BIOII CH15 PowerPoint Lecture Outlines
NAME_____________________________
Myocardial Thickness and Function
The thickness of the myocardium of the four chambers varies according to the function of each chamber.
The ATRIAL walls are thin because they deliver blood to the ventricles.
The ventricle walls are thicker because they pump blood greater distances
The right ventricle walls are thinner than the left because they pump blood into the _____________________ which are nearby and
offer very little resistance to blood flow.
The left ventricle walls are thicker because they pump blood through the body where the resistance to blood flow is greater.
Location of Heart
posterior to sternum
medial to lungs
anterior to vertebral column
base lies beneath 2nd rib at 5th intercostal space
lies upon _____________________
Coverings of Heart
The connective tissue covering he heart is called the _____________________________
Which is a serous membrane
Wall of the Heart Describe Function and Location******
Epicardium:
Myocardium:
Endocardium:
Heart Chambers
Right Atrium- receives blood from inferior vena cava superior vena cava, _______________________ sinus
Right Ventricle- receives blood from right atrium
Left Atrium- receives blood from pulmonary ________________
Left Ventricle- receives blood from left atrium
Chambers and Sulci
Right Atrium
Receives blood from 3 sources-superior vena cava, inferior vena
cava and coronary sinus
Interatrial _____________________ partitions the atria
Tricuspid valve
Blood flows through into right ventricle
has three cusps composed of dense CT covered by endocardium
Right Ventricle
Forms most of anterior surface of heart
Papillary muscles are cone shaped trabeculae carneae (raised
bundles of cardiac muscle)
Chordae __________________: cords between valve cusps and papillary
muscles
Interventricular septum: partitions ventricles
Pulmonary semilunar valve: blood flows into pulmonary trunk
Left Atrium
Forms most of the base of the heart
Receives blood from lungs - 4 pulmonary veins (2 right + 2 left)
Bicuspid valve: blood passes through into left ventricle has two cusps
to remember names of this valve, try the pneumonic _________________ Left Atrioventricular, Mitral, or Bicuspid valve
Left Ventricle
Forms the __________________ of heart
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 aorta just above valve are the openings to the
coronary arteries
Heart Sounds
The LUB DUB
Heart Valves
Atrioventricular Valves Open
A-V valves open and allow blood to flow from atria into ventricles
when ventricular pressure is lower than atrial pressure
Occurs when ventricles are relaxed, chordae tendineae are slack
and papillary muscles are relaxed
Atrioventricular Valves Close THE LUB
A-V valves _________________ preventing backflow of blood into atria
Occurs when ventricles contract, pushing valve cusps closed,
chordae tendinae are pulled taut and papillary muscles contract to
pull cords and prevent cusps from everting
Semilunar Valves THE DUB
SL valves open with ventricular contraction
allow blood to flow into pulmonary trunk and aorta
__________________________ valves close with ventricular
relaxation
prevents blood from returning to ventricles, blood
fills valve cusps, tightly closing the SL valves
Valve Function Review
Fibrous Skeleton of Heart
Dense CT rings surround the valves of the heart, fuse
and merge with the interventricular septum
Support structure for heart __________________________
Insertion point for cardiac muscle bundles
Electrical insulator between atria and ventricles
prevents direct propagation of AP’s to ventricles
Path of Blood Through the Heart
Blood Supply to Heart
Cardiac Cycle
Atrial Systole/Ventricular Diastole
_________% blood flows passively into ventricles
remaining 30% of blood pushed into ventricles
A-V valves open/semilunar valves close
ventricles relaxed
ventricular pressure increases
Cardiac Muscle Fibers
1. A functional ______________________ is a mass of merging cells that act as a unit.
2. Two syncytiums of the heart are in the atrial walls and the ventricular walls.
3. The atrial syncytium and ventricular syncytium are connected by fibers of the cardiac
conduction system.
Cardiac muscle cells -are joined end to end by __________________ discs which allow
for depolarization to spread
Cardiac muscle fibers swirl diagonally around the heart in interlacing bundles
Cardiac Conduction System
The cardiac conduction system is responsible for coordinating events of
the cardiac cycle.
The S-A __________________ node is in the wall of the right atrium, AKA called
the pacemaker because it generates the heart’s rhythmic contractions.
