The Cardiovascular system consist of what?
Heart and blood vessels
The Circulatory system consist of what?
Heart, blood vessels, and the blood
Pulmonary Circuit
Right side of the heart
Carries blood to lungs for gas exchange and back to heart
Systemic Circuit
Left side of heart
Supplies oxygenated blood to al tissues of the body and returns to it the heart.
What are the two Major divisions of the circulatory system?
Pulmonary circuit and Systemic Circuit
Left side of the heart
Fully oxygenated blood arrives from lungs via pulmonary veins
Blood sent to all organs of the body via aorta
Right side of the heart
Oxygen- poor blood arrives from inferior and superior venue cavae
The heart lies between the two lungs and within a think partition called what?
The mediastinum
Pericardium
A double- walled sac that encloses the heart
Allows heart to beat without friction, provides room to expand, yet resists excessive expansion
Anchored to diaphragm inferiorly and sternum anteriorly
Pericardial Sac (Parietal pericardium)
Superficial fibrous layer of connective tissue
Deep, thin serous layer
Visceral Pericardium (epicardium)
Serous membrane covering heart
Adipose in thick layer in some places
Coronary blood vessels travel through this layer
Pericardial Cavity
Space inside the pericardial sac filled with 5 to 30mL of pericardial fluid
The heart wall consists of what three layers?
Epicardium, myocardium, and endocardium.
Endocardium
Smooth inner lining of heart and blood vessels
Covers the valve surfaces and is continuous with endothelium of blood vessels.
Myocardium
Layer of cardiac muscle proportional to work load
~Muscle spirals around heart which produces wringing
motion
Fibrous skeleton of the heart: framework of collagenous and elastic fibers
What are the 4 chambers?
Right and left atria, Right and left ventricles.
Right and Left Atria
Two superior chambers that receive blood returning to the heart.
Right and Left Ventricles
Two inferior chambers that pump blood ion the arteries.
Anterior and Posterior interventricular sulcus
Overlies the inter ventricular septum that divides the right ventricle from the left.
Interatrial septum
Wall that separates atria
Interventricular septum
Muscular wall that separates ventricles
Atrioventricular (AV) Valves
Control blood flow between atria and ventricles
Mitral Valve
The Left AV valve
consisting of two tapered cusps.
Papillary muscles
The papillary muscles are muscles located in the ventricles of the heart. They attach to the cusps of the atrioventricular valves (also known as the mitral and tricuspid valves) via the chordae tendineae and contract to prevent inversion or prolapse of th
Pulmonary valve
Controls the opening from the right ventricle into the pulmonary trunk
Aortic valve
Controls the openings front he left ventricle into the aorta.
At rest, the coronary blood vessels supply the myocardium with how much blood per minute?
250 mL
The Pathway of blood flow through the heart:
1. Blood enters right atrium from superior and inferior venue cavae.
2. Blood in the right atrium flows through the right AV valve into right ventricle.
3. Contraction of the right ventricle forces pulmonary valve open.
4. Blood flows through pulmonary va
Immediately after the aorta leaves the left ventricle, it gives of a right and left what?
Coronary artery
Left Coronary Artery (LCA)
Travels through the coronary sulcus under the left auricle and divides into two branches.
~Anterior interventricular branch
~Circumflex branch
Anterior Interventricular Branch
Supplies blood to both ventricles and anterior 2/3 of the interventricular septum.
Circumflex branch
Passes around the left side of the heart in coronary sulcus.
Gives off left marginal branch and then ends on the posterior side of the heart
Supplies left atrium and posterior wall of left ventricle
Right Coronary Artery (RCA)
Branches off the ascending aorta and supplies right atrium and sinoatrial node (pacemaker)
Gives off two branches: the Right marginal branch and posterior interventricular branch
Right marginal branch
Supplies lateral aspect of right atrium and ventricle.
Runs toward the apex of the heart.
Posterior interventricular branch
Supplies posterior walls of ventricles.
Myocardial Infarction (MI)
Heart attack
Interruption of blood supply to the heart from a blood clot or fatty deposit (atheroma) can cause death of cardiac cells within minutes resulting
Some protection from Mi is provided by arterial anastomses which provide alternative routes of b
5% to 10% of coronary blood drains directly into heart chambers (mostly right ventricle) by way of what veins?
Thebesian veins
Part of venous drainage
Venous Drainage
Refers to the route by which blood leaves an organ
What are the routes of Venous drainage?
Great cardiac vein, Posterior interventricular (middle cardiac) vein, left marginal vein, and coronary sinus
Great Cardiac vein
Travels alongside anterior interventricular artery
Collects blood from anterior portion of heart
Empties into coronary sinus
Posterior interventricular (middle cardiac) vein
Found in posterior sulcus
Collects blood from posterior portion of heart
Drains into coronary sinus
Left Marginal Vein
Empties into coronary sinus
Coronary Sinus
Large transverse vein in coronary sulcus on posterior side of heart.
Collect blood and empties into right atrium
Autorhythmic
generating its own rhythm.
