Cardiovascular System
-Pressure- blood will flow from high pressure to low pressure *if allowed
-Pump-->blood vessels-->blood
-heart is two pumps in one
-right side pumping to the lungs
-left side pumping to rest of the body
-right side pumping to pulmonary
-left side pumping
Location of the heart
-heart sits in ventral cavity, specifically the thorastic cavity, more specifically medial stinum
-2/3 of heart to the left side
Anatomy of the heart
-heart is tilted on axis pointed to the left side
-apex points towards left hip
Pericardium
-most outer covering of heart
-most outer layer is fibrous pericardium
-function: protection, making sure it stays in the same place, keeps things out
-serous pericardium can also be broken down into two layers
-have parietal and visceral
-have dense laye
Cardidis
-will have friction if you don't have enough fluid in pericardial cavity
Epicardium
-outermost layer of the heart
-also known as visceral serous pericardium
myocardium (myo refers to muscle)
-thickness layer of heart wall is where you find cardiac heart muscles
-will find bulk of heart here
-much thicker than in ventricle than atrium
-this means it has greater role in contraction
-pushing blood out to body
Endocardium
-Most inner of heart wall called ___________ that will line all four heart chambers and continuous will all blood vessels leaving the heart
Chambers
-Right atrium, left atrium, right ventricle, left ventricle
-blood being collected or discharged out lungs and the rest of the body
-have septum
-three sulci (grooves) on outside of heart that determines where chambers are
Septum
-layer of muscle that divides ventricles and atrium
-inter means between
Coronary Sulcus
-runs around circumference of heart that divides atrium from ventricle
-sulci divides left and right ventricle
Ventricles
-sends blood out of the heart
-the discharging chambers
-walls of ventricles not smooth
-Diff. b/w right and left ventricle:
--left ventricle pumping blood out to whole body instead of just lungs
--right pumps to the lungs
Atria/atrium
-blood going into ________ (receiving chambers)
-received blood from lungs or rest of the body
-thickness of wall is smooth and thin
--don't have large contractile functions
--right atrium going to be collecting DEOXYGENATED blood from the body
--3rd sour
Coronary Sinus
where blood circulates through the heart and dumps it back into the right atrium
Oracles
appendages on heart to increase volume of blood being collected
Trabeulae Carneae
-irregular bundle of muscles throughout ventricles
--make ventricles bumpy
--will contract to push blood out to rest of body
Papillary Muscles
will be attached to valves of atria and ventricle
-make sure ventricles and atria work properly?
Flow of Blood
-in normal heart, there is only a one way _______
-pressure is going to be a huge part of how the blood flows
-blood flows from area high pressure to area of low pressure
-valves are going to be reason we have one way flow of blood
Valves
- the reason we have one way flow of blood
-valves b/w atrium and ventricle called atrioventrical _______ (AV ____)
-Tricuspid ______- have three flaps that fit together
-bicuspid ______- has two flaps
AV Valves
-AV valves open; atrial pressure greater than ventricular pressure
--Blood returning to the heart fills atria, pressing against the AV valves.
--The increased pressure forces AV valves open.
-- As ventricles fill, AV valve flaps hang limply into ventricle
Incompetent valve
-a homeostatic imbalance
-severely weakens heart
-Blood backflows so heart repumps same blood over and over
-Valve replaced with mechanical, animal, or cadaver valve
-Can have heart murmurs of blood not being pushed back correctly
Valvular stenosis
-Stiff flaps - constrict opening--> heart must exert more force to pump blood
--Cannot open valve that easily so blood has to work harder
-Valve replaced with mechanical, animal, or cadaver valve
-Can have heart murmurs of blood not being pushed back corr
Pulmonary Circuit
-deoxygenated blood that is pumped to lungs
-Right atrium --> tricuspid valve--> right ventricle
-Right ventricle--> pulmonary semilunar valve -->pulmonary trunk-->pulmonary arteries--> lungs
-Lungs--> pulmonary veins-->left atrium
Systemic circuit
-oxygenated blood pumped to the heart
-Left atrium--> mitral valve-->left ventricle
-Left ventricle-->aortic semilunar valve--> aorta
-Aorta-->systemic circulation
Pathway of Blood Through the Heart
-Equal volumes of blood pumped to pulmonary and systemic circuits
-Pulmonary circuit short, low-pressure circulation
-Systemic circuit long, high-friction circulation
-Anatomy of ventricles
-reflects differences:
--Left ventricle walls 3X thicker than rig
Arteries (coronary circulation)
-a third circuit that only serves the heart
-bringing blood to tissues of heart
-after leave left V, immediately have two articles that branch off (L and R coronary artery) and will supply heart with nutrience it needs
-are right after aortic valve
-LCA--
Branches of the Coronary Arteries
-will all branch down into myocardium
-will line all of blood cells
-make sure all cells have oxygen and nutrience in order to survive
-however they have waster products
Veins (coronary circulation)
-______ give off waste and bring blood back into the heart
-SCV,MCV, and MAJ C V- gather up all blood from coronary circulation and will join all of components of blood into cornonary sinus
-coronary sinus dumps blood into right atrium
-collecting venus b
Coronary Vessels of the Heart
-arteries and veins running along routes where you see sulci
-blockage of right coronary artery? No blood getting through?
