Exercise 4: Cardiovascular system

What were the objectives of exercise 4 the cardiovascular system?

1. To demonstrate the baroreceptor reflex using a sudden change in body position

2. Determine the effect of body position on the mean electrical axis of the heart

A baroreceptor reflex will be triggered by?

intentionally decreasing mean arterial pressure (MAP) in the subject by (a change in body position or valsalva maneuver

What two equipments did we use?

ECG and pulse plethysmography

ECG was used to measure

the heart rate (HR) and calculate the mean electrical axis of the heart (MEA)

Pulse Plethysmography was used to measure

the pulse pressure in the fingertip , to infer total peripheral resistance (TPR)

What monitors mean arterial pressure (MAP)

baroreceptors are sensory neurons that monitor mao

-as a function of stretch (a product of blood volume in the artery)

Explain what happens to the body if MAP deviates from homeostatic range

• the autonomic nervous system will trigger a reflexive response to adjust the determinants of MAP as necessary in order to restore MAP

• MAP=HRxSVxTPR

• Map=COxTPR

If map increases explain what the reflexive response would be

decrease CO and TPR

if MAP decreases explain the reflexive response

CO and TPR would both increase

Baroreceptors (stretch) are a reflection of

reflection of the volume and pressure of blood int he artery

How are traces of the heart electrical activity be recorded

by placing pairs of electrodes on different parts of the body that can pick up waves of the depolarization through the heart

Pairs of electrodes are known

-explain it

leads

one electrode is positive and one is negative

-current flow between the electrodes in a lead can be measured , providing one leads view of the wave depolarization through the heart

-by having multiple leads one can view waves of depolarization traveling in different directions

In the ECG lead electrodes are placed on the body to reflect an equilateral triangle known as Eithovens triangle

Explain the data collection for body position experiment

Lead I and Lead III ( heart rate and mean electrical axis calculation)

— we measured the R-R intervals (beats per minute BPM)