Rinichiul Anatomie Corelativa

Prof. Dr. M. VoiculescuCentrul de Medicina Interna Nefrologie Fundeni

Rinichi Anatomie RenalaM. Voiculescu -2002Anatomia normala a rinichiului

I.Aspectul macroscopica) exterior:- organ pereche- situat retroperitoneal- in jgheabul intervertebral- intre coasta 12-a vertebra lombara 3 - dimensiuni: 11 - 12 cm / 5 - 7,5 cm / 2,5 - 3 cm- greutate: B = 125 - 170 g; F = 115 - 155 g

Rinichi Anatomie RenalaM. Voiculescu -2002

Rinichi Anatomie RenalaM. Voiculescu -2002Anatomia normala a rinichiului

I.Aspectul macroscopica) exterior:

invelit intr-o capsula hilul se gaseste in partea concava hilul sinus pelvisul renal

Rinichi Anatomie RenalaM. Voiculescu -2002

Rinichi Anatomie RenalaM. Voiculescu -2002Anatomia normala a rinichiului

I.Aspectul macroscopica) exterior:

prin hil patrund artere, vene, nervi, limfatice si ureterul

Rinichi Anatomie RenalaM. Voiculescu -2002

Rinichi Anatomie RenalaM. Voiculescu -2002

Rinichi Anatomie RenalaM. Voiculescu -2002

Rinichi Anatomie RenalaM. Voiculescu -2002Anatomia normala a rinichiului

Rinichi Anatomie RenalaM. Voiculescu -2002

Rinichi Anatomie RenalaM. Voiculescu -2002Anatomia normala a rinichiului

II.Aspectul macroscopicb) Sectiunea longitudinala 1 corticala 2 medularaCorticala + Medulara = LOBSunt 14 lobi (7 anteriori si 7 posteriori)

Rinichi Anatomie RenalaM. Voiculescu -2002Anatomia normala a rinichiului

II.Aspectul macroscopicb) Sectiunea longitudinala 1 corticala 2 medularaCorticala + Medulara = LOBSunt 14 lobi (7 anteriori si 7 posteriori)

Rinichi Anatomie RenalaM. Voiculescu -2002

Rinichi Anatomie RenalaM. Voiculescu -2002Anatomia normala a rinichiului

II.Aspectul macroscopicb) Sectiunea longitudinala 1 corticala 2 medularaCorticala + Medulara = LOBSunt 14 lobi (7 anteriori si 7 posteriori)

Rinichi Anatomie RenalaM. Voiculescu -2002

I.Corticala grosimea = 1 cm aspect granular formeaza: capisoane desupra piramidelor (cortex centrilobar) septuri intre piramide (ale lui Bertin = cortexul septal) prezinta la jonctiunea cu medulara: striatii longitudinale deschise = striatiile Ferrein si contin portiunile drepte ale tubului contort proximal, ansa ascendenta groasa si tubul colector

Rinichi Anatomie RenalaM. Voiculescu -2002

Rinichi Anatomie RenalaM. Voiculescu -2002

II.Medulara este formata din: piramide: 8-18 mase striate cu bazala nivelul jonctiunii cortico-medulare

papila: varful piramidei se termina cu un varf area cribrosa care contine 10-25 (20-72; media 44) orificii = deschiderea tuburilor colectori (tubi belini)

- 2 tipuri de papile- simpla (varf convex)- compusa (varf larg si concav)

Rinichi Anatomie RenalaM. Voiculescu -2002

Rinichi Anatomie RenalaM. Voiculescu -2002Nefronul

Definitie: unitatea morfo-functionala a rinichiului

Alcatuire: glomerul (corpuscul malpighian) tubi

Rinichi Anatomie RenalaM. Voiculescu -2002

Rinichi Anatomie RenalaM. Voiculescu -2002

Rinichi Anatomie RenalaM. Voiculescu -2002

Rinichi Anatomie RenalaM. Voiculescu -2002Clasificarea nefronilor:

dupa pozitia glomerulului: 3 tipuri de nefroni: superficiali mediocorticali juxtamedulari

dupa lungimea ansei lui Henle: 2 tipuri de nefroni cu ansa scurta: 85% cu ansa lunga: 15%- nefroni superficiali si mediocorticali au anse scurte care se termina in medulara externa si chiar in corticala (nefroni corticali)- au ansa descendenta si ascendenta bine dezvoltata

