This document summarizes the physiology of excretion and kidney functions. It describes the mechanisms of urine formation including filtration, reabsorption, and secretion. It explains the structure and types of nephrons, and how countercurrent mechanisms concentrate urine. Key kidney functions are excretion of waste, homeostasis maintenance through regulating electrolytes and fluid balance, and endocrine roles like producing renin and vitamin D. The kidneys play an important role in osmoregulation by regulating water reabsorption and antidiuretic hormone levels in response to changes in plasma osmotic pressure.

1. PHYSIOLOGY OF
EXCRETION. KIDNEY
FUNCTIONS. MECHANISMS
OF URINE FORMATION.

2. lungs
Skin-
sweat
glands
liver
Organs &
tissues
kidney
GIT
blood
Excretory system
lungs - СО2, Н2О
vapour, ethers,
chlorophorm
Sweat glands- Н2О,
salts, urea, uric acid,
creatinin.
Liver – bile
pigments, products
of haemoglobin
break down
GIT - Н2О, salts
Kidney is the main
organ of excretion

3. EXCRETORY SYSTEM

4. KIDNEY

5. NEPHRON

6. Different types of nephrones
Cortical
Jucstar-medullar

7. TYPES OF NEPHRONS
Cortical – main nephrons allowing urine
formation (60-70%).
Jucstar-medullar – have long Henle loops,
enable urine concentration. (10-20%)
Superficial – have short Henle loops, play the
role of shunts (20-30%)

8. MECHANISMS OFMECHANISMS OF
URINE FORMATIONURINE FORMATION
FILTRATION
REABSORPTION
SECRETION

9. Obligatory
REABSORPTION
Facultative
REABSORPTION
Regulated
water
reabsorp-
tionfiltration
Counter-
current system

10. MECHANISM OFMECHANISM OF
GLOMERULAGLOMERULA
FILTRATIONFILTRATION

11. GLOMERULA FILTER

12. GLOMERULA FILTER
1 –capillary endothelium
2 – basal membrane
3 – podocyte
4- pores in the endothelium
5 – fissura in podocyte
membrane

13. Glomerular diuresis -
filtration
h
y
d
r
o

14. F = Р h. – Р оn. – Р f.=
70-30-20=20 mm Hg
І Blood hydrostatic pressure (Р h.) -70
mm Hg
ІІ Blood oncotic pressure (Р оn.) - 30 mm
Hg
ІІІ Ultrafiltrate hydrostatic pressure (Р f.)
- 20 mm Hg

15. Factors influencing filtration
pressure
Increase in
hydrostatic
pressure
Increase in
hydrostatic
pressure
Decrease in
oncotic
pressure
Increase in
oncotic
pressure

16. Factors determining high
hydrostatic pressure in glomerulus
Short renal artery starts right from the
abdomenal aortha
Vas afferens is twice wider than vas
efferens

17. OBLIGATORY
REABSORPTION

18. PCT epithelium structure

19. OBLIGATORYOBLIGATORY
REABSORPTIONREABSORPTION
Na+
, K+
, Ca+2
, Mg +2
, Cl--
,
SO4
2--
, HPO4
2--
, HCO3
--
,
vitamins - diffusion
Amino acids, glucose –
secondary active
transport
urea, uric acid – diffusion
H2O - оsmosis
2/3 of filtrated
urine is
reabsorped

20. SECONDARY ACTIVE
TRANSPORT
АТФ
К+
Na+
Na+
Glucose
Apical membrane
Basilar membrane

21. Urea role in urine concentration
Reabsorption – 1/3 of
filtered urea is
reabsorped in PCT; it
increases Рosm.of
parenchime & helps to
reabsorb water in DCT.
secretion
Urea
Uric acid

22. Regulation of obligatory
reabsorption
Sympathetic nervous system,
cateholamines, glucocorticoids
Intracellular messengers
Metabolism in epithelial cells (energy formed)
Substances transport

23. FACULTATIVE
REABSORPTION

24. Facultative reabsorptionFacultative reabsorption
• Sodium, chlorine – is
regulated by aldosterone &
natriuretic peptide;
• Calcium - is regulated by
parathormone, calcitonin &
Vit D3 .
Regulated reabsorption of
water under the influence of
ADH (vasopressin)

25. Aldosterone diuresis influence
Adrenal glands
Sodium decrease
aldosterone
Collecting duct
DCT

26. REGULATION OF SODIUM
REABSORPTION
Aldosteron
increases
Natriuretic
peptide
inhibits

27. Regulation of calcium reabsorption
Parathormone,
Vit D3
increases
Calcitonin
inhibits

28. АDH effect on water reabsorption in
the collecting ducts
Basilar
membrane
Apical membrane
V2receptor
GS-protein,
Gyanile
nucleotide
adenylatecyclase
АDH
c-АМP
PROTEINKINAZE
Proteins phosphorilation
Н2О
Н2О

