CARDIOVASCULAR FUNCTION IN Rana pipiens

Biology 305 Laboratory

ANNOUNCEMENTSLab 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 PHYSIOLOGYThree Main Components: Heart

Blood

Vessels

FROG CARDIOVASCULAR PHYSIOLOGYAmphibian Heart: Heart has three chambers

Two partially separate circuits

One cardiac cycle• O2-deficient blood enters heart• May mix with O2-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 PHYSIOLOGYLeopard 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 PHYSIOLOGYDivisions 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 TargetTissue

<Ach < AchTargetTissue

Parasympathetic Pathway:

= ADRENERGIC

= CHOLINERGIC

FROG CARDIOVASCULAR PHYSIOLOGYEffect of Neurotransmitters (neurohormone):

NE/Epi

Ach

FROG CARDIOVASCULAR PHYSIOLOGYExtrinsic 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 PHYSIOLOGYRelative 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

CONTRACTILITYContractility: 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

StrokeVolume (ml) or Force ofContraction

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 VOLUMEContractility:

•In mammals, NE/EPI typically increase contractility

•Results in increased force, even though they cause an increase HR

FROG CARDIOVASCULAR PHYSIOLOGYSome 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