As a cardiac impulse travels from the S-A node into the atrial syncytium,
it goes from cell to cell via gap junctions.
Conducting fibers deliver impulses from the S-A node to the A-V node.
The A-V _______________________ node is in the inferior interatrial septum
and provides the normal conduction path between the atrial and
ventricular syncytiums.
From the A-V node, impulses pass to the A-V bundle in the
interventricular septum and gives rise to bundle branches.
_____________________________ fibers carry impulses to distant regions of the
ventricular myocardium.
The ventricular walls contract with a twisting motion because the muscle
fibers in the walls form irregular whorls. Contraction of the ventricles
begins at the apex of the heart and pushes blood superiorly toward the
aortic and pulmonary semilunar valve.
Electrocardiogram EKG-ECG
Electrocardiogram
Impulse conduction through the heart generates electrical currents that
can be detected at the surface of the body.
The ECG helps to determine if the conduction pathway is abnormal, if the
heart is enlarged, and if certain regions are damaged.
EKG
Action potentials of all active cells can be detected and recorded
P wave- ______________________ depolarization
P to Q interval -conduction time from atrial to ventricular excitation
QRS complex - ventricular __________________________________
T wave - ventricular repolarization
ECG
In a typical ECG ___________________ waves accompany each heartbeat:
P wave (atrial depolarization - spread of impulse from SA node over atria)
QRS complex (ventricular depolarization - spread of through ventricles)
T wave (ventricular repolarization).
Regulation of Cardiac Cycle
CARDIAC OUTPUT
Cardiac output (CO) is the volume of blood ejected from the left
ventricle into the ______________________ each minute.
Cardiac output equals the stroke volume, the volume of blood
ejected by the ventricle with each contraction, multiplied by the
heart rate, the number of beats per minute. CO = SV X HR
Cardiac Output
CO = SV x HR at 70ml stroke volume & 75 beat/min----5 and 1/4
liters/min
entire blood supply passes through circulatory system every
minute
Cardiac reserve is maximum output/output at rest - average is
4-5x while athlete’s is 7-8x
Influences on Stroke Volume
Preload: Effect of Stretching - According to the Frank-Starling law
of the heart, a greater preload (__________________) on cardiac muscle
fibers just before they contract increases their force of contraction
during systole.
Contractility
Myocardial contractility, the strength of contraction at any given preload, is affected by positive and negative inotropic agents.
Afterload
The pressure that must be overcome before a semilunar valve can open is the afterload.
Congestive Heart Failure - blood remains in the ventricles increasing the preload and causing an overstretching of the heart
and less forceful contraction
Left ventricular failure results in pulmonary _________________________
Right ventricular failure results in peripheral edema.
Chemical regulation of heart rate
Heart rate affected by hormones (epinephrine, norepinephrine, thyroid hormones).
_________________________ (Na+, K+, Ca+2) also affect heart rate.
Other factors such as age, gender, physical fitness, and temperature also affect heart rate.
Arteries and Arterioles
Artery
_______________________ strong wall, endothelial lining
middle layer of ________________ muscle and elastic tissue
outer layer of connective tissue
carries blood under relatively high pressure
Arterioles
thinner wall than artery
endothelial lining
some smooth muscle tissue
small amount of connective tissue
helps control blood flow into a ______________________
smallest arterioles have few smooth muscle fibers
capillaries lack muscle fibers
Capillaries
smallest ______________________________ blood vessels
extensions of inner lining of arterioles
walls are endothelium only
semipermeable
sinusoids – leaky capillaries
Exchange in the Capillaries
______________________ and other substances leave
capillaries because of net outward pressure at the
capillaries’ arteriolar ends
water enters capillaries’ venular ends because of a net
inward pressure
substances move in and out along the length of the
capillaries according to their respective concentration
gradients
Venules and Veins
_________________________________ wall than arteriole
less smooth muscle and elastic tissue than arteriole
ATERY vs. VEIN
Vein
thinner wall than artery
three layers to wall but middle layer is poorly developed
some have _________________________________ valves
carries blood under relatively low pressure
serves as blood reservoir
Venous Valves –valves in veins prevent blood from falling back down the body during
diastole, valves damaged can lead to varicose veins
Blood Pressure
Blood pressure is the force the blood exerts against the inner walls of the blood vessels, most
commonly refers to pressure in _________________________.
