1-intro for cardiovascular (1)

8/2/2019 1-Intro for Cardiovascular (1)

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Cardiovascular System


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Capillary Beds


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Circulatory System & Blood

General & Pulmonary Circulation


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Note Pulmonary arteries and veins (the exceptions)


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Heart is located in themediastinum

area from the sternumto the vertebral columnand between the lungs

Location of the Heart


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Heart Anatomy


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Fig.20.02b


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Pericardial Layers of the Heart


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Heart Wall

Epicardium

visceral layer of the serous pericardium

Myocardium cardiac muscle layer

Endocardium endothelial layer of the inner myocardial surface


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Vessels returning blood to the heart include:

Right and left pulmonary veins

Superior and inferior venae cavae

Vessels conveying blood away from the heartinclude:

Aorta

Right and left pulmonary arteries

External Heart: Major Vessels of the Heart


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Atria of the Heart

Atria are the receiving chambers of the heart

Blood enters right atria from superior and inferior venae

cavae and coronary sinus

Blood enters left atria from pulmonary veins


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Ventricles of the Heart

Ventricles are the discharging chambers of the heart

Right ventricle pumps blood into the pulmonary trunk

Left ventricle pumps blood into the aorta


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ChambersBorders

SurfacesSulci


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Heart Valves

One Way Direction


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Atrioventricular Valves

A-V valves open and allow blood toflow from atria into ventricles whenventricular pressure is lower than

atrial pressure occurs when ventricles are

relaxed, chordae tendineae areslack and papillary muscles arerelaxed

A-V valves close preventing backflow ofblood into atria

occurs when ventricles contract,pushing valve cusps closed, chordaetendinae are pulled taut and papillarymuscles contract to pull cords andprevent cusps from everting


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Fig. 20.06a,b


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Semilunar Valves

SL valves open with ventricular contraction

allow blood to flow into pulmonary trunk and aorta

SL valves close with ventricular relaxation prevents blood from returning to ventricles, blood

fills valve cusps, tightly closing the SL valves

Aortic Sinuses

Nodule of semiluarvalve

Right Atrium


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Right Atrium

Receives All Venous Blood (front and behind).

Interatrial septumpartitions the atriamusculi pectinati(pectinate muscles)

Crista Terminalis


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Infindibulum

Right Ventricle

Tricuspid valveBlood flows through into right ventriclehas three cusps composed of dense CT covered by endocardium

Forms most of anterior surface of heart

Interventricular septum:partitions ventricles

Pulmonary semilunar valve:blood flows into pulmonary trunk


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Left Ventricle

Forms the apex of heart

Bicuspid (Mitral) valve:blood passes through into left ventricle

has two cusps

Chordae tendineae anchor bicuspid valve to papillary muscles(also has trabeculae carneae like right ventricle)

Aortic semilunar valve:

blood passes through valve into the ascending aortajust above valve are the openings to the coronary arteries


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Interventricular septum


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Cardiac cycle


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Pathway of Blood Through the Heart and Lungs


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Heart So nds


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Heart Sounds

Sounds of heartbeat

are from turbulencein blood flow causedby valve closure

first heart sound

(lubb) is created withthe closing of theatrioventricular valves

second heart sound(dupp) is created with

the closing ofsemilunar valves


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The A-V valves

The Tricuspid valve and the mitral valve

The Semilunar valves

The aortic and the pulmonary artery valves


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Figure 9-1 Structure of the heart, and course of blood flow through the

heart chambers and heart valves.Downloaded from: StudentConsult (on 24 November 2009 06:16 AM) 2005 Elsevier

Figure 12 2


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The heart is the pump

that propels the

blood throughthe systemic and

pulmonary circuits.

Red color indicates

blood that is

fully oxygenated.

Blue color represents

blood that is only

partially oxygenated.

Figure 12-2

Figure 12 3


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The distribution of blood

in a comfortable, resting

person is shown here.

Dynamic adjustments in

blood delivery allow a

person to respond towidely varying

circumstances,

including emergencies.