Rinichi Anatomie RenalaM. Voiculescu -2002

Rinichi Anatomie RenalaM. Voiculescu -2002Glomerulul

Definitie: structura inalt specializata a carei principala functie este filtrarea

1 milion (0,7 1,2) nefroni / rinichi la adult 0,5 milioane / rinichi la varstnici = 22 m = 9% din corticala renala = 5% din greutatea rinichiului

Rinichi Anatomie RenalaM. Voiculescu -2002Glomerulul

Definitie: structura inalt specializata a carei principala functie este filtrarea

structurat asa incat sa ofere cea mai mare suprafata de filtrare pe unitatea de volum si sa asigure cel mai ridicat coeficient de filtrare pentru apa si moleculele cu gm< 68 kD lungimea capilarelor = 13 km suprafata capilarelor = 1,6 m2

Rinichi Anatomie RenalaM. Voiculescu -2002Structura glomerul:

ghem capilar celule celule endoteliale celule epiteliale viscerle (podocitele) celule epiteliale parietale celule mesangiale

structura matriceala extracelulara: membrna bazala glomerulara mezangiu

Rinichi Anatomie RenalaM. Voiculescu -20021. Ghemul capilar

Este alcatuit din:

un conglomerat de 4-8 anse capilare suspendate in spatiul Bowman intre: arteriola aferenta arteriola eferenta sprijinite pe mesangium

Rinichi Anatomie RenalaM. Voiculescu -2002

Rinichi Anatomie RenalaM. Voiculescu -2002

Rinichi Anatomie RenalaM. Voiculescu -20021. Capilarele

Sunt formate:

1.1 celule endoteliale 1.2 MBG, partea endoteliala (lamina rara interna)

Rinichi Anatomie RenalaM. Voiculescu -20021.1 Celulele endoteliale

un singur strat de celule turtite (gros = 12 m) celulele emit prelungiri sub forma de falduri un strat subtire si fenestrat acopera MBG fenestrele au = 70 100 nm = 30% suprafata intregul versant catre lumenul capilar este acoperit de un strat de glicocalix polianoic de 15 nm

Rinichi Anatomie RenalaM. Voiculescu -2005Celula endoteliala

Rinichi Anatomie RenalaM. Voiculescu -20021.2 Membrana bazala glomerulara (1)

Este o structura membranara care se intinde la intreg ghemul capilar si se continua cu MBG tubulara

- origine: dubla endoteliala (tip IV 1 si 2) epiteliala (tip IV 3,4 si 5)- grosimea: 350- 400 nm- reprezinta: gel hidratat polianoic

Rinichi Anatomie RenalaM. Voiculescu -20021.2 Membrana bazala glomerulara (2)

- Alcatuita din 3 straturi:

- lamina densa unica, situata central (230-275 nm)- lamina rara interna (20-40 nm)- lamina rara externa (20-40 nm)

Rinichi Anatomie Renala Membrana bazala glomerularaM. Voiculescu -2002

Rinichi Anatomie Renala Membrana bazala glomerularaM. Voiculescu -2002

Rinichi Anatomie Renala Membrana bazala glomerularaM. Voiculescu -2002

Rinichi Anatomie Renala Membrana bazala glomerularaM. Voiculescu -2002

Rinichi Anatomie RenalaM. Voiculescu -2002Membrana bazala glomerulara (2)

- Contine:

- colagen tip IV dispus sub forma de retea 1 si 2 in LRI si LRE 3 si 5 in LD- laminin- fibronectin- entactin- proteoglican heparan sulfat

- Functii:

- mecanica- filtru electrostatic

M. Voiculescu -2002Rinichi Anatomie Renala

Rinichi Anatomie RenalaM. Voiculescu -2002Celulele epiteliale viscerale (podocitele) (I)

sunt cele mai mari celule din glomerul

se gasesc pe fata extera a MBG

din corpul globulos pornesc prelungiri trabeculare (procesele primare) care dau nastere la procesele secundare (piciorusele sau pedicele), care se fixeaza pe portiunea externa a MBG.

