Biology, Seventh Edition
Solomon • Berg • Martin
Chapter 42
Internal Transport
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Biology, Seventh Edition
CHAPTER 42 Internal Transport
• Diffusion
• Small, simple invertebrates
• Sponges, cnidarians, and
flatworms
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CHAPTER 42 Internal Transport
Invertebrates with no circulatory system
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CHAPTER 42 Internal Transport
• Specialized circulatory system
• Larger animals
• Blood
• Heart
• System of blood vessels
• Spaces through which blood
circulates
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Biology, Seventh Edition
CHAPTER 42 Internal Transport
• Interstitial fluid
• Tissue fluid between cells
• Brings oxygen and nutrients into
contact with cells
• All animals
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CHAPTER 42 Internal Transport
• Open circulatory system
• Arthropods and most mollusks
• Blood flows into a hemocoel
• Bathes the tissues directly
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CHAPTER 42 Internal Transport
• Closed circulatory system
• Some invertebrates
• All vertebrates
• Blood flows through a continuous
circuit of blood vessels
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Closed circulatory system
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CHAPTER 42 Internal Transport
Biology, Seventh Edition
CHAPTER 42 Internal Transport
• Vertebrate circulatory system
• Muscular heart
• Arteries
• Capillaries
• Veins
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Biology, Seventh Edition
CHAPTER 42 Internal Transport
• Vertebrate circulatory system
• Transports nutrients, oxygen,
wastes, and hormones
• Helps maintain
–Fluid balance
–Appropriate pH
–Body temperature
• Defends body against disease
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CHAPTER 42 Internal Transport
• Plasma
• Water
• Salts
• Substances in transport
• Plasma proteins
–Albumins
–Globulins
–Fibrinogen
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Biology, Seventh Edition
CHAPTER 42 Internal Transport
Blood components
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Biology, Seventh Edition
CHAPTER 42 Internal Transport
• Red blood cells (erythrocytes)
• Transport oxygen and carbon
dioxide
• Produce large quantities of
hemoglobin
–Red pigment that binds with oxygen
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CHAPTER 42 Internal Transport
• White blood cells (leukocytes)
• Defend the body against disease
organisms
• Agranular white blood cells
–Lymphocytes
–Monocytes
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CHAPTER 42 Internal Transport
• Granular white blood cells
• Neutrophils
• Eosinophils
• Basophils
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CHAPTER 42 Internal Transport
• Platelets
• Patch damaged blood vessels
• Release substances essential for
blood clotting
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CHAPTER 42 Internal Transport
• Blood clotting
• Damaged cells and platelets
release substances that activate
clotting factors
• Prothrombin is converted to
thrombin
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CHAPTER 42 Internal Transport
• Thrombin catalyzes the
conversion of fibrinogen to an
insoluble protein, called fibrin
• Fibrin forms long threads that
form the webbing of the clot
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Blood clotting
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CHAPTER 42 Internal Transport
Biology, Seventh Edition
CHAPTER 42 Internal Transport
• Arteries
• Carry blood away from the heart
• Veins
• Return blood to the heart
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CHAPTER 42 Internal Transport
• Arterioles
• Constrict (vasoconstriction)
• Dilate (vasodilation)
• Regulate blood pressure and
distribution of blood to the tissues
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CHAPTER 42 Internal Transport
• Capillaries
• Thin-walled exchange vessels
through which blood and tissues
exchange materials
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CHAPTER 42 Internal Transport
Blood flow through a capillary network
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CHAPTER 42 Internal Transport
• Vertebrate heart
• One or two atria
–Receive blood
• One or two ventricles
–Pump blood into the arteries
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CHAPTER 42 Internal Transport
• Fish heart
• Single atrium and ventricle
• Part of a single circuit of blood
flow
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CHAPTER 42 Internal Transport
• Terrestrial vertebrates
• Complex circulatory systems
separate oxygen-rich from
oxygen-poor blood
• Allows the higher metabolic rate
needed to support an active
terrestrial lifestyle
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CHAPTER 42 Internal Transport
• Amphibians
• Two atria and a ventricle
• Blood flows through a double
circuit
• Oxygen-rich blood is partly
separated from oxygen-poor
blood
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CHAPTER 42 Internal Transport
• Most reptiles
• Wall that partly divides the
ventricles, minimizing the mixing
of oxygen-rich and oxygen-poor
blood
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CHAPTER 42 Internal Transport
• Birds and mammals
• Four-chambered hearts separate
oxygen-rich blood from oxygenpoor blood
