urinary system physiology principles.ppsx

‫الرحمن‬ ‫الله‬ ‫بسم‬
‫الرحيم‬

Physiology of the
Kidney and
Urological system
Gihad Allugamie MD.
Uro-Andrologist
dr.gihadallugamie@gmail.com

Arthur Guyton
(1919-2003)
Frank H. Netter, MD
(
1906-1991
)
"
Medicine's Michelangelo
"

Frank H. Netter, MD
(
1906-1991
)
"
Medicine's Michelangelo
"

Kidneys
• Paire, Retroperitoneal
• Partially protected by
the 11th
and 12th
ribs
• Right slightly lower due
to liver
• Surrounded by renal
capsule
• Adipose capsule
• Renal fascia

• The renal artery
• segmental arteries
• interlobar arteries that
communicate with one
another via arcuate arteries.
• The arcuate arteries give off
branches called interlobular
arteries that extend into the
cortex.
• Venous return of blood is via
similarly named veins.
Blood Supply to the Kidney

Blood Supply to the Kidney
• The interlobular arteries
• afferent arteriole
• Glomerulus
• efferent arterioles
• capillary network
surrounding the tubule
system of the nephron.
• The interlobular veins are
then the collecting vessel
of the nephron capillary
system.

Characteristics of the
renal blood flow:
1, high blood flow
1200 ml/min, or 21 percent
of the cardiac output. 94%
to the cortex
2, Two capillary beds
High hydrostatic pressure
in glomerular capillary
(about 60 mmHg) and low
hydrostatic pressure in
peritubular capillaries
(about 13 mmHg)
Vesa Recta

• Kidneys make up 1 % of body mass, but
receive about 25% of cardiac output.
• Kidney has two major functions:
1
.
Filtration of blood
• Removes metabolic wastes from the body, esp. those
containing nitrogen (Urine formation)
2
.
Regulation
:
• Blood volume and composition
• Electrolytes
• Blood pH
• Blood pressure

Blood flow in kidneys and other organs
Organ Approx. blood flow
(mg/min/g of tissue)
A-V O2
difference
(ml/L)
Kidney 4.00 12-15
(depends on reabsorption of
Na+ )
Heart 0.80 96
Brain 0.50 48
Skeletal muscle
(rest)
0.05 -
Skeletal muscle
(max. exercise)
1.00 -

Nephron
• Functional unit of the
kidney
• Filtration, tubular
reabsorption, tubular
secretion
• Renal corpuscle:
– Glomerulus – capillaries
– Glomerular or Bowman’s
capsule

The Nephron
glomerulus
proximal convoluted tubule
loop of Henle
descending limb
ascending limb
distal convoluted tubule
many nephrons connect to
collecting duct
Blood flow:
afferent arteriole
efferent arteriole
Peritubular capillaries
vasa recta

Cortical nephron – glomeruli
in outer cortex & short
loops of Henle that extend
only short distance into
medulla-- blood flow through
cortex is rapid – majority of
nephrons are cortical.
Juxtamedullary nephron –
glomeruli in inner part of
cortex & long loops of Henle
which extend deeply into
medulla.– blood flow through
vasa recta in medulla is slow.

Bowman’s capsule
200 mcm
Receives filtrate

Proximal convoluted tubule
Reabsorption of water and solutes
15
mm

Nephron loop or Loop of Henle
Regulates concentration of urine
10mm , 15 mm

Distal convoluted tubule and Collecting
duct
Reabsorption of water and electrolytes
ADH, aldosterone, ANP
Tubular secretion
5
mm

30 G. Allugamie MD. 2013
Juxtaglomerular apparatus

31
• Juxtaglomerular
cells lie in the wall of
afferent arteriole
• Macula densa in
final portion of loop
of Henle – monitor
Na+
and Cl-
conc.
and water
• Control blood flow
into the glomerulus
• Control glomerular
filtration
G. Allugamie MD. 2013

HUMAN RENAL PHYSIOLOGY
• Four Main Processes:
–
Filtration
–
Reabsorbtion
–
Secretion
–
Excretion

