C8 formation of urine by the kidney
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C8 FORMATION OF URINE BY THE KIDNEY. Today I am going to introduce: 1.the microstructure of the Kidney 2. glomerular filtration. our goals are. ⑴ understand microstructure of the kidney ⑵ understand the characteristic of blood circulation in the kidney

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C8 FORMATION OF URINE BY THE KIDNEY

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C8 formation of urine by the kidney

C8 FORMATION OF URINE BYTHE KIDNEY


C8 formation of urine by the kidney

Today I am going to introduce:

1.the microstructure of the Kidney

2. glomerular filtration


Our goals are

our goals are

⑴ understand microstructure of the kidney

⑵ understand the characteristic of blood circulation in the kidney

⑶ describe glomerular filtration


C8 formation of urine by the kidney

Functions of The kidney:

⑴ regulate water and inorganic ion equilibrium .maintain constant of internal environment

regulate the osmotic pressure of body fluids;

  • the osmotic pressure is formed by electrolyte, kidney regulate value of electrolyte , acid and baseexcretion, and then regulate the osmotic pressure , the electrolyte equilibrium and adjust the balance of acid and base in body fluids.


C8 formation of urine by the kidney

  • ⑵ excrete metabolic waste end-products into the urine;

  • NH3 some poisons


C8 formation of urine by the kidney

  • ⑶ excrete foreign chemicals drugs metabolites

    ⑷gluconeogenesis

    synthesize glucose from amino acids

    .

    ⑸endocrine function

    secreteerythropoietin, renin,


Which is main function of the kidney

Which is main function of the kidney?

excrete urine

produce urine

Store urine

Transport urine


Which is main function of the ureter

Which is main function of the ureter ?

excrete urine

produce urine

Store urine

Transport urine


Mechanisms of urine formation

Mechanisms of urine formation :

(1) Filtration

(2) Secretion

(3) Reabsorption


Structure of the kidneys and urinary system

Structure of the kidneys and urinary system


Cortex

cortex

medulla


The nephron and collecting duct

The Nephron and collecting Duct

2,000,000

nephrons

Functional unit

of kidney


Composition of nephron

① composition of nephron

glomerulus

renal corpuscle

Bowman’s capsule

nephron

proximal convoluted

tubule

renal tubule

loop of Henle;

distal convoluted tubule

The collecting duct


What is functional unit of the kidney

What is functional unit of the kidney?

nephron

glomerulus

renal tubule

collecting duct


Types of nephron

② types of nephron

(1)cortical nephrons:(85% )

In the outer and middle portion of the renal cortex (shorter loops)


Cortical nephrons

cortical nephrons

juxtamedullary nephrons

loop of Henle

Collecting duct


Types of nephron1

② types of nephron

(2) juxtamedullary nephrons :

(15% )

In the inner cortex (longer

loops)


Cortical nephrons1

cortical nephrons

juxtamedullary nephrons

loop of Henle

Collecting duct


Juxtaglomerular apparatus

Juxtaglomerular Apparatus

(1)the juxtaglomerular cells:

they are specialized

myoepithelial cells

in afferent arteriole

release renin


C8 formation of urine by the kidney

monitor the concentration of NaCl in the tubular fluid and transferthe information to juxtaglomerular cells

(2)the macula densa :


What is cell of release renin

What is cell of release renin?

extraglomerular mesangial cell

juxtaglomerular cells

macula densa


What is cell of monitor the concentration of nacl in the tubular fluid

What is cell ofmonitor the concentration of NaCl in the tubular fluid?

juxtaglomerular cells

extraglomerular mesangial cell

macula densa


C8 formation of urine by the kidney

Glomerular Membrane

physical barrier

1.The endothelial layer

of the capillary

2.The basement

membrane

3.The epithelial cell

layer of Bowman’s

capsule


Special structure

special structure

Fenestra:

prevent the

filtration of all

particles with

an average size

greater than

16 millimicron.