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CHAPTER 42 Internal Transport
• Human heart
• Enclosed by a pericardium
• Valves that prevent backflow of
blood
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CHAPTER 42 Internal Transport
• Right atrioventricular (AV) valve
(tricuspid valve)
• Between right atrium & ventricle
• Mitral valve
• Between left atrium and ventricle
• Semilunar valves
• Guard the exits from the heart
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CHAPTER 42 Internal Transport
Human heart
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CHAPTER 42 Internal Transport
• Cardiac muscle fibers are
joined by intercalated discs
• The sinoatrial (SA) node
(pacemaker) initiates each
heartbeat
• A specialized electrical
conduction system coordinates
heartbeats
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CHAPTER 42 Internal Transport
• Cardiac cycle
• One complete heartbeat
• Contraction occurs during systole
• Period of relaxation is diastole
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CHAPTER 42 Internal Transport
• Beginning of ventricular systole
• Closing of the AV valves
• Low-pitched “lub” sound
• Beginning of ventricular diastole
• Closing of the semilunar valves
• Short, loud, sharp “dup” sound
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CHAPTER 42 Internal Transport
• Cardiac output (CO)
• Stroke volume times heart rate
• Stroke volume depends on
venous return and on neural
messages and hormones,
especially epinephrine and
norepinephrine
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CHAPTER 42 Internal Transport
• Starling’s law of the heart
• The more blood delivered to the
heart by the veins, the more
blood the heart pumps
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CHAPTER 42 Internal Transport
• Heart rate
• Regulated mainly by the nervous
system
• Influenced by hormones and
body temperature
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CHAPTER 42 Internal Transport
• Blood pressure
• Force blood exerts against the
inner walls of the blood vessel
• Greatest in the arteries
• Decreases as blood flows
through the capillaries
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CHAPTER 42 Internal Transport
• Blood pressure depends on
• Cardiac output
• Blood volume
• Resistance to blood flow
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CHAPTER 42 Internal Transport
• Peripheral resistance
• Resistance to blood flow
–Blood viscosity
–Friction between blood and blood
vessel wall
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CHAPTER 42 Internal Transport
Blood
pressure
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CHAPTER 42 Internal Transport
• Baroreceptors
• Sensitive to blood pressure
changes
• Send messages to the cardiac
and vasomotor centers in the
medulla of the brain
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CHAPTER 42 Internal Transport
• When blood pressure increases
• Cardiac center stimulates
parasympathetic nerves that slow
heart rate
• Vasomotor center inhibits
sympathetic nerves that constrict
blood vessels
• Blood pressure is reduced
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CHAPTER 42 Internal Transport
• Angiotensin
• Hormone that raises blood
pressure
• Aldosterone
• Helps regulate salt excretion
• Affects blood volume and blood
pressure
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Biology, Seventh Edition
CHAPTER 42 Internal Transport
• Pulmonary circulation
• Connects heart and lungs
• Systemic circulation
• Connects heart and tissues
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CHAPTER 42 Internal Transport
• Pulmonary circulation
• Right ventricle pumps blood into
the pulmonary arteries, one going
to each lung
• Blood circulates through
pulmonary capillaries in the lung
• Blood is conducted to the left
atrium by a pulmonary vein
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CHAPTER 42 Internal Transport
• Systemic circulation
• Left ventricle pumps blood into
the aorta
• Aorta branches into arteries
leading to the body organs
• Blood flows through capillary
networks within various organs
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CHAPTER 42 Internal Transport
• Blood flows into veins that
conduct it to the superior vena
cava or inferior vena cava
• Blood returns to the right atrium
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CHAPTER 42 Internal Transport
Systemic and
pulmonary
circulation
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CHAPTER 42 Internal Transport
• Coronary arteries
• Supply the heart muscle with
blood
• Hepatic portal system
• Circulates nutrient-rich blood
through the liver
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CHAPTER 42 Internal Transport
• Lymphatic system
• Collects interstitial fluid
• Returns it to the blood
• Plays an important role in
homeostasis of fluids
• Defends body against disease
• Absorbs lipids from the digestive
tract
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CHAPTER 42 Internal Transport
• Lymph
• Formed from interstitial fluid
• Lymphatic vessels
• Conduct lymph to the thoracic
duct and right lymphatic duct in
the shoulder region
• Ducts return lymph to the blood
circulatory system
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Lymphatic capillaries
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CHAPTER 42 Internal Transport