Transport systems in the body
• A circulatory system has
• A circulatory fluid
• A set of interconnecting vessels
• A muscular pump, the heart
• The circulatory system connects the fluid that
surrounds cells with the organs that exchange
gases, absorb nutrients, and dispose of wastes
• Circulatory systems can be open or closed and
vary in the number of circuits in the body
Transport systems in the body
• In insects, other arthropods, and most molluscs,
blood bathes the organs directly in an open
circulatory system
• In an open circulatory system, there is no
distinction between blood and interstitial fluid.
• Open blood system does not play a role in the
transport of gases
Transport systems in the body
• In a closed circulatory system, blood is confined
to vessels and is distinct from the interstitial
fluid
• Closed systems are more efficient at transporting
circulatory fluids to tissues and cells
• Vertebrates have closed circulatory systems
Figure 42.3
(a) An open circulatory system
(b) A closed circulatory system
Heart
Heart
Interstitial fluid
Hemolymph in sinuses
surrounding organs
Pores
Blood
Small branch
vessels in
each organ
Dorsal
Auxiliary
vessel
hearts
(main heart)
Tubular heart
Ventral vessels
The Structure of the Heart
aorta
The heart is a powerful
muscle that is situated
between your lungs,
protected by the ribcage.
pulmonary
artery (left)
aortic valve
left
pulmonary
veins
The heart pumps blood to
the lungs to get oxygen.
The heart pumps the
oxygenated blood to the
rest of the body.
right atrium
left atrium
left ventricle
right ventricle
How the Heart Works
Click to go through each
stage of the process.
right atrium
right ventricle
pulmonic valve
pulmonary artery (left)
left pulmonary veins
left atrium
left ventricle
aortic valve
aorta
Heart valves
https://www.youtube.com/watch?v=qmpd82mpVO4
What Blood Vessels Do
Arteries – carries oxygenated blood away from the heart
Capillaries – enable exchange of oxygen with body
Veins – carries blood from capillaries back to the heart to be pumped to the
lungs to be re-oxygenated.
capillaries
artery
vein
Blood Vessels
Blood Vessels
• In arteries the muscular wall is much thicker than in veins due to blood
pressure
• Blood can move against gravity in veins due to semilunar valves
• The lumen (cavity) of a vein is much bigger than an arteries
• Walls of the capillaries consist of endothelium only.
Blood Vessel Structure and
Function
• A vessel’s cavity is called the central lumen
• The epithelial layer that lines blood vessels is
called the endothelium
• The endothelium is smooth and minimizes
resistance
© 2011 Pearson Education, Inc.
Figure 42.10
Vein
LM
Artery
Red blood cells
100 m
Valve
Basal lamina
Endothelium
Endothelium
Smooth
muscle
Connective
tissue
Capillary
Smooth
muscle
Connective
tissue
Artery
Vein
Capillary
15 m
Red blood cell
Venule
LM
Arteriole
Figure 42.10a
Valve
Basal lamina
Endothelium
Smooth
muscle
Connective
tissue
Endothelium
Capillary
Smooth
muscle
Connective
tissue
Artery
Vein
Arteriole
Venule
Figure 42.10b
Vein
LM
Artery
Red blood cells
100 m
Capillary
LM
Red blood cell
15 m
Figure 42.10c
• Capillaries have thin walls, the endothelium
plus its basal lamina, to facilitate the exchange
of materials
• Arteries and veins have an endothelium, smooth
muscle, and connective tissue
• Arteries have thicker walls than veins to
accommodate the high pressure of blood
pumped from the heart
• In the thinner-walled veins, blood flows back to
the heart mainly as a result of muscle action
© 2011 Pearson Education, Inc.
Blood Flow Velocity
• Physical laws governing movement of fluids
through pipes affect blood flow and blood
pressure
• Velocity of blood flow is slowest in the capillary
beds, as a result of the high resistance and large
total cross-sectional area
• Blood flow in capillaries is necessarily slow for
exchange of materials
© 2011 Pearson Education, Inc.
Blood Pressure
• Blood flows from areas of higher pressure to
areas of lower pressure
• Blood pressure is the pressure that blood exerts
against the wall of a vessel
• In rigid vessels blood pressure is maintained; less
rigid vessels deform and blood pressure is lost
© 2011 Pearson Education, Inc.
• The heart contracts and relaxes in a rhythmic
cycle called the cardiac cycle
• The contraction, or pumping, phase is called
systole
• The relaxation, or filling, phase is called
diastole
© 2011 Pearson Education, Inc.
Figure 42.8-1
1 Atrial and
ventricular diastole
0.4
sec
Figure 42.8-2
2 Atrial systole and ventricular
diastole
1 Atrial and
ventricular diastole
0.1
sec
0.4
sec
Figure 42.8-3
2 Atrial systole and ventricular
diastole
1 Atrial and
ventricular diastole
0.1
sec
0.4
sec
0.3 sec
3 Ventricular systole and atrial
diastole
• The heart rate, also called the pulse, is the
number of beats per minute
• The stroke volume is the amount of blood
pumped in a single contraction
• The cardiac output is the volume of blood
pumped into the systemic circulation per
minute and depends on both the heart rate and
stroke volume
© 2011 Pearson Education, Inc.
• Four valves prevent backflow of blood in the
heart
• The atrioventricular (AV) valves separate each
atrium and ventricle
• The semilunar valves control blood flow to the
aorta and the pulmonary artery
© 2011 Pearson Education, Inc.
Figure 42.9-1
1
SA node
(pacemaker)
ECG
Figure 42.9-2
1
SA node
(pacemaker)
ECG
2
AV
node
Figure 42.9-3
1
SA node
(pacemaker)
ECG
2
AV
node
3
Bundle
branches
Heart
apex
Figure 42.9-4
1
SA node
(pacemaker)
ECG
2
AV
node
3
Bundle
branches
4
Heart
apex
Purkinje
fibers
• Impulses from the SA node travel to the
atrioventricular (AV) node
• At the AV node, the impulses are delayed and
then travel to the Purkinje fibers that make the
ventricles contract
© 2011 Pearson Education, Inc.
• The pacemaker is regulated by two portions of
the nervous system: the sympathetic and
parasympathetic divisions
• The sympathetic division speeds up the
pacemaker
• The parasympathetic division slows down the
pacemaker
• The pacemaker is also regulated by hormones
and temperature
© 2011 Pearson Education, Inc.
The circulatory system carries oxygen,
nutrients, and hormones to cells, and removes
waste products, like carbon dioxide.
Two types of circulation :
Circulation
Pulmonary
Systemic
The pulmonary circulation is the
portion of the circulatory system
which carries:
Pulmonary
circulation
deoxygenated blood away from the
right ventricle, to the lungs,
through the pulmonary artery
and returns oxygenated blood to
the left atrium and ventricle of the
heart through pulmonary vein.
Pulmonary
(Lung)
circulation
Process
Step 1
Heart receives deoxygenated blood from the body.
Step 2
deoxygenated Blood enters through the vena cava
into right atrium.
Step 3
blood moves from right atrium to right ventricle.
Step 4
blood is pumped from right ventricle to lungs
through the pulmonary arteries
Step 5
blood is oxygenated in lungs
Step 6
blood is returned to left atrium heart through
pulmonary veins.
Systemic
circulation
Step 1
Heart receives oxygenated blood from the lungs.
Step 2
Blood enters through the pulmonary veins .
Step 3
blood moves from left atrium to left ventricle.
Step 4
blood is pumped from left ventricle to the body
through the Aorta
Step 5
oxygen is used by body cells for cellular respiration
Step 6
blood is returned to heart through veins