Red cell


Meshwork basement membrane of the capillary

Meshwork(basement membrane of the capillary)

proteoglycan

prevents the filtration of all particles with diameter greater than 11 millimicron


Slit pores

Slit-pores


Slit pores1

Slit-pores

prevent the filtration of all particles with diameter greater than 7 millimicron.

(diameter of plasma proteins ﹥7 millimicron)

plasma proteins


C8 formation of urine by the kidney

Electrical barrier

-

-

-

-

-

-

-

-

Glycoprotein

(negatvely charge)


C8 formation of urine by the kidney

-

-

-

-

-

-

-

-

prevent filtration of

negatively charged

plasma proteins


C8 formation of urine by the kidney

Neutral substances:

﹤2 nm(millimicron) –can

be filtered easily

﹥4.2 nm--can not be filtered

between---can be filtered

proportionately

Anionic substances:

difficult to be filtered

(albumin)


C8 formation of urine by the kidney

The glomerular membrane is almost completely impermeable to all cells and plasma proteins but is highly permeable to all dissolved substances(such as electrolyte, glucose )


In following substance what substance is not filter through the glomerular membrane

In following substance , What substance is not filter through the glomerular membrane.

plasma protein

water

ions

electrolyte

glucose


Innervation of the renal vessels

Innervation of the renal vessels

Sympathetic fiber

Sympathetic nerve cause constriction of renal blood vessels, which greatly decreases blood flow to the kidney.


Renal blood flow and regulation

Renal Blood Flow and Regulation

renal artery →

afferent arteriole→

glomerular capillaries

→efferent arteriole→

peritubular capillaries

→ renal vein


C8 formation of urine by the kidney

Two capillary beds

(1)glomerular capillary bed :

high pressure

→filtering

continually

out of the

glomerulus

into Bowman’s

capsule


2 peritubular capillary bed

(2)peritubular capillary bed :

low pressure →

fluid being reabsorbed

continually into the capillaries


What is characteristic of the glomerular capillary bed

What is characteristic of theglomerular capillary bed?

low pressure

high pressure


What is characteristic of the peritubular capillary bed

What is characteristic of theperitubular capillary bed?

low pressure

high pressure


C8 formation of urine by the kidney

(1)Renal Blood Flow

① renal blood flow is about

1200ml/minute

② The renal fraction is about 21

per cent


C8 formation of urine by the kidney

③ About 94 per cent of renal blood flow goes to the renal cortex.


2 autoregulation of renal blood flow

(2) Autoregulation of Renal Blood Flow

When BP changes from

80 to 180 mmHg,

a relatively constant renal

blood flow is maintained.


Mechanism

mechanism

* When BP descends, afferent

arteriole relax and decrease resistance of afferent arteriole, and then the renal blood flow does not change.

* When BP rises, afferent arteriole

contract and increase resistance of afferent arteriole, and then the renal blood flow does not change, too


3 neuro humoral control

(3)Neuro-Humoral Control

Sympathetic nerve:

→ constriction of renal blood vessels

→decreases blood flow

Vasoconstrictor agents :

Angiotensin II

epinephrine and norepinephrine

Vasodilator agents :

bradykinin, NO and some prostaglandins


C8 formation of urine by the kidney

plasma → Bowman’s capsule→ proximal convoluted tubule → loop of Henle → distal convoluted tubule→ collecting duct → papilla → renal alyces


C8 formation of urine by the kidney

Glomerular Filtration

when blood passes

through the glomerulus,

plasma component

(water, ions, and small

molecules filter into

Bowman's capsule.


2 2 filtration pressure

2-2. Filtration Pressure

① capillary pressure

(causes filtration )

②colloid osmotic pressure

in the blood

(oppose filtration)

③capsular pressure

in Bowman’s capsule

(oppose filtration)

.

albumin

.

.

.

.

.

.

.

.

.


