P H Y S I O L O G Y

The urinary system

Miloslav Hronek

The parts of the

urinary system (excluding the urethra) and some associated

structures.(Waugh, Anne . Ross and Wilson

Anatomy and Physiology in Health and

Illness, 11th Edition. Churchill

Livingstone, 062010. p. 330).

A longitudinal

section of the right

kidney.(Waugh, Anne . Ross and Wilson Anatomy

and Physiology in Health and Illness, 11th

Edition. Churchill Livingstone, 062010. p.

331).

A nephron and

associated blood

vessels.(Waugh, Anne . Ross and Wilson

Anatomy and Physiology in Health

and Illness, 11th Edition. Churchill

Livingstone, 062010. p. 332).

16 % 4 %

Elimination of waste productsElimination organs: lungs, skin, GIT, kidneys

Prime function of kidneys

regulation of composition and volume of blood excretion of wastes and water

removing of hydrogenium (regulation of pH)

regulation blood pressure by juxtaglomerular apparatus

macula densa (monitor salt)

juxtaglomerular cells in the wall of the afferent arteriole (secretion renin)

metabolism gluconeogenesis (synthesis of new glucose molecules from

aminoacids AA glu)

synthesis of calcitriol (vitamine D)

secretion of erythropoetin

Kidney1. Nephrons

control blood concentration

and volume (remove water and

volume) .

removing of toxic wastes

dissolved in plasma from blood

ultrafiltration

2. Other parts

passageways and storage

areas

renal tubule

reabsorption and secretion

Nephron

performs 3 processes

The glomerulus and

glomerular capsule.(Waugh, Anne . Ross and Wilson Anatomy and

Physiology in Health and Illness, 11th

Edition. Churchill Livingstone, 062010. p.

334).

Glomerulus

GLOMERULUS

Filtration function, formation of primary urine

Description membrane of glomerulus

endothelium (fenestrations - 50 - 100 nm)

restricts passage of blood cells

basement membrane

fibrils in glycoprotein matrix

restricts passage of larger proteins

podocytes

specialized epithelial cells with pedicels

spaces filtration slits - restricts passage of medium sized proteins

Glomerular filtration

separation of large and small particles (to mol. weight 68 000)

filtration process

cardiac output 5 l/min perfusion of kidney 1200 ml/min -glomerular filtration rate (125 ml/min flow into tubules)

regulation of GFR: renal autoregulation by blood pressure (renin)

neural regulation sympathetic stimulation (aff. and eff. arterioles constrict)

hormonal regulation atrial natriuretic peptide (when increase blood volume - promote excretion of

water and sodium)

angiotensin (vasoconstrictor, aldosteron - reabsorption of Na+, thirst, ADH, BP)

Negative feedback

regulation of secretion of

atrial natriuretic peptide

(ANP).(Waugh, Anne . Ross and Wilson Anatomy and

Physiology in Health and Illness, 11th Edition.

Churchill Livingstone, 062010. p. 336).

Net filtration pressure

Constituents of glomerular filtrate and glomerular capillaries(Waugh, Anne . Ross and Wilson Anatomy and Physiology in Health and Illness, 11th Edition. Churchill Livingstone, 062010. p. 334).

The juxtaglomerular Apparatus

Angiotensin-converting enzyme

Renal corpuscle

Proximal convoluted tubule

Distal convuluted tubule

Distal tubule and collecting duct

Intercalated cells in late distal

tubule and collecting duct

Tubular reabsorption

(returns nutrients to the body)

a)Water

reabsorption of 99 % (170 l/day, reabsorption of 168.5 l/day, 1.5 l/day to urine)

under control of ADH

b)Glucose

glycosuria (1800 mg/l in the urine)

c)Na+

reabsorption 7/8 of NaCl in proximal tubules

reabsorption 1/8 of NaCl in the loops of Henle and distal tubules under control of aldosteron

d)Urea from Krebs urea cycle (de-amination), excretion 20

g/day

e)Uric acid excretion 20 mg/l, 2 g/day

f) Creatinine from muscle

Other hormones - influence selective

reabsorption

parathyroid hormone

comes from the parathyroid glands

regulates the reabsorption of calcium and phosphate from the

distal collecting tubules increase of calcium level in the plasma.

antidiuretic hormone

secreted by the posterior lobe of the pituitary gland

increases the permeability of the distal convoluted tubules

and collecting tubules,

increasing water reabsorption.

Negative feedback

regulation of secretion of

antidiuretic hormone

(ADH).(Waugh, Anne . Ross and Wilson Anatomy and Physiology

in Health and Illness, 11th Edition. Churchill Livingstone,

062010. p. 335).

Negative feedback regulation of

aldosterone secretion. ACE = angiotensin-converting enzyme.(Waugh, Anne . Ross and Wilson Anatomy and Physiology in Health

and Illness, 11th Edition. Churchill Livingstone, 062010. p. 336).

Tubular secretion

secretion of K+, H+, NH4+

excretion of drugs (penicilin, diuretics)

Summary of the

three processes

that form urine.(Waugh, Anne . Ross and Wilson

Anatomy and Physiology in Health

and Illness, 11th Edition. Churchill

Livingstone, 062010. p. 336).

Section of the

bladder showing

the trigone.(Waugh, Anne . Ross and Wilson

Anatomy and Physiology in Health

and Illness, 11th Edition. Churchill

Livingstone, 062010. p. 341).

Urine bladder

capacity (700 - 800 ml)

Micturition (urination)

when UB exceeds 200 400 ml stretch

receptor transmit sensory impulses to the spinal

cord sensory tract to cortex conscious desire

to expel urine urination reflex parasympathetic fibers conduct motor impulses to the

urinary bladder wall and urethral sphincter

nerve impulses from cerebral cortex inhibit to the external

urethral sphincter

Control of micturition after

bladder control is established.(Waugh, Anne . Ross and Wilson Anatomy and

Physiology in Health and Illness, 11th Edition.

Churchill Livingstone, 062010. p. 342).

Evaluation of kidney function

Blood urea nitrogen test

measure the nitrogen in blood (urea)

GFR - blood urea nitrogen

Measurement of plasma creatinine

creatinine end product of catabolism of creatinine

phosphate in skeletal muscle

poor renal function

creatinine level rises above 15 mg/l

Renal plasma clearance (RPC)

expresses how effectively the kidneys remove a substance from blood plasma

low RPC indicates a low rate of excretion in the urine

RPC = U*V/P (ml/min)

U (concentration of the substance in urine)

V (volume of urine)

P (concentration of the substance in plasma, in mg/ml)

Creatinine clearance = 140 ml/min

Clearance of inuline = 125 ml/min

Renal plasma flow

substance para-aminohippuric acid

clearance of PAH = 600 ml/min

Thank you for attention.