Functions of the Nephron
Filtration
Reabsorption Secretion
Excretion

Excretion
Secretion
Reabsorbtion
Filtration

–Filtration:
–First step in urine
formation
–Bulk transport of fluid from
blood to kidney tubule
» Isosmotic filtrate
» Blood cells and proteins don’t filter
–Result of hydraulic
pressure
–GFR = 180 L/day

–Reabsorbtion:
• Process of returning
filtered material to
bloodstream
• 99% of what is filtered
• May involve transport
protein(s)
• Normally glucose is
totally reabsorbed

–Secretion:
–Material added to lumen
of kidney from blood
–Active transport
(usually) of toxins and
foreign substances
»Saccharine
»Penicillin

• Functions of the Kidney:
– Excretion:
– Loss of fluid from body in form of urine
Amount = Amount + Amount -- Amount
of Solute Filtered Secreted Reabsorbed
Excreted

– blood enters glomerular capillary
– filters out of renal corpuscle
• large proteins and cells stay behind
• everything else is filtered into nephron
• glomerular filtrate
–plasma like fluid in glomerulus
Glomerular filtration
Occurs as fluids move
across the glomerular
capillary in response to
glomerular hydrostatic
pressure

Factors that determining the
glumerular filterability
1.Molecular weight
2.Charges of the molecule

Filtration
• Renal corpuscle
• Filtration membrane
– Fenestrated endothelium of capillaries
– Basement membrane of glomerulus
– Slit membrane between pedicels of podocytes

Forces that influence filtration
• Glomerular blood hydrostatic pressure 60
• Opposing forces:
– Plasma colloid osmotic pressure 32
– Capsular hydrostatic pressure 18

Hyperosmotic Gradient in the Renal
Medulla Interstitium

• Amount of filtrate produced in the kidneys
each minute. 125mL/min = 180L/day
• Factors that alter filtration pressure change
GFR. These include:
– Increased renal blood flow -- Increased GFR
– Decreased plasma protein -- Increased GFR.
Causes edema.
– Hemorrhage -- Decreased capillary BP --
Decreased GFR
Glomerular filtration rate (GFR)

GFR regulation : Adjusting blood flow
• GFR is regulated using three
mechanisms
1. Renal Autoregulation
2. Neural regulation
3. Hormonal regulation
All three mechanism adjust renal blood
pressure and resulting blood flow

GFR influenced by
:
• Blood pressure and blood flow
• Obstruction to urine outflow
• Loss of protein-free fluid
• Hormonal regulation
• Renin – angiotensin
• Aldosterone
• ADH
• ANP

2
.
Neural regulation of GFR
• Sympathetic nerve fibers innervate afferent
and efferent arteriole
• Normally sympathetic stimulation is low but
can increase during hemorrhage and
exercise
• Vasoconstriction occurs as a result which
conserves blood volume (hemorrhage) and
permits greater blood flow to other body
parts (exercise)

3
.
Hormonal regulation of GFR
• Several hormones contribute to GFR regulation
• Angiotensin II. Produced by Renin, released by
JGA cells is a potent vasoconstrictor. Reduces
GFR
• ANP atrial natriuretic peptide (released by atria
when stretched) increases GFR by increasing
capillary surface area available for filtration
• NO
• Endothelin
• Prostaglandin E2

Measuring GFR
• 125ml of plasma is cleared/min in glomerulus(or
180L/day)
• If a substance is filtered but neither reabsorbed nor
secreted, then the amount present in urine is its
plasma clearance (amount in plasma cleared/min
by glomerulus)
• If plasma conc. Is 3mg/L then
3 X 180/day = 540mg/day
(known) (unknown) (known)

Qualities of agents to measure GFR
Inulin: (Polysaccharide from Dahalia plant)
• Freely filterable at glomerulus
• Does not bind to plasma proteins
• Biologically inert
• Non-toxic, neither synthesized nor metabolized in
kidney
• Neither absorbed nor secreted
• Does not alter renal function
• Can be accurately quantified
• Low concentrations are enough (10-20 mg/100 ml
plasma)

Creatinine:
End product of muscle creatine metabolism
Used in clinical setting to measure GFR but
less accurate than inulin method
Small amount secrete from the tubule
Qualities of agents to measure GFR

