2.2 circulation mnr
TRANSCRIPT
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2.2 Circulatory system
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Trading with the Environment
• Every organism must exchange materials with
its environment – And this exchange ultimately occurs at the cellular
level
• In unicellular organisms – These exchanges occur directly with the
environment
• For most of the cells maing u! multicellularorganisms
– "irect exchange with the environment is not
!ossi#le
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• $ost com!lex animals have internal
trans!ort systems
– That circulate fluid% !roviding a lifeline#etween the a&ueous environment of
living cells and the exchange organs%
such as lungs% that exchange chemicals
with the outside environment
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Inverte#rate Circulation
• The wide range of inverte#rate #ody si'e
and form
– Is !aralleled #y a great diversity in circulatory
systems
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Gastrovascular Cavitiesgaster (Gk): Stomach
• (im!le animals% such as cnidarians
– )ave a #ody wall only two cells thic that
encloses a gastrovascular cavity
• The gastrovascular cavity
– Functions in #oth digestion and distri#ution of
su#stances throughout the #ody
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• (ome cnidarians% such as *ellies
– )ave ela#orate gastrovascular cavities
Figure 42.2
Circular
canal
+adial canal
5 cm$outh
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Open and Closed Circulatory
Systems• $ore com!lex animals
– )ave one of two ty!es of circulatory systems,
o!en or closed
• -oth of these ty!es of systems have three
#asic com!onents
– A circulatory fluid #lood/
– A set of tu#es #lood vessels/
– A muscular !um! the heart/
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• In insects% other arthro!ods% and most
molluscs
– -lood #athes the organs directly in an o!encirculatory system
)eart
)emolym!h in sinuses
surrounding ograns
Anterior
vessel
Tu#ular heart
0ateral
vessels
1stia
(a) An open circulatory systemFigure 42.3a
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• In a closed circulatory system
– -lood is confined to vessels and is distinct
from the interstitial fluid
Figure 42.3
Interstitial
fluid
)eart
(mall #ranch vessels
in each organ
"orsal vessel
main heart/
entral vessels Auxiliary hearts
() A closed circulatory system
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!losed systems – Are more efficient at trans!orting circulatory fluids to
tissues and cells
• )umans and other verte#rates have a closedcirculatory system – 1ften called the cardiovascular system
• -lood flows in a closed cardiovascular system – Consisting of #lood vessels and a two3 to four3
cham#ered heart
• Arteries carry #lood to ca!illaries – The sites of chemical exchange #etween the #lood
and interstitial fluid
• eins
– +eturn #lood from ca!illaries to the heart
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• A fish heart has two main cham#ers
– 1ne ventricle and one atrium
– -lood !um!ed from the ventricle
• Travels to the gills% where it !ics u! 12 and dis!oses of
C12
• Frogs and other am!hi#ians
– )ave a three3cham#ered heart% with two atria andone ventricle
– The ventricle !um!s #lood into a fored artery
• That s!lits the ventricle4s out!ut into the !ulmocutaneouscircuit and the systemic circuit
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• +e!tiles have dou#le circulation – 5ith a !ulmonary circuit lungs/ and a systemic
circuit
– Turtles% snaes% and li'ards• )ave a three3cham#ered heart
• In all mammals and #irds – The ventricle is com!letely divided into se!arate
right and left cham#ers
– The left side of the heart !um!s and receives onlyoxygen3rich #lood
•5hile the right side receives and !um!s only oxygen3!oor #lood
• A !owerful four3cham#ered heart – 5as an essential ada!tation of the endothermic way
of life characteristic of mammals and #irds
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F"#$E# A%&$"'"A# E&T"*E# (E+!E&T '",#) %A%%A*# A, '",#
(ystemic ca!illaries (ystemic ca!illaries (ystemic ca!illaries (ystemic ca!illaries
0ung ca!illaries 0ung ca!illaries0ung and sin ca!illaries6ill ca!illaries
+ight 0eft +ight 0eft +ight 0eft
#ystemic
circuit#ystemic
circuit
&ulmocutaneous
circuit
&ulmonary
circuit&ulmonary
circuit
#ystemic
circulationein
Atrium A/
)eart,
ventricle /
Artery -ill
circulation
A
A A A A A
0eft
(ystemic
aorta
+ight
systemic
aorta
Figure 42.4
• erte#rate circulatory systems
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• All #lood vessels
– Are #uilt of similar tissues
– )ave three similar layers
Figure 42.