-A) won't get nutrience and oxygen to right side of heart so tissue dies so poor pumping of lungs so you won't get as much oxygen, w
Comparisons b/w cardiac, skeletal, and smooth muscle
1. Anatomically (both striated)- striations in skeletal and cardiac muscles are from actin and myosin overlap in regular pattern
-arranged similarly
2. Physiologically- cardiac muscle more like smooth muscle (gap junctions appear in cardiac muscle)
3. One
Microscopic Anatomy of Cardiac Muscle
-Allow ions to pass from cell to cell
-Electrically couple adjacent cells
-Allows heart to be functional syncytium
-Desmosomes prevent cells from separating during contraction
Orientation of Contractile Cardiomyocytes
-all muscles cells arranged like a bundle of straws
-cardiac muscle/myocytes twisted around heart, when shortening you are twisting the muscle as well
-greater amount of blood pushed through heart if it twisted
-cardiac myocytes arrange so you can pump as
Electrical Events in the Heart
-Coordinated heartbeat is a function of:
--Intrinsic cardiac conduction system - it is a property of heart muscle and does not depend on the nervous system.
--The independent but coordinated activity is due to they autorhythmic cells and the presence of g
Intrinsic cardiac conduction system
it is a property of heart muscle and does not depend on the nervous system.
Pacemaker (Autorhythmic) Cells
-Do not need nervous system stimulation - have an unstable resting membrane potential that is always depolarizing
-Have unstable resting membrane potentials (pacemaker potentials or prepotentials) due to opening of slow Na+ channels
--Continuously depolar
Pacemaker Potential (pacemaker cells)
-1st part of action potential
-Repolarization closes K+ channels and opens slow Na+ channels--> ion imbalance--> depolarization
-This slow depolarization is due to both opening of Na+ channels and closing of K+ channels. -Notice that the membrane potentia
Depolarization (pacemaker cells)
-2nd part of action potential
-Ca2+ channels open huge influx rising phase of action potential-->Repolarization
-The action potential begins when the pacemaker potential reaches threshold. Depolarization is due
to Ca2+ influx through Ca2+ channels.
Repolarization (pacemaker cells)
-3rd part of action potential
-Inactivation of Ca2+ channels and K+ channels open--> efflux of K+
-due to Ca2+ channels inactivating and
K+ channels opening. This allows K+ efflux, which brings the membrane potential back to its most negative voltage.
The sinoatrial (SA) node
-(pacemaker)
-generates impulses
-collection of pacemaker cells in _______
--will generate electrical impulse to cause contraction
-at all junctions, you have gap junctions
-depolarization spreading throughout all atria
atrioventricular (AV) node
-The impulses pause (0.1 s)
-have to get depolarization down the ventrical
atrioventricular (AV) bundle
-connects the atria to the ventricles
--one ________ on each side toward apex of the heart and turn around and go to the outer walls
bundle branches
-conduct the impulses through the interventricular septum
subendocardial conducting network
-depolarizes the contractile cells of both ventricles.
