Transcript 9. Cardio Control

The Baroreceptor Reflex
Sensory Receptors Detect Changes in BP
Specifically - Mechanoreceptors detect changes in BP
Located in blood vessel walls:
1. Aortic bodies
2. Carotid bodies
The Baroreceptor Reflex
M.O.
BP↓
Baroreceptors (aortic arch & carotid a.a.)
∆’s to ↑BP
BP↑
∆’s to ↓BP
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.
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).
Parasympathetic
(Vagus n.)
Sympathetic
(accelerator n.)
To SA node
The Medulla Oblongata the ANS and
the Cardiovascular System
Parasympathetic Stimulation
Lowers BP
Sympathetic Stimulation
Elevates BP
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