Plasma creatinine level vs. GFR
2934

Constituent Mol. Wt. Filteration
ratio
Urea 60 1.00
Glucose 180 1.00
Inulin 5,500 1.00
Myoglobin 17,000 0.75
Hemoglobin 64,000 0.03
Albumin 69,000 0.01
Filterablility of plasma constituents vs.
water

Figure 26.15a,
b
The Effects of ADH on the distal collecting
duct and Collecting Ducts

The Role of ADH
• There is a high osmolarity of the renal medullary interstitial
fluid, which provides the osmotic gradient necessary for
water reabsorption to occur.
• Whether the water actually leaves the collecting duct (by
osmosis) is determined by the hormone ADH (anti-diuretic
hormone)
• Osmoreceptors in the hypothalamus detect the low levels
of water (high osmolarity), so the hypothalamus sends an
impulse to the pituitary gland which releases ADH into the
bloodstream.
• ADH makes the wall of the collecting duct more permeable
to water.
• Therefore, when ADH is present more water is reabsorbed
and less is excreted.

1- Water reabsorption
Obligatory water reabsorption:
• Using sodium and other solutes.
• Water follows solute to the interstitial fluid
(transcellular and paracellular pathway).
• Largely influenced by sodium reabsorption

Facultative (selective) water reabsorption:
• Occurs mostly in collecting ducts
• Through the water poles (channel)
• Regulated by the ADH
2-Water reabsorption

Secretion of ADH
Increased osmolarity
ADH
Post. Pituitary
Urge to drink
STIMULUS
cAMP
+

Facultative water reabsorption

Formation of Water Pores:
Mechanism of Vasopressin Action

• Juxtaglomerular cells lie in the wall of afferent
arteriole
• Macula densa in final portion of loop of Henle
– monitor Na+
and Cl-
conc. and water
• Control blood flow into the glomerulus
• Control glomerular filtration

Tubular reabsorption
• Water, glucose, amino acids, urea, ions
• Sodium diffuses into cell; actively pumped out
– drawing water with it

• In addition to reabsorption, also have tubular
secretion – substances move from peritubular
capillaries into tubules – a second chance to
remove substances from blood.

• By end of proximal tubule have reabsorbed:
• 60- 70% of water and sodium
• about 100% of glucose and amino acids
• 90 % of K+, bicarb, Ca++, uric acid
• Transport maximum – maximum amount of a
substance that can be absorbed per unit time
• Renal threshold – plasma conc. of a substance
at which it exceeds Tm.

Loop of Henle
• Responsible for producing a concentrated
urine by forming a concentration gradient
within the medulla of kidney.
• When ADH is present, water is reabsorbed and
urine is concentrated.
• Counter-current multiplier

Distal convoluted tubule and collecting ducts
• What happens here depends on ADH
• Aldosterone affects Na+ and K+
• ADH – facultative water reabsorption
• Parathyroid hormone – increases Ca++
reabsorption

Distal convoluted tubule and collecting ducts
• Tubular secretion to rid body of substances:
K+, H+, urea, ammonia, creatinine and certain
drugs
• Secretion of H+ helps maintain blood pH
(can also reabsorb bicarb and generate new
bicarb)

Section 3
Reabsorption and Secretion
Concept of Reabsorption and Secretion

Filtration, reabsoption, and excretion rates of substances by the
kidneys
Filtered Reabsorbed Excreted Reabsorbed
(meq/24h) (meq/24h) (meq/24h) (%)
Glucose (g/day) 180 180 0 100
Bicarbonate (meq/day) 4,320 4,318 2 > 99.9
Sodium (meq/day) 25,560 25,410 150 99.4
Chloride (meq/day) 19,440 19,260 180 99.1
Water (l/day) 169 167.5 1.5 99.1
Urea (g/day) 48 24 24 50
Creatinine (g/day) 1.8 0 1.8 0

Two pathways of the absorption
:
Lumen
Plasma
Cells
Transcellular
Pathway
Paracellular
transport