Artery ein
788 9m
Artery /ein
Arteriole/enule
Connective
tissue
(mooth
muscle
Endothelium
Connective
tissue
(mooth
muscle
Endothelium
alve
Endothelium
-asement
mem#rane
Ca!illary
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• (tructural differences in arteries% veins% and ca!illaries – Correlate with their different functions
• Arteries have thicer walls – To accommodate the high !ressure of #lood !um!ed from the heart
• In the thinner3walled veins – -lood flows #ac to the heart mainly as a result of muscle action
Figure 42.01
"irection of #lood flow
in vein toward heart/alve o!en/
(eletal muscle
alve closed/
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• The velocity of #lood flow varies in the
circulatory system
– And is slowest in the ca!illary #eds as a result of thehigh resistance and large total cross3sectional area
Figure 42.00
:%888
;%888
s e c /
A r e a . c m 2 /
(ystolic
!ressure
"iastolic
!ressure
:8
;8
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-lood =ressure
• -lood !ressure
– Is the hydrostatic !ressure that #lood exerts against the wallof a vessel
• (ystolic !ressure – Is the !ressure in the arteries during ventricular systole
– Is the highest !ressure in the arteries
• "iastolic !ressure – Is the !ressure in the arteries during diastole
– Is lower than systolic !ressure
• -lood !ressure is determined !artly #y cardiac out!ut – And !artly #y !eri!heral resistance due to varia#le
constriction of the arterioles
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• -lood !ressure
– Can #e easily measured in humans
Figure 42.02
Artery
+u##er cuff
inflatedwith air
Artery
closed
728 728
=ressure
in cuff
a#ove 728
=ressure
in cuff#elow 728
=ressure
in cuff
#elow 8
(ounds
audi#le in
stethosco!e
(ounds
sto!
'lood pressure
reading 0211
A ty!ical #lood !ressure reading for a 283year3oldis 728>8. The units for these num#ers are mm of
mercury )g/B a #lood !ressure of 728 is a force thatcan su!!ort a column of mercury 728 mm high.
0
A s!hygmomanometer% an inflata#le cuff attached to a
!ressure gauge% measures #lood !ressure in an artery.
The cuff is wra!!ed around the u!!er arm and inflated
until the !ressure closes the artery% so that no #loodflows !ast the cuff. 5hen this occurs% the !ressure
exerted #y the cuff exceeds the !ressure in the artery.
2 A stethosco!e is used to listen for sounds of #lood flow
#elow the cuff. If the artery is closed% there is no !ulse
#elow the cuff. The cuff is gradually deflated until #lood
#egins to flow into the forearm% and sounds from #lood!ulsing into the artery #elow the cuff can #e heard with
the stethosco!e. This occurs when the #lood !ressure
is greater than the !ressure exerted #y the cuff. The
!ressure at this !oint is the systolic !ressure.
3
The cuff is loosened further until the #lood flows freely through the artery and the sounds #elow the cuffdisa!!ear. The !ressure at this !oint is the diastolic
!ressure remaining in the artery when the heart is relaxed.
