Cardiovascular Regulation Coleman Exercise Physiology McArdle, Katch, and Katch, 4 th ed.

How does your blood pressure remain normal?

Mechanisms Autoregulation –Local changes in blood flow and capillaries (vasodilators and vasoconstrictors) Neural mechanisms –If autoregulation does not normalize tissue conditions –Responds to changes in arterial pressure or blood gas levels –Autonomic NS Endocrine Mechanisms –Short-term adjustments, long-term changes in performance (blood volume)

Regulation of the Cardiovascular System Blood Flow Regulation

In a small group Use the white board to predict how the endocrine system OR nervous system could affect blood pressure Which hormones? Which part of the NS?

Neural Regulation Sympathetic influence –Epinephrine ↑HR and ↑ contractility –Norepinephrine: general vasoconstrictor Parasympathetic influence –Acetylcholine→↓HR endurance (aerobic)

Neural Regulation

Cardiac Accelerator Nerves Sympathetic Fibers Stimulate Sinoatrial node (pacemaker) & ventricles Increase heart rate Increase contractility Increase pressure

Vagus Nerve Parasympathetic Nerve Releases acetylcholine Slows heart rate Lowers pressure

Peripheral Influences on HR Peripheral receptors monitor state of active muscle; modify vagal or sympathetic Baroreceptors Chemoreceptors –Monitor pCO 2, H +, pO 2 Hormones

Baroreceptors Baroreceptors (pressure) in carotid sinus and aortic arch. Respond to change in homeostasis –BP above or below normal

Baroreceptors stimulated Medulla oblongata  Inhibits cardioaccelatory center  Stimulates cardioinhibitory center, inhibits vasomotor centers -Vagus releases ACh to reduce rate and strength of contractions -Dilation of arterioles -What would this do to BP?

Baroreceptors inhibited: what would it look like? Vasoconstriction Increased cardiac output BP elevated

Chemoreceptors Respond to changes in CO2, O2 or pH in blood Carotid bodies Aortic bodies Medulla oblongata monitors CSF

How would you explain the action of chemoreceptors? Draw a flow chart of negative feedback

Endocrine match with a buddy! A.) Antidiuretic (ADH) B.) Angiotensin II C.) Erythropoietin (EPO) D.) Atrial Natriuretic (ANP) 1_____ stimulates ADH and aldosterone, makes you thirsty, inc. BP 2_____ stimulated by inc. BP, dec. BP and volume by loss of Na+ ions, urine, block ADH, vasodilation 3_____ kidney, inc. blood volume for more O2 4_____ posterior pit., vasoconstriction inc. BP, conserves water to prevent reduction in blood volume

Heart Hormones A4 B1 C3 D2

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