Mechanism of Transport
1, Primary Active Transport
2, Secondary Active Transport
3, Pinocytosis
4, Passive Transport

Secondary active transport
Na+
glucose
Na+
H+
out in out in
co-transport counter-transport
(
symport
( )
antiport
)
Co-transporters will move one moiety,
e.g. glucose, in the same direction as
the Na+
.
Counter-transporters will move one
moiety, e.g. H+
, in the opposite direction
to the Na+
.
Tubular
lumen
Tubular Cell
Interstitial
Fluid
Tubular
lumen
Tubular Cell
Interstitial
Fluid

Pinocytosis:
Some parts of the tubule, especially
the proximal tubule, reabsorb large
molecules such as proteins by
pinocytosis.

1. Transportation of Sodium, Water and
Chloride
(1)Sodium, water and chloride reabsorption
in proximal tubule
Proximal tubule, including the proximal
convoluted tubule and thick descending
segment of the loop

Reabsorb about 65 percent of the filtered sodium, chloride, bicarbonate, and potassium
and essentially al the filtered glucose and amino acids.
Secrete organic acids, bases, and hydrogen ions into the tubular lumen.

The sodium-potassium ATPase: major force for
reabsorption of sodium, chloride and water
In the first half of the proximal tubule, sodium is
reabsorbed by co-transport along with glucose,
amino acids, and other solutes.
In the second half of the proximal tubule, sodium
reabsorbed mainly with chloride ions.
Sodium, water and chloride reabsorption in
proximal tubule

The second half of the proximal tubule has a
relatively high concentration of chloride (around
140mEq/L) compared with the early proximal tubule
(about 105 mEq/L)
In the second half of the proximal tubule, the higher
chloride concentration favors the diffusion of this ion
from the tubule lumen through the intercellular
junctions into the renal interstitial fluid.
Sodium, water and chloride reabsorption
in proximal tubule

(
2
)
Sodium and water transport in the
loop of Henle
The loop of Henle consists of
three functionally distinct
segments:
the thin descending segment,
the thin ascending segment,
and the thick ascending
segment.

High permeable to water
and moderately
permeable to most solutes
but has few mitochondria
and little or no active
reabsorption.
Reabsorbs about 25% of
the filtered loads of
sodium, chloride, and
potassium, as well as
large amounts of calcium,
bicarbonate, and
magnesium.
This segment also
secretes hydrogen ions
into the tubule

Mechanism
of sodium,
chloride,
and
potassium
transport in
the thick
ascending
loop of
Henle

2. Glucose Reabsorption
Glucose is reabsorbed along with Na+
in the
early portion of the proximal tubule.
Glucose is typical of substances removed from
the urine by secondary active transport.
Essentially all of the glucose is reabsorbed,
and no more than a few milligrams appear in
the urine per 24 hours.

‫الكلية‬ ‫وظائف‬
:
Function of the Kidney
•
: ‫الرئيسية‬ ‫الكلية‬ ‫وظائف‬
•
1
‫الدم‬ ‫سوائل‬ ‫وتركيب‬ ‫حجم‬ ‫على‬ ‫المحافظة‬ -
(
Blood volume .and composition
)
•
2
. ) ‫البول‬ ‫طريق‬ ‫(عن‬ ‫الدم‬ ‫من‬ ‫والسموم‬ ‫الفضالت‬ ‫تزيل‬-
•
3
‫االس‬ ‫تركيز‬ ‫على‬ ‫للمحافظة‬ ‫الهيدروجين‬ ‫ايون‬ ‫من‬ ‫الزائدة‬ ‫الكمية‬ ‫طرح‬ -
( ‫للدم‬ ‫الهيدروجيني‬
pH 7.4
.)
•
4
( ‫السوائل‬ ‫لهذه‬ ‫األسموزي‬ ‫والضغط‬ ‫الجسم‬ ‫سوائل‬ ‫على‬ ‫المحافظة‬ -
300
‫ملي‬
‫لتر‬/‫ازموول‬
300
Osmm/L
)
•
5
‫الرينين‬ ‫انزيم‬ ‫افراز‬ ‫طريق‬ ‫عن‬ ‫الدم‬ ‫ضغط‬ ‫الكلية‬ ‫تنظم‬ -
(
Renin
)
‫هرمون‬ ‫ينشط‬ ‫والذي‬
‫األنجوتنسينوجن‬
(
Renin Angitensin system
)
•
6
‫النخامية‬ ‫للغدة‬ ‫الخلفي‬ ‫الفص‬ ‫من‬ ‫البول‬ ‫ادار‬ ‫مضاد‬ ‫هرمون‬ ‫افراز‬ ‫تنظم‬ ‫كما‬ -
(
Antidiuretic hormone ADH
)
‫األلدوستيرون‬ ‫وهرمون‬
(
Aldosterone
)
‫الغدة‬ ‫من‬
‫الحمراء‬ ‫للكريات‬ ‫المولد‬ ‫الهرمون‬ ‫تصنيع‬ ‫معدل‬ ‫في‬ ‫تتحكم‬ ‫انها‬ ‫كما‬ ‫الجاركلوية‬
‫باألريثروبيوتين‬ ‫والمعروف‬
(
Erythropoitin
)
‫الهرمونات‬ ‫بعض‬ ‫تنظم‬ ‫كما‬ ،
. ‫كالبروستاقالندين‬

