Transcript Chapter 23


Giraffes have
– Very strong hearts
– Higher blood
pressure
– Sinuses that
function like check
valves to lower
pressure to head
when bending down
– Valves in veins of
legs to keep blood
moving upward
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Blood and respiratory gasses are passed
through which organ system?

Circulatory system

All cells need
– Nutrients
– Gas exchange
– Removal of wastes

Diffusion alone is inadequate for large and
complex bodies
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◦ A gastrovascular cavity in cnidarians and
flatworms serves
– Digestion
– Distribution of substances
◦ Most animals use a circulatory system
– Blood
– Heart
– Blood vessels
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1. Open circulatory systems
– Arthropods and many molluscs
– Heart pumps blood through open-ended vessels
– Cells directly bathed in blood
Tubular heart
Pores
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2. Closed circulatory systems
– Vertebrates, earthworms, squids, octopuses
– Blood stays confined to vessels
– A heart pumps blood through arteries to
capillaries; veins return blood to heart
Arteriole
Capillary beds
Artery
(O2-rich blood)
Venule
Vein
Gill
capillaries
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Artery
(O2-poor blood)
Atrium
Ventricle
Heart
 Land vertebrates have
double circulation
Lung capillaries
– Separate pulmonary
(lung) and systemic
(body) circuits
– Two circuits that do
not mix
–
Right side pumps
blood from body
to lungs
–
Left side pumps
blood from lungs
to body
Pulmonary
circuit
A
V
Right
A
V
Left
Systemic
circuit
Systemic capillaries
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◦Four-chambered hearts
Lung capillaries
– Crocodilians, birds,
mammals
– Two atria and two
ventricles
– Higher blood pressure
– Supports more
efficient movement
of blood
Pulmonary
circuit
A
A
V
V
Left
Right
Systemic
circuit
Systemic capillaries
THE HUMAN
CARDIOVASCULAR
SYSTEM
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8
Superior
vena cava
Capillaries of
head, chest, and
arms
Pulmonary
artery
Pulmonary
artery
Capillaries
of right lung
9
Capillaries
of left lung
Aorta
2
7
2
3
3
4
5
10
4
Pulmonary
vein
Right atrium
6
1
9
Pulmonary
vein
Left atrium
Left ventricle
Right ventricle
Inferior
vena cava
Aorta
8
Capillaries of
abdominal region
and legs
◦ The mammalian heart
– Two thin-walled
atria that
– Pump blood
– To ventricles
– Two thick-walled
ventricles that
– Pump blood
Right
atrium
To lung
To lung
Left atrium
From lung
From lung
Semilunar
valve
Semilunar
valve
Atrioventricular
(AV) valve
Atrioventricula
(AV) valve
– To lungs and all
other body regions
Left
Right
ventricle ventricle
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◦ During diastole,
blood flows
Veins  heart
◦ During systole,
blood flows
Atria  ventricles
1 Heart is
relaxed.
2 Atria
contract.
Semilunar
valves
closed
0.1 sec
Systole
AV valves
are open.
0.3 sec
0.4 sec
Semilunar
valves
are open.
Diastole
AV valves
closed
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3 Ventricles
contract.
◦ Cardiac output
– Amount of blood/minute pumped into systemic circuit
◦ Heart rate
– Number of beats/minute
◦ Heart valves
– Prevent the backflow of blood
◦ Heart murmur
– A defect in one or more heart valves
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◦ The pacemaker (SA node)
– Sets the rate of heart contractions
– Generates electrical signals in atria
◦ The AV node
– Relays these signals to the ventricles
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Pacemaker
(SA node)
AV node
Specialized
muscle fibers
Right
atrium
Apex
1 Pacemaker
generates
signals
to contract
ECG
2 Signals spread
through atria
and are delayed
at AV node
3 Signals relayed
to apex of heart
4 Signals spread
through
ventricle
◦ An electrocardiogram (ECG or EKG)
– Records electrical changes in heart
◦ Heart rate normally adjusts to body needs
◦ Abnormal rhythms may occur in a heart attack
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Heart

A heart attack is damage to cardiac muscle
– Typically from a blocked coronary artery
Superior
vena cava
Pulmonary
artery
Right
coronary
artery
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Aorta
Left
coronary
artery
Blockage
Dead
muscle
tissue

Stroke
– Death of brain tissue from blocked arteries in the
head
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
Atherosclerosis
– Plaques develop inside inner walls of blood vessels
– Plaques narrow blood vessels
– Blood flow is reduced
Connective
tissue
Smooth
muscle Epithelium
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Plaque

Capillaries
– Thin walls—a single layer of epithelial cells
– Narrow—blood cells flow in a single file
– Increase surface area for gas and fluid exchange
Red
blood
cell
Capillary
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Nuclei of
smooth
muscle
cells
Capillary
Interstitial
fluid
Tissue
cell
Diffusion of
molecules
Capillaries allow the transfer of substances
through their walls
◦ Blood and interstitial fluid exchange
substances
– By diffusion
– By pressure flow through clefts between epithelial
cells
◦ Blood pressure forces fluid out of capillaries at
the arterial end
◦ Osmotic pressure draws in fluid at the venous
end
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Tissue cells
Blood
pressure
Interstitial
fluid
Osmotic
pressure
Osmotic
pressure
Arterial
end of
capillary
Net fluid
movement out
Blood
pressure
Net fluid
movement in
Venous
end of
capillary