Sequence of Electrical Excitation in the intrinsic conduction system
SA node-->AV node-->AV bundle-->bundle branches-->subendocardial conducting network
Action Potentials of Cardiac Cells
-pacemaker never has flat RMB (resting membrane potential)
-has pacemaker potential, a slight depolarization that is caused by an influx of sodium leaking into cell
-potassium leaves cell making cell go more negative again on inside
-ion direction differe
Contractile Cell
have plateau phase where the membrane potential stays about the same
Depolarization (contractile cardiac cell)
-is due to Na+ influx through fast voltage-gated Na+ channels. A positive feedback cycle rapidly opens many Na+ channels, reversing the membrane potential. Channel inactivation ends this phase
-ion flowing into cell is sodium!
-peak is when sodium channel
Plateau phase (contractile cardiac cell)
-due to Ca2+ influx through slow Ca2+ channels.
This keeps the cell depolarized because few K+ channels are open.
-plateau phase due to calcium (+) coming into cell while you have some potassium (+) leaving
Repolarization (Contractile Cardiac Cell)
-due to Ca2+ channels inactivating and K+
channels opening. This allows K+ efflux, which brings the membrane potential back to its resting voltage
-only potassium channels open so MP goes back to RMP in repolarization
Ion Flux in Contractile AP
-way AP looks due to ions flowing in or out of cell
--has characteristic phases
APs and Contraction in Skeletal Muscle
-Skeletal muscle fast twitch fiber: the refractory period is very short compared with the amount of time required for the development of tension
-skeletal muscles that are stimulated repeatedly will exhibit summation and tetanus
APs and Contraction in Contractile Cardiomyocytes
-cardiac muscle fiber: the refractory period lasts almost as long as the entire muscle twitch
-long refractory period in a cardiac muscle prevents tetanus
-tension increasing then relaxing then increasing in tension again
-don't want cardiomyocytes to fat
ECG
compilation of all electrical activity going on in the heart
EKG
put electropads on heart to measure electrical activity
Heart Waves/Deflections
corresponds with some action that is going on in the heart
P Wave
-Atrial depolarization, initiated by the SA node, causes the ______
-beginning of ______ going to be when SA mode fires
--whole _______ when atrium depolarizing
--once pacemaker cells fire AP, it starts the ______
Gap after P wave
-With atrial depolarization complete, the impulse is delayed at the AV node
-have sometime where you have a gap where atria depolarized
--everything funneled through little spot to get to ventricles
--can have depolarization of atria during delay
--normal
QRS Complex
-Ventricular depolarization begins at apex, causing the ______ complex. Atrial repolarization occurs.
--abnormally shaped spike is QRS that is representative of ventricular depolarization, mmoves through septum
--indicates that ventricles depolarizing
--i
Lag after QRS Complex
Ventricular depolarization is complete so ventricles will contract now
T Wave
-Ventricular repolarization begins at apex, causing the ______
-when ventricles repolarize where you start to have relaxation of ventricles
-along way all of these section is indicative of some electrical activity occurring
End after T Wave
-Ventricular repolarization is complete
-once you get to end you come back to beginning
-one cycle is one complete heart beat
P-R Interval
-Beginning of atrial excitation to beginning of ventricular excitation. This also includes atrial depolarization and contraction.
-time it takes to get from P to R
S-T Segment
Entire ventricular myocardium depolarized
Q-T interval
Beginning of ventricular depolarization through ventricular repolarization
Normal sinus rhythm
Normal ECG trace
Junctional rhythm
The SA node is nonfunctional. As a result:
� P waves are absent.
� The AV node paces the heart at 40-60 beats per minute
Second-degree heart block
The AV node fails to conduct some SA node impulses.
� As a result, there are more P waves than QRS waves.
� In this tracing, there are usually two P waves for each
QRS wave.
Ventricular fibrillation
-Electrical activity is disorganized. Action potentials occur randomly throughout the ventricles.
� Results in chaotic, grossly abnormal ECG deflections.