‫الكلية‬ ‫وظائف‬ ‫تابع‬
•
‫•لغذائي‬‫ا‬ ‫•لتمثيل‬‫ا‬ ‫عمليات‬ ‫في‬ ‫الكلية‬ ‫تشارك‬
(
metabolism
)
‫سكر‬ ‫لإلنتاج‬ ‫الدهنية‬ ‫او‬ ‫•بروتينية‬‫ل‬‫ا‬ ‫المواد‬ ‫تكسير‬ ‫طريق‬ ‫عن‬
‫سكرية‬ ‫او‬ ‫كربوهيداثية‬ ‫غير‬ ‫مواد‬ ‫من‬ ‫الجلوكوز‬
(
Gluconeogenesis
)
‫مرض‬ ‫وعند‬ ‫الصيام‬ ‫فترة‬ ‫اثناء‬
‫السكري‬
•
‫تصنيع‬ ‫في‬ ‫الكلية‬ ‫تشارك‬ ‫كما‬
‫د‬ ‫لفيتامين‬ ‫الفعال‬ ‫الشكل‬
(
D
)
( ‫الكلسيتيرول‬
Calcitiriol
‫امتصاص‬ ‫في‬ ‫يساعد‬ ‫والذي‬ )
.‫الدم‬ ‫الى‬ ‫الغذاء‬ ‫من‬ ‫الكالسيوم‬
•
‫إزالة‬ ‫في‬ ‫بوظيفتها‬ ‫القيام‬ ‫على‬ ‫الكلية‬ ‫مقدرة‬ ‫عدم‬ ‫حالة‬ ‫وفي‬
‫تسمم‬ ‫تسمى‬ ‫حالة‬ ‫تحدث‬ ) ‫•كلوي‬‫ل‬‫ا‬ ‫(الفشل‬ ‫الدم‬ ‫من‬ ‫الفضالت‬
( ‫باليوريميا‬ ‫الدم‬
Uremia
‫•لسام‬‫ا‬ ‫للمستوى‬ ‫اليوريا‬ ‫وصول‬ )
‫من‬ ‫اكثر‬ ‫الدم‬ ‫في‬
50
/‫ملجم‬
100
‫الطبيعية‬ ‫•ة‬‫ل‬‫(الحا‬ ‫دم‬ ‫مل‬
10
-
30
/‫ملجم‬
100
)‫دم‬ ‫مل‬
•
Dehydro-chlesterol
‫األغذية‬ ‫بعض‬ ‫وفي‬ ‫الجلد‬ ‫تحت‬ ‫يوجد‬
( ‫د‬ ‫فيتامين‬ ‫وصورة‬
vit-D
)
‫لإلستعادة‬ ‫قابلة‬ ‫غير‬
•
‫البنفسجية‬ ‫فوق‬ ‫األشعة‬ ‫وجود‬ ‫في‬
UV
• 1,2,3 dihydroxycholecalciferol
• 1,2,3 (OH)-D3
• In liver
•
25hydroxychlecalciferol
• In kidneys
•
Calcitriol 1,25 (OH)D3
•
‫من‬ ‫الكالسيوم‬ ‫امتصاص‬ ‫تنشط‬ ‫التي‬ ‫الصورة‬ ‫وهي‬
‫الدم‬ ‫الى‬ ‫الغذاء‬

