2.2 Circulation MNR

8/16/2019 2.2 Circulation MNR

1/30

2.2 Circulatory system


2/30

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


3/30

• $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


4/30

Inverte#rate Circulation

• The wide range of inverte#rate #ody si'e

and form

– Is !aralleled #y a great diversity in circulatory

systems


5/30

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


6/30

• (ome cnidarians% such as *ellies

– )ave ela#orate gastrovascular cavities

Figure 42.2

Circular

canal

+adial canal

5 cm$outh


7/30

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/


8/30

• 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


9/30

• 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


10/30

!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


11/30

• 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


12/30

• +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


13/30

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


14/30

• 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


15/30

• (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/


16/30

• 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


17/30

-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


18/30

• -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


19/30

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


20/30

• 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


21/30

• 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


22/30

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


23/30

-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


24/30


25/30

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


26/30

• 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


27/30

• 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


28/30

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


29/30

Figure 42.05

!ellular elements 457

!ell type umer

!er µ0 mm


30/30

• +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

2.2 Circulation MNR

Documents

Transcript of 2.2 Circulation MNR