1-Renal Physiology 1 (Renal Functions & Basic Concepts).ppt

Pharmacy
kidney disease
Renal pysiology

1. (Renal Physiology 1)(Renal Physiology 1)
Renal Functions and Basic ConceptsRenal Functions and Basic Concepts
Dr Ahmad Ahmeda
[email protected]
Cell phone: [phone]
We drip, drip, drip, all day and all night, three to four
times more by day than by night, drip from the kidneys
into the silent pool of the bladder, an underground
dripping into an underground lake.
(Gustav Eckstein 1817)
1

2. Learning Objectives:Learning Objectives:
•Enumerate general functions of the kidney.
•Identify and describe that the nephron is the
structural and function unit of the kidney.
•Explain glomerular filtration membrane & filtration
forces.
•Describe mechanism of filtration & composition of
the glomerular filtrate.
•Calculate the net filtration pressure using
parameters of Starling forces.
2

3. Urinary System OrgansUrinary System Organs
3

4. Urinary System OrgansUrinary System Organs
4

5. Urinary System OrgansUrinary System Organs
5

6. Kidney FunctionsKidney Functions
1)1)FilterFilter 200 liters of blood daily, allowing toxins,
metabolic wastes, and excess ions to leave the
body in urine,
2)2)RegulationRegulation of water and electrolyte balance:
Maintain the proper balance between water and
salts, and acids and bases,
3)3)ExcretionExcretion of bioactive substances (hormones and
many foreign substances, especially drugs) that
affects body function,
6

7. Kidney FunctionsKidney Functions
4)Regulation of arterial blood pressureblood pressure: by
production of renin (vasoactive substances) and
regulate volume and chemical makeup of the
blood,
5)Regulation of red blood cells productionblood cells production:
erythropoietin hormone to stimulate RBC
production by bone marrow,
7

8. Kidney FunctionsKidney Functions
6)Regulation of vitamin D productionvitamin D production : 25,
cholecalciferol will be activated in the kidneys to
1,25 dihydrocholecalciferol D
3,
7)7)GluconeogenesisGluconeogenesis: during prolonged fasting
glucose can be synthesized in the liver and
kidneys.
8

9. •Layers of Tissue Supporting the Kidney
Renal capsule Renal capsule – fibrous capsule that prevents kidney
infection
Adipose capsule Adipose capsule – fatty mass that cushions the kidney
and helps attach it to the body wall
Renal fascia Renal fascia – outer layer of dense fibrous connective
tissue that anchors the kidney
9
Tissue Supporting the KidneyTissue Supporting the Kidney

10. 10

11. Internal AnatomyInternal Anatomy
•A frontal section shows
three distinct regions
–CortexCortex: – the light
colored, granular
superficial region
–MedullaMedulla: – exhibits
cone-shaped
medullary (renal)
pyramids
11

12. 12

13. The NephronThe Nephron
•Nephrons are the structural and
functional units that form urine,
consisting of:
–GlomerulusGlomerulus – a tuft of capillaries
associated with a renal tubule
–Glomerular (BowmanGlomerular (Bowman’’s) s)
capsule capsule – blind, cup-shaped end
of a renal tubule that completely
surrounds the glomerulus
13

14. The NephronThe Nephron
–Renal corpuscleRenal corpuscle – the
glomerulus and its Bowman’s
capsule
–Glomerular endotheliumGlomerular endothelium –
fenestrated epithelium that
allows solute-rich, virtually
protein-free filtrate to pass from
the blood into the glomerular
capsule
14

15. Anatomy of the Glomerular CapsuleAnatomy of the Glomerular Capsule
•The external parietal layer is a
structural layer
•The visceral layer consists of
modified, branching epithelial
podocytespodocytes
•Extensions of the octopus-like
podocytes terminate in foot
processes
•Filtration slits – openings between
the foot processes that allow filtrate
to pass into the capsular space
15

