Transcript Heart and circulation.

Cardiovascular Adjustments
Prof. K. Sivapalan
Cardiovascular adjustment in
exercise [isotonic].
• Skeletal muscles require more nutrients
and produce more wastes and heat.
• CVS, RS, and other systems has to adjust
to meet the needs.
• The muscles respond to impulses in motor
nerves in any exercise: fight of flight.
• The needs of muscles are met by various
mechanisms.
2013
Regional Circulation
2
Nervous adjustments.
• As the brain perceives the idea of exertion and
starts planning appropriate movements,
hypothalamus also becomes activated.
• It activates the sympathetic system and inhibits
parasympathetic system.
• This brings anticipatory changes in heart and
circulation.
• These changes are reinforced when exertion
begins through impulses from proprioceptors.
2013
Regional Circulation
3
Anticipatory changes.
•
•
•
•
Heart rate and force increase.
Blood pressure increases- systolic.
Splanchnic, renal, coetaneous flow reduce.
? Vasodilatation in skeletal muscles. [vaso
dilator nerves].
• Dilatation in coronary vessels but no change in
cerebral flow.
• Adrenal medulla and cortex increase secretions.
[detail after study of endocrines]
2013
Regional Circulation
4
Changes due to muscle action.
• Muscle pump increases venous return and
the cardiac output.
• Metabolites cause local vasodilatation.
Other effects:
• Increased heat stimulates thermoregulatory center and causes coetaneous
vasodilatation.
• Respiratory pump.
• Increased oxygen extraction.
2013
Regional Circulation
5
Net circulatory changes.
•
•
•
•
•
•
•
•
•
Increased heart rate and force of contraction.
Increased end-diastolic volume.
Decreased end-systolic volume.
Increased cardiac output.
Muscular, skin and coronary vasodilatation.
No significant change in cerebral flow.
All other places- vasoconstriction.
Slightly decreased peripheral resistance.
Increased systolic and decreased diastolic
pressure
2013
Regional Circulation
6
Isometric exercise.
•
•
•
•
Sustained muscle contraction.
Increase in peripheral resistance.
Systolic and diastolic pressure increase.
? Yoga.
2013
Regional Circulation
7
Effects of training.
•
•
•
•
•
•
•
Inrease in stroke volume.
Decrease pulse rate.
Quick return to basal valuse after exercise.
Reduced coagulability.
Healthy vessels.
Muscle and bone development.
[Feeling better.]
2013
Regional Circulation
8
Hemorrhage.
•
•
•
•
•
Loss of blood- reduced blood volume
Reduced venous return.
Reduced cardiac output.
Reduced blood pressure.
Heart rate increases before pressure
drops.
2013
Regional Circulation
9
Compensation to hypovolemia.
• Anxiety and excitement stimulate
sympathetics and adrenals.
• Reduced stretch of baro receptors:
– Less inhibition to VMC.
– Less stimulation to CIC.
• Renal compensation- renin – angeotensin
– aldesteron.
• Tissue fluid dynamics.
2013
Regional Circulation
10
Severe hemorrhage.
• Moderate loss- as in blood donation:
– Effective compensation by mobilizing venous
reservoir.
• If unable to compensate:
–
–
–
–
–
–
2013
Circulation mainly to vital organs.
Severe peripheral vaso constriction.
Tachycardia.
Reduced pulse pressure – thready pulse.
Reduced tissue fluid.
Prolong reduced perfusion – acidosis.
Regional Circulation
11
Shock.
• Peripheral circulatory failure.
• Emergency- if not recovered goes in
irreversible shock and death.
• Causes:
– Hypovolemic
– Cardiogenic.
– Distributive. [anaphylactic or septic]
– Neurogenic [pain, fear]
2013
Regional Circulation
12