Blood and Circulation

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Blood and Circulation

• Starr/McMillans
• Human Biology
• Fourth Edition
• Chapter 7

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Key Concepts

• All cells survive by exchanging substances with
  their surroundings
• Blood is the transport medium of the circulatory
  system
• A four-chambered heart pumps blood through the
  body
• The circulatory circuits are the pulmonary and
  systemic circuits

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Key Concepts

• Arteries transport blood away from the heart
  whereas veins transport blood toward the heart
• Arterioles control blood-flow through each organ
• Capillaries are the vessels where diffusion takes
  place
• Capillaries group into venules, which group into
  veins

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Cardiovascular System (7.5)

• The Cardiovascular System (CV) transports
  substances to and from the interstitial fluid
• Main Elements
• 1) Blood
• 2) Heart
• 3) Blood vessels
• Arteries, arterioles, capillaries
• venules, veins
• each has a different function and therefore a
  different structure

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Components

• The rate and volume of blood flow through the CV
  system can be adjusted as conditions vary
  (homeostasis)
• Blood flows rapidly through arteries but slows
  down considerably as they branch into capillaries
• The lymphatic system collects fluids and solutes
  that leak out due to pressure from the pumping
  heart

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FOOD, WATER INTAKE
OXYGEN INTAKE
DIGESTIVE SYSTEM
RESPIRATORY SYSTEM
elimination of carbon dioxide
nutrients, water, salts
CO2
O2
water, solutes
CIRCULATORY SYSTEM
URINARY SYSTEM
elimination of food residues
elimination of excess water, salts, wastes
transport to and from cells
Fig. 7.8, p. 144
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How are the pulmonary arteries and veins
different?
CAROTID ARTERIES
JUGULAR VEINS
ASCENDING AORTA
SUPERIOR VENA CAVA
PULMONARY ARTERIES
PULMONARY VEINS
CORONARY ARTERIES
HEPATIC PORTAL VEIN
BRACHIAL ARTERY
RENAL ARTERY
RENAL VEIN
INFERIOR VENA CAVA
ABDOMINAL AORTA
ILIAC ARTERIES
ILIAC VEINS
Fig. 7.9, p. 145
FEMORAL ARTERY
FEMORAL VEIN
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The Heart A Durable Pump (7.6)
Myocardium - cardiac muscle tissue (makes up most
of heart) Pericardium - tough, fibrous sac that
surrounds, protects, and lubricates Endocardium
- smooth, inner lining of connective tissue and
epithelial cells
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right lung
left lung
diaphragm
pericardium
rib cage
Fig. 7.10a, p. 146
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aorta
(superior vena cava)
(left pulmonary artery)
(left pulmonary veins)
cardiac vein
left coronary artery
right coronary artery
cardiac vein
(inferior vena cava)
Fig. 7.12, p. 147
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Internal Structure of Heart
Septum divides heart into two halves (right,
left) Two chambers in each half Atrium (upper,
receives) Ventricle (lower, pumps) Valves
between chambers AV valve, semilunar valve
Coronary circulation- feeding
the cells of the heart (This is where by-pass
surgery comes in)
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Coronary circulation

• Coronary circulation are the vessels that feed
  the cardiac (heart) muscle tissue itself
• If these vessel become blocked with plaque or a
  blood clot, a heart attack will result
• Open heart by-pass surgery is designed to by-pass
  the blocked vessel by harvesting a healthy vessel
  from somewhere else in the body (leg)
• The blood flow is then restored

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arch of aorta
superior vena cava (from head, upper limbs)
trunk of pulmonary arteries
right semilunar valve (shown closed) to
the pulmonary trunk
left semilunar valve (shown closed) to aorta
right pulmonary veins (from lungs)
left pulmonary veins (from lungs)
left atrium
right atrium
left AV valve (shown open)
right AV valve (shown open)
left ventricle
right ventricle
endothelium and underlying connective tissue
muscles that prevent valve from everting
inner layer of pericardium
inferior vena cava (from trunk, legs)
septum (partition between heart's two halves)
hearts apex
Fig. 7.10b, p. 146
myocardium
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The Cardiac Cycle
Heartbeat One sequence of contraction and
relaxation Systole - Contraction
Phase Diastole - Relaxation Phase The cardiac
cycle produces an audible lub-dup sound The
lub is the AV valves closing as the two
ventricles contract The dup is the semilunar
valves closing as the ventricles relax
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The Cardiac Cycle
Mid-to-late Diastole
Ventricular Systole
Early Diastole
Page 147
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aDiastole (mid-to-late). Ventricles fill, atria
contract.
bVentricular systole (atria are still in
diastole). Ventricles eject.
cDiastole (early). Both chambers relaxed.
Fig. 7.13, p. 147
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three cusps
two cusps
left atrioventricular valve (bicuspid or mitral
valve)
right atrioventricular valve (tricuspid)
left semilunar valve (between left ventricle and
aorta)
right semilunar valve (between right ventrical
and pulmonary arteries)
Fig. 7.11, p. 147
Fill in heart diagram
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Blood Circulation (7.7)

