[4] physiology renal functions

8/13/2019 [4] Physiology Renal Functions

1/27

Renal Functions


2/27

Renal Functions

1: Regulation of Water and ElectrolyteBalance

2: Excretion of Metabolic Waste

3: Excretion of Bioactive Substances

(Hormones and Many Foreign

Substances, Specifically Drugs) That

Affect Body Function 4: Regulation of Arterial Blood

Pressure


3/27

5: Regulation of Red Blood Cell

ProductionErythropoietin is secreted by the renal cells

(particular group cells in the interstitium).

6: Regulation of Vitamin D ProductionThe activeform of vitamin D (1,25-

dihydroxyvitamin D3), is actually made in

the kidneys,

7: Gluconeogenesis

Most gluconeogenesis occurs in the liver,

but a substantial fraction occurs in the

kidne s, articularl durin a rolon ed


4/27

Anatomy of the Kidneys and Urinary

System

Gambar


5/27


6/27

The Nephron

Each kidneycontains

approximately 1

million nephrons, Each nephron

consists of a

spherical filteringcomponent, called

the renal corpuscle,

and a tubuleextendin from the


7/27

The Renal Corpuscle

consists of glomerulus(pl. glomeruli) orglomerular capillaries, surrounded by a

balloon-like hollow capsule: Bowman's

capsule


8/27

Proximal

convoluted

tubule

Capsule

space

Efferent arteriole

Pedicel

Podocyte

Endothelium

of glomerulus

Afferent arteriole

Juxtaglomerular

cell

Parietal layer of

glomerular capsule

Structure of the Bowmans (glomerular) capsule


9/27

Filtration barrier consists of 3 layers;

the capillary endothelium of theglomerular capillaries, a rather thick

basement membrane, and a single-

celled layer of epithelial cells the endothelial cells of the capillaries,

is perforated by many large fenestrae

("windows"), like a slice of Swisscheese, and is freely permeable to

everything in the blood except red blood

cells and platelets


10/27


11/27

The basement membrane in the middle is

a gel-like acellular meshwork of

glycoproteins and proteoglycans, like a

kitchen sponge.

The epithelial cells that rest on the

basement membrane and face Bowman'sspace are calledpodocytes. Small

"fingers," calledpedicels(or foot

processes), extend from each arm of thepodocyte and are embedded in the

basement membrane. Pedicels

interdigitate with the pedicels from


12/27

Spaces between adjacent pedicelsconstitute the path through which the

filtrate, once through the endothelial

cells and basement membrane, travelsto enter Bowman's space.

The functional significance of this

anatomic arrangement is that it permitsthe filtration of large volumes of fluid

from the capillaries into Bowman's

space but restricts filtration of large

lasma roteins such as albumin.


13/27

mesangial cells

is found in the centralpart of the glomerulus between and

within capillary loops.

act as phagocytes and remove trappedmaterial from the basement membrane,

also contain large numbers of

myofilaments and can contract inresponse to a variety of stimuli in a

manner similar to vascular smooth

muscle cells


14/27

The Tubule


15/27

The cells in the thick ascending limbclosest to Bowman's capsule (between

the afferent and efferent arterioles) are

specialized cells known as the maculadensa.

the tubular epithelium has a one-cell

thickness throughout, however,beginning in the second half of the distal

convoluted tubule, 2 cell types are found

in most of the remaining segments.


16/27

principal cells are the majority of cellsin the particular segment, is considered

specific for that segment,

in tercalated cells are individual cellsthat Interspersed among the segment-

specific cells , type A and B


17/27

Blood Supply to the Nephrons

Normally only about 20% of the plasma(and none of the erythrocytes) entering

the glomerulus is filtered from the

glomerulus into Bowman's capsule. Gambar


18/27

Arcuate artery

Arcuate vein

Thin ascending limbof the loop of Henl

Thick ascending limbof the loop of Henl

Distal convoluted tubule

Proximal convolutedtubule

Collecting duct

Descending limbloop of Henl

Vascular supply to the nephron

Vasa recta

GlomerulusAfferent arteriole

Efferent arteriole


19/27


20/27

The

Juxtaglo

merular

Apparatu

s

is made up of 3 cell types: (1) granular cells,

which are differentiated smooth muscle cellsin the walls of the afferent arterioles; (2)

extraglomerular mesangial cells; and (3)

macula densa cells, specialized thick

ascending limb epithelial cells.


21/27

The granular cells are the cells that secrete

the hormone renin, a crucial substance for

control of renal function and blood

pressure.

The extraglomerular mesangial cells are

morphologically similar to and continuouswith the glomerular mesangial cells but lie

outside Bowman's capsule.

The macula densa cells are detectors ofthe luminal content of the nephron at the

very end of the thick ascending limb and

contribute to the control of glomerular


22/27

Basic Renal

Processes


23/27

The volume of filtrate formed per unittime is known as the glomerular filtration

rate (GFR). In a normal young adult

male, the GFR is an incredible 180L/day (125 mL/min)!


24/27

Regulation of Renal Function

Neural signals originate in thesympathetic celiac plexus. Sympathetic

signals exert major control over renal

blood flow, glomerular filtration, andrelease of vasoactive substances (the

renin-angiotensin system).intrarenal

chemical messengers Hormonal signals originate in the

adrenal gland, pituitary gland, and heart.


25/27

The adrenal cortex secretes the steroidhormones aldosterone and cortisol, and

the adrenal medulla secretes the

catecholamines epinephrine andnorepinephrine.

The pituitary gland secretes the

hormone arginine vasopressin (alsocalled ADH).

The heart secretes hormones, natriuretic

peptides, that contribute to signaling


26/27

Referensi


27/27

Thank you

[4] physiology renal functions

Documents