4
8
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Ca!illary Function
• Ca!illaries in ma*or organs are usually filled toca!acity
– -ut in many other sites% the #lood su!!ly varies
• Two mechanisms – +egulate the distri#ution of #lood in ca!illary #eds
• In one mechanism
– Contraction of the smooth muscle layer in the wallof an arteriole constricts the vessel
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• In a second mechanism
– =reca!illary s!hincters control the flow of
#lood #etween arterioles and venules
Figure 42.03 ac
=reca!illary s!hincters Thoroughfare
channel
ArterioleCa!illaries
enule(a) #phincters rela6ed
() #phincters contracted
enule Arteriole
(c) !apillaries and larger vessels (#E%)
28 µm
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• The difference #etween #lood !ressure
and osmotic !ressure
– "rives fluids out of ca!illaries at the arterioleend and into ca!illaries at the venule end
At the arterial end of a
ca!illary% #lood !ressure isgreater than osmotic !ressure%
and fluid flows out of the
ca!illary into the interstitial fluid.
Ca!illary +ed
#lood
cell
7: µm
Tissue cell ITE+(TITIA0 F0DI"
Ca!illary
et fluid
movement out
et fluid
movement in
"irection of
#lood flow
-lood !ressure
1smotic !ressure
Inward flow
1utward flow
= r e s s u r e
Arterial end of ca!illary enule end
At the venule end of a ca!illary%
#lood !ressure is less than
osmotic !ressure% and fluid flows
from the interstitial fluid into theca!illary.
Figure 42.04
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Fluid +eturn #y the 0ym!hatic
(ystem• The lym!hatic system
– +eturns fluid to the #ody from the ca!illary#eds
– Aids in #ody defense• Fluid reenters the circulation
– "irectly at the venous end of the ca!illary #ed
and indirectly through the lym!hatic system
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-lood Com!osition and
Function• -lood is a connective tissue with cells
sus!ended in !lasma• -lood in the circulatory systems of verte#rates
– Is a s!eciali'ed connective tissue
• -lood consists of several inds of cells – (us!ended in a li&uid matrix called !lasma
• The cellular elements – 1ccu!y a#out ;: of the volume of #lood
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Plasma
• -lood !lasma is a#out 8 water
• Among its many solutes are
– Inorganic salts in the form of dissolved ions%
sometimes referred to as electrolytes
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• The com!osition of mammalian !lasma
&lasma 557
!onstituent %a8or 9unctions
5ater (olvent for
carrying other
su#stances
(odium
=otassium
Calcium
$agnesium
Chloride
-icar#onat
e
1smotic #alance
!) #uffering% andregulation of
mem#rane
!ermea#ility
Al#umin
Fi#rinogen
Immunoglo#ulins
anti#odies/
=lasma !roteins
Icons #lood electrolytes
1smotic #alance%
!) #uffering
(u#stances trans!orted #y #loodutrients such as glucose% fatty acids% vitamins/
5aste !roducts of meta#olism
+es!iratory gases 12 and C12/
)ormones
"efense
Figure 42.05
(e!arated#lood
elements
Clotting
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• Another im!ortant class of solutes is the
!lasma !roteins – 5hich influence #lood !)% osmotic !ressure%
and viscosity
• arious ty!es of !lasma !roteins
– Function in li!id trans!ort% immunity% and #lood
clotting
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Cellular Elements
• (us!ended in #lood !lasma are two classesof cells
– +ed #lood cells% which trans!ort oxygen
– 5hite #lood cells% which function in defense
• A third cellular element% !latelets
– Are fragments of cells that are involved in
clotting
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Figure 42.05
!ellular elements 457
!ell type umer
!er µ0 mm
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• +ed #lood cells% or erythrocytes
– Are #y far the most numerous #lood cells
– Trans!ort oxygen throughout the #ody
• The #lood contains five ma*or ty!es of white
#lood cells% or leuocytes
– $onocytes% neutro!hils% #aso!hils% eosino!hils% and
lym!hocytes% which function in defense #y
!hagocyti'ing #acteria and de#ris or #y !roducing
anti#odies
• =latelets function in #lood clotting