Transcript The Cardiovascular System

Tainted Love
Introduction

Function:
– Transport materials around body

Components:
– Heart
– Blood Vessels
The Heart

Layers in Cross Section:
– Pericardium- outermost sac enclosing heart
– Pericardial Fluid- fluid between pericardium
and epicardium
– Epicardium- tight fitting layer surrounding
heart; also called visceral pericardium
– Myocardium- cardiac muscle layer
– Endocardium- smooth inner layer of heart
Heart Structure

Four chambers:
– Right and left atriareceive blood into heart
– Right and left ventriclepump blood back out of
the heart

Two sides are separated
by septum
Valves

Four Valves in Heart:
1. Tricuspid - between right atrium and right
ventricle
2. Pulmonary Semilunar - between right
ventricle and pulmonary trunk
3. Mitral (Bicuspid) - between left atrium and
left ventricle
4. Aortic semilunar - between left ventricle
and aorta
Two Circulations of Blood

Pulmonary:
– Back and forth to lungs

Systemic:
– Back and forth to body
Path of Blood Through Heart
Exit Slip
1) What chamber is this?
 2) Which valve is between
right atrium and right ventricle?
 3) Which circuit (pulmonary or systemic)
brings blood back and forth to lungs?

1) Right atrium
 2) Tricuspid
 3) Pulmonary

Internal Heart
Identification
Vessels Supplying the
Heart

Coronary arteries
– First two branches off of the
aorta
– Supply blood to heart

Cardiac veins
– Return blood from heart
tissues
– Drain into coronary sinus

Coronary sinus
– Returns blood back to right
atrium
Cardiac Cycle
Sequence of events that occur during
every regular heartbeat
 Systole - contraction
 Diastole - relaxation
 Refer to timeline

THE FLOW OF BLOOD THROUGH THE HEART
Heart Sounds
Lubb - sound of atrioventricular (AV) valves
closing
 Dupp - sound of semilunar valves closing

Lubb, Dubb, …. Lubb, Dubb….

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made by the closing of the heart valves.
"lub" made by the contraction of the
ventricles and the closing of the
atrioventricular valves.
“dupp" made by the semilunar valves
closing.
Reminder about Cardiac
Tissue

Complex network of interconnecting cells
– Connected by intercalated discs
– Allows them to transfer impulse rapidly and
work together (functional syncytium)

Two sets in heart:
– One in atria, one in ventricles

Kept separate from each other
Cardiac Conduction Intro
Electrical impulses cause heart structures
to contract
 Travel down a system of specialized fibers

QUICK REVIEW OF HEART
Purpose
 Pumps blood
Basic Anatomy
 4 chambers
 2 sides
 4 valves
33
THE CONDUCTINGY
SYSTEM
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SA Node
Inter-nodal pathway
AV Node
Bundle of HIS
Bundle Branches
Purkinje Fibers
34
RELATIONSHIP
35
Why do we do an ECG?

Measures:
– Any damage to the heart
– How fast your heart is beating and whether it is beating
normally
– The effects of drugs or devices used to control the heart
(such as a pacemaker)
– The size and position of your heart chambers

Ordered if:
–
–
–
–
You
You
You
You
have chest pain or palpitations (pounding/racing heart)
are scheduled for surgery
have had heart problems in the past
have a strong history of heart disease in the family
Pathway for Conduction

Sinoatrial node (SA node)
– Pacemaker
– Causes atria to contract

Junctional Fibers
– Delay impulse reaching ventricle by their small
diameter
Atrioventricular node (AV node)
 Purkinje fibers

– Cause ventricles to contract
Electrocardiogram
Also know as ECG
 Electrical recording of
myocardium during
cardiac cycle
 P wave

– Atrial depolarization

QRS complex
– Ventricle depolarization
and atrial repolarization

T wave
– Ventricle repolarization
Electrocardiogram (cont)
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Each electrical signal begins in a group of cells called the sinus node or sinoatrial (SA) node. The SA node is
located in the right atrium (AY-tree-um), which is the upper right chamber of the heart. (Your heart has two
upper chambers and two lower chambers.)
In a healthy adult heart at rest, the SA node sends an electrical signal to begin a new heartbeat 60 to 100 times a
minute.
From the SA node, the signal travels through the right and left atria. This causes the atria to contract, which
helps move blood into the heart's lower chambers, the ventricles (VEN-trih-kuls). The electrical signal moving
through the atria is recorded as the P wave on the EKG.
The electrical signal passes between the atria and ventricles through a group of cells called the atrioventricular
(AV) node. The signal slows down as it passes through the AV node. This slowing allows the ventricles enough
time to finish filling with blood. On the EKG, this part of the process is the flat line between the end of the P wave
and the beginning of the Q wave.
The electrical signal then leaves the AV node and travels along a pathway called the bundle of His. From there,
the signal travels into the right and left bundle branches. The signal spreads quickly across your heart's
ventricles, causing them to contract and pump blood to your lungs and the rest of your body. This process is
recorded as the QRS waves on the EKG.
The ventricles then recover their normal electrical state (shown as the T wave on the EKG). The muscle stops
contracting to allow the heart to refill with blood. This entire process continues over and over with each new
heartbeat.
Control of Heart Rate

Cardiac Center of Medulla Oblongata
– Parasympathetic
 Constant braking action; acetylcholine
– Sympathetic
 Increases heart rate; norepinephrine

Blood Pressure Receptors
– Decreases heart rate

Impulses from Cerebrum and Hypothalamus
– Decrease heart rate

Changes in K and Ca concentrations
Thumbs Up, Down
Coronary arteries supply blood to heart.
– UP!
 The lubb of your heart is the sound of the
AV closing/opening.
– UP!
 An ECG measures your blood pressure.
– DOWN! It measures your cardiac cycle.