� Seen in acute heart attack and after an electrical shock
The Cardiac Cycle (Mechanical Cycle)
-systole-contraction
-diastole-relaxation
-electrical events cause mechanical event to happen
-depolarization leads to contraction of that part of the heart
=depolarization of atria at P
-QRS is going to be depolarization of ventricles, following by systo
Ventricular Filling
-1st event of cardiac cycle
-Both the atria and ventricles are in diastole (relaxed)
-Blood coming into the atria flows directly into the ventricles
--AV valves are open; pressure in the downstream ventricle is lower than the upstream atria
-Bump in the v
End Diastolic Volume
-the last part of ventricular filling
-volume of blood in each ventricle at end of ventricular diastole
--How much blood you can get into ventricles
Ventricular Systole
-Depolarization wave spreads to ventricles
-Atria relax; ventricles begin to contract
-Rising ventricular pressure closing of AV valves
1st heart sound - "lub"
-Isovolumetric contraction phase - all valves are closed
-same volume of blood in this phase
-
Isovolumetric contraction phase
-part of ventricular systole
-all valves are closed
--same volume of blood in this phase
Ventricular ejection phase
-part of ventricular systole
-ventricular preslarge arteries, forcing SL valves open
End Systolic Volume
volume of blood remaining in each ventricle after systole
Stroke Volume
how much blood you end up with and can eject out the ventricle
Isovolumetric Relaxation (means both AV and SL valves will be closed
Same amount of blood)
-Ventricles & atria relax
-Atria filling
-Semilunar valves close
--blood wants to go from high to low, but can't do that with circuit so SL valves close
-Ventricles totally closed chambers
-When atrial pressure exceeds that in ventricles -->AV valves open
Blood flow in the Cardiac Cycle
-1. Blood flow through the heart is controlled entirely by pressure changes.
-2. Blood flows down a pressure gradient through any available opening.
-3. Heart valves keep the blood flowing in the forward direction.
Dicrotic Notch
-place where ventricle starts relax, sharp rise as blood goes into aorta
--when you push the first amounts of blood into the aorta
Heart Sounds
-Two sounds (lub-dup) associated with closing of heart valves
--First sound is closing of AV valves at beginning of ventricular systole
--Second sound is closing of SL valves at beginning of ventricular diastole
--Pause between lub-dups indicates heart re
Aortic Valve
sounds heard in 2nd intercostal space at right sternal margin
Pulmonary Valve
sounds heard in 2nd intercostal space at left sternal margin
Mitral Valve
sounds heard over heart apex (in 5th intercostal space) in line with middle of clavicle
Tricuspid Valve
sounds typically heard in right sternal margin of 5th intercostal space
Heart Murmurs
-abnormal heart sounds heard when blood hits obstructions
-Usually indicate valve problems
--includes abnormal heart sounds heard when blood hits obstructions
--includes Stenotic valve
--includes incompetent (or insufficient valves)
Incompetent (or insufficient) valve
-fails to close completely, allowing backflow of blood
--Causes swishing sound as blood regurgitates backward from ventricle into atria
Stenotic Valve
-fails to open completely, restricting blood flow through valve
-Causes high-pitched sound or clicking as blood is forced through narrow valve
-Harder to push blood through valve
Cardiac Output (CO)
-Volume of blood pumped by each ventricle in one minute
-CO = stroke volume (SV) � heart rate (HR)
--SV = volume of blood pumped out by one ventricle with each beat
--HR = number of beats per minute
-tells us how well heart is pumping
-EDV vs ESV (how muc
Stroke Volume
-SV = EDV - ESV
-Three main factors affect SV:
--Preload: degree of stretch of cardiac muscle cells before they contract (how much blood getting into ventricle before contraction)
---Stretch to right length to get right contraction
--Contractility - contr
Regulation of Heart Rate (Extrinsic Innervation of the Heart)
-Sympathetic --> increases rate and force
-Parasympathetic--> rate (decrease)
-Arteries-go way from heart
-capillaries- exchanges
-veins- go toward heart
-nErvous system can modify what is going on in heart
--chemical modifiers that will affect the heart
Hormones (Chemical Regulation of Heart Rate)
-Epinephrine from adrenal medulla increases heart rate and contractility
-Thyroxine increases heart rate; enhances effects of norepinephrine and epinephrine
-Intra- and extracellular ion concentrations (e.g., Ca2+ and K+) must be maintained for normal hea
Other Factors that Influence Heart Rate
-Age
--Fetus has fastest HR
-Gender
--Females faster than males
-Exercise
--Increases HR
--Getting more oxygen to skeletal muscles
-Body temperature
--Increases with increased temperature
Right Atrium
going to be collecting DEOXYGENATED blood from the body
Left Atrium
collecting OXYGENATED blood from lungs
Right Ventricle
pumps to the lungs
Left Ventricle
pumping blood out to whole body instead of just lungs