises

reducing diameter of blood vessels by half ..... raises resistance TPR total peripheral resistance (_______)

total peripheral resistance = resistance to blood flow through all ____ of body’s blood vessels along which blood is currently flowing

arteries blood vessels exposed to highest blood pressure thick walls

elastic _________ but relatively _____________ stiff-limited compliance stretch

compliance of artery walls: high blood pressure prime jobs: 1) withstand ________________________ continuous 2) help produce ______________________ blood flow relaxed even when ventricles are _____________ example open

bulge the aortic valve outward

s e m ilu n a r v a lv e

d u r in g v e n t r ic u la r systole

demonstrates the elasticity of aortic valve d u r in g v e n t r ic u la r diastole

le ft v e n t ricle

a o rt a

blood flow

clo s e d s e m ilu n a r v a lv e

le ft v e n t ricle

blood flow

a rt e ry

from figure 14.7

spring back of the aortic valve

a o rt a

blood flow

a rt e ry

arterial pressure: measurement and calculations -focus on arterial BP in systemic circuit systolic pressure arteries arterioles capillaries venules veins when left ventricle is contracting

when left ventricle is relaxing

pulse pressure systolic-diastolic

mean arterial pressure (MAP)= diastolic + (pulse presure/3) systolic pressure

average BP (mm Hg)

diastolic pressure

100

systolic BP

75 s y s t e m ic c irc u la t io n 50

diastolic BP

25

0 arteries

spends a lot more time diastolic pressure in diastolic from figure 14.8 so cant just take the average of DP and SP

arterioles

capillaries venules

veins

from figure 14.9

diastole MAP is weighted toward ____________ pressure diastole because heart spends more time in _____________

the changing diameter of arteries is an important characteristic

arterioles

small arteries >>> >>> capillaries walls - elastic tissue, bands of there’s always some smooth muscle contraction less contraction: resistance falls more contraction: resistance rises most resistance of all blood vessels, arterioles offer the _____________ to blood flow

changing arteriole diameter affects resistance - key arteriole function blood flow prime job: 1) distribution of _______________

a rt e ria l s id e * a rt e rio le s

a r t e r i e s

h e a rt *

o rg a n / t is s u e

*

o rg a n / t is s u e

*

o rg a n / t is s u e

v e i n s

ve no us s id e

c a p illa rie s

h e a rt

h e a rt 1 . 5 L/ m in

1 . 5 L/ m in

1 . 0 L/ m in

0 . 5 L/ m in

0 . 5 L/ m in

0 . 5 L/ m in

c a pilla rie s

c a pilla rie s

from figure 14.11

prime job: 2) blood pressure in ___________ arteries

arterial BP rises

a r t e r i e s

h e a rt v e i n s

arterial BP

a r t e r i e s

h e a rt v e i n s

many arterioles many arterioles TPR falls rises TPR MAP falls MAP rises TPR MAP = CO x ________ due to heart

due to blood vessels

why be concerned about arterial BP?

by keeping the arterial BP high enough it keeps blood flowing through the system the thing that drives blood flow is arterial BP

arterioles function fundmentally depends on construction and dilation why do arterioles constrict and dilate? own smooth muscle answer: 1) capabilities of their ___________________ 2) response to influences _____________________ from outside arterioles

response of arterioles themselves oxygen first example - response to local concentration of ____________

suppose ... o x y g e n le v e l in t is s u e decreasescarb o n d iox id e le v e l in t is s u e increasing in re s p o n s e . . . art e rio le s m o o t h m u s cle contract less re s is t an ce falls b lo o d flo w t o t h e local t is s u e increases happens when local metabolic activity ______________ decreases happens when local blood flow has been ______________ hyperemia called “________________”