2934
Renal Response to Hemorrhage

‫البول‬ ‫مكونات‬
Urine composition
•
‫قشائيا‬ ‫اصفر‬ ‫الطبيعي‬ ‫البول‬ ‫لون‬
•
‫الماء‬ ‫يكون‬
95
‫اما‬ ‫البول‬ ‫من‬ %
5
: ‫وتشمل‬ ‫فيه‬ ‫المذابة‬ ‫المواد‬ ‫من‬ %
•
1
‫بالجسم‬ ‫الضارة‬ ‫النيتروجينية‬ ‫المواد‬ ‫من‬ ‫الخاليا‬ ‫في‬ ‫البروتينية‬ ‫المواد‬ ‫هدم‬ ‫او‬ ‫ايض‬ ‫نواتج‬ -
.‫والكريتانين‬ ‫واالمونيا‬ ‫البولينا‬ ‫وحمض‬ ‫البولينا‬ ‫مثل‬
•
2
‫اإللكتروليتات‬ -
(
Electrolytes
)
‫والكلوريد‬ ‫واالمونيوم‬ ‫والبوتاسيوم‬ ‫الصوديوم‬ ‫أيونات‬ ‫وتشمل‬
‫والكبريتات‬ ‫والفوسفات‬ ‫والبيكربونات‬
•
3
.‫البول‬ ‫طريق‬ ‫عن‬ ‫الجسم‬ ‫تصيب‬ ‫التي‬ ‫الممرضة‬ ‫البكتيريا‬ ‫تنتجها‬ ‫التي‬ ‫السامة‬ ‫المواد‬ -
•
4
‫اليوروكروم‬ ‫اصباغ‬ ‫وخاصة‬ ‫األصباغ‬ -
(
Urochromes
)
‫تكسر‬ ‫من‬ ‫تشتق‬ ‫مصفرة‬ ‫اصباغ‬
‫في‬ ‫توجد‬ ‫احيانا‬ ‫والعقاقير‬ ‫األطعمة‬ ‫بعض‬ ‫اصباغ‬ ‫إليها‬ ‫يضاف‬ ، ‫الكبد‬ ‫في‬ ‫الحمراء‬ ‫الدم‬ ‫خاليا‬
‫البول‬
•
6
‫البول‬ ‫طريق‬ ‫عن‬ ‫منها‬ ‫الزائدة‬ ‫تستخلص‬ ‫الهرمونات‬ -
•
‫المخاطية‬ ‫والمواد‬ ) ‫البالزما‬ ‫(بروتين‬ ‫واأللبيومين‬ ‫والجلكوز‬ ‫الدم‬ ‫مثل‬ ‫العادية‬ ‫غير‬ ‫المكونات‬
‫الحصوات‬ ‫او‬ ‫البول‬ ‫مع‬ ‫تطرد‬ ‫او‬ ‫تغسل‬ ‫ثم‬ ‫ومن‬ ‫البولية‬ ‫المجاري‬ ‫داخل‬ ‫تتصلب‬ ‫التي‬
. ‫البول‬ ‫مع‬ ‫تخرج‬ ‫ثم‬ ‫تترسب‬ ‫التي‬ ‫الصغري‬

pH
• Normally 4.8 – 8.0
• Higher in alkalosis, lower in acidosis
• Diabetes and starvation ↓ pH
• Urinary infections ↑ pH
– Proteus and pseudomonas are urea splitters
125

Specific gravity
• Normal values 1.025 -1.032
• High specific gravity can cause precipitation of
solutes and formation of kidney stones
• When tubules are damaged, urine specific
gravity approaches that of glomerular filtrate
– 1.010 – remains fixed = 2/3 of nephron mass
has been lost
126

