Fisiology Renal System

LELI MULYATI,SKp,M.Kep.Sp.MB

Renal system summary

Functions:1. Remove wastes from the body (urine)2. Regulates fluid balance, maintains

homeostasis

Structures: 2 kidneys - filter blood, produce urine 2 ureters - transport urine (kidneys to

bladder) bladder - reservoir for urine urethra - transport of urine

FUNGSI GINJAL Kidneys carry out four functions

Filter nitrogenous wastes, toxins, ions, etc. from blood to be excreted as urine.

Regulate volume and chemical composition of blood (water, salts, acids, bases).

Produce regulatory enzymes.Renin – regulates BP/ kidney function Erthropoeitin – stimulates RBC production from marrow.

Metabolism of Vitamin D to active form.

Vascular component of nephronMade up of blood vessels:

1. Glomerulus - network of capillaries within Bowman’s capsule

2. Afferent arteriole - leading into glomerulus

3. Efferent arteriole - leading out of glomerulus

4. Peritubular capillaries - surrounding tubules

5. Vasa recta - specialised loops of blood vessels around long Loop of Henle (juxtamedullary nephrons)

Blood supply to the kidney:

Renal arteries from abdominal aorta enter hilum and branch:

1. Interlobar arteries - pass through renal columns and reach junction between medulla and cortex

2. Arcuate arteries run parallel with the base of the pyramids

3. Interlobular arteries move up into the cortex and branch to form the afferent arteriole

The peritubular capillaries unite to form the interlobular veins, arcuate vein, interlobar vein, renal vein

The renal vein exits at hilus and joins the IVC

Nephrons: 85% are cortical, 15% are juxtamedullary

Renal corpuscle

III. Renal CorpuscleSecondary processes interdigitate around

glomerular capillaries. The narrow space between processes is the filtration slit. 19-5

Glomerular FiltrationGlomerular Filtration

afferent arteriole

glomerulus

efferent

arteriole

Bowman’s capsule

Filters blood; proteins can’t pass through

Proximal Convoluted Tubule

Reabsorbs: water, glucose, Reabsorbs: water, glucose, amino acids, and sodium.amino acids, and sodium.

•65% of Na+ is reabsorbed•65% of H2O is reabsorbed•90% of filtered bicarbonate

(HCO3-)

•50% of Cl- and K+

Loop of Henle

Creates a gradient of increasing Creates a gradient of increasing sodium ion concentration towards sodium ion concentration towards the end of the loop within the the end of the loop within the interstitial fluid of the renal pyramid.interstitial fluid of the renal pyramid.

•25% Na+ is reabsorbed in the loop

•15% water is reabsorbed in the loop

•40% K is reabsorbed in the loop

Distal Convoluted Tubule

Under the influence of the hormone Under the influence of the hormone aldosterone, reabsorbs sodium and aldosterone, reabsorbs sodium and secretes potassium. Also regulates secretes potassium. Also regulates pH by secreting hydrogen ion when pH by secreting hydrogen ion when pH of the plasma is low.pH of the plasma is low.

• only 10% of the filtered NaCl and 20% of water remains

Collecting Duct

Allows for the osmotic Allows for the osmotic reabsorption of water.reabsorption of water.

ADH (antidiuretic hormone)- makes collecting ducts more permeable to water-- produce concentrated urine

From the original 1800 g NaCl, only 10 g appears in the urine

Urine

Water- 95%Nitrogenous waste:

• urea• uric acid• creatinine

Ions:• sodium• potassium• sulfate• phosphate

vein

artery

afferent

arteriole

efferent arteriol

e

glomerulus

peritubular

capillaries

Bowman’s capsule

proximal convoluted tubuledistal convoluted tubule

loop of

Henle

collecting duct

Regulation of Water BalanceRegulation of Water Balance

Brain monitors water content of bloodBrain monitors water content of blood

If low water content, pituitary releases ADHIf low water content, pituitary releases ADH

ADH travels in blood to nephronADH travels in blood to nephron

ADH causes more water to move from urine back ADH causes more water to move from urine back into bloodinto blood

Ureters Pyelogram (colour-enhanced)

tubes that transport urine from renal pelvis to bladder

20-30 cm long

muscular walls - peristaltic waves force urine down to bladder

retroperitoneal

pressure in the bladder compresses ureter, helps prevent backflow of urine

(physiological valve) - still allows urine to flow into the bladder

Bladder

hollow muscular organ retroperitoneal, posterior

to pubic symphysis

Capacity ~ 300-400 ml (max = 1000 ml)

empty: looks like a deflated balloon, rugae

full spherical rises above abdominal cavity

Males: anterior to rectum, above prostate

Females: inferior to uterus, anterior to vagina

Martini p983

Support of bladder Martini p983

superior surfaces - peritoneum

middle umbilical ligament - superior border to umbilicus

lateral umbilical ligaments - sides of bladder to umbilicus

At base, tough ligamentous bands anchor bladder to pelvic and pubic bones

Trigone : triangular area bounded by openings of ureters and exit to urethra

cystitis - inflammation of the bladder wall

Urethra Martini p983

Female ~ 4cm long opens to exterior between

clitoris and vaginal opening

Male ~ 20 cm long passes through prostate

gland

pierces urogenital diaphragm

enters penis and extends throughout length

opens at urethral orifice

Micturition reflex:Stretch receptors stimulated when filled to

~ 200 ml afferent fibres to spinal cord motor neurons to sm in bladder wall contracts m. detrusor and increases

pressure

need to relax both internal and external sphincter - external under voluntary control

if external sphincter does not relax, internal sphincter remains closed & sm in bladder wall relaxes again

Once volume exceeds 500 ml, micturition reflex may generate enough P to open internal sphincter

leads to reflexive relaxation of external sphincter