Heart
Muscular blood pump, located within the thoracic cavity between the lungs. Is shaped like a blunt cone and is roughly the size of a closed fist (larger in physically fit people).
Heart Functions
Generating blood pressure
Routing Blood
sending blood to either the pulmonary or systemic circulation.
Regulating blood supply to rest of body
left
The _____ side of the heart is larger than the other, leading to the heart’s tilted placement.
Pericardium
(Pericardial sac) double tissue layer surrounding the heart, forms the pericardial cavity, outside layer is fibrous pericardium (tough CT).
Serous Pericardium Layers
Parietal pericardium (superficial)
Visceral pericardium (deep)
(separated by pericardial fluid)
Layers of Heart
<Superficial to Deep>
Epicardium (different name, same as visceral pericardium).
Myocardium = muscle layer
Endocardium = simple squamous + CT
trabeculae carneae
The inner surface of ventricles contain ridges and columns called ___________________.
Heart Chambers
A) 2 atria (singular = atrium)
B) 2 ventricles
One of each on left and right, can be seen internally and externally.
Sulcus
Groove on surface of the heart, location of fat and blood vessels.
Coronary Sulcus
Anterior Interventricular Sulcus
Posterior Interventricular Sulcus
right atrium
The Superior Vena Cava and Inferior Vena Cava are the two large veins that bring blood to the heart from the rest of the body. Both deposit blood into the ____________.
left atrium
Four pulmonary veins bring blood from lungs to _____________.
Arteries Leaving Heart
A) Pulmonary trunk takes blood from ventricle to lungs.
B) Aorta takes blood from left ventricle to the rest of body.
Interatrial Septum
Right and left atria are separated by _________________.
Fossa Ovalis
Slight depression on the right side of interatrial septum.
Foramen Ovale
Former hole in heart for embryo’s blood to skip lungs.
Interventricular Septum
Separates right and left ventricles.
Direction of Blood Flow
Right Atrium
Right Ventricle
Lungs
Left Atrium
Left Ventricle
Rest of Body
Heart Valves
Folds of endocardium that allow blood to flow into or out of the ventricles, but not in reverse direction.
Two Types:
Atrioventricular Valves
Semilunar Valves
Atrioventricular Valves
Type of heart valve, located between an atrium and a ventricle.
Tricuspid Valve
Bicuspid/Mitral Valve
Semilunar Valves
Type of heart valve, located between a ventricle and an artery, both have three pocket-like cusps.
Aortic Valve
Pulmonary Valve
Tricuspid Valve
Three cusps of flaps, between right atrium and right ventricle.
Bicuspid Valve
(Mitral Valve) Two cusps between the left atrium and left ventricle.
Papillary muscles
To open the atrioventricular valves, each ventricle has ___________________, which are cone shaped and each is attached to a strong CT string.
Chordae Tendineae
Strong CT string that each papillary muscle is attached to. Pulls open flaps of atrioventricular valves when the papillary muscles flex.
Coronary Circulation
Since the heart is very active muscle, it needs a good blood supply.
Coronary Arteries
A) Left coronary artery
Splits Into:
Anterior Interventricular Artery
Circumflex Artery
B) Right coronary artery
Splits Into:
Right Marginal Artery
Posterior Interventricular Artery
same
Most veins follow the _____ routes of the arteries (within the sulci).
Coronary Sinus
The blood from most cardiac veins drain into this one large vein, which dumps blood into right atrium.
Cardiac Muscle AP
Steps:
Resting Membrane Potential
Rising Phase - Na+ channels open = depolarization
Plateau - Ca+2 channels open = partially maintains depolarization.
Repolarization - K+ channels open
Resting Membrane Potential Again
False
T or F: Cardiac muscle APs are faster than skeletal muscle APs.
True
T or F: The cardiac muscle still has an absolute and relative refractory period, the absolute refractory period is considerably longer in cardiac muscle, but that is because the whole AP is much longer.
Autorhythmic
Able to stimulate itself to contract at regular intervals, the heart does not need the NS or any other body system to beat.
Sinoatrial Node
Cardiac fibers located at a spot in the right atrium can spontaneously generate an AP. The AP will spread, so whole heart will contract.
Slow Depolarization
Unlike other muscle fibers, cardiac cells at SA node after an AP immediately leak in Na+ followed by Ca+2.
Prepotential
Once threshold is readed, next AP is generated.
pacemaker
SA node is often referred to as the ______________.
conducting
The heart has a ____________ system to help AP spread throughout the heart.
first
After the SA node begins AP, it will spread throughout right and left atria, atria contract ______.
delayed
When AP reaches a spot in the right atrium known as the atrioventricular (AV) node, the AP is ___________.
Atrioventricular bundle
Eventually, the slowed AP follows the __________________, cardiac cells delivering AP to ventricles. The AV bundle splits into right and left bundles for each ventricle.
Purkinje Fibers
Many small branches off of right and left bundles.
Electrocardiogram
(ECG or EKG) Measures electrical activity of the heart, electrical ups and downs indicate what’s occuring within the heart.
Consists Of:
P wave
QRS complex
T wave
P wave
Depolarization of atria
QRS complex
Depolarization of ventricles and repolarization of atria.
T wave
Repolarization of ventricles
Pericarditis
Inflammation of the serous pericardium, quite painful (every heartbeat), often unknown cause but can be from inflation, CT diseases, or radiation damage.
Cardiac Tamponade
Fluid or blood accumulates in the pericardial sac, can quickly be fatal if fluid is not drained, pressures heart.
Causes Include: heart wall rupture, malignant tumor, radiation damage, or trauma from an accident.
Congenital Heart Disease
Abnormal heart development.
