URINARY SYSTEM.
KIDNEY (KD).
1. KD is composed of : a) connective tissue capsule, b) CORTEX, c) MEDULLA (in centre).
2.
Cortex is composed of NEPHRONS - it are structural and functional
units of KD.
3.
NEPHRON is composed of: 1) renal corpuscle, 2) system of tubules. Renal corpuscle is composed of: a) glomerulus, b) Bowmans capsule.
Glomerulus is composed of 40
fenestrated capillaries.
Bowmans
capsule is composed of : parietal layer, .
visceral layer, urinary space between 2 layers.
Visceral layer is composed of PODOCYTES.
Podocyte- is irregular-shaped
epithelial cell with
long primary
process, which branches on short
pedicels (secondary processes).
Tri-layered
basal lamina locates between fenestrated capillary and podocytes and contains lamina densa. Lamina densa is composed of mashwork from collagen fibrills. Diameter of openings =4 nm.
Filtration barrier is composed of: 1) fenestrated endothelial cell of glomerulus, 2) tri-layered basal lamina, 3) filtration SLITS between pedicels of PODOCYTE.
1st phase of urine production – is
ultrafiltration. It happens from glomerular capillaries
through filtration barrier into urinary space. 5 substancies are filtered and pass to proximal and distal tubules. That are:1) 150 liters of H2O per day, 2) LOW molecular blood proteins and amino acids, 3)glucose, 4) Na+ ions, 5) urea. This mixture is PRIMARY urine. In proximal and distal nephron tubules primary urine undergoes to
2nd phase of urine production – it is
reabsorption (RA).. It happens from lumen of tubules through
epithelial cell into
secondary peritubular capillaries. Wall of
proximal tubules is composed of simple cuboidal epith. 1cell has abundance of
4 organells, that fulfil
RA :1) apical
microvilli (for RA of glucose), 2) basal
folds (for RA of H2O), 3)
mitochondria -for RA of Na ions, 4)
lysosomes/pinocytotic vesicles (for RA of proteins). After proximal tubules proteins and glucose disappear
completely. Wall of
distal tubules is composed of simple cuboidal epith. 1cell has abundance of
ONLY 2 organells, that fulfil
RA : 1) basal
folds (RA of H2O), 2)
mitochondria ( RA of Na ions).
Wall of
collecting tubule is composed of simple columnar/cuboidal epith. Cells are classified on:
1) Principal (pale) cell . Funct.: a) after
ADH stimulation it reabsorbs
H2O, b) secrets
prostaglandins in blood. 2) Intercalated cells. A lot of mitochondria. Funct.:Secretion of
H+ ions into urine. It is
3rd phase of urine production —
secretory phase.
After collecting tubules fluid becomes
secondary urine. It contains only
3 subst.(after filtration of
5 subst.): a) H2O (1.5-2.0 L/day), b) toxic UREA, c) Na+ ions. It is released from the body.
RENIN apparatus: 1) JUXTAGLOMERULAR cells. It are :a) locate in tunica
media of
afferent arteriole, b) tissue type-are modified smooth
muscle cells with secretory
granules, c) Funct.:
secretion of enzyme
RENIN in blood, 2) MACULA DENSA cells. It are: a) locate in wall of
distal tubules, b) tissue type-is TALL, NARROW COLUMNAR
epithelial cells, nuclei are
near to each other, c) basement membrane is
absent, d) Funct.: it are
Na+ receptors.
URETER
Wall is composed of 4 TUNICS: 1)
folded T. MUCOSA, 2) T. SUBMUCOSA (L.I.C.T.), 3) MUSCULARIS externa, 4) T.adventitia(L.I.C.T). T. mucosa is composed of: a)
TRANSITIONAL epith., b) lamina propria (L.I.C.T). Muscularis externa (
smooth muscle tiss.) has a) in UPPER one half
2 layers (inner –longitud., outer –circular), b) in LOWER one half
3 layers (outer and inner -are longitud., middle- circular).
URINARY BLADDER
Wall is composed of 4 TUNICS: 1)
folded (excepting trigone) T. MUCOSA, 2) T. SUBMUCOSA (L.I.C.T.), 3) MUSCULARIS externa, 4) T.adventitia(L.I.C.T). T. mucosa is composed of: a)
TRANSITIONAL epith., b) lamina propria (L.I.C.T ). Muscularis externa (
smooth muscle tiss.) has
3 layers (outer and inner -are longitud., middle- circular). Pecularities of
trigone: a) T.mucosa is smooth,
NOT folded, b) T. submucosa is
absent.
Составитель – доцент В.В. Бондаренко.