Lab 7: Human Circulatory System Physiology

Question 1

What is the hearts rhythmical contraction sequence triggered by?

Answer 1

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

Question 2

What is an excellent conductor of electricity and electrical activity?

Answer 2

Bodily fluids

Question 3

Can electrical activity be easily recordable at the surface of the body?

Answer 3

yes!

Question 4

Using electrodes placed on opposing sides of the heart, this electrical current can be measured as an electrical potential across the body surface and displaced over time as an

Answer 4

Electrocardigram (ECG)

Question 5

P wave-

Answer 5

Atrial deplorization

Question 6

QRS complex

Answer 6

atrial replorization and ventricular depolarization

Question 7

T wave

Answer 7

Ventricular repolarization

Question 8

Several aspects of the heart activity can be modified by what?

Answer 8

autonomic nervous system

Question 9

electrical signals to initiate vertebrate heart contraction originates in what?

Answer 9

myocardial cells

Question 10

How is excitation or inhibition of the heart accomplished?

Answer 10

by changes to the contraction rate and various other parameters associated with myocardial contraction. an obvious example of excitiation is excercise.

Question 11

On an ECG a change in heart rate can be easily measured as a change in

Answer 11

P-P interval.

Question 12

How is an increased heart rate accomplished by?

Answer 12

reducing the time between beats (T-P interval) and the overall time that a complete depolarization/repolarization cycle occurs ( P-T interval). the latter is accomplished by altering the conduction velocity of the electrical signals as they travel throughout the heart.

Question 13

where does the blood go once it is ejected from the heart?

Answer 13

Arterial system

Question 14

The arterial system functions as a what?

Answer 14

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

Question 15

What is the relation between heart function and centralized blood pressure?

Answer 15

Increased heart function will increase centralized blood pressure!

Question 16

Vasconstriction

Answer 16

of the arteries will increase centralized blood pressure

Question 17

Vasodilation

Answer 17

of the arteries will decrease centralized blood pressure

Question 18

Autonomic nervous system effects on the arterial system can be used to alter…

Answer 18

the distribution of blood to various organs in the body depending on the metabolic needs of the animals. Ex.) blood flow to the gut decreases during exercise, while blood flow to the skeletal muscle increases dramatically.

Question 19

Can the autonomic nervous system directly influence heart rate?

Answer 19

Yes

Question 20

In fight or flight the sympathetic nervous system releases…

Answer 20

epinephrine from the adrenal glad which binds to receptors on the heart causing it to beat faster.

Question 21

what does the parasympathetic release?

Answer 21

acetycholine from the vagus nerve binds to receptors on the heart causing it to beat slower.

Question 22

baroreceptor reflex:

Answer 22

is one of the most important of these feedback loops. This reflex normally acts to ensure that central arterial blood pressure is maintained at a level appropriate for metabolic activities in the body, but that is no too high to cause rupture of arterial vessels or excess fluid leakage from the capillaries.

Question 23

What activity uses the barrorector alot

Answer 23

Diving uses the baroreceptor reflex to coordinate heart activity arterial blood pressure and peripheral blood flow. Diving usually causes selective pheripheral vasoconstriction. However this selective vasconstriction that takes lace during diving has the potential to cause a significant increase in the blood pressure of the central arteries.

Question 24

Diving bradycardia

Answer 24

where heart rate is substantially reduced to ensure that blood pressure in central arteries does not exceed safe levels.

Question 25

Heart rate (beats/minute) =

Answer 25

(60 seconds/minute) / seconds/beat

Question 26

What is a involuntary trigger?

Answer 26

Cold water

Question 27

What is a voluntary trigger?

Answer 27

Holding breathe