Heart Flashcards
What does the cardiovascular system consist of ?
heart, blood and blood vessels
How many times des the heart beats?
100k times per day
How many times does the heart beat per lifetime?
2.9 Billion
How many circuits is the heart lined with the CV system ?
2 Main circuits
Carries blood to and from the lungs to the heart
Pulmonary Circuit
Transports blood to and through the body (heart to tissues and back to the heart
Systemic circuit
Arteries carry blood ?
Away from heart and towards tissues
Veins to heart
Away from tissue
Great Vessels
Largest veins and arteries
Capillaries
Smallest
How many chambers does the heart has? (cut half of the coronal plane)
4 chambers
Left atrium and Left ventricles
L- atrium collects blood from pulmonary circuit dumps into L- ventricle
R- atrium collects blood from __ and dumps into ___
systemic circuit; R- ventricle
What contracts first in the heart then what ?
The atria’s contract first, then ventricles.
What’s the outer muscle of the heart?
Epicardium ( Visceral pericardium)
What’s the middle muscle of the heart?
Myocardium - spiral bundles of muscles
What’s the inner muscle of the heart?
Endocardium ( simple squamous cells)
Outer _____ pericardium prevents overfilling. helps to protect
Fibrous
The heart is surrounded by ____ to protect it from friction ?
pericardial sac
Inner ____ pericardium
Serous
Outer parietal layer, inner visceral layer (epicardium)
Increases fluid in pericardial space when infected
Pericarditis
Deep groove on the border between atria/ventricles
Coronary Sulcus
Expandable extension of the atrium “ Ear-like”
Auricle
The posterior interventricular sulcus contains ?
Fat pads (stripped to see cardiac vessels)
The Anterior interventricular sulcus is the ???
Boundary between L and R ventricles
What type of tissue is the Myocardium?
Connective tissue of the heart
Cells are wrapped in elastic sheath- adjacent cells crosslinked
-Provide physical support
-Distributes force of contractions
-Prevent overextension
-Provides recoil effect
Ventricles are separated by ?
Atrioventricular septum— Big muscle right in the middle
What separates the atriums?
Thinner Inter-atrial septum
What valve separates the atriums from their ventricle ??
Atrioventricular valve
what valve is in the Right atrium?
Tricuspid valve
This valve is in the Left atrium
Mitral (bi-cuspid valve)
There are one-way valves to help direct blood flow and prevent backflow and to ensure proper pressure and gradient flow
Located in between the aorta and L ventricle and pulmonary vein and R ventricle
Semilunar valves
What muscle is on the posterior right side of the atrium and interatrial septum?
Pectinate muscles
What muscle arises from the ridges to to anchor the chordae tendinea whose job is to pull on the tricuspid valve and bicuspid valve?
Papillary muscle
This section -muscle ridges- prevents overdistention, increased performance, prevents suction.
Trabeculae Carneae
What Atrium receives blood from superior and inferior vena cava
Right Atrium
From Head, neck, upper limbs, and chest
Superior vena cava
Trunk, viscera lower limbs
Inferior vena cava
____ connects L and R atriums in embryonic stages- closed at birth- left over depression called _____
Foramen Ovale; Fossa Ovalis
What atrium receives blood from L and R pulmonary veins?
Left Atrium
Why does blood move from atrium to ventricles ?
trabeculae carnae are more prominent
Ventricle muscle is much thicker on ???
Left than Right because contractile force is needed
This valve prevents backflow into the atrium from ventricles ?
Atrioventricular valves
Ventricle contraction causes papillary muscle contraction and the AV valves swing closed to prevent backflow- chordae tendinea tense- prevents AV valves from swinging up into atria
Regurgitation
This valves don’t need chords no contraction- 3 flaps support each other like a stool
Semilunar valves
The right atrium receives blood from?
Superior and inferior vena cava
The left atrium receives blood from ??
