Post on 30-Jan-2016
description
Abstracts and Test 2• Earning up to 5 points for Test # 2 based
on topics of Frog Heart Lab:– Regulation of pacemaker cells by
temperature, hormones, neurotransmitters, antagonists
– Heart block: 1st, 2nd, and 3rd degree– The conducting system– Strategies for prolonging survival of in vitro
organs
Cardiac Cycle Animation
1QQ #24 for 10:30Write each letter and circle the letter of correct statements.
a) Heart murmurs are caused by the closure of heart valves.
b) The first heart sound is produced by the closure of the atrioventricular valves.
c) Blood is about 65% plasma.
d) Pacemaker cells produce action potentials that last about 200-300 milliseconds.
e) Chordae tendonae and papillary muscles prevent eversion of the semilunar valves.
1QQ #24 for 11:30Write each letter and circle the letter of correct statements.
a) The buffy coat is thicker in a person with an infection.
b) The first heart sound is produced by the closure of the atrioventricular valves.
c) Blood is about 45% plasma.
d) Pacemaker cells produce action potentials that last about 200-300 milliseconds.
e) The tricuspid valve is situated between the right ventricle and the pulmonary artery.
F=Q=ΔP/RFlow = Pressure gradient/Resistance
from Ohm’s Law (V=IR)
R = 8Lη/πr4
Q= ΔP πr4
8LηPoiseulle’s equation
S 8
Double radius … 16x flow
Half radius….1/16th flow
R = 8Lη/πr4
Cardiac Output = Heart Rate X Stroke Volume
What regulatesheart rate?
CO = HR x SV
5L/min = 72 beat/min x 70 ml/beat
The Cardiac Cycle animation
S 1
What regulatesStroke Volume?
Figure 12.11
SA node cells do not have stable resting membrane potential, spontaneously produce AP, are Pacemaker cells
S 5
S 4
Figure 12.22Intrinsic Rate = 100 beat/min
S 15
2 effects of Parasymp:hyperpolarization &slower depolarization
Effect of “Beta blockers”
NE EPI ACh
mAChR
Effect of atropine
Beta-adrenergic receptors
S 6
Recall: CO = HR x SV
Fibrous connective tissue between atria and ventricles prevents the conduction of action potential. Only route is via AV node, bundle of His, bundle branches, Purkinje fibers, and to ventriclular myofibers.
What prevents the AP from being conducted from ventricles to atria?
S 7
1st Heart Sound = Closure of Atrioventricular (AV) valves at beginning of Ventricular Systole
2nd Heart Sound = Closure of Semilunar valves at beginning of Ventricular Diastole
S 8 “Sis-toe-lee”
“die-ass-toe-lee”
Figure 12.20Systolic
Diastolic
Ejection Fraction = SV/EDV
Atrial Fibrillation
Ventricular Fibrillation & Defibrillation
Stroke Volume
Animation
S 9
Events are same for Cardiac Cycle for Right Side of Heart; only difference is lower systolic pressures in right atrium and right ventricle.
S 10
CO = HR x SV
5L/min = 72 beat/min x 70 ml/beat 35L/min = ? beat/min x ? ml/beat
S 1
So far, we’ve dealt with the factors that control Cardiac Output by changing heart rate.
+ sympathetic- parasympathetic
2
1
3
The Cardiac Cycle animation
Figure 12.20
Stroke Volume
Animation
S 2
Frank-Starling Law of the Heart
FS LoH = SV is proportional to EDV
Ventricular Function Curve
Does not depend on hormones or nerves
Assures that the heart adjusts its output based on VENOUS RETURN
Ways to enhance Venous Return:1) muscle contractions2) “respiratory pump”3) venoconstriction
S 3
↑VR→ ↑EDV → ↑SV
Respiratory pump
Muscle pump
Mechanical pump for bedridden patients
Fig. 09.21
Low EDV
High EDV
Length-tension “curve” for Cardiac muscle
Overinflation of ventricles leads to less effective pumping
S 4
Overinflation of ventricles results in reduction in stroke volume
S 5
Treatments?…..diuretics
Contractility
NE from Symp postganglionics & EPI from Adrenal medulla
Note: cardiac myofibers NOT innervated by parasympathetic division
Increase Ejection Fraction
S 6
3 Effects of SympatheticStimulation
1: Increase rate of contraction2: Increase peak tension3: Decrease twitch duration
S 7
Why should the contraction be shorter?
Summary: Control of Stroke Volume
• End diastolic volume (preload)
• Contractility (strength of ventricular contraction due to adrenergic stimulation)
• Pressure in arteries that must be overcome = Afterload
FS LoH
S 8
Afterload is analogous to trying to pump more air into a tire that is already fully inflated (heart contracting to overcome diastolic pressure.)
High blood pressure increases the workload of the heart….. Cardiac hypertrophy….increase chance of irregular conduction of AP through heart
S 9
Hypertrophic cardiomyopathy
CO = HR x SV
5L/min = 72 beat/min x 70 ml/beat 35L/min = ? beat/min x ? ml/beat
S 11 Factors that control Cardiac Output by changing heart rate and stroke volume.
+ sympathetic- parasympathetic
VR and EDV (FSLoH)
Contractility (catecholamines)
Afterload (MAP)