Neurohumeral Influences

Question 1

Parasympathetic Stimulation is also known by what term?

Answer 1

Cholinergic

Question 2

Where is the PNS control center located?

Answer 2

Medulla oblongata; Cardioinhibitory center

Question 3

What structures does the PNS innervate?

Answer 3

Via vagus n. (CN X), innervates SA/AV node

Sparsely innervates myocardium

Question 4

What hormone does the PNS (cholinergic) release?

Answer 4

Acetylcholine

Question 5

What is the function of the PNS system?

Answer 5

Slows rate and force of myocardial contraction and decrease myocardial metabolism

Causes coronary artery vasoconstriction

Question 6

What is another term for SNS ?

Answer 6

Adrenergic

Question 7

Where is the SNS control center located?

Answer 7

Medulla oblongata, cardioacceleratory center

Question 8

The SNS innervates what?

Answer 8

Via cord segments T1-T4, upper thoracic to superior cervical chain ganglia—Innervates SA/AV node, conduction pathways and myocytes; releases epinephrine and norepinephrine

Question 9

What is the function of the SNS?

Answer 9

Causes increase in the rate and force the myocardial contraction and myocardial metabolism

Causes coronary artery vasodilation

Question 10

What are drugs called that increase sympathetic functioning?

Answer 10

Sympathomimetics

Question 11

What are drugs called that decrease sympathetic functioning?

Answer 11

Sympatholytics

Question 12

Baroreceptors (pressreceptors) are located where?

Answer 12

-closed in walls of arctic arch and carotid sinus; via vasomotor center

Question 13

What are baroreceptors main function?

Answer 13

Control HR

Question 14

The baroreceptor circulator reflex..explain.

Answer 14

Respond to changes in blood pressure

Question 15

Explain the concept of circulatory reflex.

Answer 15

1. Increased BP > PNS stimulated > Decreased rate/force of cardiac contraction > Sympathetic inhibiton > decreased Peripheral resistance
2. Decreased BP > SNS stimulated > increased HR/BP + vasoconstriction of peripheral blood vessels
3. Increased R atrial. Pressures causes reflex acceleration of HR

Question 16

Where are chemoreceptors located?

Answer 16

Carotid body

Question 17

Chemoreceptors are sensitive the changes in what?

Answer 17

Blood chemicals: O2, CO2, lactic acid

Question 18

Concept of chemoreceptors

Answer 18

Increased CO2 or decreased O2, or decreased pH (elevated lactic) results up ab Increase in HR

Increased O2 levels result in a decrease in HR

Question 19

When body temperature increases what happens to the HR?

Answer 19

Increase in body temp = increase in HR

Question 20

What is hyperkalemia?

Answer 20

Increased K+ ions, which DECREASE rate and force of contraction

Question 21

Hyperkalemia results in what kind of ECG changes?

Answer 21

1. widened PR interval and QRS

2. tall T waves

Question 22

What is hypokalemia?

Answer 22

Decrease K+ ions

Question 23

What kind of changes does hypokalemia produce?

Answer 23

Flattened T waves

prolonged PR and QT intervals

Arrhythmias, may progress to ventricular fibrillation

Question 24

What is hypercalcemia

Answer 24

Increased Ca+ ions

Question 25

What does hypercalcemia do to the Heart?

Answer 25

Increase heart actions

Question 26

What is hypocalcemia?

Answer 26

Decreased Ca+

Question 27

How does hypocalcemia affect the heart?

Answer 27

Depresses heart actions

Question 28

What is hypermagnesemia?

Answer 28

Increased magnesium is a calcium blocker which can lead to arrhythmias or cardiac arrest

Question 29

What is hypomagnesemia?

Answer 29

Decreased magnesium causes ventricular arrhythmias, coronary artery vasospasms, and sudden death

Question 30

Increased peripheral resistance __________ arterial blood volumes and pressure

Answer 30

Increases