Turtle heart lab quiz questions

Why does the turtle heart not stop when it is removed from the turtles body a placed in ringers solution?

AV node is still firing

ANS on heart

Affected by the vagal nerve S= speeds up heart P= slows down heart

What happens when the atria are separated from the ventricle? Explain how this happens?

Atria beats regular, ventricle 1/2 as fast because AV node AV node takes over

What conditions in humans could cause AV blocks?

Myocardium infraction

What is the effect of atropine by itself? What is the effect of atropine following ACh?

No effect Speeds it up to normal heart rate

What effects does Epi have on the heart?

No effect Epi binds with beta 1 receptors activates adenylate cyclase which increases ATP production

Ectopic

Out of place

Focus(foci)

Point

Diastole

Relaxation

Vagal escape

Ventricles start beating again Occurs when the SA node fails from heart attack,ischemia, then AV node takes over

Compare the rates of beating of the seperated atria and ventricles?

Ventricles=beat slower because AV nodes take over SA=70-130 BPM AV= 40-60 BPM

Which parts of the heart contact first? Last?

atria then ventricles

Compensatory pause

2 cardiac cycles

Systole

Contraction

Know how to determine heart rate in BPM

Count pulse

AP's spread across the heart like a wave causing

Depolarization followed by repolarization causing contraction and relaxation

Premature ventricular contraction

Ectopic focus, PVC causes AP's so the atria fires, ventricles can't due to refractory period Drugs, MI(heart attack), ischemia(lack of oxygen in blood),genetics

When during the cardiac cycle is blood pressure highest? Lowest?

H= at peak of systole L=end of diastole

Would the human heart respond similarly to temperature changes? Does this ever happen?

Human heart responds similarly to turtle heart, during a heart transplant they put the heart in cold ringers solution so the ions and molecules move slower

What would the human heart do if removed from body?

Keep beating-> pacemaker(SA node)

What is the sinus venous?

SA node of the turtle heart(controls ventricles)

AP's in the human heart begin in the?

SA node->spreads through atria->AV node->ventricles

Vagal stimulation on the heart

Should slow heart down ACh binds with muscarinic receptors on SA node->opens K channels which lower SA node

How does cold ringer's solution affect the heart?Why? Mechanism?

Slow the heart down, slows down ions, AP's go slower

ACh

Slows heart rate Binds with muscrainic receptors

How does 42 degree ringer solution affect the heart? Why? Mechanism?

Speeds it up, speeds up ions, makes APs go faster