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Frog Heart Muscle. Contraction Pathway SA node Atria AV node Ventricles Gap Junctions Slows transmission of AP Increases in Na+ conductance; causes AP;

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Presentation on theme: "Frog Heart Muscle. Contraction Pathway SA node Atria AV node Ventricles Gap Junctions Slows transmission of AP Increases in Na+ conductance; causes AP;"— Presentation transcript:

1 Frog Heart Muscle

2 Contraction Pathway SA node Atria AV node Ventricles Gap Junctions Slows transmission of AP Increases in Na+ conductance; causes AP; autorrhythmic Bundle of His Purkinje fibers

3 Heart rate Frequency of AP created by the SA node – Fires 100x/min on own – Adult heart rate is about 70 bpm. WHY?

4 Regulated by: 1.Sympathetic neurons 2.Parasympathetic neurons 3.Levels of circulating epinephrine

5 PNSSensory neuronsMotor neuronsAutonomic NS Parasympathetic NS Sympathetic NSSomatic NS

6 Autonomic Nervous System Parasympathetic NS Rest and Digest Decrease HR, BP, contraction strength/rate, increase systole duration Sympathetic NS Fight or Flight Increase HR, BP, contraction strength/rate, decrease systole duration

7 SA Node Firing Rate Altered by: 1.Changes in autonomic nerve activity – Sympathetic – Vagal 2.Circulating hormones – Hyperthyroidism – Hypothyroidism 3.Serum ion concentration – Hyperkalemia – Hypokalemia 4.Cellular hypoxia – Usually from ischemia 5.Drugs

8 Drugs Ca 2+ channel blockers β blockers Atropine – Nightshade plant (tomato family)

9 Amphibian Heart 2 atria 1 ventricle O2 and deO2 blood separated by conus arteriosis and timing of atrial contractions. Pressure differences is systemic and pulmonary circuits can allow O2 and deO2 blood to mix via an intercardiac shunt. Helps stabilize O2 content in blood, thermoregulate, and allow the skin to be used as a respiratory organ. Sinus venosus = SA node in mammals.

10 Homework Write a Results, and Discussion for this lab. Answer ALL questions within the text.

11 Course Reviews Please do them ASAP. Print the confirmation at the end. 5 extra credit points for completing this!! Please provide constructive criticism if you have any. I’m always trying to improve my teaching!


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