• Diabetes insipidus = 1.003
• Diabetes mellitus = 1. 030
• Emesis or fever = 1.040
127

Microscopic analysis
• Red blood cells – should be few or none
– Hematuria – large numbers of rbc’s in urine
– Catheterization
– Menstruation
– Inflamed prostate gland
– Cystitis or bladder stones
• Crystals –
– Infection
– Inflammation
– Stones
• White blood cells
– Pyuria
– Urinary tract infection
• Bacteria
128

Substances not normally present in urine
• Acetone
• Bile, bilirubin
• Glucose
• Protein – albumin
–Renal disease involving glomerulus
129

Blood Urea Nitrogen BUN
• Urea produced by breakdown of amino acids -
influenced by diet, dehydration, and hemolysis
• Normal range 10-20 mg/ dL
• If the GFR decreases due to renal disease or
blockage, or decreased blood flow to kidney -
BUN increases
• General screen for abnormal renal function
130

Creatinine clearance
• Creatinine is an end product of muscle
metabolism
• Muscle mass is constant; creatinine is constant
• Normal 0.7 – 1.5 mg/ dL in plasma
• Can then be compared to creatinine in urine
over 24 hour period to determine clearance
131

• Creatinine clearance is an indirect measure of
GFR and renal blood flow
• Creatinine is neither reabsorbed nor secreted,
just freely filtered.
• Amount excreted = amount filtered
• Useful to monitor changes in chronic renal
function
• Increases with trauma with massive muscle
breakdown
132

Diagnostic testing
• Inulin clearance not absorbed or secreted =
GFR
• PAH not absorbed ; actively secreted = renal
plasma flow (RPF)
133

6. Control of Calcium Excretion by the
Kidneys
(1) Calcium is both filtered and reabsorbed in the kidneys but
not secreted
(2) Only about 50 per cent of the plasma calcium is ionized,
with the remainder being bound to the plasma proteins.
(3) Calcium excretion is adjusted to meet the body’s needs.
(4) Parathyroid hormone (PTH) increases calcium
reabsorption in the thick ascending lops of Henle and distal
tubules, and reduces urinary excretion of calcium

An Overview of Urine Formation

INNERVATION OF THE KIDNEY
Nerves from the renal plexus (sympathetic nerve) of
the autonomic nervous system enter kidney at the
hilusinnervate smooth muscle of afferent &
efferent arteriolesregulates blood pressure &
distribution throughout kidney
Effect:
(1) Reduce the GPF and GFR and through
contracting the afferent and efferent artery (α
receptor)
(2) Increase the Na+
reabsorption in the proximal
tubules (β receptor)
(3) Increase the release of renin (β receptor)

Nerve reflex:
1. Cardiopulmonary reflex and Baroreceptor Reflex
2. Renorenal reflex
Sensory nerves located in the renal pelvic wall are activated
by stretch of the renal pelvic wall, which may occur during
diuresis or ureteral spasm/occlusion.
Activation of these nerves leads to an increase in afferent
renal nerve activity, which causes a decrease in efferent renal
nerve activity and an increase in urine flow rate and urinary
sodium excretion.
This is called a renorenal reflex response.

The series of mechanisms leading to activation of
renal mechanosensory nerves include:
Increased renal pelvic pressure increases the
release of bradykinin which activates protein kinase
C which in turn results in renal pelvic release of
PGE2 via activation of COX-2.
PGE2 increases the release of substance P via
activation of N-type calcium channels in the renal
pelvic wall.

Humoral Regulation
1. Antidiuretic Hormone (ADH)

• Retention of Water is controlled by ADH:
–ADH Release Is Controlled By:
• Decrease in Blood Volume
• Decrease in Blood Pressure
• Increase in extracellular fluid (ECF)
Osmolarity

2
.
Aldosterone
• Sodium Balance Is Controlled By Aldosterone
–Aldosterone:
• Steroid hormone
• Synthesized in Adrenal Cortex
• Causes reabsorbtion of Na+
in DCT & CD
–Also, K+ secretion

• Effect of Aldeosterone:
The primary site of aldosterone action is on the
principal cells of the cortical collecting duct.
The net effect of aldosterone is to make the kidneys
retain Na+
and water reabsorption and K+
secretion.
The mechanism is by stimulating the Na+
- K+
ATPase pump on the basolateral side of the
cortical collecting tubule membrane.
Aldosterone also increases the Na+
permeability of
the luminal side of the membrane.