= _____________ blood flow increased

smooth muscle direct response of arteriole _________________

what happens if oxygen levels climb above normal? arterioles constrict in those areas-hyporemia blood pressure second example - response to local ________________

s u p p os e art e riole BP increases t h e n , a rt e riole b lo od flo w increases as a re s u lt , s t re t ch o f art e rio le s m o ot h m u s cle s m oo t h m u s cle re s p o n d s b y pushing back a rt e riole as a re s u lt , re s is t a n ce increases an d b lo o d flo w

increases

autoregulation called “__________________” smooth muscle direct response of arteriole _________________ with stretch-sensitive _____________ fibers muscle brain found in _________ and some other organs / tissues

what happens if arterial BP falls below normal? arterials dilate

arterioles response of influences outside arterioles primarily from sympathetic autonomic nervous system receptors for norepinephrine and epinephrine on smooth muscle cells in arterioles in many tissues, arterioles have an abundance of ALPHA receptors in cardiac muscle and skeletal muscle arterioles same substances - epi and norepi - lead to different responses how? contract more and lead to constriction other chemical substances also influence arterioles smooth muscle relaxation - dilation smooth muscle contraction - constriction combination of inside and outside influences two examples 1) exercise blood flow

s k e le t a l m u s cle s k in h e a rt b ra in GI t ra ct k id n e y s

exercise

rest 1.0 0.25 0.2 0.7 1.25 1.0

L/ m in L/ m in L/ m in L/ m in L/ m in L/ m in

20.0 0.65 1.15 0.8 1.05 0.85

L/ m in L/ m in L/ m in L/ m in L/ m in L/ m in

how does the change during exercise occur?

2) mean arterial pressure (MAP)

o rg a n / t is s u e o rg a n / t is s u e o rg a n / t is s u e

o rg a n / t is s u e o rg a n / t is s u e o rg a n / t is s u e

most arterioles constricted TPR MAP

most arterioles dilated TPR MAP

remember, MAP = __________

short-term regulation of MAP arterial baroreceptors

“baro” = b a ro re c e p t o r s

in t e rn al ca ro t id art e rie s

monitor systemic arterial t o card io va s cu la r co n t rol ce n t e r in b rain s t e m b aro re ce p t o r s e n s o ry affe re n t a x o n s

s e n s o ry e n d in g s in w a ll o f art e ry

a ort a

ca ro t id a rt e ry

s t re t ch o f a rt e ria l w a ll

d e p o lariz a t ion of s e n s o ry e n d in g s

normal

normal

fre q u e n cy o f APs in b aro re ce p t o r s e n s o ry a ffe re n t s

elevated arterial BP normal arterial BP

normal

depressed arterial BP

if arterial BP in systemic arteries departs from normal .... cardiovascular control center in brainstem coordinates a reflexive response that tries to move BP an example: baroreceptor reflex suppose MAP begins to due to stretch of arterial baroreceptors depolarization of sensory endings AP frequency in baroreceptor afferents to cardiovascular control center c a r d io v a s c u la r c o n t r o l c e n t e r a c t iv a t e s a u t o n o m ic n e r v o u s s y s t e m sympathetic activity

veins

heart SA node

myocardium contractility

HR

parasympathetic activity

SV

constriction

arterioles constriction

venous return to heart EDV

CO

TPR MAP

arterioles anaphylactic shock (cardiovascular) “shock” = sudden, sharp drop part of a severe allergic reaction molecules released by immune system produce widespread ___________ of vessel smooth muscle and ___________ of bood vessels arterial BP __________________ dangerous decline in a quick, effective treatment:

capillaries smallest blood vessels

1

most numerous blood vessels thinnest-walled blood vessels o n e ce ll t h ick slow flow of blood 0 . 1 m m / s e c exchange prime job: site of _________

h u g e s u rfa ce are a 6500 sq feet

b lo o d p las m a b lo o d p las m a

three kinds of capillary walls 1 - slightly leaky 2 - very leaky

e n d o t h e lial ce ll in t e rs t it ial f lu id air s acs in lu n g s 1 - slightly leaky

in te rs tit ia l flu id

^

e n d o th e lia l ce lls

v

b lo od

3 - tight

3 - tight

2 - very leaky in te rs tit ia l flu id e n d o th e lia l ce lls b lo od

brain bloo d from figure 14.17 brain barri er

capillaries exchange across capillary walls includes fluid movement blood plasma w a t e r filtration flow out m ovem ent bp primary factor: o u t o f b lo o d

water m ovem ent in t o b lo o d

interstitial fluid --> ISF

absorption flow in blood plasma...