Download Chapter 23: The Circulatory System 8/27/2011 Organs of the Circulatory System

8/27/2011
Chapter 23:
The Circulatory System
1. The Heart
2. The Blood Vessels
3. Blood & Lymph
4. Cardiovascular Health
Organs of the Circulatory System
Heart
pumps the blood
Blood vessels
Blood
veins, arteries, capillaries
red & white blood cells, blood plasma
(we’ll also look at lymph and lymphatic vessels)
Roles of the Circulatory System
• deliver O2, remove CO2
• transport nutrients, wastes, hormones
• regulate temperature & pH
• immune protection (antibodies, white blood cells)
1. The Heart
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left
atrium
right
atrium
The
Human
Heart
semilunar
valve
semilunar
valve
atrioventricular
(AV) valve
atrioventricular
(AV) valve
left
ventricle
right
ventricle
2
1
Semilunar
valves
Heart is
closed
relaxed.
Atria
contract.
The Cardiac
Cycle
0.1 sec
Systole
AV valves
are open.
0.4 sec
0.3 sec
3
Ventricles
contract.
Semilunar
valves
are open.
Diastole
AV valves
closed
Control of the Heartbeat
The synchronous contraction of cardiac muscle cells is
controlled by the sinoatrial (SA) & atrioventricular (AV) nodes.
1 Signals from the
SA node spread
through the atria.
SA node
(pacemaker)
2
Signals are
delayed at the
AV node.
AV node
3
Specialized muscle
fibers pass signals
to the heart apex.
4 Signals spread
throughout the
ventricles.
Specialized
muscle fibers
Right
atrium
Apex
ECG
• ea beat starts at the SA node
atrial contraction
• signal spreads to AV node, ventricles
ventricular contraction
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superior
vena cava
capillaries of
head, chest, and arms
8
pulmonary
artery
pulmonary
artery
aorta
9
capillaries
of right lung
2
capillaries
of left lung
7
2
3
3
5
4
10
pulmonary
vein
4
right atrium
pulmonary
vein
6
1
9
left atrium
left ventricle
right ventricle
aorta
inferior
vena cava
Blood Circulation
8
capillaries of
abdominal region
and legs
2. The Blood Vessels
Blood Vasculature
Arteries, arterioles:
• conduct blood flow away
from the heart
• usually oxygenated blood
Veins, venules:
• conduct blood flow toward
the heart
• usu. deoxygenated blood
Capillaries:
• smallest vessels
• where “exchange” occurs
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Types of Blood Vessels
Epithelium
Capillary
Basal lamina
Valve
Epithelium
Epithelium
Smooth
muscle
Connective
tissue
Smooth
muscle
Connective
tissue
Artery
Vein
Venule
Arteriole
Capillaries
Red
blood
cell
Capillary
Nuclei of
smooth
muscle
cells
• allows diffusion of gases
(O2, CO2), nutrients, and
wastes between blood &
tissues
Capillary
Interstitial
fluid
Tissue
cell
Unlike larger vessels,
capillary walls are only
1 cell thick, barely wide
enough for RBCs to
pass through
Diffusion of
molecules
• some fluid (plasma)
“leaks out” as well
3. Blood and Lymph
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What does Blood consist of?
Plasma (55%)
Constituent
Major functions
Water
Solvent for
carrying other
substances
Ions (blood electrolytes)
Sodium
Potassium
Calcium
Magnesium
Chloride
Bicarbonate
Plasma proteins
Osmotic balance,
pH buffering, and
maintaining ion
concentration of
interstitial fluid
Cellular elements (45%)
Cell type
Centrifuged
blood
sample
Red blood cells
(erythrocytes)
White blood cells
(leukocytes)
Osmotic balance
and pH buffering
Fibrinogen
Clotting
Immunoglobulins
(antibodies)
Defense
Number
per L (mm3) of blood)
Functions
5–6 million
Transport of
O2 and
some CO2
5,000–10,000
Defense
and immunity
Lymphocytes
Basophils
Eosinophils
Substances transported by blood
Nutrients (e.g., glucose, fatty acids, vitamins)
Waste products of metabolism
Respiratory gases (O2 and CO2)
Hormones
Monocytes
Neutrophils
Platelets
250,000–
400,000
Blood clotting
Where do Blood Cells come from?
Multipotent
stem cells
(in bone marrow)
Lymphoid
stem cells
Myeloid
stem cells
Basophils
Erythrocytes
Platelets
Lymphocytes
Eosinophils
Monocytes
Neutrophils
Oxygen Transport
Oxygen is transported by red
blood cells (RBCs)
• aka erythrocytes
• don’t have a nucleus!
• vast majority of blood cells
(~99%) are RBCs
Oxygen binds to
hemoglobin in RBCs
• each hemoglobin
molecule binds 8 O2
• vast majority of protein
in RBCs is hemoglobin
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The Lymphatic System
A vascular system distinct
from the circulatory system
• conducts fluid “leaked” from
the blood called lymph
• returned to blood at vena cava
• lymph is filtered through
structures called lymph nodes
• full of immune cells, important
part of the immune response
• also transports fats from
digestion in small intestine
Lymphatic Vessels
Fluid leaked from
capillaries is taken
up by “lymph
capillaries”
• lymph is conducted into
larger lymphatic vessels
• lymph passes through
lymph nodes before being
“dumped” into the blood
at the vena cava
4. Cardiovascular Health
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Pressure (mm Hg)
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120
100
80
60
40
20
0
Systolic
pressure
Blood
Pressure
Diastolic
pressure
Relative sizes and
numbers
blood
of bloodTypical
pressure
vessels 120 systolic
Veins
Venules
Arterioles
Capillaries
Artery
closed
Venae cavae
1
Pressure
in cuff
at 70
Pressure
in cuff
at 120
120
70
Arteries
Artery
Pressure
in cuff
above 120
120
Rubber cuff
inflated
with air
Aorta
Velocity (cm/sec)
70 diastolic
50
40
30
20
10
0
2
Sounds
audible in
stethoscope
3
Sounds
stop
4
Artificial Pacemakers
Wire
leading
to SA node
Artificial
pacemaker
Heart
Coronary Arteries & Heart Attacks
Superior
vena cava
Pulmonary
artery
Right
coronary
artery
Aorta
Left
coronary
artery
Blockage
Dead
muscle
tissue
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Key Terms for Chapter 23
• atrium, ventricle, aorta, vena cava
• sinoatrial, atrioventricular nodes
• hemoglobin, white blood cells, platelets, plasma
• arteries, arterioles, veins, venules, capillaries
• lymph, lymph nodes
• stem cell, heart attack
Relevant Review Questions:
1, 2, 4, 5
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