29. Secretion –Secretion – substances transportsubstances transport
from blood to urinefrom blood to urine
urea, weak acids & bases,
ammonium, ammonia
(diffusion)
Organic acids & bases,
penicilinum (active
transport)
Sodium, potassium, аmonia,
urea

30. Counter-current system

31. Types of epithelium in canaliculli

32. Counter-current system mechanism
Н2О
Н2О
Н2О
Na
Na
Роsm
Роsm

34. SCHEME OF PROCESSES IN FINAL URINESCHEME OF PROCESSES IN FINAL URINE
FORMATIONFORMATION
FILTRATION
REABSORPTION
SECRETION
EXTRUSION
WITH FINAL
URINE

35. Filtration Reabsorption Secretion Filtration&
reabsorption
Filtration&
Secretion
inulin Glucose
(normally)
K Urea, glucose in
hyperglucemia
Diodrast

36. Non-threshold substances
Non-threshhold
substances – are
substances which are
excreted with final
urine regardless of
their concentration in
blood

37. Velocity of glomerular filtration -Velocity of glomerular filtration -
clearensclearens
Velocity of glomerular filtration (Velocity of glomerular filtration (clearens)clearens) is a
volume of blood plasma which was filtrated
via kidney in certain time.
Filtrometric substances are used toFiltrometric substances are used to
define clearensdefine clearens (инулин, креатинин), they
are non-threshold substances which are
neither secreted nor reabsorped
In man – 125 ml/min
In woman -110 ml/min

38. CLEARENS DETERMINATION
Рcr. х F = Ucr. х VРcr. х F = Ucr. х V
Рcr.Рcr. Creatinin concentration in blood plasma;
U cr.U cr. Creatinin concentration in final urine;
FF –volume of primary urine;
VV- volume of final urine.
Ucr. х VUcr. х V
Рcr.Рcr.
F=F=

39. Threshold UBSTANCES
Threshold
SUBSTANCES – are
substances which
have threshold of
elimination & are
excreted with final
urine only if their
concentration in blood
is above threshold

40. KIDNEY FUNCTIONS
CONNECTED WITH
URINE FORMATION

41. EXCRETION OF:
End products of metabolism (urea, uric
acid, creatinin)
Pigments which are formed at haemoglobin
breakdown (urobilin, urochrome)
Metabolites of hormones & other
biologically active substances
Drugs & substances which enter with food

42. HOMEOSTASIS MAINTENANCE
due to excretion of threshold
substances
Ionic content of blood(Na, Cl, K, SO4,)
Osmotic pressure (Na & H2O)
Q (volume of blood in circulation) & BP
(due to regulation of water excretion)
Glucose & amino acids level
Blood pH regulation (due to regulation of
H+
, bicarbonate, sulfate, phosphate anions
excretion)

43. KIDNEY FUNCTIONS
NOT CONNECTED WITH
URINE FORMATION

44. ENDOCRINE FUNCTION:
Renin-angiotensine-aldosterone system
Vit D3
Erithropoetins
Anticoagulating system factors (urokinase,
heparine,antithrombines)
Prostaglandines (A2, E2)
Kinins (bradikinin, kallikrein)

46. METABOLIC
Protein metabolism (fermentative
hydrolysis of proteins with amino acids
formation and their release into the blood
stream)
Carbohydrates metabolism (glucose
reabsorption & gluconeogenesis)
Lipids metabolism (tryacilglicerides
&phospholipids formation)

47. KIDNEY IN
HOMEOSTASIS
MAINTENANSE

48. Salt-water balance regulation
Isotonic solution,
food
intestines
v. portae
liver
Physiological swelling
(up to 30%) Hepatic
osmoreceptors
hypotalamus
АDH
Н2О reabsorption
diuresisQ

49. Kidney in osmotic pressure regulation
Decrease in
ADH
secretion
Increase in
ADH
secretion
Increased
water
reabsorption
in kidney
decreased
water
reabsorption
in kidney Decrease in
plasma
osmotic
pressure
Decrease
in plasma
osmotic
pressure

50. Osmotic pressure regulation
Роsm
blood
Hypothalamus
osmoreceptors
SO &
PV nn.
Posterial
pituitary
АDH
Н2О reabsorption
diuresis
Q
Роsm
Adrenal glands
aldosterone
Na+
reabsorption

51. OSMOTIC PRESSURE REGULATION
РOSM
Hypothalamus
osmoreceptors
SO &
PV nn
Posterior pituitary
АDH
Н2О reabsorption
diuresis
Роsm
Nauretic hormone
выделение Na+

52. Q REGULATION
Q
threshold
350 ml
BP
Volume receptors
of hypothalamus
Volume receptors
of atrium
АDH
SO &
PV nn.
Н2О reabsorption
diuresis
Q

53. BP
UGА
renin
angiotensin
Adrenal glands
aldosterone
Na+
reabsorption
Н2О
reabsorption
Q
Рosm
=
EFP filtration
diuresis

54. Q REGULATION
Q
Volume receptors
of hypothalamus
АDH
Н2О reabsorption
diureisRight atrium
Na-uretic hormone
Na+
excretion
Q