MedSurge: Ch.52 Cardiovascular Problems Flashcards
What side of the body is the heart on?
Left.
How many layers of the heart are there?
3
What are the three layers of the heart?
The epicardium is the outermost layer of the heart.
The myocardium is the middle layer and is the actual contracting muscle of the heart.
The endocardium is the innermost layer and lines the inner chambers and heart valves.
What is the Pericardial Sac?
Encases and protects the heart from trauma and infection
What are the two layers of the pericardial sac?
The parietal pericardium is the tough, fibrous outer membrane that attaches anteriorly to the lower half of the sternum, posteriorly to the thoracic vertebrae, and inferiorly to the diaphragm.
The visceral pericardium is the thin, inner layer that closely adheres to the heart.
Where is the pericardial sapce?
The pericardial space is between the parietal and visceral layers; it holds 5 to 20 mL of pericardial fluid, lubricates the pericardial surfaces, and cushions the heart.
How many chambers of the heart are there?
4
What is the job of the right atria?
The right atrium receives deoxygenated blood from the body via the superior and inferior vena cava.
What is the job of the right ventricle?
The right ventricle receives blood from the right atrium and pumps it to the lungs via the pulmonary artery.
What is the job of the left atrium?
The left atrium receives oxygenated blood from the lungs via 4 pulmonary veins.
What is the job of the left ventricle?
The left ventricle is the largest and most muscular chamber; it receives oxygenated blood from the lungs via the left atrium and pumps blood into the systemic circulation via the aorta.
What is the 4 valves of the heart?
There are 2 atrioventricular valves, the tricuspid and the mitral, which lie between the atria and ventricles.
There are 2 semilunar valves, the pulmonic and the aortic.
What is the sinoatrial (SA) node?
The main pacemaker that initiates each heartbeat
Where is the SA node located?
It is located at the junction of the superior vena cava and the right atrium.
How much does the SA node generate? What is it controlled by?
The SA node generates electrical impulses at 60 to 100 times per minute and is controlled by the sympathetic and parasympathetic nervous systems.
What is the AV node?
Atrioventricular (AV) node
Where is the AV node located?
Located in the lower aspect of the atrial septum.
What is the job of the AV node?
Receives electrical impulses from the SA node.
If the SA node fails, the AV node can initiate and sustain a heart rate of 40 to 60 beats per minute.
What is the bundel of his?
- A continuation of the AV node; located at the interventricular septum
- It branches into the right bundle branch, which extends down the right side of the interventricular septum; and the left bundle branch, which extends into the left ventricle.
- The right and left bundle branches terminate in the Purkinje fibers.
What are the Purkinje fibers?
- Purkinje fibers are a diffuse network of conducting strands located beneath the ventricular endocardium.
- These fibers spread the wave of depolarization through the ventricles.
- Purkinje fibers can act as the pacemaker with a rate between 20 and 40 beats per minute when higher pacemakers (such as the SA and AV nodes) fail.
! The right main coronary artery does what?
The right main coronary artery supplies the right atrium and ventricle, the inferior portion of the left ventricle, the posterior septal wall, and the SA and AV nodes.
What does the left main coronary artery consist of?
The left main coronary artery consists of 2 major branches, the left anterior descending (LAD) and the circumflex arteries.
What does the LAD DO?
The LAD artery supplies blood to the anterior wall of the left ventricle, the anterior ventricular septum, and the apex of the left ventricle.
What do the circumflex arteries do?
The circumflex artery supplies blood to the left atrium and the lateral and posterior surfaces of the left ventricle.
What is the main job in a nutshell of the coronary arteries?
They supply blood to the capillaries of the myocardium.
If a blockage occurs in the coronary arteries what can happen?
Myocardial infarction (MI).
What are the four heart sounds?
- The first heart sound (S1) is heard as the atrioventricular valves close and is heard loudest at the apex of the heart.
- The second heart sound (S2) is heard when the semilunar valves close and is heard loudest at the base of the heart.
- A third heart sound (S3) may be heard if ventricular wall compliance is decreased and structures in the ventricular wall vibrate; this can occur in conditions such as heart failure or valvular regurgitation. However, a third heart sound may be normal in individuals younger than 30 years.
- A fourth heart sound (S4) may be heard on atrial systole if resistance to ventricular filling is present; this is an abnormal finding, and the causes include cardiac hypertrophy, disease, or injury to the ventricular wall.
! The faster the heart rate?
The faster the heart rate, the less time the heart has for filling. At very fast rates the cardiac output decreases.
What is the normal sinus heart rate?
The normal sinus heart rate is 60 to 100 beats per minute.
What is considered sinus tachycardia?
A heart rate more than 100 beast per min.
What is sinus bradycardia?
less than 60 beats per min.
What makes up the autonomic nervous system?
Sympathetic and parasympathetic nervous system.
What do we get when we stimulate the sympathetic nerve fibers? What does that do?
releases the neurotransmitter norepinephrine, producing an increased heart rate, increased conduction speed through the AV node, increased atrial and ventricular contractility, and peripheral vasoconstriction.
When does the body stimulate the sympathetic nerve fibers?
Stimulation occurs when a decrease in pressure is detected.
What happens when we stimulate the parasympathetic nerve fibers?
Stimulation of the parasympathetic nerve fibers releases the neurotransmitter acetylcholine, which decreases the heart rate and lessens atrial and ventricular contractility and conductivity. Stimulation occurs when an increase in pressure is detected.
What are baroreceptors?
Baroreceptors (specialized nerve endings affected by changes in the arterial BP), also called pressoreceptors, are located in the walls of the aortic arch and carotid sinuses.
What stimulates the baroreceptors?
Increases in arterial pressure stimulate baroreceptors, and the heart rate and arterial pressure decrease.
What does a decrease in arterial pressure do to the baroreceptors?
Decreases in arterial pressure reduce stimulation of the baroreceptors and vasoconstriction occurs, as does an increase in heart rate.
What are the stretch receptors?
Stretch receptors, located in the vena cava and the right atrium, respond to pressure changes that affect circulatory blood volume.
What happens when the When the BP decreases as a result of hypovolemia?
A sympathetic response occurs, causing an increased heart rate and blood vessel constriction; when the BP increases as a result of hypervolemia, an opposite effect occurs.
What is the generic name of Antidiuretic hormone ?
Vasopressin.
How does Antidiuretic hormone (vasopressin) influences BP?
indirectly by regulating vascular volume.
Increases in blood volume result in what when it comes to antidiuretic hormone?
Increases in blood volume result in decreased antidiuretic hormone release, increasing diuresis, decreasing blood volume, and thus decreasing BP.
What happens to ant-diuretic hormone when blood volume decreases?
Decreases in blood volume result in increased antidiuretic hormone release; this promotes an increase in blood volume and therefore BP.
What is renin?
A potent vasoconstrictor, causes the BP to increase.