CARDIOVASCULAR FUNCTION IN Rana pipiens Biology 305 Laboratory

ANNOUNCEMENTS Lab Quiz Next Week: Based on: Virtual Mouse Lab Frog Cardiovascular Lab

ANNOUNCEMENTS Oral & Poster Presentation: –Researched, written, prepared, presented as group –All individuals in group receive SAME grade –Combo is approx. 25% of final grade! –You must choose ONE lab from the semester: –Excluded labs include: »Lab #1 & 2 »“Virtual” labs

ANNOUNCEMENTS Oral & Poster Presentation: –Majority of info for presentation comes directly from your lab notebook »Data, observations, tables, graphs and answers to questions –The oral presentation will be given first, followed by the poster »Absolutely NO LATE submissions!

NEXT WEEK’S EXERCISE: FROG CARDIOVASCULAR PHYSIOLOGY The CV System: CV system is tied to respiratory system

FROG CARDIOVASCULAR PHYSIOLOGY Three Main Components: Heart Blood Vessels

FROG CARDIOVASCULAR PHYSIOLOGY Amphibian Heart: Heart has three chambers Two partially separate circuits One cardiac cycle O 2 -deficient blood enters heart May mix with O 2 -rich blood from lung Blood pumped out of heart to rest of body

ANATOMICAL FEATURES OF THE AMPHIBIAN HEART Sinus Venosus: Region of pacemaker cells between vena cava and right atrium

FROG CARDIOVASCULAR PHYSIOLOGY Leopard Frog (Rana pipiens): Use of force transducer Measure frequency and relative force of contraction May observe both atrial & ventricular contraction (systole) on trace

FROG CARDIOVASCULAR PHYSIOLOGY Regulation of Heart Rate Represents Balance: –Intrinsic Factors: –Extrinsic Factors:

FROG CARDIOVASCULAR PHYSIOLOGY Intrinsic Factors: Innervations of the Heart: –Autonomic Nervous System (ANS) has two subdivisions that influence HR & force of contraction

FROG CARDIOVASCULAR PHYSIOLOGY Divisions of ANS: Sympathetic Division Parasympathetic Division The two divisions work antagonistically

FROG CARDIOVASCULAR PHYSIOLOGY Parasympathetic Division –Releases Acetylcholine (Ach) Sympathetic Division –Releases Norepinephrine (NE)

AUTONOMIC PATHWAYS Sympathetic Pathway: < Ach< NE Target Tissue < Ach< Target Tissue Parasympathetic Pathway: = ADRENERGIC = CHOLINERGIC

FROG CARDIOVASCULAR PHYSIOLOGY Effect of Neurotransmitters (neurohormone): NE/Epi Ach

FROG CARDIOVASCULAR PHYSIOLOGY Extrinsic Factors: Agonists: Antagonists:

CARDIOVASCULAR TERMINOLOGY Cardiac Output (CO): Amount of blood pumped by ventricle per unit time

CARDIOVASCULAR TERMINOLOGY Heart Rate (HR): Number of contractions per minute Derived directly from period:

CARDIOVASCULAR TERMINOLOGY Stroke Volume (SV): Volume of blood ejected from heart during ventricular contraction

FROG CARDIOVASCULAR PHYSIOLOGY Relative Force of Contraction: Measured by amplitude of periodic cycle Influenced by:

CHANGES IN FORCE OF CONTRACTION & STROKE VOLUME Starling’s Law of the Heart : Amount of blood in ventricle when systole begins (EDV) influences force of contraction

CONTRACTILITY Contractility: Intrinsic ability of a cardiac muscle fiber to contract at a given length Agents that increase contractility are called Agents that decrease contractility are called

STARLING’S LAW OF THE HEART Stroke Volume (ml) or Force of Contraction End Diastolic Volume (ml) Normal Stretch of Myocardial Cells Causes Greater Force of Contraction (& SV) ^ * Stroke Volume As A Function of EDV

CHANGES IN FORCE OF CONTRACTION & STROKE VOLUME Contractility: In mammals, NE/EPI typically increase contractility Results in increased force, even though they cause an increase HR

FROG CARDIOVASCULAR PHYSIOLOGY Some Hints For Lab: Avoid Contamination: label ALL beakers & pipettes!!! Apply NE, Ach& cold Ringers to heart and observe response (frequency/amplitude) on computer Apply Ringer’s solution often –Especially between each treatment Take baseline readings BEFORE addition of ea. treatment! After running agents of known origin, consult with group members on how to test identity of an unknown