The Cardiovascular System - Week 3 Flashcards
Major components of the cardiovascular system
- the HEART - which acts as a pump
- BLOOD VESSELS (vasculature) - which acts as routes or pathways for blood
- BLOOD - which serves as a transport medium
Principle FUNCTIONS of the CARDIOVASCULAR system:
- TRANSPORT substances such as blood cells, gases, nutrients, wastes, hormones, heat, and others from one part of the body to another
- DEFENSE - WBC’s and other components of the blood participate in defensive and immune reactions against foreign invaders or damaged/infected cells
- PREVENT FLUID LOSS from body with the ability of blood to clot
Endocrine function of the heart
synthesis of ANP (decreases BP)
What are the TWO CIRCUITS of circulation
Pulmonary circulation
Systemic circulation
Pulmonary circulation
involves the flow of blood between the heart and lungs
Systemic circulation
refers to the flow of blood between the heart and all other organs of the body
in each circuit, ARTERIES LEAD…..while veins lead….
ARTERIES LEAD AWAY FROM THE HEART CHAMBERS WHILE VEINS LEAD BACK TOWARDS THE HEART CHAMBER
where is the heart located
in the MEDIASTINUM - the space in the thoracic cavity between the two lungs
Pericardium
a sac that surrounds the heart
What fills the cavity between the layers of the pericardium?
pericardial fluid
Function of the pericardium
ANCHORS the heart to surrounding structures while the FLUID REDUCES FRICTION during heart contraction
the walls of the heart include:
the inner ENDOCARDIUM lining the vessels
thick MYOCARDIUM consisting of cardiac muscles.
How many chambers are in the human heart? Upper and lower chambers?
4 chambers
upper chambers: Atria
Lower chambers: ventricles
Atria
upper chambers that receive blood from veins
Right atrium: from the body (systemic)
Left atrium: from the lungs (pulmonary)
Ventricles
lower chambers that pump blood from the heart into arteries
Right Ventricle: to the lungs (pulmonary) - 1/4” thick
Left Ventricle: to the body (systemic) - 3/4” thick
The myocardium of the left ventricle is much thicker than that of the other chambers due to
its increased workload
Interatrial septum
separates the R and L atria
Interventricular septum
separates the two ventricles
Valves
prevent backflow
Atrioventricular (AV) valves
tricuspid and mitral
Tricuspid valve
between R atrium and R ventricle
Mitral valve
between L atrium and L ventricle
Pulmonary and arotic valves
aortic valve
pulmonary valve
Aortic valve
between L ventricle and aorta
Pulmonary valve
between R ventricle and pulmonary trunk
LARGE ARTERIES such as the aorta are
quite ELASTIC
the force of ventricles contracting and the blood driven from them causes arteries to stretch
When ventricles relax, the RECOIL ACTION of large arteries such as the aorta continues to…
drive blood through the arteries
if it weren’t for the valves, the artery would also drive blood back into the ventricle during ventricular relaxation
name the great blood vessels
superior and inferior vena cava
pulmonary trunk
left and right pulmonary veins
aorta
superior and inferior vena cava
lead into the R atrium (from systems)
Pulmonary trunk
leads from the R ventricle and branches into L AND R PULMONARY ARTERIES that lead to each lung
L and R pulmonary veins
lead into the L atrium (from the lungs)
Aorta
leads from the L ventricle to the body
SPECIALIZED HEART MUSCLE CELLS
known as autorythmic fibers since they are “self-excitable” – they can INITIATE ACTION POTENTIALS that trigger heart contractions on their own - not in response to nerve impulse
THE CONDUCTION SYSTEM is made of specialized muscles cells such as:
SA node
AV node