Arterial Blood Pressure
Systolic pressure is the maximum pressure and is created when the ventricles contract.
Diastolic pressure is the minimum pressure and is created when the ventricles relax.
A pulse is the alternate expanding and recoiling of an arterial wall.
Factors that Influence Arterial Blood Pressure
Heart Action
Stroke volume
Cardiac output
Blood Volume
Peripheral Resistance
Viscosity
Control of Blood Pressure -Factors affecting stoke volume and heart rate are mechanical, neural, and chemical.
If blood pressure rises, baroreceptors initiate the cardioinhibitory reflex which decreases blood pressure.
If blood pressure falls, the cardioaccelerator reflex occurs which increases ___________________________________ stimulation
to the heart, which _____________________________________ heart rate and cardiac output, which increases blood pressure.
Other factors that increase HR and BP are emotional responses, exercise, and a rise in body temperature.
When arterial blood pressure suddenly increases, baroreceptors signal the vasomotor center, and
_____________________________ sympathetic outflow to arterial walls, which results in a decrease in blood pressure.
Chemicals that influence peripheral resistance are carbon dioxide, oxygen, and hydrogen ions.
Central Venous Pressure
Central venous pressure is the pressure within the heart.
Central venous pressure is of special interest because it affects the pressure within the peripheral veins.
An increase in central venous pressure can lead to peripheral _________________________________.
Blood Flow Through Alveoli
cells of alveolar wall are tightly joined together
the high osmotic pressure of the interstitial fluid draws water out of them
Life-Span Changes
cholesterol deposition in blood vessels
heart enlargement
death of cardiac muscle cells
increase in fibrous connective tissue of the heart
Clinical Problems
MI = myocardial infarction
death of area of heart muscle from lack of O2
replaced with scar tissue
results depend on size & location of damage
increase in adipose tissue of the heart
_______________________________ in blood pressure
decrease in resting heart rate
Blood clot
use clot dissolving drugs streptokinase or t-PA & HEPARIN
balloon angioplasty
Angina pectoris-heart pain from ischemia of cardiac muscle
CAD
Coronary artery disease CAD is a condition in which the heart muscle receives an inadequate amount of blood due to
obstruction of its blood supply. It is the leading cause of death in the United States each year. The principal causes of
obstruction include ___________________________________________________, coronary artery spasm, or a clot in a coronary artery.
Risk factors for development of CAD include high blood cholesterol levels, high blood pressure, cigarette smoking, obesity,
diabetes, “type A” personality, and sedentary lifestyle.
Atherosclerosis is a process in which smooth muscle cells proliferate and fatty substances, especially cholesterol and
triglycerides accumulate in the walls of the medium and large arteries in response to stimuli, such as endothelial damage
Diagnosis of CAD includes such procedures as cardiac catheterization and cardiac angiography.
Treatment options for CAD include drugs and coronary artery __________________________________ grafting, and stents
Risk factors in heart disease:
high blood cholesterol level
high blood pressure
cigarette smoking
obesity & lack of regular exercise.
Other factors include:
diabetes mellitus
genetic predisposition
male gender
high blood levels of fibrinogen
left ventricular hypertrophy
Plasma Lipids and Heart Disease
Risk factor for developing heart disease is high blood cholesterol level.
promotes growth of fatty plaques
very low-density lipoproteins (VLDLs)
Most lipids are transported as lipoproteins
_________________ remove excess cholesterol from circulation
low-density lipoproteins (LDLs)
LDLs are associated with the formation of fatty plaques
high-density lipoproteins (HDLs)
VLDLs contribute to increased fatty plaque formation
There are two sources of cholesterol in the body:
in foods we ingest & formed by liver
Desirable Levels of Blood Cholesterol for Adults
TC (total cholesterol) under 200 mg/dl
LDL under 130 mg/dl
HDL over 40 mg/dl
Normally, triglycerides are in the range of 10-190 mg/dl.
Among the therapies used to reduce blood cholesterol level are exercise, diet, and ______________________________ DRUGS.