Rinichi Anatomie RenalaM. Voiculescu -2005Podocit

Rinichi Anatomie RenalaM. Voiculescu -2002Celulele epiteliale viscerale (podocitele) (III)

Rinichi Anatomie RenalaM. Voiculescu -2002Celulele epiteliale viscerale (podocitele) (II)

piciorusele adiacente provin din prelungiri podocitare celulare diferite si interdigiteaza formand o retea care confera rezistenta capilarelor.

intre picioruse se delimiteaza un spatiu de 40nm (25-60nm) numit fanta de filtrare

The slit diaphragm of podocytes is a specialized cell junction with signaling propertiesNephrinNeph 1

ARHITECTURA PORULUI DE FILTRARERinichi Anatomie Renala

Rinichi Anatomie RenalaM. Voiculescu -2002

NephrinNeph 1Nephrin and Nephr1 are adhesion proteins of Ig superfamily

PSignaling at the slit diaphragmAKTcell survivalMAPKtranscriptional regulationpolarity signalingCbIendocytosisEndoSynactin remodelingCortTRPmechanosensationPI3 kinaseCD2APZO-1PodocinFyn

Rinichi Anatomie RenalaM. Voiculescu -2002Celulele epiteliale viscerale (podocitele) (III)

fanta are un diafragm central gros de 6 nm peste care trece ca un pod de o parte si de alta filamente fine cu diametrul de 7 nm.

rezulta o serie de pori rectngulari cu dimensiuni de 4/14 nm, numiti porii fantei de filtrare.

podocitele sunt acoperite spre MBG de un strat de podocalyxin, glicoproteina anionica bogata in acid sialic, gros de 20 60 nm.

functii: filtru- mecanic- electrostatic

Rinichi Anatomie RenalaM. Voiculescu -2002Celulele epiteliale parietale

se gasesc pe MBG si impreuna formeaza foita externa a capsulei Bowman

se continua cu- cu epiteliul visceral la polul vascula- cu epiteliul tubulr l polul urinar

raspund prin proliferare bcu formare de excrescente semilunare in urma stimularii cu:- fibrina- TNF- PGF sunt plate, sarace in organite si lipsite de prelungiri citoplasmatice

Rinichi Anatomie RenalaM. Voiculescu -2002Mesangiumul

situat axial in glomerul este format din:

celule mesangiale matrice

Rinichi Anatomie RenalaM. Voiculescu -20021. Celulele mesangiale sunt pericite au configuratie stelata prelungirile citoplasmatice patrund in spatiul subendotelial printre celulele endoteliale contin filamente de actina si miozina sunt prezenti receptori pentru angiotensina prostaglandine (PGE2, PGI) peptidul natriuretric atrial parathormon vasopresina

functii contractila endocitica (macrofag glomerular) endocrina inflamatorie: interleukina-1, TNF, prostaglandine, metaloproteine fibrilogenetica: PDGF, TGF- formarea mesangiumului

Diagrama ultrastructurala a mesangiuluiCelule mezangialeCelula endotelialaPodocitMesangiu

Rinichi Anatomie RenalaM. Voiculescu -20022. Matricea mesangiala

produsa de celulele mesangiale contine: substanta fundamentala colagen tip IV (bogat in condroitin sulfat) fibronectin laminin proteoglicani

fibrilele au = 10-16 nm sunt orientate paralel intre prelungirile celulelor mesangiale si MBG

Rinichi Anatomie RenalaM. Voiculescu -2005Mesangiu

Rinichi Anatomie RenalaProliferare mezangialaM. Voiculescu -2002

Rinichi Anatomie RenalaProliferare mezangiala + sclerozaM. Voiculescu -2002

Rinichi Anatomie RenalaProliferare mezangiala + scleroza + necroza fibrinoidaM. Voiculescu -2002

Rinichi Anatomie RenalaProliferare mezangiala + scleroza + necroza fibrinoida + excrescenteM. Voiculescu -2002

Slide 2Moxonidine (4-chloro-N-(imidazolidine-2-ylidene)-6-methoxy-2-methyl-5-pyrimidinamine) is a centrally acting antihypertensive drug.

The blood pressure-lowering effect of moxonidine is due to a highly selective action in the rostral ventrolateral medulla, which leads to a reduction in overactivity of the sympathetic nervous system.

Slide 2Moxonidine (4-chloro-N-(imidazolidine-2-ylidene)-6-methoxy-2-methyl-5-pyrimidinamine) is a centrally acting antihypertensive drug.