Figure 12-3

Figure 12 61


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Dynamic adjustments

in blood-flow distribution

during exercise result

from changes in cardiac

output

and from changes in

regional

vasodilation/vasoconstric

tion.

Figure 12-61


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Figure 9-2 "Syncytial," interconnecting nature of cardiac muscle fibers.

Downloaded from: StudentConsult (on 24 November 2009 06:16 AM)

2005 Elsevier


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Figure 9-3 Rhythmical action potentials (in millivolts) from a Purkinje fiber and

from a ventricular muscle fiber, recorded by means of microelectrodes.Downloaded from: StudentConsult (on 24 November 2009 06:16 AM)

2005 Elsevier

Figure 12-17


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The prolonged refractory period of cardiac muscle

prevents tetanus, and allows time for ventricles to

fill with blood prior to pumping.

Figure 12-17


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Figure 9-5 Events of the cardiac cycle for left ventricular function, showing changes in left

atrial pressure, left ventricular pressure, aortic pressure, ventricular volume, the

electrocardiogram, and the phonocardiogram.Downloaded from: StudentConsult (on 24 November 2009 06:16 AM) 2005 Elsevier

Figure 12-18


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Systole:ventricles contracting

Diastole:

ventricles relaxed

Figure 12 18

Figure 12-19


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Pressure and volume changes in the

left heart during a contraction cycle.

Figure 12 19

Figure 12-20


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Pressure changes in the right heart during a contraction cycle.

Figure 12 20

Figure 12-4


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Though pressure is higher in the lower tube, the flow rates

in the pair of tubes is identical because they both have the

same pressure difference (90 mm Hg) between points P1

and P2

.

Figure 12 4


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Figure 12-11


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The sinoatrial node is

the hearts pacemaker

because it initiates

each wave of excitation

with atrial contraction.

The Bundle of His and other parts

of the conducting system deliver

the excitation to the apex of the

heart so that ventricular contraction

occurs in an upward sweep.

g


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Figure 12-12

The action potential of a

myocardial pumping cell.

The rapid opening of voltage-gatedsodium channels is responsible for

the rapid depolarization phase.


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Figure 12-12

The prolonged plateau of

depolarization is due tothe slow

but prolonged opening ofvoltage-gated calcium channels

PLUS

closure of potassium channels.




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Figure 12-12

Opening of potassium

channels results in the

repolarization phase.




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Figure 12-12



Opening of potassium

channels results in the


The prolonged plateau of

depolarization is due tothe slow

but prolonged opening ofvoltage-gated calcium channels

PLUS

closure of potassium channels.

The rapid opening of voltage-gatedsodium channels is responsible for the

rapid depolarization phase.

Figure 12-13


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Figure 12 13

Sodium ions leaking in throughthe F-type [funny] channels

PLUS

calcium ions moving in through

the T [calcium] channels cause a

threshold graded depolarization.

The rapid opening of voltage-gated

calcium channels is responsible

for the rapid depolarization phase.

Reopening of potassium channelsPLUS

closing of calcium channels

are responsible for the


The action potential of an

autorhythmic cardiac cell.


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Figure 12-16


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Control of the Heart by the Sympathetic and Parasympathetic

Nerves

Increases HR

Increases Force of Heart Contraction

Increases Cardiac Output

Decreases HR

Decreases Strength of Heart Muscle

Pages 112-113,

and 121 from

Guyton and Hall

Figure 12-23


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To speed up the heart rate:

deliver the sympathetic hormone, epinephrine, and/or

release more sympathetic neurotransmitter (norepinephrine), and/or

reduce release of parasympathetic neurotransmitter (acetylcholine).

Figure 12-26


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Sympathetic signals (norepinephrine and epinephrine) cause a stronger and

more rapid contraction anda more rapid relaxation.


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Figure 12-22


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Figure 9-10 Cardiac sympathetic and parasympathetic nerves. (The vagus nerves

to the heart are parasympathetic nerves.)Downloaded from: StudentConsult (on 24 November 2009 06:16 AM)

2005 Elsevier


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Figure 9-11 Effect on the cardiac output curve of different degrees of sympathetic

or parasympathetic stimulation.Downloaded from: StudentConsult (on 24 November 2009 06:16 AM)

2005 Elsevier

Figure 12-35


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Sympathetic stimulation ofalpha-adrenergic receptors causes

vasoconstriction to decrease blood flow to that location.