• Two side-by-side pumps
• Two cardiovascular circuits

Pulmonary Circuit Receives blood from tissues and
circulates it through lungs for gas exchange
Systemic Circuit Carries blood to and from the
tissues
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Pulmonary Circuit
Right atrium to right ventricle Right semilunar
valve Pulmonary arteries Capillary beds in
lungs Pulmonary veins to left atrium
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Systemic Circuit
Left atrium to left ventricle Left semilunar
valve Aorta, arteries, arterioles Capillary
beds in tissues Venules to veins Superior and
inferior vena cava Right atrium
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right pulmonary artery
left pulmonary artery
capillary bed of left lung
capillary bed of right lung
pulmonary trunk
(to systemic circuit)
(from systemic circuit)
pulmonary veins
heart
lungs
Fig. 7.14a, p. 148-9
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Click to view animation.
animation
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capillary beds of head and upper extremities
aorta
(to pulmonary circuit)
(from pulmonary circuit)
heart
capillary beds of other organs in thoracic cavity
diaphragm
capillary bed of liver
capillary beds of intestines
Fig. 7.14b, p. 148-9
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Click to view animation.
animation
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Distribution of Blood - Heart Output

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Heart-saving drugs (7.8)

• Cardiovascular diseases claim about 750,000 lives
  each year
• New wonder drugs statins have greatly
  helped
• Reduce LDL (bad) cholesterol
• Interrupt the metabolic pathway in the liver that
  creates cholesterol
• Increase livers output of receptor proteins that
  bind with and remove LDL from bloodstream
• Raise the HDL (good) level
• Lower blood levels of triglycerides
• Dramatically reduce risk of heart attack and
  stroke
• Both caused by plaque build-up in blood vessels
  (fatty, cholesterol-rich deposits)
• Statins also seem helpful for people who dont
  have problem cholesterol but have plaque due to
  heredity

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How the heart contracts (7.9)

• Cardiac conduction system - 1 of the cardiac
  muscle cells that do not contract
• Includes self-excitatory pacemaker cells
• These cells spontaneously produce and conduct
  electrical impulses that stimulate contractions
  in the hearts contractile cells
• These electrical impulses called action
  potentials
• Even if all nerves to heart are cut, it will
  continue beating
• These cells are built very differently,
• they branch then connect with one another at
  their ends
• Intercalated discs (communication junctions)
  bridge the plasma membranes on ends of adjoining
  cells
• Contraction signals spread rapidly across the
  junctions

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junction between adjacent cells
intercalated disc
Fig. 7.16, p. 150
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Contraction continued..

• Excitation begins in SA (sinoatrial) node, a
  small mass of cells in upper wall of right atrium
• Generates wave after wave, 70-80 times/minute
• Spread over both atria, causing them to contract
• Then rapidly reaches
• The AV node in the septum
• Bundles of conducting fibers extend from AV node
  to each ventricle
• At intervals along each bundle are conducting
  cells called Purkinje fibers that branch off and
  make contact with muscle cells in the ventricles
• When a stimulus reaches the AV node, it slows
  before quickly passing along Purkinje fibers to
  ventricles this gives the atria time to finish
  contracting before the ventricles go
• The SA node fires impulses at highest frequency
  and is called the cardiac pacemaker

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Cardiac Conduction System (7.9)

• SA node
• Cardiac pacemaker
• AV node
• Bundles of conducting fibers
• Purkinje fibers

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SA node
AV node
AV bundle
Purkinje fibers
Fig. 7.17, p. 150
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Click to view animation.
animation
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Mechanism of Contraction

• Cardiac muscle
• Striated
• Communication junctions

Intercalated disk