Lab IV. - Questions

Question 1

How does acetylcholine effect on the heart function?

Answer 1

A natural parasympathetic neurotransmitter liberated from the synapses of the n. Vagus. It exerts negative chrono, bathmo, dromo and isotopic effect on the heart through type 2 muscarinic receptors

Question 2

How does atropine effect the heart function?

Answer 2

Atropine is the competitive antagonist of acetylcholine. It binds to the muscarinic acetylcholine receptors without stimulating them.

Question 3

How does epinephrine effect the heart function?

Answer 3

Epinephrine is a natural sympathetic hormone liberated from the adrenal medulla. It has several stimulating effects on the heart:

1) Increases pacemaker -> heart rate (positive chronotropic effect)
2) Velocity of contraction (Vmax) maximal isometric tension (Sm) are increased (positive inotropic effect)
3) Lowers the threshold potential of the pacemaker cells (positive bathmotropic effect)
4) Facilitates stimulus conduction (positive dromotropic effect)

Question 4

How does propranolol effect the heart function?

Answer 4

Propranolol is a sympathicolyticum that inhibits type beta1 & beta2 adrenoceptors.

Question 5

How does verapamil effect on the heart function?

Answer 5

Verapamil is a Ca2+ channel blocker drug. Primarily blocks L type calcium channels, which delays the elicitation of spontaneous diastolic depolarization mainly in the AV node causing irregular heart beats (arrhythmia).
Dilates the coronaries -> facilitates the nutrient supply of the heart.
It also blocks power to the muscle fibers so the power of the heart decreases.

Question 6

What is pulse pressure?

Answer 6

The pressure in arterial system

Question 7

Pulse pressure in humans?

Answer 7

40 mmHg / 5.3 kPa

Question 8

Normal diastolic pressure in humans?

Answer 8

75-80 mmHg / 10.0-11.0 kPa

Question 9

Why does edema happened with Ringer’s solution?

Answer 9

Protein free solution pass unhindered through blood vessel walls to interstices

Question 10

What is the effect of pharmacological concentrations of epinephrine? And which receptors does it influence?

Answer 10

Vasoconstriction all over the body, through alpha1 adrenergic receptors.

Question 11

Equation for effective filtration pressure?

Answer 11

Peff = Pheff - Poeff

Question 12

Equation for flow rate in the capillaries?

Answer 12

Q = Peff x CFC

Question 13

Factors of the diffusion rate?

Answer 13

Conc. Gradient and transit time of substance, permeability and diffusion area.

Question 14

Method of measuring blood pressure?

Answer 14

Indirect - by auscultatory method or by digital method.

Question 15

How to determine diastolic pressure?

Answer 15

Disappearance of the tapping sound when releasing the cuff pressure.

Question 16

What does the ISF depend on?

Answer 16

Blood pressure, hydrostatic pressure, oncotic pressure and tissue turgor.

Question 17

Is myogen dependent on the CNS?

Answer 17

No, it’s independent.

Question 18

What happens when you get a local hypoxia?

Answer 18

Metatrioles contract due to increased hydrostatic pressure.

Question 19

Is pulse pressure age dependent? Why?

Answer 19

Yes because systolic increase and diastolic decrease by age.

Question 20

Equation for mean arterial pressure?

Answer 20

Pavarage = (Psystolic + 2xPdiastolic) / 3

Question 21

How to measure systolic pressure?

Answer 21

First sound when releasing pressure in cuff

Question 22

How to measure blood pressure by ausculatory method?

Answer 22

By using the Riva-Rocci sphygmomanometer

Question 23

Effect of prolonged perfusion with ringer’s solution?

Answer 23

Oedema

Question 24

What blood cell type is mainly in mural flow

Answer 24

WBC

Question 25

What type of acetylcholine receptors are present in the heart?

Answer 25

Muscarinic acetylcholine receptors (beta1 & beta2)

Question 26

Describe a normal PQ segment (physiological background, shape)

Answer 26

Represents the action potential through the AV node. The voltage difference is too small to be detected it makes an isoelectric line

Question 27

Give the normal cardiac axis range

Answer 27

-30 110 degrees

Question 28

Describe a normal T wave (physiological background, direction)

Answer 28

The pattern of ventricular repolarization, the so called T wave varies between species. In humans and carnivores it is usually an upward deflection (like the P wave that indicates depolarization). The background of this phenomenon is that repolarization begins where cells were depolarized last, i.e. repolarization starts at ventricular epicardium and propagates towards the endocardium.

Question 29

List the main steps of determining the cardiac axis

Answer 29

1) the peak values of the R waves in each standard lead should be measured first.
2) construct at least 2 out of the possible 3 vectors projected to the plane of the given electrodes. The integral vector of these projected vectors is termed the R vector in the frontal plane. The direction of this integral vector is the cardiac axis in the frontal plane.