NURS 301 MEDSURG TEST 2 STUDY GUIDE | RATED 100%: LIBERTY UNIVERSITY
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NURS 301 (NURS301)
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Liberty University
NURS 301 MEDSURG TEST 2 STUDY GUIDE | RATED 100%: LIBERTY UNIVERSITYNURS 301 MEDSURG TEST 2 STUDY GUIDE | RATED 100%: LIBERTY UNIVERSITYNURS 301 MEDSURG TEST 2 STUDY GUIDE | RATED 100%: LIBERTY UNIVERSITYNURS 301 MEDSURG TEST 2 STUDY GUIDE | RATED 100%: LIBERTY UNIVERSITY
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NURS 301 Test 2 Study Guide
Ch. 32-38: Cardiovascular Unit Part 1
Anatomy and Physiology Review
The Heart
o Endocardium- thin inner lining of the heart
o Myocardium- Middle muscular layer
o Epicardium- Outer fibrous membrane
o Pericardium- 2 layered “sac” that surrounds the heart; consists of Visceral layer (inner)
and Parietal layer (outer)
▪ Pericardial sac contains 10-30 mL of pericardial fluid that prevents a friction rub
• Increased pericardial fluid= cardiac tamponade
• Decreased pericardial fluid= Friction rub
Systemic Circulation: Blood Flow through the Heart
1. Right atrium receives blood from the superior and inferior vena cava and coronary sinus
2. Blood passes from right atrium through the tricuspid valve to the right ventricle
3. Blood passes from the right ventricle through the pulmonic valve into the pulmary artery and to
the lungs for oxygenation
4. Pulmonary vein returns freshly oxygenated blood back to the left atrium
5. Blood passes from left atrium to the left ventricle through the mitral valve
6. Blood exits the left ventricle through the aortic valve out into the aorta and to the body
o A/V valves: Tricuspid and Bicuspid (mitral)
o Semilunar valves: Pulmonic and aortic
o Exception: Arteries normally always carry oxygenated blood, but the pulmonary artery is the
exception! It carries deoxygenated blood to the lungs, and the pulmonary vein carries oxygenated
blood back to the heart from the lungs
o Remember: Tissue Paper My Assets! (Valves right to left in order of blood flow)
Coronary Circulation: Myocardial Blood Supply
o The heart has its own circulatory system
o Right above the cusps of the aortic valve are the Sinuses of Valsalva which open into the right
and left coronary artery
o Blood flows to the heart muscle during diastole
▪ Myocardium receives blood during diastole!
o Right coronary artery supplies the right atrium and the right ventricle (part of the posterior left
ventricle)
o Left coronary artery branches into the left anterior descending and the left circumflex artery
that supply the left atrium and left ventricle
o Definitions:
A. Ischemia= Tissue Hypoxia; Inadequate blood flow to meet the myocardial oxygen
needs Reversible lack of oxygen to tissues causing hypoxia
• The pain that goes along with myocardial ischemia is called angina pectoris
B. Infarction= Result of permanent loss of blood supply and cellular death; Irreversible tissue
death
C. Perfusion= Measure of blood flow and oxygen delivery to tissues.
• No perfusion can lead to MI, stroke, or acute renal failure!
• Check bowel sounds, pedal pulses
, 2
• Check kidney perfusion by measuring urinary output. A patient should produce at
least 30 mL/hr
Conduction System
a) SA Node- specialized nerve tissue (the heart’s pacemaker).
