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The Cardiovascular System

VIEWS: 16 PAGES: 31

									CARDIOVASCULAR FUNCTION
IN Rana pipiens

Biology 305 Laboratory
ANNOUNCEMENTS
BIOL305L MIDTERM GRADE DISTRIBUTION
35                       A = 90 – 100%
30                       B = 80 – 89%
                         C = 70 – 79%
25                       D = 60 – 69%
                         F = Below 60%
20
15                         # Students

10
5
0
     F   D   C   B   A
ANNOUNCEMENTS
   MIDTERM
    – Request for Regrades
          –   Handled by me
          –   You can LOOSE points!
          –   Request for Regrade Form is REQUIRED
          –   Must be specific to particular question
          –   No exams in pencil will be regraded
          –   Deadline = one week after exam is turned back
                » Please turn in at start of your lab
                » Please do not disturb me in my office!
ANNOUNCEMENTS
   Lab Report #2:
   Based on next lab!
    –   Researched and written INDIVIDUALLY
    –   Plagiarism = 0 + academic penalties!
    –   Take notes and record all data during lab
    –   Outline will be given out next week
                » Two scientific journal articles required as references

                » Turnitin.com
ANNOUNCEMENTS
Lab Quiz Next Week:
   Based on:
       • Virtual Mouse Respiration Lab
       • Frog Cardiovascular Lab
THIS WEEK’S EXERCISE:
VIRTUAL MOUSE EXERCISE
The Virtual Mouse Respiration Lab:
 A Test of Rubner’s Surface Rule
    • Applies to endotherms

       – “Warm-blooded animals”

          » Regulate body temp & generate heat through
            metabolism
THIS WEEK’S EXERCISE:
VIRTUAL MOUSE EXERCISE
What We Know:
   As a sphere increases in size:

    – Volume (V) grows proportional
      to the raduis3

    – Surface area (SA) grows proportional to the radius2

   Therefore SA is related to V to the power 2/3 or 0.67
THIS WEEK’S EXERCISE:
VIRTUAL MOUSE EXERCISE
Rubners Surface Rule:
   Assuming an animal is a sphere, small animals
    have less volume per unit SA than their larger
    counterparts

       • Cells in smaller endotherms have a higher
         metabolic rate to compensate for a greater amount
         of heat lost across the surface of their bodies
THIS WEEK’S EXERCISE:
VIRTUAL MOUSE EXERCISE
The Virtual Mouse
Respiration Lab:

   Results:

   Lg mouse consumes more O2/min
    – Higher overall metabolic rate
THIS WEEK’S EXERCISE:
VIRTUAL MOUSE EXERCISE
The Virtual Mouse
Respiration Lab:
Results:
   Sm mouse consumes more
    O2/min/gm
     – Higher mass specific metabolic rate


   Same trend found for all mammals
     – Mass specific metabolic rate declines as
       body mass increases
THIS WEEK’S EXERCISE:
VIRTUAL MOUSE EXERCISE
The Virtual Mouse
  Respiration Lab:
 Rubner’s Surface Rule:
    – Gives incomplete explanation!

    – Slope = 0.75 instead of
      theoretical value of 0.63

    – Mass specific metabolic rate in
      ectotherms indicates same trend

   Scientists not entirely clear
    why differences are observed
THIS WEEK’S EXERCISE:
VIRTUAL MOUSE EXERCISE
The Virtual Mouse Respiration Lab:
 What Scientists Know About Small Animals:
     • They have relatively high respiratory + heart rate

     • Their Hemoglobin (Hb) is relatively concentrated
         – Hb-O2 Curve is R-shifted at tissues:
             » Hb has lower affinity  more O2 released

     • They have high mitochondrial densities, surface area & enzyme
       activity

     • They have relatively high capillary density
NEXT WEEK’S EXERCISE:
FROG CARDIOVASCULAR
PHYSIOLOGY
The CV System:

   CV system tied to respiratory system

       • Functions in gas exchange & transport of nutrients and
         waste products
FROG CARDIOVASCULAR
PHYSIOLOGY
Three Main
 Components:
   Heart
       • Muscular organ that pumps blood
         through body

   Blood
       • Fluid (connective tissue)

   Vessels
       • Tubes for directing blood transport
FROG CARDIOVASCULAR
PHYSIOLOGY
The Heart:

   Primarily functions to provide
    pressure to move blood to its
    ultimate destination:

            – The tissues
EVOLUTION OF
THE VERTEBRATE HEART




Fish & Mammals:
   Two Extremes in Vertebrate Circulation
       • A gradual separation of heart into TWO
         SEPARATE PUMPS
              » occurred as vertebrates progressed from aquatic to
                terrestrial respiration
EVOLUTION OF
THE VERTEBRATE HEART
Fish:
 Heart has two chambers
 One circuit
       • No Pulmonary Circuit
   One cardiac cycle:
       • Blood p/u O2 in gills
       • O2 delivered to tissues
       • O2 -poor blood returns to heart
EVOLUTION OF
THE VERTEBRATE HEART
Amphibian:
   Heart has three chambers
    – One ventricle
 Two partially separate circuits
 One cardiac cycle
       • O2-deficient blood enters heart
       • May mix with O2-rich blood from lungs
       • Blood pumped out of heart to rest of body
EVOLUTION OF
THE VERTEBRATE HEART
Birds & Mammals:
 Heart has 4 separate chambers
       • Two atria
       • Two ventricles
   Two separate circuits
       • Systemic circuit
       • Pulmonary circuit


   O2-rich and O2-deficient blood
    do NOT mix
ANATOMICAL FEATURES OF
THE AMPHIBIAN HEART
Sinus Venosus:

   Region of pacemaker cells
    between vena cava and right
    atrium

    – Sinoatrial node (SA) in mammals
      probably evolved from SV
CARDIOVASCULAR PHYSIOLOGY
Frog Heart Consists of Two Types of Cells:

   Myocardial Autorhythmic Cells
       • Initiate rhythmic contractions w/o external stimulation
         (myogenic)

           – Set pace of the heartbeat


   Myocardial Contractile Cells
       • Contract in response to depolarization

           – Push blood into vessels tissues
CARDIOVASCULAR PHYSIOLOGY
    Some Terms to Know:
       •   Cardiac Output
       •   Heart Rate
       •   Stroke Volume
       •   Contractility
       •   Systole
       •   Diastole
       •   Ventricle
       •   Atria
Cardiac Output (CO)              CARDIAC
                                 OUTPUT
   Measure of amount of blood
    pumped from the heart per
    unit time

       • Units = ml/min

        CO = HR * SV
Heart Rate (HR)                  HEART
                                 RATE
   The number of contractions
    per unit time

    – Units = bpm
Stroke Volume (SV):
                              STROKE
                              VOLUME
   Volume of blood ejected
    from heart during
    ventricular contraction

    – Units = mL
           CONTRACTILITY
Contractility:

   Intrinsic ability of a cardiac muscle fiber to
    contract at a given length
STARLING’S LAW OF THE HEART
               Stroke Volume As A Function of EDV


  Stroke
  Volume
                                                  ^
                                                    Normal
  (ml) or
  Force of
  Contraction

                                     *
                      End Diastolic Volume (ml)
Stretch of Myocardial Cells Causes Greater Force of Contraction (& SV)
^ Some chemical agents can affect contractile force irrespective of
   level of stretch
CARDIOVASCULAR PHYSIOLOGY

    Regulation of Heart Rate and Force of
     Contraction Represents a Balance:

        • Intrinsic Factors


        • Extrinsic Factors
CARDIOVASCULAR PHYSIOLOGY
    Intrinsic & Extrinsic Factors:
     – Autonomic Nervous System
          – Sympathetic Discharge (NE)
          – Parasympathetic Discharge (Ach)

     – Endocrine System
          – Hormones (Epi & NE)

     – Drugs
          – Agonists & Antagonists

     – Temperature
PRIMARY AUTONOMIC
NEUROTRANSMITTERS (NT)
   Acetylcholine (Ach):
       • Main NT of the parasympathetic division
       • Binds to cholinergic receptors


   Norepinephrine (NE):
       • Main NT of the sympathetic division
       • Binds to adrenergic receptors
CARDIOVASCULAR PHYSIOLOGY
Purpose of Next Weeks Lab:

   Determine effect of both intrinsic & extrinsic
    factors on CO, HR and Force of Contraction.

   Determine to what extent Starlings Law applies to
    the frog heart

								
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