Circulation
Chapter 34
Mader: Biology 8th Ed.
Transport in Invertebrates
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Invertebrates Without a Circulatory System
–  Each cell can independently exchange
gases and rid itself of wastes.
Mader: Biology 8th Ed.
Mader: Biology 8th Ed.
Open or Closed Invertebrate Circulation
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Two types of circulatory fluids:
–  Blood - contained within blood vessels.
–  Hemolymph - flows into hemocoel.
Open Circulatory System
–  Heart pumps hemolymph via vessels into
tissue spaces.
Closed Circulatory System
–  Blood pumped by the heart into a system
of blood vessels.
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Open Circulatory System
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Closed Circulatory System
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Figure 42.2 Open and closed circulatory systems
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Transport in Vertebrates
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All vertebrates have a closed,
cardiovascular system.
–  Atria receive blood.
–  Ventricles pump blood from the heart.
v Arteries - Carry blood away from heart.
Ø  Arterioles
v Capillaries - Exchange materials with
tissue fluid.
v Veins - Return blood to heart.
Ø  Venules
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Mader: Biology 8th Ed.
Figure 42.8 The structure of blood vessels
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Comparison of Circulatory Pathways
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Fish - Blood flows in single loop.
–  Single atrium and single ventricle.
Amphibians - Blood flows in double loop.
–  Two atria with single ventricle.
Other vertebrates - Blood flows in a double
loop.
–  Heart divided by septum into separate
sides.
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Circulatory Circuits
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Figure 42.0 External gills of a salmon
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Transport in Humans
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Human Heart
–  Fist-sized, cone-shaped, muscular organ.
v Myocardium composed largely of
cardiac tissue.
–  Lies within a sac (pericardium).
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External Heart Anatomy
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•
Transport in Humans
Septum separates halves.
–  Four chambers
v Two upper, thin atria.
v Two lower, thick ventricles.
Ø  Atrioventricular valves
§  Tricuspid
§  Bicuspid
Ø  Semilunar valves
§  Pulmonary
§  Aortic
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Internal Heart Anatomy
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Figure 42.5 The mammalian heart: a closer look
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Figure 42.4 The mammalian cardiovascular system: an overview
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Transport in Humans
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Blood must go through lungs to pass from
the right side to the left side of the heart.
–  Right side of heart pumps blood to the
pulmonary circuit.
–  Left side of the heart pumps blood to the
systemic circuit.
Oxygen-poor blood never mixes with
oxygen-rich blood.
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Heartbeat
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Systole - Contraction of heart chambers.
Diastole - Relaxation of heart chambers.
–  Pulse - Wave effect that passes down the
walls of arterial blood vessels when aorta
expands and then recoils following
ventricular systole.
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Figure 42.6 The cardiac cycle
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Heartbeat
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Rhythmic contraction due to cardiac
conduction system.
–  Sinoatrial node (SA) keeps the heartbeat
regular.
–  Atrioventricular node (AV) signals
ventricles to contract.
v Purkinje Fibers
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Heartbeat
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Electrocardiogram (ECG) is a recording of
the electrical changes that occur in
myocardium during a cardiac cycle.
–  When SA node triggers an impulse, the
atrial fibers produce an electrical charge
(P wave).
v P wave indicates atria are about to
contract.
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Figure 42.7 The control of heart rhythm
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Conduction System of the Heart
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Vascular Pathways
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Human cardiovascular system includes two
major circular pathways:
–  Pulmonary Circuit
v Takes oxygen-poor blood to the lungs
and returns oxygen-rich blood to the
heart.
–  Systemic Circuit
v Takes blood throughout the body from
the aorta to the vena cava.
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Mader: Biology 8th Ed.
Blood Pressure
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Systolic Pressure results from blood forced
into the arteries during ventricular systole.
Diastolic Pressure is the pressure in the
arteries during during ventricular diastole.
Blood pressure normally measured with a
sphygmomanometer on the brachial artery.
–  Systolic/Diastolic
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Velocity and Blood Pressure
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Figure 42.10 The interrelationship of blood flow velocity, cross-sectional area of blood vessels, and blood pressure
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Blood Pressure
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The beat of the heart supplies pressure that
keeps blood moving in the arteries.
–  Skeletal muscle contraction pushes blood
in the veins toward the heart.
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Mader: Biology 8th Ed.
Figure 42.11 Measurement of blood pressure (Layer 1)
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Figure 42.11 Measurement of blood pressure (Layer 2)
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Figure 42.11 Measurement of blood pressure (Layer 3)
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Figure 42.11 Measurement of blood pressure (Layer 4)
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Cardiovascular Disorders
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Hypertension - High blood pressure.
Atherosclerosis - Accumulation of fatty
materials in inner linings of arteries.
Stroke - Cranial arteriole bursts or is
blocked by an embolus.
Heart attack - Myocardial infarction.
Coronary artery becomes partially blocked.
–  Angina pectoris - Squeezing sensation.
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Coronary Arteries and Plaque
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Figure 42.14 The composition of mammalian blood
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Figure 42.14x Blood smear
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Figure 42.15 Differentiation of blood cells
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Blood - A Transport Medium
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Homeostasis Functions
–  Transports substances to and from
capillaries for exchange with tissue fluid.
–  Guards against pathogen invasion.
–  Regulates body temperature
–  Clots preventing blood loss
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Plasma
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Plasma contains many types of molecules
including nutrients, wastes, salts, and
proteins.
–  Buffer blood.
–  Maintain osmotic pressure.
–  Proteins involved in clotting.
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Red Blood Cells
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Small, biconcave disks that, at maturity, lack
a nucleus and contain hemoglobin.
–  Hemoglobin contains four globin protein
chains, each associated with an ironcontaining group.
v Manufactured continuously in bone
marrow of skull, ribs, vertebrae, and
ends of long bones.
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White Blood Cells
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Usually larger than red blood cells, contain a
nucleus, and lack hemoglobin.
Inflammatory Response
–  Neutrophils enter tissue fluid and
phagocytize foreign material.
–  Lymphocytes help fight infection.
v T Cells attack infected cells.
v B Cells produce antibodies.
–  Antigens cause body to produce
antibodies.
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Platelets
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Platelets result from fragmentation of
megakaryocytes.
–  Involved in coagulation.
v Blood clot consists of platelets and red
blood cells entangled within fibrin
threads.
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Blood Clotting
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Figure 42.16x Blood clot
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Capillary Exchange
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Oxygen and nutrients exit a capillary near
the arterial end.
Carbon dioxide and waste molecules enter
a capillary near the venous end.
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Capillary Exchange
Mader: Biology 8th Ed.
Mader: Biology 8th Ed.