“Little Cowboy”. Homeostasis and The Heart Tissues and Organs Depend on Appropriate Blood Flow...
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Transcript of “Little Cowboy”. Homeostasis and The Heart Tissues and Organs Depend on Appropriate Blood Flow...
“Little Cowboy”
Homeostasis and The Heart
Tissues and Organs Depend on Appropriate Blood Flow (Perfusion)
Supply = Demand
Starling’s Law: Intrinsic Control of HeartVenous Return determines “stretch”
of cardiac myocytes: Venous Return = Stretch Stretch = Force and Rate
Known as PreloadExercise Increases Venous
Return / Preload / Force & Rate
Extrinsic Control: Baroreceptor ReflexBaroreceptors: Sense stretch in
artery walls(Stretch = Pressure)Aorta Internal Carotid Artery
Afferent Signals to Cardioregulatory Centers: Medulla Oblongata
Perfusion homeostasis by addressing pressure problems:
Heart Rate Decreases
Pressure Increases
InhibitionOf PressureSignals
Baroreceptor Reflex…Efferent Signals from Autonomic
Nervous System:Parasympathetic: Decrease HRSympathetic: Increase HRAdrenal: Increase HR
How do you think pressure affects perfusion of vital tissues?
Decreased CO Threatens Vital OrgansCardiac Response:
Increase HR (to compensate for decreased pressure/SV)
Vascular Response:Direct more of the total blood
volume to vital tissuesAway from less vital tissues
Extrinsic Control: Chemoreceptor Reflexes Increased Metabolism produces more
CO2, acids, and Temp:
Chemoreceptors (mostly in the medulla oblongata) initiate:
SNS stimulation: Rescues from “metabolic buildup” by HR
PSNS stimulation: Slows the heart when CO2, acids and temp recover
Exercise = PreloadWorking muscles “squeeze” more
blood back to heart Increased Venous Return =
Increased PreloadStarling Law is important in
initial increases in Exercise CO
Exercise Stimulates SNSCardioregulatory centers + SNS:
Stimulate SA Node to increase HRStimulate Adrenal Medulla to
release Norepinepherine, which increases HR
Increase contractility and SVIncrease myocardial blood flow
Exercise increases CO2, H+ and Temperature
Chemoreceptors stimulate SNS and adrenal medulla
Increase HR and SV
Exercise Applications:Vital Organs: Heart, Lungs, Brain
(Kidney)How does Exercise affect the “Priority”
of blood flow to “vital organs”?What TWO tissues during exercise
have high priority for perfusion? (become vital organs)
Vital Tissues during Exercise:Working Muscles
Larger muscles = more blood volume = greater venous return
Skin (cooling)BrainHeartLungs
Meeting the Demand: More “Vital Organs”Cardiac Response:
Increased CO by Increased SV * HR
Preserving Blood flow to “HLB”Vascular Response:
Redistributing blood flow from less vital tissues…more later
Think About This: Explain the
difference between an “athlete’s” heart and an non-athlete’s heart:
Address Cardiac Output and Heart rate at rest and exercise.
Athlete vs. Non-Athlete
Ventricle Volume and Mass
Max SV = Max HR Max CO Resting HR Resting SV = Resting CO
More Thinking: How do you think
cardiac output is affected in paraplegic athletes?
What are the dominant muscles? Where?
Would swimmers be similar?
Upper Body Athletes:
Smaller Active Muscle Mass =
Venous Return SV = HR CO
At Maximum Exercise
Summarize: The HeartFunctions of the Heart:
Blood Pressure = PerfusionDirecting Blood: Lungs / Body
Anatomy – LocationLocation / OrientationChambers / ValvesTissues: Epicardium, myocardium,
endocardium
Summary: Anatomy, cont:
Coronary ArteriesPericardium
Blood Flow Through HeartBeginning at Right Atria…Relative O2 contents
Cardiac Myocytes:Anatomy and Action Potentials
Summary: Conduction System of Heart:
SA, AV nodes, AV bundles, bundle branches, purkinje fibers
ECGCardiac Cycle:
Atrial systole - diastoleVentricular systole and diastoleHeart Sounds / Murmurs
Summary: Regulation of Cardiac Output Intrinsic Regulation:
Starling’s Law Extrinsic Regulation:
SNS, PSNS, Endocrine Exercise and Homeostasis:
Perfusion to “VITAL ORGANS” Intrinsic and Extrinsic Controls