AV bundle (bundle of HIS)
R and L bundle branches
Perkinje fibers
SA NODE
the hearts natural pacemaker
high capacity for self-excitation
located in the upper posterior part of R atrium
AV NODE
specialized tissue located between atria and ventricles of the heart
conducts electrical signals from the atria to the ventricles
the HIS-Perkinje fibers conduct the electrical signal from the AV node to the ventricles, via the:
AV bundle (bundle of HIS)
R and L bundle branches
Purkinje fibers
Although the SA node typically sets the pace of a health heart…
ANY PART OF THE CONDUCTION SYSTEM COULD INITIATE A HEART CONTRACTION
SYMPATHETIC STIMULATION (T1-5) of the heart
INCREASES HR AND THE STRENGTH OF MUSCLE CONTRACTION
PARASYMPATHETIC STIMULATION (vagus nerve) of the heart
DECREASES HR AND THE STRENGTH OF MUSCLE CONTRACTION
AN ELECTROCARDIOGRAM (ECG OR EKG) IS A
RECORD OF THE ELECTRICAL ACTIVITY of the heart
EKG’S PROVIDE INFORMATION ON
the axis (tilt) of the heart
HR
Heart rhythm
thickness of myocardium
conduction problems
+ more
less info about structural abnormalities such as valve disorders
the atria of the heart contract first, ventricles second, creating a
two-phased heart contraction
the CARDIAC CYCLE
the period from the beginning of one heartbeat to the beginning of the next heartbeat.
Relaxation must be complete before a new cycle begins.
The cardiac cycle lasts about…
0.8 seconds at 70 beats per minute
SYSTOLE
period of heart (chamber) contraction
DIASTOLE
the period of heart (chamber) relaxation
Atrial systole is followed by
ventricular systole
CARDIAC OUTPUT (CO)
the total volume of blood pumped (usually by the L vent.) per unit of time (usually per minute)
CO = HR x SV (stroke volume)
Cardiac output is primarily controlled by
the oxygen requirements of the body
The heart is a. ____ _____ that does not regulate its own output
DEMAND PUMP
Cardiac output can be increased by
increasing HR
increasing SV
Increasing both HR and SV (within limits)
Heart rate (HR)
measured by the number of heart contraction per minute
normal resting HR changes with
age
Bradycardia
<60 bpm
Tachycardia
> 100 bpm
Maximum heart rate (MHR)
the highest heart rate an individual can achieve without severe problems
maximal heart rate (MHR) equation
MHR = 220 - age
STROKE VOLUME (SV)
THE AMOUNT OF BLOOD EJECTED BY THE L VENTRICLE IN ONE CONTRACTION (PER STROKE)
END DIASTOLIC VOLUME (EDV)
volume of blood in the ventricle at the end of diastole (after filling)
normal adult = 120mL
END SYSTOLIC VOLUME (ESV)
volume of blood in the ventricle at the end of systole (after contraction)
moral adult = 50 mL
Resting HR in endurance athletes may be well below average, why?
increased EDV and SV
high stroke volume means there is a lot of blood moving in each stroke that it doesn’t have to beat as often
CARDIAC RESERVE
the % increase in CO that can be achieved during maximal exercise
EJECTION FRACTION (EF)
Definition + formula
the fraction (%) of blood pumped out of a filled ventricle during systole
EF = SV/EDV
CORONARY ARTERIES SUPPLY OXYGEN AND NUTRIENTS TO
THE CAPILLARY BEDS OF THE HEART MUSCLE
coronary arteries branch off the aorta just beyond the aortic valve and has
2 main coronary arteries
what is the #1 cause of death in the United States?
CORONARY ARTERY DISEASE (CAD)
ATHEROSCLEROSIS
the buildup of plaque in the artery walls, which narrows the lumen or inside of the vessel through which blood would flow
MYOCARIDAL ISCHEMIA
refers to a lack of blood flow to the heart muscle
MYOCARDIAL INFARCTION
refers to the death of heart muscle, commonly called a “heart attack”
CARDIAC VEINS “DRAIN” THE…
CAPILLARIES OF THE MYOCARDIUM OF CO2 AND WASTES
