Circulatory and Gas Exchange Systems

1
How long can you hold your breath?
Brett LaMaster - constant ballast free diving
record 266 ft., 2 ½ minutes
Francisco Ferreras (Pipin) - no limits free
diving record 439 ft. two breath record 515
ft, 2 ½ minutes
2
How long can you hold your breath?
Brett LaMaster - constant ballast free diving
record 266 ft., 2 ½ minutes Francisco Ferreras
(Pipin) - no limits free diving record 439 ft.
two breath record 515 ft, 2 ½ minutes Martin
Stepaneck - first person to hold his breath
underwater on purpose gt 8 min his record 8
min. 6 seconds
3
Circulation and Gas Exchange

• Chapter 42

4

• 1 mm rule
• Diffusion is an effective means of
• transporting substances (e.g.,
• gases) only when the distance is
• lt 1 mm

5

• Open circulatory systems greatly increase the
  efficiency of transport of substances within a
  body relative to diffusion

Fig. 42.3
6

• Closed circulatory systems are even more
  efficient than open circulatory systems

Fig. 42.3
7

• In vertebrates Circulatory system gas
  exchange organs cardiovascular system

8

• Fish have 2-chambered hearts

A single circuit with 2 sets of capillaries,
which limits the maximum aerobic metabolic rates
of fishes
Fig. 42.4
9

• Fish have 2-chambered hearts

Gill capillaries are the sites of gas exchange
with the environment
Fig. 42.21
10

• Fish have 2-chambered hearts

Counter-current exchange helps maximize the
efficiency of gas exchange
Fig. 42.21
11

• Fish have 2-chambered hearts

Counter-current exchange helps maximize the
efficiency of gas exchange
Fig. 42.21
12

• Amphibians have 3-chambered hearts

Three chambers allows for double circulation,
i.e., two circuits, such that blood passes
through a single set of capillaries in each
round-trip from and back to the heart
Fig. 42.4
13

• Amphibians have 3-chambered hearts

In most amphibian larvae, the capillaries of the
pulmocutaneous circuit are found in gills
Fig. 42.4
14

• Amphibians have 3-chambered hearts

However, most adult amphibians exchange gases
through lungs and their skin
Fig. 42.4
15

• Mammals have 4-chambered hearts

Fig. 42.4
16
Systemic
Pulmonary
Systemic
Fig. 42.5
17
Heart valves prevent backflow of blood
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Fig. 42.6
19
The Cardiac Cycle
The pacemaker (sinoatrial node) sets the tempo of
the heartbeat
Fig. 42.8
20
The Cardiac Cycle
The signals spread through the atria, but are
delayed at the atrioventricular node
Fig. 42.8
21
The Cardiac Cycle
The signals are then conveyed via Purkinje fibers
to the apex of the heart
Fig. 42.8
22
The Cardiac Cycle
A wave of contraction across the ventricles ensues
Fig. 42.8
23
The Cardiac Cycle
During atrial and ventricular diastole, the whole
heart is relaxed
Fig. 42.7
24
The Cardiac Cycle
Atrial systole follows, in which the atria
contract
Fig. 42.7
25
The Cardiac Cycle
Ventricular systole follows, in which the
ventricles contract
Fig. 42.7
26
Heart rate (pulse)

• Nervous system and hormones control the
  pacemakers rhythm
• Resting pulse is around 70 beats per minute
• Strenuous activity or stress can raise the pulse
  to 170 or more

27
Measuring blood pressure
Blood pressure is measured by two values
Systolic pressure during ventricular
contractions Diastolic pressure between
ventricular contractions
Fig. 42.12
28
Measuring blood pressure
The cuff is inflated to stop blood flow in the arm
Fig. 42.12
29
Measuring blood pressure
Pressure is released from the cuff until blood
flow is just audible below the cuff blood passes
through the cuff only at highest pressure
(systolic pressure)
Fig. 42.12
30
Measuring blood pressure
Further pressure is released from the cuff until
blood flow is continuous and no longer audible
(diastolic pressure)
Fig. 42.12
31
Blood flows out of and away from the ventricular
chambers via arteries
Fig. 42.9
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Arteries have thick walls whose elasticity helps
keep blood moving
Fig. 42.9
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Arteries branch into arterioles
Fig. 42.9
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Arterioles branch into capillaries
Fig. 42.9
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Gas exchange occurs across capillaries, whose
walls are one cell thick
Fig. 42.9
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Gas exchange occurs across capillaries, whose
walls are one cell thick
We have 50,000 miles of them
Few human cells are gt 100 µm from a capillary
Red blood cells
Capillary wall
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Capillaries connect to venules
Fig. 42.9
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Venules connect to veins
Fig. 42.9
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Veins have valves that help prevent backflow
Fig. 42.9
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What is blood?

