3. Physiology
        3.2. Cardiovascular
            3.2.4. Regulatory mechanisms
                3.2.4.2. Regulation of peripheral blood flow
                    3.2.4.2.3. Systemic control by nervous system
3.2.4.2.3.2. Baroreceptors

Baroreceptors

[Ref: WG21:chp31]

Stretch receptors in the walls of the heart and blood vessels.

Stimulated by distention of the structures

 

Neural pathways

Step 1

Afferent fibres from baroreceptors project to medulla.

Most end in the nucleus of the tractus solitarius (NTS)

Neurotransmitter: probably glutamate

Step 2

From NTS to caudal and intermediate ventrolateral medulla (CVLM, IVLM)

--> Excitatory (?glutaminergic) projections

Step 3

From CVLM, IVLM to RVLM

--> Inibitory (GABA) projections

Step 4

From RVLM

--> IML

 

Thus,

Increase in BP

--> Increase in baroreceptor activity

--> Increase in inhibition of RVLM (where stimulatory sympathetic neurons are)

Resulting in:

End-result:

 

High pressure baroreceptors

i.e.

Note:

Carotid sinus baroreceptors

... small dilation of the internal carotid cartery just above the bifurcation of the common carotid artery

Afferent neural pathway from carotid sinus

--> Sinus nerve

--> Glossopharyngeal (IX) nerve

--> NTS

Aortic arch baroreceptors

... in the wall of the arch of the aorta

Note:

Cardiopulmonary baroreceptors

aka Low pressure baroreceptors

aka Volume receptors

Located in the walls of right and left atria, at the entrance of SVC and IVC

Atrial stretch receptors

Two types:

Discharge of type B is increased by increased distention of atrial walls

e.g. increase venous return,

Note:
Dischage is decreased by PEEP

Increased discharge of atrial stretch receptors

... causes:

Other notes

[KB2:p23]

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