Chapter 12 - Cardiovascular System Disorders Flashcards
What is the parietal pericardium?
the outer fibrous percardium that attached the heart to the diaphragm.
Epicardium
i.e. visceral pericardium, serous membrane that provides small amount of lubricating fluid within pericardial cavity between the two membranes. Facilitates heart movement.
Myocardium
middle layer. Cardiac muscle cells. L ventricular wall thickest.
Endocardium
inner wall of the heart. forms the heart valves.
Atriventicular valves
atria from ventricles. Right side tricuspid, left bicuspid.
Semilunar valves
aortic and pulmonary valves
How does cardiac muscle differ from skeletal muscle?
multinucleated, involuntary, has intercalated discs, autonomic, doesn’t store calcium, no nerves in cardiac muscle (there is more here, double check)
SA node
initiates impulses “pacemaker” of the heart. Wall of R atrium. Initiates sinus rhythm (70bpm) - can be altered by ANS and hormones like epinephrine
AV node
floor of R atrium, slight delay in conduction to allow for filling,
AV bundle
impulse from AV node continues to left and right bundle branches
Purkinje fibers
terminal network of fibers, simultaneous contraction of two ventricles.
ECG:
P wave
QRS wave
T wave
Contraction of atria
Depolarization of ventricles (masks atrial repolarization)
Repolarization of ventricles
Where is the cardiac control center?
Medulla oblongata, controls rate and force of contraction.
Baroreceptors
detect changes in BP, located in aorta and internal carotid.
Sympathetic stimulation of the heart
Cardiac accelerator - increases HR & contractility, beta-1 adrenergic receptors (important for some drugs like beta blockers)
Parasympathetic stimulation of the heart
CN X - vagus
decreases HR
Factors that increase HR
increased thyroid hormone or epinephrine elevated body temperature/increased environmental temperature exertion/exercise smoking stress response pregnancy pain
What are the two major arteries?
Right & Left coronary arteries, part of systemic circulation, branch of aorta distal to aortic valve.
Left coronary artery divides into
Left anterior descending (interventricular) - supplies anterior wall of of ventricles, anterior septum, and bundle branches
Left circumflex - supplies L atrium, lateral/posterior walls of L ventricle
Obstruction of the L coronary artery leads to..
disturbances in the pumping capability of L ventricle, leads to CHF.
R coronary artery divides into
right marginal
posterior interventricular artery
Supplies R side of heart and inferior portion of L ventricle and posterior interventricular septum. SA & AV node.
Obstruction of R coronary artery
disturbances of AV node, dysrhythmias.
When in blood flow in the myocardium greatest?/reduced?
greatest - diastole
reduced - systole
How does most of the blood return into the heart
via coronary sinus emptying into R atrium.
Cardiac cycle
Atria relaxed (fills with blood) –> AV valves open –> blood flow into ventricles –> atria contract remaining blood forced into ventricles –> atria relax –> ventricles contract –> AV valves close/semilunar valves open –> blood into aorta and pulmonary artery –> ventricles relax
“Lub” “dub”
closure of AV valves (beginning of systole), closure of semilunar valves respectively (w/ ventricular diastole)
Murmurs
Caused by incompetent valves
Pulse deficit
Difference in rate between apical and radial pulses
Cardiac output
Blood ejected by a ventricle in 1 minute
CO = SV x HR
Stroke volume
Volume of blood pumped out of 1 ventricle in 1 contraction.
Cardiac reserve
ability of the heart to increase output in response to increased demand
Preload
Amount of blood delivered to heart by venous return. Mechanical state of the heart at teh end of diastole with the ventricles at their max volume
Afterload
Force required to eject blood from ventricles
(Determined by peripheral resistance in arteries).
Increased by high diastolic pressure resulting from excessive vasoconstriction.
Normal blood pressure
120/70 mmHg @ rest
Systolic pressure
Exerted when blood is ejected from ventricles (high)
Diastolic pressure
Sustained pressure when ventricles relax (lower)
What is BP altered by?
Cardiac output, blood volume/viscosity, venous return, rate and force of heart contractions, elasticity of arteries, and peripheral resistance to blood flow.
Pulse pressure
Difference between systolic and diastolic
Hormones affecting BP
ADH - increase BP
Aldosterone - increase BV increase BP
Renin-angiotensin-aldosterone - vasoconstriction/increase BP
SNS & epinephrine at beta-1 adrenergic receptors do what?
Increase both rate and force of contraction.
SNS, epinephrine and norepinephrine increase what?
vasoconstriction by stimulating alpha 1 receptors in the arterioles of skin and viscera (increases venous return)
General treatment measures for cardiac disorders
Dietary modification, regular exercise program, cessation of smoking, drug therapy
Arteriosclerosis
General term for all types of arterial changes , loss of elasticity, lumen gradually narrows, cause of increased BP
Atherosclerosis
Differentiated by the presence of atheromas that form in large arteries.
Atheroma
plaques consisting of lipids, cells, fibrin, and cell debris, often with attached thrombi. Presence of turbulent blood floe (esp at bifurcations) encourage development.
Primary sites: abdominal aorta, femoral and iliac arteries.
Low density lipoproteins
LDL - transports cholesterol from liver to cells “bad” lipoprotein (high lipid content), major contributor to atheroma formation.
High density lipoproteins
HDL - transports cholesterol away from the peripheral cells to the liver “good” low lipid content. Catabolism and excretion in the liver.
Process for atherosclerosis
Begins with endothelial injury of artery, inflammation in area, elevated c-reactive protein, WBC and lipids accumulate in the intima & media, smooth muscle cells proliferate, plaque forms/inflammation persists, platelets adhere to rough damaged surface, lipids/fibrous tissue continue to build up, arterial flow becomes turbulent, cycle continues until there is total occlusion.
Non-modifiable risk factors for atherosclerosis
Age (> 40), gender (men), genetic/familial
Modifiable risk factors for atherosclerosis
Obesity/diets high in cholesterol/animal fat. Sedentary Smoking DM Poorly controlled hypertension Oral contraceptives + smoking