• Blood is the fluid that carries nutrients, gases,
  hormones and wastes around the body
• Blood consists of
• plasma (the liquid part) 55 of volume
• cellular components 45 of volume(red blood
  cells, white blood cells, platelets)
• Average adult human has 5 to 6 L of blood (about
  8 of body mass)

41
What is blood?
Plasma is a straw-colored liquid that contains
dissolved proteins, salts, minerals, and hormones
42
What is blood?
Red blood cells
White blood cells
Platelets
43
What is blood?
Red blood cells erythrocytes
These are the most numerous cells in the blood
Their dimpled shape gives them extra surface area
They are packed full of the pigment hemoglobin
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What is blood?
Hemoglobin
Four subunit polypeptide chains
Each subunit polypeptide chain has an iron-rich
heme group
Each heme group can reversibly bind one O2
molecule
45
What is blood?
Hemoglobin
Carries 70 times more O2 than dissolves in the
plasma
Also carries CO2, but with much less affinity
than for O2
46
What is blood?
Red blood cells erythrocytes
Produced in the bone marrow
Live 120 days
Dead and damaged cells are removed from
circulation by the liver and spleen
47
What is blood?
White blood cells ? 5 types of leukocytes
Produced by the bone marrow
Collective function is to fight infection
Fig. 42.16
48
What is blood?
Platelets
Fragments that bud off of larger cells in the
bone marrow
They are especially valuable in the clotting
response
A clot forms as platelets, RBCs, and a fibrin
network stick together
49
The lymphatic system
Capillaries are leaky, and much fluid passes out
of them into the interstitial spaces
Fig. 43.5
50
The lymphatic system
The fluid is taken up by lymph capillaries, at
which point the fluid is referred to as lymph
Fig. 43.5
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The lymphatic system
Lymph vessels are valved and empty into main
veins of the circulatory system
Fig. 43.5
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The lymphatic system
Lymphocytes are also important components of
lymph
Fig. 43.5
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The lymphatic system
Lymphocyte-rich nodes help filter the lymph and
serve as sites of attack on microbial invaders
Fig. 43.5
54
The lymphatic system
Structures labeled in the figure are especially
active traps of microbial invaders
Fig. 43.5
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The lymphatic system
Lymphocytes develop in the thymus and bone marrow
Fig. 43.5
56
Elephantiasis caused by a parasitic worm,
most common in parts of Africa, reduces the
lymphatic systems ability to take up fluids
that leak out of capillaries
The lymphatic system
Just like other organ systems, the lymphatic
system can malfunction
57
The respiratory system
Each lung contains 2 million alveoli, with a
total surface area of 75 m2
Fig. 42.23
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The respiratory system
Alveoli have thin, moist walls and are surrounded
by capillaries
Fig. 42.23
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The respiratory system
Oxygen diffuses from the air in the air spaces of
the alveoli into the blood of the capillaries
Fig. 42.23
60
The respiratory system
Carbon dioxide diffuses from the blood of the
capillaries into the air of the air spaces of the
alveoli
Fig. 42.23
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The respiratory system
When the diaphragm contracts, the chest cavity
expands, and the lungs fill with air
Fig. 42.23
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The respiratory system
When the diaphragm contracts, the chest cavity
expands, and the lungs fill with air
Fig. 42.24
63
Birds have especially efficient respiratory
systems
When a bird inhales, some of the air passes
through its lungs and some fills its air sacs
Fig. 42.25
64
Birds have especially efficient respiratory
systems
When a bird exhales, air continues to move in the
same direction through the lungs, as the air
sacs empty
Fig. 42.25
65
Birds have especially efficient respiratory
systems
The microscopic, tube-like chambers of gas
exchange in bird lungs are known as parabronchi
Fig. 42.25
66
Cardiovascular diseases
Disorders of the heart and blood vessels
Leading causes of death in the USA ( 1 million
people each yr)
Hypertension (high blood pressure), often caused
by constriction of the arteries and arterioles,
can strain the heart
Hypertension often results from plaque buildup
67
Plaques are thickened artery and arteriole walls
smooth muscle infiltrated by lipids (especially
low-density lipoproteins, LDLs, the bad
cholesterols)
Cardiovascular diseases
68
Atherosclerosis is the condition in which plaques
impair circulationArteriosclerosis is a more
advanced condition in which plaques become
hardened by calciumdeposits
Cardiovascular diseases
69
Plaques are often sites of clotting within
vessels thrombus (clot formed found at the
site of blockage) or embolus (clot transported
within the blood to its site of blockage)
Cardiovascular diseases
70
Restricted blood flow within the coronary
arteries (which deliver blood to heart tissues)
may cause chest pains (angina)
Cardiovascular diseases
71
Blockage from a thrombus or embolus of coronary
arteries is one cause of heart attack
Cardiovascular diseases
A similar blockage in the brain is a cause of
stroke
72
Exercise, low-fat diet, and abstinence from
smoking and alcohol abuse all promote a healthy
heart
Cardiovascular diseases
73
A gratuitous public-service announcement
Smoking and health
Nicotine in tobacco smoke is a powerfully
addictive drug
74
Smoking and health
Each yr 430,000 people die in the U.S. from
smoking related diseases
Principal causes of death are lung cancer,
emphysema, chronic bronchitis, heart disease,
strokes, and other cancers
Smoking costs U.S. tax payers about 100 billion
annually in health care for the uninsured and
losses of productivity
75
Smoking and health
Toxins in tobacco smoke inhibit the cilia that
line the respiratory tract so that they cannot
remove particulates
Toxins also impair white blood cells abilities
to combat infectious microbes, which leads to
chronic infections like bronchitis
76
Smoking and health
Emphysema occurs as alveoli become brittle and
rupture, creating holes in the lungs
77
Smoking and health
Carcinogens (cancer-causing agents) in tobacco
smoke accumulate in the lungs
78
Smoking and health
Passive smoking breathing second-hand smoke
Estimated to cause 3,000 deaths from lung disease
and 37,000 deaths from heart disease in
non-smokers in the U.S. each year
79
Smoking and health
Healing begins as soon as someone quits smoking
Risks of lung cancer, heart attack, and other
diseases gradually diminish after someone quits
smoking, so its never too late to quit!