Week 2 Neurohormonal Influence on Cardiac System Flashcards
The autonomic nervous system influences the
heart and blood vessels through direct and neural and indirect neurohormonal mechanisms
The sympathetic receptors of the heart are
primarily beta-adrenergic receptors and are located on the sinus node and within the myocardium
Stimulation of the receptors by the neurotransmitter norepinephrine increases the overall activity of the hear by increasing
the heart rate, force of contraction, and results in coronary artery dilation
The normal parasympathetic influence via the vagus nerve has a primary impact on
the resting heart , influencing resting HR substantially more than SNS
Parasympathetic stimulation results in
depression of HR, decreased force of atrial contraction, and decreased speed of conduction through AV node
The impact of direct parasympathetic influence on peripheral blood vessels is limited to
a vasodilatory effect on the bowel, bladder, and genitals
Myocardial oxygen supply depends on the delivery of oxygenated blood through
the coronary arteries, the oxygen-carrying capacity of arterial blood and the ability of the myocardial cells to extract oxygen from the arterial blood
Myocardial oxygen demand
the energy cost to the myocardium
Hemoglobin and hematocrit level depict the
oxygen carrying capacity within the system
Hypokalemia (low potassium)
produces arrhythmias with flattened T waves and depressed ST segments, as well as bilateral lower extremity muscle cramping
Hypocalcemia
low blood serum
Sodium value
135-145
Potassium value
3.5-5.0
Chloride value
95-105
BUN value
10-20
Creatine value
0.5-1.2
Calcium value
9-11
Glucose value
70-110
Carbon dioxide value
20-29
Magnesium value
1.5-2.5
Hemoglobin female
12-16
Hemoglobin male
13-18
Hemacrit female
36-46
Hemacrit male
37-49
4 functions of a pacemaker
1.) ability to sense intrinsic cardiac function
2.) ability to stimulate cardiac depolarization in response to failed intrinsic activity
3.) the ability to respond to increased metabolic demand by providing rate-responsive pacing
4.) ability to provide diagnostic information stored within the pacemaker