The 2 pulmonary veins
deliver blood to the heart itself and arise from the base of
the aorta
Coronary arteries
BP is highest in
aorta and systemic circuit
R and L coronary arteries originate at the R and L aortic sinuses to give
blood to
myocardium
R - coronary artery follows coronary sulcus around the heart supplies
blood to:
-R atrium
-Both ventricles
-Conducting system of heart
L coronary artery supplies to
- L - Ventricle
- L - Atrium
- Interventricular septum
Branching off from the L- coronary artery is the
circumflex and LAD
_______Connects L to R as to prevent de-oxygen if one
side gets damaged
Circumflex artery
runs
along the surface of the interventricular surface
Left Anterior Descending Interventricular artery (LAD)
Connections like circumflex are called?
Anastomoses
begins on the anterior (front) portion the heart
following the interventricular sulcus; Drains blood from the LAD
Great Cardiac Vein
drains the myocardium
Coronary Sinus
What are the 2 Heart specialized cells
Autorhythmic (pacemaker) cells and Contractile (cardiac cells)
Control and coordinate heartbeat – contain
their own electrical current (no true resting membrane) - sinoatrial node,
atrioventricular node, atrioventricular bundle, L/R bundle branches and purkinje
fibers (in this order)
Autorhythmic (pacemaker) cells
sinoatrial node, atrioventricular node
Nodal Cells
Originates in the Posterior wall of the R-
atrium.
- Generates “sinus rhythm” (60-80 beats per minute)
- Sends projections to L atrium Bachmus bundle
Sino-Atrial node (SA)
sends fiber to interventricular
septum and continues the transfer of the depolarization
-Takes 0.1 second delay to allow time for each atria to contract
- Less gap junctions
b.) Conducting cells additnally make up the atrioventricular bundle, L/R
bundle branches and purkinje fibers
i.) Connect the SA and AV nodes/ propagate signals to the contractile
tissue of the heart
Atrio-Ventricular node (AV)
produce power propelling blood
a.) Action potential flows through the heart tissue causing contraction
Contractile (cardiac) cells
Damage to conducting pathways result in ?
conducting deficits (reduce BPM)
Abnormal conduction outside the SA and AV nodes is an
ectopic pacemaker
(disrupts timing)
At threshold Na+ rushes in due to “fast”
Na+ channels
(Phase 0) Rapid Depolarization
K+ leaks out of contractile cells causing a drop in voltage.
This activates Ca2+ channels.
(Phase 1) Plateau
Ca2+ influx and K+ outflow continues giving the voltage
plateau phase.
b.) Together they 1. Delay repolarization and 2. Keeps membrane potential
at 0mV for extended period long to aid in contraction
c.) Cells contract similar to muscle cells: action potential transferred via T-
tubules, activation of sarcoplasmic reticulum, release of calcium, binds to
troponin and allow myosin and actin to cause a power stroke
(Phase 2)
Ca2+ channels in the contractile cell now close;
due to reduced cation transportation from repolarization of nodal cells. More K+
channels now open and more K+ leaves the cell.
(Phase 3) Repolarization
cells won’t respond to another impulse: 1.
Absolute refractory period (no stimulus can cause depolarization) and 2. Relative
refractory period (a strong signal can cause depolarization)
6.) To depolarize you need the three fundamental ions (similar to muscles) Na+,
K+, and Ca2+
7.) Heart needs to contract for longer - Ca2+ helps sustain/prolong the contraction.
(Phase 4) Refractory Period
When the atria depolarize as a result of the SA node actions on the heart tissue
you get the
“P” wave
When the ventricles (both of them) contract to push blood in their respective
systems you get the
“QRS” wave
where the ventricles contract and atrial repolarization takes
place (but cannot see)
The “R” wave
When the ventricles repolarize is when the you get the?
