Transcript How Does Gravity Affect Blood Circulation?

BIOLOGY
CONCEPTS & CONNECTIONS
Fourth Edition
Neil A. Campbell • Jane B. Reece • Lawrence G. Mitchell • Martha R. Taylor
CHAPTER 23
Circulation
Modules 23.1 – 23.3
From PowerPoint® Lectures for Biology: Concepts & Connections
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How Does Gravity Affect Blood Circulation?
• As with all land animals, the giraffe and the
corn snake are constantly subject to the force of
gravity
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• The circulatory system
keeps blood pumping
despite gravity’s pull
– Muscle contractions help
blood travel uphill in the
veins of a giraffe’s long
legs
– The wriggling of the corn
snake squeezes its veins
and increases circulation
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• Most animals have a circulatory system
– It transports O2 and nutrients to cells
– It takes away CO2 and other wastes
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
23.1 The circulatory system associates intimately
with all body tissues
• Capillaries are microscopic blood vessels
– They form an intricate network among the tissue
cells
Capillary
Red
blood
cell
Figure 23.1A
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– No substance has to diffuse far to enter or leave
a cell
Capillary
INTERSTITIAL
FLUID
Diffusion of
molecules
Tissue
cell
Figure 23.1B
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MECHANISMS OF INTERNAL TRANSPORT
23.2 Several types of internal transport have
evolved in animals
• In cnidarians and
flatworms, the
gastrovascular cavity
functions in both
– digestion
– internal transport
Mouth
Circular
canal
Figure 23.2A
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• Most animals have a separate circulatory
system, either open or closed
• Open systems
– A heart pumps blood through open-ended
vessels into spaces between cells
Tubular heart
Pores
Figure 23.2B
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• Closed systems
– A heart pumps blood through arteries and
capillary beds
– The blood returns to the heart via veins
Capillary beds
Arteriole
Artery
(O2-rich blood)
Venule
Vein
Atrium
Gill
capillaries
Artery
Ventricle
(O2-poor blood)
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Heart
Figure 23.2C
23.3 Vertebrate cardiovascular systems reflect
evolution
Gill capillaries
• A fish has a single
circuit of blood flow
Heart:
Ventricle (V)
Atrium (A)
Systemic capillaries
Figure 23.3A
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• The cardiovascular system of land vertebrates
has two circuits
Lung capillaries
• The pulmonary circuit
– conveys blood between
the heart and gasexchange tissues
PULMONARY
CIRCUIT
A
• The systemic circuit
– carries blood between
the heart and the rest
of the body
A
V
Right
V
Left
SYSTEMIC
CIRCUIT
Systemic capillaries
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Figure 23.3B