Blood Vessels
System of closed tubes filled with blood
 Arteries

– Carry blood away from heart

Arterioles
– Smaller branches of arteries

Capillaries
– Thin-walled vessels where nutrients, fluid, gases, and
wastes are exchanged

Venules
– Small veins
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Veins
– Large vessels returning blood to heart
Layers of Blood Vessel
Walls

Tunica externa
– Outermost layer composed of connective
tissue with some elastic and collagenous
fibers

Tunica media
– Middle layer composed of smooth muscle and
elastic fibers

Tunica interna (endothelium)
– Single layer of squamous epithelium
Control of Vessel Diameter

Vasoconstriction
– Sympathetic nervous system impulses cause vessels
to constrict

Vasodialation
– Inhibition of impulse causes dialation
Arteries
Carry blood away from heart under high
pressure
 Has the thickest tunica media and tunica
externa of all blood vessels

Arterioles
Smaller branches of arteries
 Walls thin as the vessels get smaller
 Eventually lose tunic externa
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Capillaries
Site of exchange
 Only tunica interna remains
 Has small openings between
endothelial cells where
materials can leak out
 Pre-capillary sphincters

– Smooth muscle at start of
capillary that can close the
capillary bed and divert blood
flow
Exchange of Materials
1.
2.
3.
4.
5.
6.
Oxygen and nutrients diffuse out of the
capillary
Carbon dioxide and wastes diffuse back into
capillary
Plasma Proteins don’t leave the blood
Fluid is forced out of the capillary at the
arteriole side due to blood pressure
Fluid is brought back into the capillary due to
osmotic pressure at the venule side
Fluid not recollected is brought back to the
blood through the lymphatic system
Venules and Veins

Venules
– Smaller veins
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Veins
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–
–
–
–
–
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Large lumen
Thinner tunica media
Thinner tunica externa
Return blood to heart
Low pressure
Blood reservoir
Contains valves
 Protect against backflow
Pumps your blood SONG!
Heart Disorders

Myocardial infarction (MI)
– Otherwise known as heart attack
– Def: Blood clot obstructs a coronary atery or
one of its branches – killing part of the heart
– Causes:
 Diet (high in fat and/or salt)
– Causes build-up in plague (causes blood clot)
 Stress (usually from another illness)
– Symptoms:
 Pain in right arm, shortness of breath, increased
heart rate
Heart Disorders

Atherosclerosis
– Def: arterial disease, hardening of arteries
– Very common
– Causes:
 Plague build-up (caused by diet high in fat)
– Forms clots, blood has issues flowing through
 Aging (older you get, more they harden)
 Heavy alcohol use
 Not exercising (EVER!)
 Obesity
– Can lead to heart attack or stroke
Heart Disorders

Hypertension
– Def: High blood pressure
 Ex: 140/90 (normal – 120/80)
– Causes:
 Diet (high in fat and/or salt)
 Genetics (heart disease, diabetes)
 Stroke or heart attack
 Pregnancy/labor
 Kidney disease
 Race (African-Americans on average have high BP)
 Gender
Heart Disorders

Varicose veins
– Def: ruptured veins
– Causes:
 Abnormal dilations
– Caused by increased
blood pressure due
to gravity
– Standing for
abnormally long
periods of time
Blood Pressure
Force blood exerts on blood vessel walls
 Highest in arteries; lowest in veins
 Max point:

– During ventricular systole; called systolic
pressure
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Min point:
– Before next ventricular contraction; called
diastolic pressure
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Normal arteriole blood pressure: 120/80
Factors the Affect Blood
Pressure
Heart Action
 Blood Volume
 Peripheral
resistance
 Blood viscosity
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Heart Action

Stroke Volume
– Volume of blood discharged from the left
ventricle during each contraction

Cardiac output
– Volume of blood discharged from the left
ventricle/ minute
– Cardiac Output=Stroke volume x Heart rate (bpm)

Cardiac output has proportional
relationship to blood pressure
Peripheral Resistance
Blood moving against vessel walls creates
friction that impedes flow
 If vessels are constricted, blood pressure
raises
 If vessels are dilated, blood pressure
lowers

Blood Viscosity

Viscosity
– Ease that a fluid flows
– Increases when there are more formed
elements or plasma proteins
– As viscosity increases so does blood pressure
Controlling Blood
Pressure

Cardiac Output
– Strength of ventricle contraction is controlled by
amount of
– Baroreceptors- send messages to medulla oblongata
about how to influence SA node

Peripheral resistance
– Changes in blood pressure cause changes in medulla
oblongata’s

Vein reservoir
– During exercise or venoconstriction more blood