“T” wave
Extend from the end of the wave to the beginning of the next
Segments
Variable and include at least one wave
Intervals
atrial depolarization to the start of QRS complex (extensions
more than 200msec indicate damage to AV or conducting pathways)
P-R interval
an be lengthened by electrolyte,
medication, conducting problems
Q-T interval (single re/de-polarization)
99% of the atrial and ventricle walls are made up of
cardiac/contractile cells
contraction of chamber (atrium, ventricle)
Systole
relaxation of chamber (Filling with blood occurs here)
Diastole
BP rises in___ and decreases in ___ (high to low)
Systole; Diastole
begins with topping off the ventricles contracting to push 30% of
remaining bloods into ventricles
Atrial systole
no blood enters as pressure is higher than in veins
Atrial diastole
ullest amount of blood in ventricles in cardiac
cycle (occurs after atrial systole and before ventricles contract)
End-Diastolic Volume
is the contraction (without moving blood)
generating pressure and tension - not yet strong enough to push the blood out.
Isovolumetric contraction
occurs next finally reaching threshold for pressure to eject
blood out into the aorta and pulmonary vein
Ventricle Systole
Amount of blood left in the ventricles after
semilunar valves close (less than EDV)
End-Systolic Volume
now occurs where all valves are closed and myocardium
relaxes regaining threshold from action potential
Ventricle Diastole
ventricle pressure still greater than atrial
pressure - nothing flows into ventricles called
Isovolumetric relaxation
Semilunar valves opening/ AV valves closing
Lubb
Semilunar valves close/ AV valves open
Dubb
The number of beats per minute and is affected by hormones
and/or CNS
Heart Rate
Is the amount of blood pumped out the ventricle during each
contraction SV = EDV - ESV
Stroke Volume
Is the amount of blood which leaves the left ventricle in one
minute CO (mL/minute) = HR (Beat/minute) x SV (mL/beat)
Cardiac Output
is nerve network of the heart and is the connection point for
the SNS where NE is released.
Cardiac Plexus
Cardiac centers in brain control rate
cardioinhibitory and
cardioacceleratory (nuclei in the medulla oblongata)
Degree of stretching in ventricle muscle cells during ventricle
diastole high EDV = high preload
Preload
is amount of blood that returns/reaches atria more means
increased heart rate
Venous return
a.) Filling Time – decides preload and is the duration of ventricle diastole
(faster heart rate = shorter filling time)
Factors affecting EDV:
Increased stretch beyond optimal length reduces
force of contraction
a.) Greater stretch = greater contraction = preload
Frank-Starling Principle
atrial reflex) occurs when the heart rate increases in
response to a rise in atrial pressure. This is a compensatory mechanism since
increased right atrial pressures frequently result from elevated left heart pressures
from decreased cardiac output.
Bainbridge reflex
Preload
factor affecting ESV
b.) Ventricular contractility – Amount of force produced during a
contraction at a given preload SNS, T4/3, Glucagon, Drugs, Ions,
Acidosis
One factor affecting ESV
Afterload - Amount of tension that the contracting ventricle must
produce to force open the semilunar valve and eject blood (aka amount of
resistance that must be overcome)
factor affecting ESV
High afterload
Low stroke volume
Vasodilatation (_________afterload) and vasoconstriction
(__________ afterload, ex; aortic valve dysfunction, plaque,
HBP)
Decreases; increases
SA node, SNS, PNS, T4/3, Body Temp, Ions, partial
pressure of CO2 and Oxygen, age, fitness
Factors affecting HR
Maximal cardiac output - Resting cardiac output
Cardiac Reserve
Trained athletes increase _____ by 700% (limit to increase)
cardiac output
weakening of left
ventricle after a loss or extreme stress – ECGs and blood enzymes resemble heart
attacks!
Broken Heart Syndrome (Takotsubo cardiomyopathy)
If the heart was merely a pump it would take roughly 1 million times the
strength to push the blood through the system use
water hydrodynamics
to circulate
When we evaluate heart’s muscle itself, we find it is wrapped in a helical way causes_____
toroidal field
i.) Muscular milking (valves)
ii.) Respiratory pump (High to low)
iii.) Venomotor Constriction via SNS
c.) Myocardial Infarction – reduce preload
Factoring increasing venous return:
