Download Circulatory Responses

Circulatory Responses
Purpose
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transport oxygen to tissues
transport of nutrients to tissues
removal of wastes
regulation of body temperature
Organization
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arteries - away from heart (oxygenated)
veins - to heart (deoxygenated)
arterioles - branches
capillaries - smallest arteries
venules - smallest veins
mixed venous blood - from entire body
Structure of the Heart
The Heart has Two Pumps
• pulmonary - pumps blood to the lungs and
back to the left side of the heart from the
lungs
• systemic - pumps blood to the rest of the
body and back to the right side of the heart
The Myocardium
Cardiac Cycle
• Systole
– contraction phase
– 0.3 sec at rest down to 0.2 sec during heavy
exercise
• Diastole
– relaxation phase
– 0.5 sec at rest down to 0.13 sec during heavy
exercise
The Cardiac Cycle
• Systole
– Contraction phase
• Diastole
– Relaxation phase
Pressure Changes During the
Cardiac Cycle
Insert fig 9.4
• two heart sounds
– 1st closing of the atrioventricular valves
– 2nd closing of the aortic and pulmonary valves
Blood Pressure
• arterial blood pressure estimated using
sphygmomanometer
– systolic/diastolic
– males 120/80
– females 110/70
• Hypertension
– resting BP of 140/90
– primary or secondary
Blood Pressure Determination
• Pulse pressure
– difference between systolic and diastolic
• Mean arterial pressure (MAP)
– product of cardiac output and total vascular
resistance (sig?)
– average pressure during cardiac cycle
– determines rate of blood flow through system
– MAP = DBP +.33 (pulse pressure)
Factors Affecting Blood Pressure
• Blood pressure can be increase by
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increase in blood volume
increase in heart rate
increase in blood viscosity
increase in stroke volume
increased peripheral resistance
Anterior View of the Heart
Normal electrocardiogram at rest
Use of ECG for Diagnosis (ST
depression)
Cardiac Output
• Q = HR x SV
– Q = cardiac output
– HR = heart rate
– SV = stroke volume
• Implications during exercise???
Insert table 9.1
Regulation of Heart Rate
• Parasympathetic control
– cardiovascular control center (medulla
oblongota)
– vagus nerve
– acetylcholine decreases activity of both SA and
AV nodes
– can increase HR by removal
HR Regulation cont’d
• Sympathetic control
– cardiac accelerator nerves at SA and AV nodes
– norepinephrine released which increases HR
and force of contraction
– responsible above 100 bpm
Autonomic Control of HR
Regulation of Stroke Volume
• end diastolic volume (EDV) - volume of
blood in ventricles at the end of diastole
– Frank-Starling Law
– increase in contractility increases volume
pumped per beat
– venous return
• average aortic blood pressure
• strength of ventricular contraction
Factors Regulating Venous
Return
• venoconstriction
– reduces volume capacity of veins to store blood
– sympathetic control
• muscle pump
• respiratory pump
– inspiration reduces intrathoracic pressure
The Skeletal Muscle Pump
Components of Blood
• Plasma
– Liquid portion of blood
– Contains ions, proteins, hormones
• Cells
– Red blood cells
• Contain hemoglobin to carry oxygen
– White blood cells
– Platelets
• Important in blood clotting
• Hematocrit
– Percent of blood composed of cells
Hematocrit