1. The Baroreceptor Reflex 1. Aortic bodies 2. Carotid bodies Sensory Receptors Detect Changes in BP Specifically - Mechanoreceptors detect changes in BP Located in blood vessel walls:

2. Baroreceptors (aortic arch & carotid a.a.) If  BP, then  freq of Action Potential firing to M.O > changes to  BP. If  BP, then  freq of Action Potential firing to M.O > changes to  BP. M.O. ∆’s to ↓BP ∆’s to ↑BP ↓ ↑ BP The Baroreceptor Reflex

3. Modulation of the Heart by the ANS At rest, heart has Parasympathetic modulation (slows it from 90-100 down to 70-80 beats/min). When excited, Para dissipates and Sym takes over. When heart has Sympathetic modulation (increases to ~120 beats/min).

4. To SA node Parasympathetic (Vagus n.) Sympathetic (accelerator n.)

5. The Medulla Oblongata the ANS and the Cardiovascular System Parasympathetic Stimulation Lowers BP Sympathetic Stimulation Elevates BP

6. Modulation of the Heart the Endocrine System Hormones, such as E stimulate the heart rate and force of contraction (S.V.) via  receptors. Atrial Natriuretic Peptide (ANP) is released from the atria when the heart is over-stretched. ANP Causes: 1) vasodilation and 2)  Na + excretion