Rennin-Angiotensin-Aldosterone
System
Fall in NaCl, extracellular fluid volume, arterial blood pressure
Juxtaglomerular
Apparatus
Renin
Liver
Angiotensinogen
+
Angiotensin I Angiotensin II Aldosterone
Lungs
Converting
Enzyme
Adrenal
Cortex
Increased
Sodium
Reabsorption
Helps
Correct
Angioten
sinase A
Angiotension III

Regulation of the Renin Secretion:
• Renal Mechanism:
1) Tension of the afferent artery (stretch receptor)
2) Macula densa (content of the Na+ ion in the
distal convoluted tubuyle)
• Nervous Mechanism:
Sympathetic nerve
• Humoral Mechanism:
E, NE, PGE2, PGI2

3. Atrial natriuretic peptide(ANP)
• ANP is released by atrium in response to
atrial stretching due to increased blood
volume
• ANP inhibits Na+
and water reabsorption,
also inhibits ADH secretion
• Thus promotes increased sodium excretion
(natriuresis) and water excretion (diuresis) in
urine

• 1) APs generated by stretch receptors
• 2) reflex arc generates APs that
• 3) stimulate smooth muscle lining bladder
• 4) relax internal urethral sphincter (IUS)
• 5) stretch receptors also send APs to Pons
• 6) if it is o.k. to urinate
– APs from Pons excite smooth muscle of bladder and relax
IUS
– relax external urethral sphincter
• 7) if not o.k.
– APs from Pons keep
EUS contracted

• Decline in the number of functional nephrons
• Reduction of GFR
• Reduced sensitivity to ADH
• Problems with the micturition reflex
Changes with aging include:

Ureters
•
‫المثانة‬ ‫في‬ ‫يصبا‬ ‫ان‬ ‫الى‬ ‫للكلية‬ ‫الكلوي‬ ‫الحوض‬ ‫من‬ ‫يمتدان‬ ‫طويالن‬ ‫انبوبان‬ ‫هما‬
‫البولية‬
(
Urinary bladder
.)
•
‫الحالب‬ ‫طول‬ ‫يتراوح‬
25
-
30
‫المثانة‬ ‫بإتجاه‬ ‫سمكا‬ ‫يزدادان‬ ‫وجداراه‬ ‫سم‬
‫وقطرة‬
1.7
‫سم‬
•
‫حيث‬ ‫المثانة‬ ‫الى‬ ‫البول‬ ‫جريان‬ ‫على‬ ‫الحالب‬ ‫لجدران‬ ‫التموجية‬ ‫الحركات‬ ‫تساعد‬
. ‫االحليل‬ ‫طريق‬ ‫عن‬ ‫الجسم‬ ‫خارج‬ ‫البول‬ ‫يطرح‬ ‫المثانه‬ ‫امتالء‬ ‫عند‬ ‫ثم‬ ‫يتجمع‬
•
: ‫طبقات‬ ‫ثالث‬ ‫من‬ ‫الحالب‬ ‫جدار‬ ‫يتركب‬
•
1
( ‫المخاطية‬ ‫الداخلية‬ ‫الطبقة‬-
Mucosa
‫مادة‬ ‫بإفراز‬ ‫تقوم‬ ‫انتقالية‬ ‫طالئية‬ ‫وهي‬ )
‫المذابة‬ ‫والمواد‬ ‫البول‬ ‫بحموضية‬ ‫تاثره‬ ‫من‬ ‫والحيلولة‬ ‫الحالب‬ ‫جدار‬ ‫لحماية‬ ‫المخاط‬
. ‫فيه‬
•
2
‫ناعمة‬ ‫او‬ ‫ملساء‬ ‫طولية‬ ‫عضالت‬ ‫من‬ ‫تتكون‬ ‫العضلية‬ ