Circulatory Systems

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Circulatory Systems
In humans, blood returning to the
heart from the lungs returns to:
1.
2.
3.
4.
5.
the right ventricle.
the right atrium.
the left ventricle.
the left atrium.
both the left and
right sides of the
heart.
70%
30%
0%
1
0%
2
3
0%
4
5
Systole refers to the contraction of the:
1. major arteries.
2. SA node.
3. atria and
ventricles.
4. left atrium.
5. aorta.
82%
9%
9%
0%
1
2
3
4
0%
5
Mammals, birds and ______ have four
chambered hearts.
1. fish and sharks
2. snakes and lizards
3. alligators and
lizards
4. crocodiles an
alligators
5. salamanders and
lizards
64%
27%
9%
0%
1
0%
2
3
4
5
Exchange of materials
• Animal cells exchange material across their
cell membrane
– fuels for energy
– nutrients
– oxygen
– waste (urea, CO2)
• If you are a 1-cell organism that’s easy!
– diffusion
• If you are many-celled that’s harder
Overcoming limitations of diffusion
Minimizes the distance that
substances must diffuse
CO2
CO2
aa
aa
CO2
CHO
NH3
O2
NH3
CH
aa
aa
CO2
NH3
CO2
CO2
NH3
NH3
CO2
CH
NH3
NH3
CO2
CHO
O2
CO2
CO2
O2
CH
aa
O2
NH3
NH3
CHO
CO2
aa
Open and closed circulatory systems differ
in the size of the hearts used to pump
blood.
1. True
2. False
50%
1
50%
2
Animal Circulatory Systems
• All animals have:
– circulatory fluid = “blood”
– tubes = blood vessels
– muscular pump = heart
open
hemolymph
closed
blood
Open circulatory system
• invertebrates
• insects,
arthropods,
mollusks
• Structure
– no separation
between blood &
interstitial fluid
• hemolymph
Closed circulatory system
• Invertebrates
• earthworms, squid,
octopuses
• Vertebrates
• Structure
– blood confined to vessels &
separate from interstitial
fluid
• 1 or more hearts
• large vessels to smaller
vessels
• material diffuses between
blood vessels &
interstitial fluid
closed system = higher pressures
Vertebrate circulatory system
• Adaptations in closed system
– number of heart chambers differs
2
low
pressure
to body
3
4
low O2
to
body
high
pressure
& high O2
to body
What’s the adaptive value of a 4 chamber heart?
4 chamber heart is double pump = separates oxygen-rich & oxygen-poor
blood; maintains high pressure
Evolution of vertebrate circulatory system
fish
2 chamber
V
amphibian
3 chamber
A
A
A
V
reptiles
3 chamber
A
V
A
V
birds & mammals
4 chamber
A
V
A
V
In which animal does aortic blood have less
oxygen than blood in the pulmonary vein?
1.
2.
3.
4.
5.
frog
chicken
monkey
fish
human
50%
50%
0%
1
2
0%
3
0%
4
5
Evolution of 4-chambered heart
• Selective forces
– increase body size
• protection from predation
• bigger body = bigger stomach for herbivores
– endothermy
• can colonize more habitats
– flight
• decrease predation & increase prey capture
• Effect of higher metabolic rate
– greater need for energy, fuels, O2, waste
removal
• endothermic animals need 10x energy
• need to deliver 10x fuel & O2 to cells
convergent
evolution
Vertebrate cardiovascular system
• Chambered heart
– atrium = receive blood
– ventricle = pump blood out
• Blood vessels
– arteries = carry blood away from heart
• arterioles
– veins = return blood to heart
• venules
– capillaries = thin wall, exchange / diffusion
• capillary beds = networks of capillaries
In a one-circuit pathway, blood pressure:
cc
no
to
s
oe
...
n
ur
i
h
r ic
O
2
D
th
e
d
bl
oo
in
th
e
in
rin
gs
B
er
...
tin
.
te
s
af
...
tly
an
ifi
c
hi
gh
Is
s
si
gn
nt
th
ro
u
gh
ou
...
.
0% 0%
ro
p
E.
17%
D
D.
33%
ns
ta
C.
50%
co
B.
Is constant throughout the
system
Drops significantly after
gas exchange has taken
place
Is higher in the intestinal
capillaries than at the gill
capillaries
Brings O2 rich blood
directly to the heart
Does not occur in the
animal kingdom
Is
A.
Mammalian Blood Flow
Blood vessels
arteries
veins
artery
venules
arterioles
arterioles
capillaries
venules
veins
Arteries: Built for high pressure pump
• Arteries
– thicker walls
• provide strength for high pressure
pumping of blood
– narrower diameter
– elasticity
• elastic recoil helps
maintain blood
pressure even
when heart relaxes
Veins: Built for low pressure flow
• Veins
– thinner-walled
– wider diameter
Blood flows
toward heart
Open valve
• blood travels back to heart
at low velocity & pressure
• lower pressure
– distant from heart
– blood must flow by skeletal muscle contractions
when we move
Closed valve
» squeeze blood through veins
– valves
• in larger veins one-way valves
allow blood to flow only toward heart
Capillaries: Built for exchange
• Capillaries
– very thin walls
• lack 2 outer wall layers
• only endothelium
– enhances exchange across
capillary
– diffusion
• exchange between blood &
cells
Controlling blood flow to tissues
• Blood flow in capillaries controlled by
pre-capillary sphincters
• supply varies as blood is needed
• after a meal, blood supply to digestive tract increases
• during strenuous exercise, blood is diverted from digestive tract to
skeletal muscles
– capillaries in brain, heart, kidneys & liver usually filled to
capacity
sphincters open
sphincters closed
Exchange across capillary walls
Fluid & solutes flows out
of capillaries to tissues
due to blood pressure
Lymphatic
capillary
Interstitial fluid flows
back into capillaries
due to osmosis
 plasma proteins  osmotic
• “bulk flow”
pressure in capillary
BP > OP
BP < OP
Interstitial
fluid
Blood
flow
85% fluid returns
to capillaries
Capillary
Arteriole
15% fluid returns
via lymph
Venule
Mammalian
circulation
systemic
pulmonary
systemic
Mammalian heart
to neck & head
& arms
Coronary arteries
Coronary arteries
bypass surgery
Heart valves
• 4 valves in the heart
– flaps of connective tissue
– prevent backflow
SL
• Atrioventricular (AV) valve
– between atrium & ventricle
– keeps blood from flowing back
into atria when ventricles contract
• “lub”
• Semilunar valves
– between ventricle & arteries
– prevent backflow from arteries into
ventricles while they are relaxing
• “dupp”
AV
AV
Lub-dupp, lub-dupp
• Heart sounds
– closing of valves
– “Lub”
SL
• recoil of blood against
closed AV valves
– “Dupp”
AV
AV
• recoil of blood against
semilunar valves
• Heart murmur
– defect in valves causes hissing sound when stream of
blood squirts backward through valve
Cardiac cycle
• 1 complete sequence of pumping
– heart contracts & pumps
– heart relaxes & chambers fill
– contraction phase
• systole
• ventricles pumps blood out
– relaxation phase
• diastole
• atria refill with blood
systolic
________
diastolic
pump
(peak pressure)
_________________
fill (minimum pressure)
110
____
70
Measurement of blood pressure
• High Blood Pressure (hypertension)
– if top number (systolic pumping) > 150
– if bottom number (diastolic filling) > 90
Bloody well ask
some questions, already!
2008-2009
Please make your selection...
1.
2.
3.
4.
5.
Choice One
Choice Two
Choice Three
Choice Four
Choice Five
0%
1
0%
2
0%
0%
3
4
0%
5

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