Ex.) Septal Defect
Septal Defect
Hole between right and left sides of heart.
Patent Ductus Arteriosus
A fetal blood vessel connecting pulmonary trunk to aorta never closes before birth, blood can skip lungs, good for fetus, bad after birth.
Coronary Thrombosis
(Heart Attack) Sudden blockage of a coronary blood vessel, cardiac tissue will die without oxygen.
Infarct
(Myocardial Infarction) Region of dead heart tissue
Aspirin
_______ is well known to discourage thrombus formation = discourages heart attacks.
Atherosclerotic Lesions
More gradual blockages of blood vessels, results from buildup of cholesterol.
less blood flow = reduced ability of heart to pump blood
patient feels fatigue, and often chest pain.
Angina Pectoris
Pain felt in the left arm and left side of chest, is often a sign of a current or impending heart attack.
Cardiac Arrhythmia
Abnormal (or loss of) heart rhythm.
Tachycardia
Heart rate >100 bpm.
Bradycardia
Heart rate <60bpm.
Ectopic Focus
Any location of heart other that SA node which generates an AP, disrupts heart beat.
Cardiac Cycle
Repetitive pumping process of heart.
AV valves open
Atrial systole
AV valves close and ventricular systole, atrial diastole
Semilunar valves open
Semilunar valves close and ventricular diastole.
True
T or F: The heart can be viewed as two pumps (right side for lungs, left side for rest of body). Each pump has an atrium and a ventricle.
Atrium
Pumps and fills ventricles with blood.
Ventricles
Pumps and pushes blood through either lungs or systemic circulation.
Atrial Systole
Contraction of atria.
Atrial Diastole
Relaxation of atria.
End-diastolic Volume
Volume of blood in ventricles at end of relaxation.
Systolic Pressure
Maximum pressure within aorta.
Dicrotic Notch
Slight dip in aortic pressure from recoil of blood into ventricles (as semilunar valves close).
Diastolic Pressure
Minimum aortic pressure.
First Heart Sound
“lubb” = closing of AV valves.
Second Heart Sound
“dupp” = closing of semilunar valves.
Third Heart Sound
(Often very quiet/cannot be heard) = splashing of blood inside ventricles.
Murmur
Abnormal heart sounds, normally from a faulty valve.
Incompetent
(Valve staying open) = gurgling or swishing noise.
Stenosed
(Valve opening too tight) = “rushing” noise.
movement
Blood pressure is important for ___________ of blood. Blood moves from areas of high pressure to low pressure.
Mean Arterial Pressure
(MAP) average pressure in the aorta. MAP = CO x PR
Cardiac Output
(CO) Amount of blood pumped by the heart per minute.
CO = HR x SV
Peripheral Resistance
(PR) Total resistance against pumping blood.
Heart Rate
(HR) beats per minute (bpm).
Stroke Volume
(SV) volume of blood pumped during each heartbeat. It is larger during exercise because end diastolic volume is larger because of more venous return.
SV = End-diastolic volume - End-systolic volume
Venous Return
Blood returning to heart.
Cardiac Reserve
(CR) Difference between maximum CO and resting Co, athletes have larger amounts, couch potatoes do not.
CR = CO (Exercise) - CO (Resting)
Intrinsic Heart Regulation
Means of heart regulating itself (does not need NS or hormones).
A) Starling Law of the Heart
B) Preload/Afterload
Starling Law of the Heart
Resting time between beats increases, cardiac fibers contract with more force, this only applies until a maximum length of time.
Preload
Amount ventricle walls are stretched at the end of diastole, increases result in increased contraction strength = greater cardiac output too.
Afterload
Pressure against the ventricle’s pumping of blood, increases result in more work for heart.
Extrinsic Heart Regulation
Modification of heart rate and stroke volume from NS and hormones.
A) Hormones: Epinephrine & Norepinephrine, stimulate the heart to beat faster and with more force, produced in adrenal glands.
B) Nerves: Vagus nerve and cardiac nerves
Vagus Nerve
Innervates (connects to and stimulates) SA node and AV node, slows heart rate.
Cardiac Nerves
Innervates SA node, AV node, and myocardium, increases heart rate and increases force of contraction.
Homeostasis
Process of maintaining desired internal conditions.
Heart Maintains & Adapt these Conditions:
Blood pressure
Oxygen levels
Ion levels
Body temperature
Baroreceptors
Stretch receptors in large arteries including aorta.
measure blood pressure by detecting stretching of artery walls.
The reflexes work to increase/decrease heart rate and force of contraction in response to pressure.
Cardioregulatory Center
Portion of medulla oblongata (of brain) which receives baroreceptor APs and regulates NS heart stimulation as well as epinephrine and norepinephrine release. Increased artery wall stretching = decreased heart rate & contraction force.
Adrenal Medullary Mechanism
Process of releasing epinephrine and norepinephrine in response to large loss of blood pressure.
Emotions
___________, such as anger, excitement, and anxiety can stimulate heart rate and increase force of contraction.
Depression
_____________ can lower the heart rate and force of contraction.
Chemoreceptors
Sensory receptors that respond to chemical changes, detect oxygen, carbon dioxide and H+ levels. In extreme cases, such as the heart being deprived of oxygen, will activate cardiovascular reflexes.
Lower
Changes in K+ and Ca+2 levels will change the heart rate and force of contraction.
Increased K+ = _______ heart rate & stroke volume
Increase Ca+2 = ________ heart rate by higher stroke volume.
Body temperature
As ________________ increases, heart rate increases.
Blood Pressure
Measure of the force blood exerts against blood vessel walls, it cycles with the rhythm of the heart.