The SA node is located at the top of the right atrium
If a patient has a “sinus rhythm,” it means the bat originated from the SA node. However,
“sinus” can include brady, normal, or tachy rates
b) Action Potential- Electrical impulse travels through the heart and leads to contraction
c) Contraction- Occurs when calcium flows into cardiac cells after depolarization
d) AV Node- allows time for atria to fill by providing a break in the contraction
Mid way point; a pause to allow the atria to fill
e) Bundle of His- Picks up the impulse and spreads it over the ventricles by way of the Purkinje Fibers
f) Repolarization- cells return to former state
g) Systole- absolute refractory period during which the cardiac muscle gradually recovers and is
excitable again. During contraction, the heart briefly loses its self excitability
o Auscultation:
S1= Closing of AV valves (lub)
S2= Closing of SL valves (dub)
S3= Ventricular gallop (“KenTUCKy”)- d/t fluid overload, CHF, or murmur; common in peds
S4= Atrial Kick (TENessee)
EKG
1) P-Wave= Depolarization (contraction) of the atrium
2) PR Interval= Measure of the time required for the impulse to spread from the SA node to
the ventricle (from top to bottom of heart)
3) QRS Interval= Depolarization (contraction) of ventricles
4) T-Wave= Repolarization of ventricles
5) U-Wave= If present, may mean hypokalemia or repolarization abnormalities
Three Electrolyes that Influence the Heart:
o Potassium
o Calcium
o Magnesium
ST elevation of 1 mm off baseline indicates ischemia and/or infarction!
“STEMI”= tombstone on EKG!
EKG Strip: (Know the times! Assume each strip is 6 seconds, so multiply “R’s” by 10 to get HR)
o Each small box is 0.04 seconds, each large box is 0.20 seconds
o P wave= 0.06-0.12 seconds
o PR Interval= 0.12-0.20 seconds
o QRS Complex= 0.04-0.12 seconds
Cardiac Output
CO= amount of blood pumped per minute.
CO= HR (heart rate) x SV (blood ejected per beat in mL)
o Cardiac Output: WNL= 4-8 L/min (LITERS)
o Stroke Volume: WNL 60-70 mL/beat (MILILITERS)
Ex. CO= HR x SV
= 70 bmp x 70 mL
= 490 mL/min 4.9 L/min
Normal Blood Volume: (since CO=4-8 L/min, you pump entire blood volume within 1 minute!)
o Female: 4-6 L
o Male: 4-8 L
, 3
Generally, if heart rate goes up, cardiac output will go up. But this is only true to a certain point.
If HR is greater than 120 bpm sustained, CO would decrease b/c chambers don’t have time to fill
causing the stroke volume to decrease!
o It is ok to have a HR >120 bmp acutely, but just don’t discharge the patient until it is
managed
Three Components of SV: (Cardiac meds will affect one of these)
1) Preload= Volume!
▪ The volume of blood in the ventricles at the end of diastole, before the next
contraction
▪ End diastolic volume (EDV) determines the amount of “stretch” placed on the
myocardial fibers
▪ Ex. An ejection fraction of 70% means 30% of blood remains in ventricle after
contraction
▪ Causes of increased preload: (too much blood left in the heart)
➢ Hypervolemia/fluid overload
➢ Cardiac valve regurgitation (murmurs allow for back up)
➢ Pump failure/CHF
➢ Multiple blood transfusions
➢ Salt tablet
▪ Causes of decreased preload: (not enough blood return to the heart)
➢ Hypovolemia/Low circulatory blood volume
➢ Hemorrhagic shock/Bleeding
➢ Lasix
➢ Dehydration
➢ Diabetes insipidus (no ADH)
➢ Anaphylaxis (vasodilation)
2) Afterload= Resistance!
▪ Reflects the vascular resistance against which the left ventricle pumps
▪ Affected by size of ventricle, vascular wall tension, and arterial blood pressure
▪ Causes of increased afterload:
➢ Vasoconstriction or meds that vasoconstrict
➢ Hypertension
➢ Fight or flight
➢ Smoking
➢ Stress
▪ Causes of decreased afterload:
➢ Calcium channel blockers or other vasodilators
➢ Hypotension
➢ Distributive shock
3) Contractility= Squeeze!
▪ Speaks to how “in shape” the muscle is
▪ When contractility rises, the SV rises by increasing the emptying of the ventricles
▪ Causes of increased contractility:
➢ Epinephrine/norepinephrine SNS
➢ Stress
➢ Positive inotropes such as Digoxin
▪ Causes of decreased contractility:
➢ Increased aging
o * Increasing preload, afterload, or contractility increases the workload of the heart and
increases the need for oxygen. We need to manage our stress and hypertension!
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