Post on 25-Aug-2020
ANATOMIA FUNZIONALE DEL RENE
UNITA’ FUNZIONALE DEL RENE: il nefrone
ANATOMIA FUNZIONALE DEL RENE
IL CORPUSCOLO RENALE: CAPSULA DEL BOWMAN
APPARATO JUXTAGLOMERULARE
MECCANISMI IMPLICATI NELLA FORMAZIONE DI URINA
MECCANISMI IMPLICATI NELLA FORMAZIONE DI URINA: FILTRAZIONE GLOMERULARE
SCAMBI CAPILLARI
DINAMICA DELLA FILTRAZIONE GLOMERULARE
Pg=45mmHg Pc=10mmHg πG=25mmHg πC=0
Pressione netta (Puf)=10mmHg
Feedback tubuloglomerulare
RIASSORBIMENTO di glucosio e amminoacidi
RIASSORBIMENTO di glucosio: a tubulare massimo
RIASSORBIMENTO PASSIVO DI SOLUTI
RIASSORBIMENTO PASSIVO DI UREA
CLEARANCE RENALE
CLEARANCE RENALE
Figure 20-6, steps 1–4
Collecting duct cell
Second messenger signal
Collecting duct
lumen
Medullary interstitial
fluid Vasa recta
Filtrate 300 mOsM
cAMP
Exocytosis of vesicles
Vasopressin receptor
700 mOsM 600 mOsM
Aquaporin-2 water pores
600 mOsM
Cross section of kidney tubule
Vasopressin
Vasopressin binds to membrane receptor.
Receptor activates cAMP second messenger system.
Water is absorbed by osmosis into the blood.
Storage vesicles Cell inserts AQP2 water pores into apical membrane.
H2O H2O
H2O
H2O
1
2
3
4 1
2
3
4
Figure 20-12, steps 1–5
New channels
P cell of distal nephron
Translation and protein synthesis
Proteins modulate existing channels and pumps
New pumps
K+
Na+
K+ secreted
Na+ reabsorbed
Lumen of distal tubule
Interstitial fluid Blood
Aldosterone Aldosterone
receptor
K+
Na+
Na+
Aldosterone combines with a cytoplasmic receptor.
Hormone-receptor complex initiates transcription in the nucleus.
New protein channels and pumps are made.
Aldosterone-induced proteins modify existing proteins.
Result is increased Na+ reabsorption and K+ secretion.
K+
ATP
ATP
1
2
3
4
5
1 2 3
4
5
Sistema renina-angiotensina-aldosterone
Urine Concentration
Figure 20-4, steps 1–4
50–1200 mOsM urine excreted
300 mOsM 300 mOsM
600 mOsM
900 mOsM
1200 mOsM 1200
300 100
Distal tubule
Proximal tubule
Loop of
Henle
CORTEX MEDULLA
Permeability to water and solutes is regulated by hormones.
Variable reabsorption of water and solutes
Ions reabsorbed but no water Only water
reabsorbed
Isosmotic fluid leaving the proximal tubule becomes progressively more concentrated in the descending limb.
Removal of solute in the thick ascending limb creates hyposmotic fluid.
Hormones control distal nephron permeability to water and solutes.
Urine osmolarity depends on reabsorption in the collecting duct.
1
2 3
4
1
2
3
4
Collecting duct
Figure 20-5a
Water Reabsorption
Figure 20-5b
MECCANISMO di moltiplicazione CONTROCORRENTE
RUOLO DEI VASA RECTA (SCAMBIATORI CONTROCORRENTE)
REGOLAZIONE DELLA PRODUZIONE DI ADH
Figure 19-18b, steps 1–3
Stretch receptors fire.
Parasympathetic neurons fire. Motor neurons stop firing.
Smooth muscle contracts. Internal sphincter passively pulled open. External sphincter relaxes.
(b) Micturition
Internal sphincter External sphincter
Tonic discharge inhibited
Higher CNS input may facilitate or
inhibit reflex Sensory neuron
Parasympathetic neuron
Motor neuron
Stretch receptors
1
2
3
1 2
3
2 3
MINZIONE
MECCANISMO RENALE DI RIASSORBIMENTO DEL BICARBONATO