Sympathetic stimulation ofbeta-adrenergic receptors leads to

vasodilation to cause an increase in blood flow to that location.

Figure 12-36


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Diversity among signals that influence contraction/relaxation

in vascular circular smooth muscle implies a diversity of

receptors and transduction mechanisms.


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Figure 9-12 Constancy of cardiac output up to a pressure level of 160 mm Hg. Only

when the arterial pressure rises above this normal limit does the increasing

pressure load cause the cardiac output to fall significantly.


2005 Elsevier


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Figure 18-1 Anatomy of sympathetic nervous control of the circulation. Also shown by the

red dashed line is a vagus nerve that carries parasympathetic signals to the heart.Downloaded from: StudentConsult (on 24 November 2009 07:30 AM)

2005 Elsevier


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Figure 18-2 Sympathetic innervation of the systemic circulation.


2005 Elsevier


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Figure 18-3 Areas of the brain that play important roles in the nervous regulation

of the circulation. The dashed lines represent inhibitory pathways.Downloaded from: StudentConsult (on 24 November 2009 07:30 AM)

2005 Elsevier


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Ref: Chapter 10 in Guyton and 12 in Vander

Rhythmical Excitation of the Heart

Specialized Excitatory and Conductive System of the

Heart

S-A node

A-V node

A-V bundle

Purkinjie fibers

Figure 12-10


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Figure 10-1 Sinus node, and the Purkinje system of the heart, showing also the A-V

node, atrial internodal pathways, and ventricular bundle branches.Downloaded from: StudentConsult (on 24 November 2009 06:31 AM)

2005 Elsevier


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Figure 10-2 Rhythmical discharge of a sinus nodal fiber. Also, the sinus nodal action potential

is compared with that of a ventricular muscle fiber.


2005 Elsevier


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Figure 14-2 Normal blood pressures in the different portions of the circulatory system when

a person is lying in the horizontal position.


2005 Elsevier

In response to the pulsatile contraction of the heart:


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Figure 12-29

pulses of pressure move throughout the vasculature, decreasing

in amplitude with distance

Capillary wallsFigure 12-37


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The capillary is

the primary point

exchange between

the blood and the

interstitial fluid(ISF).

Intercellular clefts

assist the exchange.

are a single

endothelial cell

in thickness.

Figure 12-38


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Capillaries lack smooth muscle, but contraction/relaxation of circular smooth muscle

in upstream metarterioles and precapillary sphincters determine the volume of

blood each capillary receives.


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There are many, many capillaries, each with slow-moving

blood in it, resulting in adequate time and surface area

for exchange between the capillary blood and the ISF.

Figure 12-40

Figure 12-41


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Absorption: movement of fluid and solutes into the blood.

Filtration: movement of fluid and solutes out of the blood.

Figure 12-31


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Cardiovascular Physiology


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Cardiovascular Physiology

CO = HR x SV, as follows.

The heart is the pump that moves the blood. Its activity can be

expressed as cardiac output (CO) in reference to the amount

of blood moved per unit of time.

Chapter 12:


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Mean arterial pressure, which drives the blood, is the sum of the diastolic

pressure plus one-third of the difference between the systolic and

diastolic pressures.

Chapter 12:

Cardiovascular Physiology (cont.)

The autonomic system dynamically adjusts CO and MAP.

Blood composition and hemostasis are described.


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Figure 14-3 Interrelationships among pressure, resistance, and blood flow.


2005 Elsevier


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Figure 14-10 Vascular resistances: A, in series and B, in parallel.


2005 Elsevier


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Figure 14-12 Effect of hematocrit on blood viscosity. (Water viscosity = 1.)


2005 Elsevier


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Figure 15-11 Venous valves of the leg.


2005 Elsevier


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Figure 15-7 Auscultatory method for measuring systolic and diastolic arterial

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