Lab Seven

Question 1

What does the cardiac cycle in humans and other vertebrates involve?

Answer 1

The sequential contraction of the atria and the ventricles.

Question 2

What is the heart’s rhythmical contraction sequence triggered by?

Answer 2

Action potentials from myocardial cells that are conducted in a coordinated fashion throughout the entire heart.

Question 3

What are excellent conductors of electricity?

Answer 3

Bodily fluids.

Question 4

Where can electrical activity easily be recorded?

Answer 4

The electrical activity in the interior portion of the body can be easily recorded at the body surface.

Question 5

What is an Electrocardiogram (ECG)?

Answer 5

The electrical current measured as an electrical potential across the body surface, displayed over time.

Question 6

What does the P wave represent?

Answer 6

Atrial depolarization.

Question 7

What does the QRS complex represent?

Answer 7

Atrial repolarization and ventricular depolarization.

Question 8

What does the T wave represent?

Answer 8

Ventricular repolatization.

Question 9

When does atrial repolarization occur?

Answer 9

It occurs during ventricular depolarization.

Question 10

Where can a change in heart rate easily be measured?

Answer 10

In the P-P interval.

Question 11

How is an increased heart rate accomplished?

Answer 11

Measured in beats per minute, it’s accomplished by reducing the time between beats (T-P interval) and the overall time that a complete depolarization/repolarization cycle occurs (P-T interval).

Question 12

What does the arterial system function as?

Answer 12

A pressure reservoir, in that the amount of blood flow is directly related to the pressure difference along an artery.

Question 13

When is the highest level of pressure?

Answer 13

Immediately after the ventricles contract, known as systolic blood pressure.

Question 14

When is the lowest level of pressure?

Answer 14

Just prior to the next contraction of the ventricles, known as the diastolic blood pressure.

Question 15

What is blood pressure often represented as?

Answer 15

Systolic/diastolic, 120 mmHg/80 mmHg.

Question 16

What can control the degree of contraction of the smooth muscles found in the walls of the arteries?

Answer 16

Signals from the autonomic nervous system, which will have a direct impact on blood pressure.

Question 17

What does Vasoconstriction do?

Answer 17

Vasoconstriction of the arteries will increase centralized blood pressure.

Question 18

What does Vasodilation do?

Answer 18

Vasodilation of the arteries will decrease centralized blood pressure.

Question 19

Autonomic nervous system effects on the arterial system can be used to:

Answer 19

Regulate blood pressure and alter the distribution of blood to various organs in the body, depending on the metabolic needs of the body. Can also influence heart rate.

Question 20

What is the Fight or Flight response?

Answer 20

A sympathetic nervous system response that releases epinephrine from the adrenal glands, which binds to receptors on the heart - causing it to beat faster.

Question 21

What is the Rest and Digest response?

Answer 21

A parasympathetic nervous system response that releases acetylcholine from the vagus nerve, binding to receptors on the heart - causing it to beat slower.

Question 22

What can peripheral feedback loops within the autonomic nervous system do?

Answer 22

Coordinated heart activity, arterial blood pressure, and overall blood flow.

Question 23

What is the Baroreceptor Reflex?

Answer 23

One of the most important peripheral feedback loops, acts to ensure central arterial blood pressure is maintained at a level appropriate for metabolic activities in the blood, but that it is not too high to cause rupturing of the arterial vessels or excess fluid leakage from the capillaries.

Question 24

What does diving cause?

Answer 24

Selective peripheral vasoconstriction and a sharply reduced blood flow to limbs, gut, and the skin - driving blood to the organs that need oxygen the most.

Question 25

What is Diving Bradycardia?

Answer 25

A baroreceptor-mediated response where the heart rate is substantially reduced to ensure that blood pressure in the central arteries does not exceed safe levels.