The blood pressure-lowering effect of moxonidine is due to a highly selective action in the rostral ventrolateral medulla, which leads to a reduction in overactivity of the sympathetic nervous system.

Slide 2Moxonidine (4-chloro-N-(imidazolidine-2-ylidene)-6-methoxy-2-methyl-5-pyrimidinamine) is a centrally acting antihypertensive drug.

The blood pressure-lowering effect of moxonidine is due to a highly selective action in the rostral ventrolateral medulla, which leads to a reduction in overactivity of the sympathetic nervous system.

Slide 2Moxonidine (4-chloro-N-(imidazolidine-2-ylidene)-6-methoxy-2-methyl-5-pyrimidinamine) is a centrally acting antihypertensive drug.

The blood pressure-lowering effect of moxonidine is due to a highly selective action in the rostral ventrolateral medulla, which leads to a reduction in overactivity of the sympathetic nervous system.

Slide 2Moxonidine (4-chloro-N-(imidazolidine-2-ylidene)-6-methoxy-2-methyl-5-pyrimidinamine) is a centrally acting antihypertensive drug.

The blood pressure-lowering effect of moxonidine is due to a highly selective action in the rostral ventrolateral medulla, which leads to a reduction in overactivity of the sympathetic nervous system.

Slide 2Moxonidine (4-chloro-N-(imidazolidine-2-ylidene)-6-methoxy-2-methyl-5-pyrimidinamine) is a centrally acting antihypertensive drug.

The blood pressure-lowering effect of moxonidine is due to a highly selective action in the rostral ventrolateral medulla, which leads to a reduction in overactivity of the sympathetic nervous system.

Slide 2Moxonidine (4-chloro-N-(imidazolidine-2-ylidene)-6-methoxy-2-methyl-5-pyrimidinamine) is a centrally acting antihypertensive drug.

The blood pressure-lowering effect of moxonidine is due to a highly selective action in the rostral ventrolateral medulla, which leads to a reduction in overactivity of the sympathetic nervous system.

Slide 2Moxonidine (4-chloro-N-(imidazolidine-2-ylidene)-6-methoxy-2-methyl-5-pyrimidinamine) is a centrally acting antihypertensive drug.

The blood pressure-lowering effect of moxonidine is due to a highly selective action in the rostral ventrolateral medulla, which leads to a reduction in overactivity of the sympathetic nervous system.

Slide 2Moxonidine (4-chloro-N-(imidazolidine-2-ylidene)-6-methoxy-2-methyl-5-pyrimidinamine) is a centrally acting antihypertensive drug.

The blood pressure-lowering effect of moxonidine is due to a highly selective action in the rostral ventrolateral medulla, which leads to a reduction in overactivity of the sympathetic nervous system.

Slide 2Moxonidine (4-chloro-N-(imidazolidine-2-ylidene)-6-methoxy-2-methyl-5-pyrimidinamine) is a centrally acting antihypertensive drug.

The blood pressure-lowering effect of moxonidine is due to a highly selective action in the rostral ventrolateral medulla, which leads to a reduction in overactivity of the sympathetic nervous system.

Slide 2Moxonidine (4-chloro-N-(imidazolidine-2-ylidene)-6-methoxy-2-methyl-5-pyrimidinamine) is a centrally acting antihypertensive drug.

The blood pressure-lowering effect of moxonidine is due to a highly selective action in the rostral ventrolateral medulla, which leads to a reduction in overactivity of the sympathetic nervous system.

Slide 2Moxonidine (4-chloro-N-(imidazolidine-2-ylidene)-6-methoxy-2-methyl-5-pyrimidinamine) is a centrally acting antihypertensive drug.

The blood pressure-lowering effect of moxonidine is due to a highly selective action in the rostral ventrolateral medulla, which leads to a reduction in overactivity of the sympathetic nervous system.

Slide 2Moxonidine (4-chloro-N-(imidazolidine-2-ylidene)-6-methoxy-2-methyl-5-pyrimidinamine) is a centrally acting antihypertensive drug.

The blood pressure-lowering effect of moxonidine is due to a highly selective action in the rostral ventrolateral medulla, which leads to a reduction in overactivity of the sympathetic nervous system.

Slide 2Moxonidine (4-chloro-N-(imidazolidine-2-ylidene)-6-methoxy-2-methyl-5-pyrimidinamine) is a centrally acting antihypertensive drug.