16. 16

17. Renal TubuleRenal Tubule
•Proximal convoluted tubule Proximal convoluted tubule (PCT) – composed
of cuboidal cells with numerous microvilli and
mitochondria.
–Reabsorbs water and solutes from filtrate and
secretes substances into it.
17

18. Renal TubuleRenal Tubule
•Loop of Henle Loop of Henle – a hairpin-shaped loop of the renal
tubule
–Proximal part is similar to the proximal convoluted
tubule.
–Proximal part is followed by the thin segment
(simple squamous cells) and the thick segment
(cuboidal to columnar cells).
•Distal convoluted tubule Distal convoluted tubule (DCT) – cuboidal cells
without microvilli that function more in secretion than
reabsorption.
18

19. Connecting TubulesConnecting Tubules
•The distal portion of the distal convoluted tubule
nearer to the collecting ducts.
•Two important cell types are found here:
–Intercalated cellsIntercalated cells
•Cuboidal cells with microvilli.
•Function in maintaining the acid-base balance of the
body.
–Principal cellsPrincipal cells
•Cuboidal cells without microvilli.
•Help maintain the body’s water and salt balance.
19

20. Types of NephronsTypes of Nephrons
•Cortical nephrons Cortical nephrons – 85% of nephrons; located in
the cortex
•Juxtamedullary nephrons:Juxtamedullary nephrons:
–Are located at the cortex-medulla junction
–Have loops of Henle that deeply invade the
medulla
–Have extensive thin segments
–Are involved in the production of concentrated
urine
20

21. 21

22. Juxtaglomerular Apparatus (JGA)Juxtaglomerular Apparatus (JGA)
•Where the distal tubule lies against the
afferent (sometimes efferent) arteriole
•Arteriole walls have juxtaglomerular (JG)
cells
–Enlarged, smooth muscle cells
–Have secretory granules containing renin
–Act as mechanoreceptors
22

23. Juxtaglomerular Apparatus (JGA)Juxtaglomerular Apparatus (JGA)
•Macula densaMacula densa
–Tall, closely packed distal tubule cells
–Lie adjacent to JG cells
–Function as chemoreceptors or osmoreceptors
–The cells of the macula densa are sensitive to the
ionic content and water volume of the fluid in the
tubule
–produce molecular signals that promote renin
secretion by the juxtaglomerular cells
23

24. Juxtaglomerular Apparatus (JGA)Juxtaglomerular Apparatus (JGA)
•Mesanglial cellsMesanglial cells
–Have phagocytic and contractile properties
–Influence capillary filtration
–Intraglomerular mesangial cells provide
structural support and regulate blood flow of the
glomerular capillaries by their contractile activity
24

25. 25

26. Filtration MembraneFiltration Membrane
•Filter that lies between the blood and the interior of
the glomerular capsule
•It is composed of three layers
–Fenestrated endothelium of the glomerular
capillaries (Pores are 50-100 nm in diameter)
–Visceral membrane of the glomerular capsule
(podocytes)
–Basement membrane composed of fused basal
laminae of the other layers.
26

27. 27

28. 28

29. Filtration MembraneFiltration Membrane
•Glomerular filtration membrane is highly
permeable to water and small molecules (less
than 10.000 MW)
•Large molecules (more than 70.000 MW
especially proteins are not filtered due to their
large size and negative electrical charge because
their passage is repulsed by negatively charged
glycoproteins present on endothelial pores,
basement membrane and podocytes.
29

30. Composition of Glomerular Composition of Glomerular
FiltrationFiltration
•Glomerular Filtrate has almost the same
composition as that of plasma, except that it
has no significant amount of proteins (it has
about 0.003%)
•It is less than 1/2000 protein as compared with
plasma.
30

31. Innervation of the kidneyInnervation of the kidney
•Sympathetic nerves supply renal blood vessels,
regulate blood flow, filtration, water reabsorption,
rennin secretion.
•↑ sympathetic = constriction, ↓ blood flow
•There is no parasympathetic innervation
31

32. 32

33. 33