Arteries and veins
– Lined by single layer of epithelial cells; smooth muscle in
walls
– Veins have one-way valves that restrict backward flow
Epithelium
Epithelium
Smooth
muscle
Connective
tissue
Capillary
Basal lamina
Valve
Epithelium
Smooth
muscle
Connective
tissue
Artery
Vein
Arteriole
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Venule
– Pressure from
muscle contractions
– Squeezes veins
– One-way valves limit
blood flow to one
direction, towards
heart
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Direction of
blood flow
in vein
Valve
(open)
Skeletal
muscle
Valve
(closed)
– Deep Vein Thrombosis (DVT)
– Blood pools deep within body- usually lower leg or thigh
– Clot can form- travel to lungs- pulmonary embolism
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–
–
–
–
–
Maintain healthy weight
Don’t smoke
Stretch or move legs on long flights or car rides
Compression garments
Blood thinners
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◦ Blood pressure
– The force blood exerts on vessel walls
– Depends on
– Cardiac output
– Resistance of vessels
– Decreases as blood moves away from heart
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Pressure (mm Hg)
120
100
80
60
40
20
0
Systolic
pressure
Diastolic
pressure
Venae cavae
Veins
Venules
Capillaries
Arterioles
Arteries
50
40
30
20
10
0
Aorta
Velocity (cm/sec)
Relative sizes and
numbers
of blood
vessels

Blood pressure is
– Highest in ________
– Lowest in _________

Blood pressure is measured as
– Systolic pressure—caused by ventricular contraction
– Diastolic pressure—low pressure between
contractions
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
Hypertension is a serious cardiovascular problem
– Consistent pressures above either
– 140 systolic
– 90 diastolic
Typical blood
pressure
120 systolic
70 diastolic
Pressure
in cuff
above 120
120
Rubber cuff
inflated
with air
Artery
1
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Pressure
in cuff
at 70
Pressure
in cuff
at 120
120
70
Sounds
audible in
stethoscope
Artery
closed
2
3
Sounds
stop
4

Hypertension causes
– Heart to work harder, weakening heart over time
– Increased plaque formation from tiny ruptures
– Increased risk of blood clot formation

Hypertension can cause
– Heart attacks
– Strokes
– Kidney failure
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STRUCTURE
AND FUNCTION
OF BLOOD
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
Plasma is about 90% water

Plasma contains
– Various inorganic ions
– Proteins, nutrients
– Wastes, gases
– Hormones
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Plasma (55%)
Constituent
Major functions
Water
Solvent for
carrying other
substances
Ions (blood electrolytes)
Osmotic balance,
pH buffering, and
maintaining ion
concentration of
interstitial fluid
Sodium
Potassium
Calcium
Magnesium
Chloride
Bicarbonate
Plasma proteins
Osmotic balance
and pH buffering
Fibrinogen
Clotting
Immunoglobulins
(antibodies)
Defense
Substances transported by blood
Nutrients (e.g., glucose, fatty acids, vitamins)
Waste products of metabolism
Respiratory gases (O2 and CO2)
Hormones
Centrifuged
blood
sample
◦ Red blood cells (erythrocytes)
– Transport O2 bound to hemoglobin
◦ White blood cells (leukocytes)
– Function inside and outside the circulatory
system
– Fight infections and cancer
◦ Platelets
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Cellular elements (45%)
Cell type
Functions
Number
3
per µL (mm ) of blood
Erythrocytes
(red blood cells)
5–6 million
Centrifuged
blood
sample
Leukocytes
5,000–10,000
(white blood cells)
Transport of
oxygen (and
carbon dioxide)
Defense and
immunity
Lymphocyte
Basophil
Eosinophil
Monocyte
Neutrophil
Platelets
250,000–
400,000
Blood clotting
Plasma (55%)
Constituent
Major functions
Water
Solvent for
carrying other
substances
Ions (blood electrolytes)
Osmotic balance,
pH buffering, and
maintaining ion
concentration of
interstitial fluid
Sodium
Potassium
Calcium
Magnesium
Chloride
Bicarbonate
Plasma proteins
Cellular elements (45%)
Cell type
Functions
Number
per µL (mm3) of blood
Erythrocytes
(red blood cells)
5–6 million
Centrifuged
blood
sample
Leukocytes
5,000–10,000
(white blood cells)
Transport of
oxygen (and
carbon dioxide)
Defense and
immunity
Osmotic balance
and pH buffering
Fibrinogen
Clotting
Immunoglobulins
(antibodies)
Defense
Substances transported by blood
Nutrients (e.g., glucose, fatty acids, vitamins)
Waste products of metabolism
Respiratory gases (O2 and CO2)
Hormones
Lymphocyte
Basophil
Eosinophil
Neutrophil
Platelets
Monocyte
250,000–
400,000
Blood clotting
◦ Function:
◦ If too few:
– Anemia: abnormally low amounts of hemoglobin
or red blood cells
– Causes fatigue due to lack of oxygen in tissues
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
Function: Clot formation during tissue damage
◦ When a blood vessel is damaged
– Platelets help trigger the conversion of fibrinogen to
fibrin
– Fibrin forms a net with cells (clot) that plugs the
leak
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1
Platelets adhere
to exposed
connective tissue
Epithelium
Connective
tissue
Platelet
1
Platelets adhere
to exposed
connective tissue
2
Platelet plug
forms
Epithelium
Connective
tissue
Platelet
Platelet plug
1
Platelets adhere
to exposed
connective tissue
2
Platelet plug
forms
3
Epithelium
Connective
tissue
Platelet
Platelet plug
Fibrin clot
traps
blood cells