Ex: Heart because it doesn't depend on the nervous system for its rhythm. It has its own pacemaker and electrical system
Cardiocytes (cardiomyocytes)
Striated, short, thick, branched cells, one central nucleus surrounded by light-staining mass of glycogen
Intercalated discs
Join cardiocytes end to end.
The Cardiac Conduction system:
1. SA node fires.
2. Excitation spreads through atrial myocardium
3. AV node fires.
4. Excitation spreads down AV bundle.
5. Purkinje fibers distribute excitation through ventricular myocardium.
The Cardiac Conduction system in further detail in order:
1. The Sinoatrial (SA) node is a patch of modified cardiocytes in the right atrium, just under the epicardium near the superior vena cava. This is the pacemaker that initiates each heartbeat and determines the heart rate.
2. Signals from the SA node sprea
is the heart sympathetic or parasympathetic?
Both- even though the heart has its own pacemaker, it does receive both sympathetic and parasympathetic nerves that modify the heart rate and contraction strength.
Ex: Sympathetic stimulation can raise the heart rate to as high as 230 bpm, and parasympath
Systole
Contraction
The heart would beat too fast without what nerve?
The Vagus Nerve (X)
Diastole
Relaxation
Systole and diastole usually refer to the action of what?
The ventricles
Sinus Rhythm
Normal heartbeat triggered by the SA node
Adult at rest is typically 70 to 80 bpm (vagal tone), although heart rates from 60 to 100 bpm are not unusual.
Electrocardiogram (ECG or EKG)
Composite of all action potentials of nodal and myocardial cells detected, amplified and recorded by electrodes on arms, legs, and chest.
A typical ECG shows what three principal deflections above and below the baseline?
The P wave, QRS complex, and T wave
P Wave
SA node fires, atria depolarize and contract
Atrial systole begins 100ms after SA Signal
QRS complex
Ventricular depolarization
Complex shape of spike due to different thickness and shape of the two ventricles
T Wave
Ventricular depolarization and relaxation
Arrhythmia
Any deviation of the ECG
What are the types of Cardiac Arrhythmias?
1. Sinus rhythm (normal)
2. Ventricular fibrillation- most serious
3. Atrial fibrillation
4. Heart block
5. Premature ventricular contraction
Valvular Insufficiency Disorders
Any failure of a valve to prevent reflux (regurgitation), the backward flow of blood.
Ex: Mitral Valve Prolapse
Mitral Valve Prolapse
Insufficiency in which one or both mitral valve cusps bulge into atria during ventricular contractions
Hereditary in 1 out of 40 people
may cause chest pain and shortness of breath
First heart sound (S1)
Louder and longer "lubb", occurs with closure of AV valves, turbulence in the bloodstream, and movements of the heart wall.
Second heart sound (S2)
Softer and sharper "dupp", occurs with closure of semilunar valves, turbulence int he bloodstream, and movements of the heart wall.
Auscultation
Listening to sounds made by the body
Stroke Volume (SV)
is the volume of blood pumped from one ventricle of the heart with each beat
Is about 70 mL
Ejection Fraction
is the fraction of outbound blood pumped from the heart with each heartbeat. It is commonly measured by echocardiogram and serves as a general measure of a person's cardiac function. Ejection fraction is typically low in patients with Systolic congestive
Equal output by the two ___ is essential to homeostasis.
Ventricles
The Necessity of Balanced Ventricular Output
a) if the left ventricle pumps less blood than the right blood pressure back s up into the lungs and causes pulmonary edema. b) if the right ventricle pumps less blood tan the left, pressure backs up in the systemic circulation and causes systemic edema.
Cardiac Output (CO)
Amount ejected by each ventricle in 1 minute
CO= HR x SV
(heart rate x stroke volume)
Heart rate is most easily measured by what?
taking a person's pulse.
Tachycardia
Resting adult heart rate above 100 bpm
Stress, anxiety, drugs, heart disease, or fever
Loss of blood or damage to myocardium
Fast
Bradycardia
Resting adult heart rate of less than 60 bpm
In sleep, low body temperature, and endurance trained athletes
Positive Chronotropic agents
Factors that raise the heart rate
Negative chronotropic agents
Factors that lower the heart rate`
Baroreceptors (pressoreceptors)
Signal cardiac center
Pressure sensors in aorta and internal carotid arteries
Blood pressure decreases, signal rate drops, cardiac center increases heart rate
If blood pressure increases, signal rate rises, cardiac center decreases heart rate
The other factor in cardiac output is stroke volume. This, in turn, is governed by what 3 variables?
Preload
Contractility
Afterload
Preload
The amount of tension in ventricular myocardium immediately before it begins to contract
Increased during exercise
Contractility
Refers to how hard the myocardium contracts for a given preload
Afterload
The sum of all forces a ventricle must overcome before it can eject blood
Positive inotropic agents
Increase contractility
can cause: hypercalcemia
Negative inotropic agents
Reduce contractility
can cause hypocalcemia
Coronary Artery Disease (CAD)
a constriction of the coronary arteries usually resulting from atherosclerosis: an accumulation of lipid deposits that degrade the arterial wall and obstruct the lumen
begins when endothelium damaged by hypertension, diabetes, or other causes
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