The blood pressure-lowering effect of moxonidine is due to a highly selective action in the rostral ventrolateral medulla, which leads to a reduction in overactivity of the sympathetic nervous system.

Slide 2Moxonidine (4-chloro-N-(imidazolidine-2-ylidene)-6-methoxy-2-methyl-5-pyrimidinamine) is a centrally acting antihypertensive drug.

The blood pressure-lowering effect of moxonidine is due to a highly selective action in the rostral ventrolateral medulla, which leads to a reduction in overactivity of the sympathetic nervous system.

Slide 2Moxonidine (4-chloro-N-(imidazolidine-2-ylidene)-6-methoxy-2-methyl-5-pyrimidinamine) is a centrally acting antihypertensive drug.

The blood pressure-lowering effect of moxonidine is due to a highly selective action in the rostral ventrolateral medulla, which leads to a reduction in overactivity of the sympathetic nervous system.

Slide 2Moxonidine (4-chloro-N-(imidazolidine-2-ylidene)-6-methoxy-2-methyl-5-pyrimidinamine) is a centrally acting antihypertensive drug.

The blood pressure-lowering effect of moxonidine is due to a highly selective action in the rostral ventrolateral medulla, which leads to a reduction in overactivity of the sympathetic nervous system.

Slide 2Moxonidine (4-chloro-N-(imidazolidine-2-ylidene)-6-methoxy-2-methyl-5-pyrimidinamine) is a centrally acting antihypertensive drug.

The blood pressure-lowering effect of moxonidine is due to a highly selective action in the rostral ventrolateral medulla, which leads to a reduction in overactivity of the sympathetic nervous system.

Slide 2Moxonidine (4-chloro-N-(imidazolidine-2-ylidene)-6-methoxy-2-methyl-5-pyrimidinamine) is a centrally acting antihypertensive drug.

The blood pressure-lowering effect of moxonidine is due to a highly selective action in the rostral ventrolateral medulla, which leads to a reduction in overactivity of the sympathetic nervous system.

Slide 2Moxonidine (4-chloro-N-(imidazolidine-2-ylidene)-6-methoxy-2-methyl-5-pyrimidinamine) is a centrally acting antihypertensive drug.

The blood pressure-lowering effect of moxonidine is due to a highly selective action in the rostral ventrolateral medulla, which leads to a reduction in overactivity of the sympathetic nervous system.

Slide 2Moxonidine (4-chloro-N-(imidazolidine-2-ylidene)-6-methoxy-2-methyl-5-pyrimidinamine) is a centrally acting antihypertensive drug.

The blood pressure-lowering effect of moxonidine is due to a highly selective action in the rostral ventrolateral medulla, which leads to a reduction in overactivity of the sympathetic nervous system.

Slide 2Moxonidine (4-chloro-N-(imidazolidine-2-ylidene)-6-methoxy-2-methyl-5-pyrimidinamine) is a centrally acting antihypertensive drug.

The blood pressure-lowering effect of moxonidine is due to a highly selective action in the rostral ventrolateral medulla, which leads to a reduction in overactivity of the sympathetic nervous system.

Slide 2Moxonidine (4-chloro-N-(imidazolidine-2-ylidene)-6-methoxy-2-methyl-5-pyrimidinamine) is a centrally acting antihypertensive drug.

The blood pressure-lowering effect of moxonidine is due to a highly selective action in the rostral ventrolateral medulla, which leads to a reduction in overactivity of the sympathetic nervous system.

Slide 2Moxonidine (4-chloro-N-(imidazolidine-2-ylidene)-6-methoxy-2-methyl-5-pyrimidinamine) is a centrally acting antihypertensive drug.

The blood pressure-lowering effect of moxonidine is due to a highly selective action in the rostral ventrolateral medulla, which leads to a reduction in overactivity of the sympathetic nervous system.

Slide 2Moxonidine (4-chloro-N-(imidazolidine-2-ylidene)-6-methoxy-2-methyl-5-pyrimidinamine) is a centrally acting antihypertensive drug.

The blood pressure-lowering effect of moxonidine is due to a highly selective action in the rostral ventrolateral medulla, which leads to a reduction in overactivity of the sympathetic nervous system.

