Ch. 10 Egans Flashcards
Approx 2-3rds of the heart lies to the left of the ______ between the _______?
Midline of the sternum ; between the 2nd and 6th rib
The apex of the heart is located where?
The tip of the left ventricle and lies above the diaphragm at 5th intercostal space
The base of the heart is located where?
Lying below the second rib (formed by the atria).
The heart is enclosed in a sac called the _____?
Pericardium
What is the fibrous pericardium?
Tough loose fitting and inelastic sac surrounding the heart.
What is serous pericardium?
Consist of 2 layers:
Parietal layer: inner lining of the fibrous pericardium
Visceral layer: covering the outer surface of the heart and great vessels
What is pericardial fluid?
A thin layer of fluid that separates the two layers of the serous pericardium
What is pericarditis?
Inflammation of the pericardium
What is pericardial effusion?
An abnormal amount of fluid that accumulates between the layers
What is cardiac tamponade?
A large pericardial effusion that lessens the pumping function of the heart, which compresses the heart muscle, leading to a serious decrease in blood flow to the body
What are the three layers of the heart wall?
• The outer epicardium
• Middle myocardium
• Inner endocardium
The ________ composes the bulk of the heart muscle and consist of bands of involuntary striated muscle fibers.
Myocardium
Where are the AV valves located?
Between the atria and ventricles
The valve on the right is called the….?
Tricuspid valve
The valve on the left is called the….?
Bicuspid or mitral valve
When do the AV valves close?
During systolic contraction of the ventricles, preventing backflow of blood into the atria
What is regurgitation?
The back flow of blood through a malfunctioning leaky valve.
What is stenosis?
Narrowing or constriction of valve outlet, which causes blood to back up and increased pressure in the proximal chamber and vessels.
What happens in mitral stenosis?
High pressures in the left atrium back up into the pulmonary circulation and these high pressures can cause pulmonary edema and diastolic murmur.
What are the semilunar valves?
They separate the ventricles from their arterial outflow tracts, the pulmonary artery (in the right) and the aorta (in the left).
What do the semilunar valves do?
- Consist of 3 half moon shaped cusps
- These valves prevent back flow of blood into the ventricles during diastole (or when the the chambers of the heart fill with blood).
Partial obstruction of the coronary artery may lead to what?
Tissue ischemia or angina pectoris
Complete obstruction of the coronary artery may cause what?
Tissue death or myocardial infarction
What are the three types of CAD?
- Angina pectoris
- non-ST segment elevation myocardial infarction
- ST segment elevation myocardial infarction
What are the 4 key properties that the myocardial tissue possesses?
- Excitability
- Inherit rhythmicity or automaticity
- Conductivity
- Contractility
The period during which the myocardium cannot be stimulated is called the ______ and lasts approx ______ nearly as long as the heart contraction or systole.
Refractory period ; 250ms
What are the 2 major subdivisions of the heart?
Systemic circulation & pulmonary circulation
What does the systemic circulation begin with?
The aorta on the left ventricle and ends with the right atrium
Rule of thumb pg. 207
A cardiac tamponade should be suspected in patient presenting with hypotension, JVD, pulses paradoxus, tachycardia, tachypnea, narrowing pulse pressures, and/or severe dyspnea.
What are the three major components of systemic circulation?
- The arterial system
- The capillary system
- The venous system
What does the arterial system consist of?
Large, highly elastic, low resistance, arteries and small, muscular arterioles of varying resistance.
Together the large arteries are called what?
Conductance vessels
What is another name for arterioles?
Resistance vessels
The ______ maintains a constant exchange of nutrients and waste products for the tissues of the body.
Capillary system
What does the venous system consist of?
Small expandable venules, veins, and larger more elastic veins
acts as a reservoir for circulation
What are the four mechanisms that aid the venous return to the heart?
- Sympathetic venous tone
- Skeletal muscle pumping or milking
- Cardiac suction
- Thoracic pressure difference is caused by respiratory efforts.
# 4 is most important for RTs
Although the heart is a single organ it functions as ______ separate pumps
2
The right side of the heart generates a systolic pressure of approximately _______ to drive blood through the low resistance, low pressure pulmonary circulation.
25mmHg
The left side of the heart generates systolic pressure at approximately _________ to propel blood through the higher pressure, high resistance, systemic circulation
120mmHg
The sum of all frictional forces opposing blood flow through the systemic circulation is called?
Systemic vascular resistance (SVR)
What must SVR equal?
The difference in pressure between the beginning, and the end of the circuit divided by the flow
What is the formula for SVR?
What is PVR?
Resistance in pulmonary circulation
What is the formula for MAP?
MAP= (COxSVR)+CVP OR Volume/capacity
What is the normal range for MAP?
80-100mmHg
What can happen if MAP decreases below 60 mmHg?
untreated shock, perfusion to the brain and kidney is severely compromised and organ failure may occur in minutes.
Contractions have to be ______
Synchronized
What does positive inotropic mean? What meds are used?
Increased contractility
digoxin and dopamine
What does negative inotropic mean? What meds are used?
Decreased contractility
Verapamil & procainamide
Systemic venous blood returns to_______?
RA via SVC & IVC
Pulmonary vasculature begins with______?
Pulmonary artery out of the RV to RA
What is a sound you can hear with pulmonary edema?
Diastolic murmur
What is the formula for cardiac output?
CO=HRxSV
What is cardiac output?
Total amount of blood pumped in one minute
What are the 3 factors that SV is affected by?
- Preload
- Afterload
- Contractility
What is the formula for PVR?
PVR = MPAP-LAP/CO
