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AP 2 20
Cardiovascular!
60
Anatomy
Undergraduate 1
04/01/2012

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Term
THE HEART
Definition
• Four-chambered muscular organ
• Lies in mediastinum with apex on diaphragm, 2/3 of its bulk to left of midline of body and 1/3 to right
Term
• Apical beat may be counted by
Definition
placing stethoscope in 5th intercostal space on line with left midclavicular point
Term
• Covering of heart
Definition
– Loose-fitting, inextensible sac (fibrous pericardium) around heart, lined with serous pericardium (parietal layer), which also covers outer surface of heart (visceral layer or epicardium)
– Small space between parietal and visceral layers of serous pericardium contains few drops of pericardial fluid
Term
• Function of covering
Definition
protection against friction
Term
• Wall -
Definition
epicardium, myocardium (muscular wall), endocardium (lining)
Term
• Intercalated discs found in myocardium allow
Definition
direct contact between cells and muscle action potentials to spread from one fiber to another
Term
• Cavities are formed by 2 atria and 2 ventricles
Definition
; atria separated by interatrial septum (contains fossa ovalis) and ventricles are separated by interventricular septum
Term
ventricles have irregular folds called
Definition
trabeculae carneae
Term
• Between atria and ventricles are
Definition
atrioventricular (AV) orifices
Term
guarded by
Definition
cuspid valves
Term
valves consist of 3 parts
Definition
flaps, chordae tendinae, and papillary muscle
Term
• Between ventricles and arterial circulation
Definition
are semilunar valves
Term
semilunar valves
Definition
pulmonary semilunar (right side), aortic semilunar (left side)
Term
• Left ventricle receives blood via
Definition
both major branches of left coronary artery and from one branch of right coronary artery
Term
• Right ventricle receives blood
Definition
via both major branches of right coronary artery and one branch of left coronary artery
Term
• Each atrium receives blood
Definition
from one branch of its respective coronary artery
Term
• Only a few anastomoses(connection, joining together)
Definition
between larger branches
Term
• SA node (pacemaker of heart)
Definition
– Small mass of modified cardiac muscle at junction of superior vena cava and right atrium
– Inherent rhythmicity of SA node impulses set basic rate of heartbeat
Term
– Ratio of sympathetic(Go up)/parasympathetic(slow down) impulses to node per minute and blood concentrations of epinephrine and thyroid hormone act on
Definition
node to modify its activity and alter heart rate. Acedacholine is going to decrease heart rate.
Term
• Atrioventricular node (AV node)
Definition
small mass of modified cardiac muscle in septum between 2 atria
Term
• AV bundle and bundle of His
Definition
special cardiac muscle fibers originating in AV node and extending down interventricular septum
Term
• Purkinje fibers
Definition
extension of bundle of His fibers out into walls of ventricles
Term
• Sympathetic fibers
Definition
in cardiac nerves
Term
parasympathetic fibers
Definition
in vagus
Term
Both form
Definition
form cardiac plexuses
Term
• Fibers from plexuses terminate
Definition
mainly in SA node
Term
• Sympathetic impulses tend to
Definition
accelerate and strengthen heartbeat; vagal impulses slow heartbeat
Term
• Electrocardiogram
Definition
• Record of the heart’s action currents (impulse conduction)
Term
• Components of electrocardium
Definition
– P wave , – QRS complex – T wave
Term
– P wave
Definition
depolarization of atria(Contracting of the atria)
Term
– QRS complex
Definition
depolarization of ventricles(contracting of ventricles)(Atria’s relax)
Term
– T wave
Definition
repolarization of ventricles(the ventricles are relaxing)
Term
• Cardiac cycle
Definition
Superior and Inferior Vena Cave
-Right Atrium
-Tricuspid valve
-Right Ventricle
-Semilunar valve
-Pulmonary Artery
-Lungs
-Pulmonary Vein
-left Atrium
-Bicuspid Valve
-Left Ventricle
-Semilunar valve
-Aorta
-Body back to beginning!
Term
• Consists of
Definition
systole and diastole of atria and ventricles
Term
atria contract and as they relax
Definition
ventricles contract
Term
• Cycle takes about
Definition
0.8 seconds or from 70-80 times/minute
Term
– Atrial systole
Definition
- AV valves open and SL valves closed; ventricles relaxed; preceded by P wave
Term
– Ventricular filling
Definition
rapid influx of blood into ventricles after opening of AV valves; characterized by gradual increase in ventricular pressure and volume reducing ventricular filling
Term
– Ventricular systole
Definition
rapid ejection of blood from ventricles followed by reduced ejection (residual volume is blood remaining in ventricles following ejection phase - amount increases in heart failure); AV valves close resulting in first heart sound (lubb)
Term
– Ventricular diastole
Definition
ventricles relax; semilunar valves close resulting in 2nd heart sound (dupp)
Term
• Cardiac output (CO)
Definition
is total amount of blood ejected into arteries each minute
Term
CO determined by
Definition
– Volume of blood pumped by the ventricles per beat (stroke volume)
Term
Heart Rate
Definition
Number of heart beats per minute, 5 liters pumped throughout the heart in one beat
Term
• Cardiac reserve
Definition
is ratio between maximum cardiac output a person can achieve and cardiac output at rest (avg. 4-5 times that of rest)
Term
– Preload
Definition
greater preload (stretch) on cardiac muscle fibers before contraction increases force of contraction (Frank-Starling law of the heart) 70% will be ejected with stroke volume (What fills the fintrical) (stroke volume-90%-90ml going out, 10 left.
Weak heart? Contarctility is only a 50% it affects blood pressure.)
Term
– Contractility
Definition
strength of contraction (Strength of contraction affects stroke volume.)
Term
• Increasing factors
Definition
sympathetic stimulation, glucagon, epinephrine, increased calcium in ECF
Term
• Decreasing factors
Definition
- inhibition of sympathetic system, anoxia, acidosis, some anesthetics, increased potassium
Term
– Afterload
Definition
pressure that must be exerted by the ventricles to exceed the pressure in the arteries
Term
• Autonomic nervous system control is result of
Definition
opposing influences between parasympathetic (vagus) and sympathetic (accelerator nerve) stimulation (acetylcholine and norepinephrine)
Term
• Centers within medulla oblongata act
Definition
on heart rate
Term
– Cardioinhibitory center
Definition
parasympathetic impulses to slow heart rate
Term
• Medulla oblongata
Definition
– Cardioaccelerator center
Term
– Cardioaccelerator center
Definition
sympathetic stimuli that increases heart rate
Term
• Cardiac pressoreflexes (baroreceptors)
Definition
stretch receptors that send impulses to the cardioinhibitory and accelerator centers and influence ANS outflow
Term
– Carotid sinus reflex
Definition
stimulation (by high blood pressure) causes reflex slowing of heart
Term
– Aortic reflex
Definition
stimulation (by high blood pressure) causes reflex slowing of the heart
Term
– Decrease in aortic or carotid blood pressure
Definition
initiates reflex acceleration of heart
Term
• Chemoreceptors located near
Definition
baroreceptors called carotid and aortic bodies
Term
baroreceptors called carotid and aortic bodies
Definition
detect changes in blood level of oxygen, carbon dioxide and hydrogen ions.
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