Slide 2Moxonidine (4-chloro-N-(imidazolidine-2-ylidene)-6-methoxy-2-methyl-5-pyrimidinamine) is a centrally acting antihypertensive drug.

The blood pressure-lowering effect of moxonidine is due to a highly selective action in the rostral ventrolateral medulla, which leads to a reduction in overactivity of the sympathetic nervous system.

Slide 2Moxonidine (4-chloro-N-(imidazolidine-2-ylidene)-6-methoxy-2-methyl-5-pyrimidinamine) is a centrally acting antihypertensive drug.

The blood pressure-lowering effect of moxonidine is due to a highly selective action in the rostral ventrolateral medulla, which leads to a reduction in overactivity of the sympathetic nervous system.

Slide 2Moxonidine (4-chloro-N-(imidazolidine-2-ylidene)-6-methoxy-2-methyl-5-pyrimidinamine) is a centrally acting antihypertensive drug.

The blood pressure-lowering effect of moxonidine is due to a highly selective action in the rostral ventrolateral medulla, which leads to a reduction in overactivity of the sympathetic nervous system.

Slide 2Moxonidine (4-chloro-N-(imidazolidine-2-ylidene)-6-methoxy-2-methyl-5-pyrimidinamine) is a centrally acting antihypertensive drug.

The blood pressure-lowering effect of moxonidine is due to a highly selective action in the rostral ventrolateral medulla, which leads to a reduction in overactivity of the sympathetic nervous system.

Slide 2Moxonidine (4-chloro-N-(imidazolidine-2-ylidene)-6-methoxy-2-methyl-5-pyrimidinamine) is a centrally acting antihypertensive drug.

The blood pressure-lowering effect of moxonidine is due to a highly selective action in the rostral ventrolateral medulla, which leads to a reduction in overactivity of the sympathetic nervous system.

Slide 2Moxonidine (4-chloro-N-(imidazolidine-2-ylidene)-6-methoxy-2-methyl-5-pyrimidinamine) is a centrally acting antihypertensive drug.

The blood pressure-lowering effect of moxonidine is due to a highly selective action in the rostral ventrolateral medulla, which leads to a reduction in overactivity of the sympathetic nervous system.

Slide 2Moxonidine (4-chloro-N-(imidazolidine-2-ylidene)-6-methoxy-2-methyl-5-pyrimidinamine) is a centrally acting antihypertensive drug.

The blood pressure-lowering effect of moxonidine is due to a highly selective action in the rostral ventrolateral medulla, which leads to a reduction in overactivity of the sympathetic nervous system.

Slide 2Moxonidine (4-chloro-N-(imidazolidine-2-ylidene)-6-methoxy-2-methyl-5-pyrimidinamine) is a centrally acting antihypertensive drug.

The blood pressure-lowering effect of moxonidine is due to a highly selective action in the rostral ventrolateral medulla, which leads to a reduction in overactivity of the sympathetic nervous system.

Slide 2Moxonidine (4-chloro-N-(imidazolidine-2-ylidene)-6-methoxy-2-methyl-5-pyrimidinamine) is a centrally acting antihypertensive drug.

The blood pressure-lowering effect of moxonidine is due to a highly selective action in the rostral ventrolateral medulla, which leads to a reduction in overactivity of the sympathetic nervous system.

Slide 2Moxonidine (4-chloro-N-(imidazolidine-2-ylidene)-6-methoxy-2-methyl-5-pyrimidinamine) is a centrally acting antihypertensive drug.

The blood pressure-lowering effect of moxonidine is due to a highly selective action in the rostral ventrolateral medulla, which leads to a reduction in overactivity of the sympathetic nervous system.

Slide 2Moxonidine (4-chloro-N-(imidazolidine-2-ylidene)-6-methoxy-2-methyl-5-pyrimidinamine) is a centrally acting antihypertensive drug.

The blood pressure-lowering effect of moxonidine is due to a highly selective action in the rostral ventrolateral medulla, which leads to a reduction in overactivity of the sympathetic nervous system.

Slide 2Moxonidine (4-chloro-N-(imidazolidine-2-ylidene)-6-methoxy-2-methyl-5-pyrimidinamine) is a centrally acting antihypertensive drug.

The blood pressure-lowering effect of moxonidine is due to a highly selective action in the rostral ventrolateral medulla, which leads to a reduction in overactivity of the sympathetic nervous system.