Afferent arteriole

afferent arteriole

The effective filtration pressure(EFP)

efferent arteriole

①the glomerular pressure

EFP = ① - (②+ ③)

② glomerular colloid osmotic pressure

③ capsular pressure


C8 formation of urine by the kidney

① the glomerular pressure :

45 mmHg.

② colloid osmotic pressure

in the blood

increase from 25 to 35 mmHg.

③ capsular pressure: 10 mmHg

45mmHg

10mmHg

25-35mmHg


C8 formation of urine by the kidney

(1) afferent side :

EFP=45-(25+10)=10mmHg

filter

(2) efferent side :

EFP=45-(35+10)= 0mmHg

filterstop

45mmHg

10mmHg

25-35mmHg


2 3 glomerular filtration rate gfr

2-3.Glomerular Filtration Rate (GFR)

The quantity of glomerular

filtrate formed each minute in

all nephrons of both kidneys.

(normal:125 ml/min)

180 L/d

99 % reabsorbed

1 % excreted as urine


Filtration fraction

660ml/min

125/660=19%

filtration fraction

The ratio that

GFR and

renal plasma

flow.

GFR=125ml/min

renal plasma flow

=660ml/min

Filtration fraction

=125/660=19%


Filtration coefficient k f

filtration coefficient (Kf )

It image the condition of

the area and permeability of

glomerular membrane.

a constant in nomal

change in kidney disease

GFR= Filtration pressure • Kf


C8 formation of urine by the kidney

2-4. determinants of the glomerular fitration rate

GFR= Filtration pressure • Kf


C8 formation of urine by the kidney

(1) Effect of Glomerular Capillary

Pressure

Because of autoregulation, 80 mmHg ~ 180 mmHg. the glomerular filtration rate is constant

BP ↑(over 180mmHg) → glomerular capillary pressure↑ → effective filtration pressure ↑ → GFR↑


C8 formation of urine by the kidney

(2) Effect of the Plasma

Colloid Osmotic pressure

Liver function ↓ or proteinuria

→ plasma colloid osmotic pressure↓

→ effective filtration pressure ↑

→ GFR↑


C8 formation of urine by the kidney

ureter occlusion caused by

ureteral calculus, cancer etc.

→ Capsular Pressure↑ →

effective filtration pressure

→ GFR

(3) Effect of Bowman’s

capsule Pressure


C8 formation of urine by the kidney

(4)Effect of Renal Blood Flow

renal blood flow↑

→plasma colloid osmotic pressure rises slowly →

GFR ↑

①the glomerular pressure

EFP = ① - (②+ ③)

② glomerular colloid osmotic pressure

③ capsular pressure


Renal plasma flow

renal plasmaflow

flitrate

Concentration of plasma protein%

renal blood flow

plasma colloid

osmotic pressure

rises fastly

Concentration of plasma protein in normal


The glomerular pressure

the glomerular pressure

renal blood flow

in normal

glomerular colloid

osmotic pressure

capsular pressure

length


C8 formation of urine by the kidney

the glomerular pressure

renal blood

flow

glomerular colloid

osmotic pressure

capsular pressure

length


C8 formation of urine by the kidney

renal blood

flow

the glomerular pressure

Glomerular

colloid

osmotic

pressure

capsular pressure

length


C8 formation of urine by the kidney

(5)Glomerular capillary filtration

coefficient

(1)Kf : the area and permeability

of glomerular membrane

Permeability↑→ Hematuria,

proteinuria

the area →urine in chronic nephritis


We have studied

We have studied:

1. the anatomy construction of the kidney

2. the characteristic of blood circulation in the kidney

3. glomerular filtration


Please answer the questions

Please answer the questions

1.Explain physiology word:

Glomerular Filtration Rate

filtration fraction

2. What is functional unit of the kidney?

3. What is composition of nephron

4. What are characteristic of the glomerular capillary bed and peritubular capillary bed

5. The effective filtration pressure

6.Factors Affecting GFR


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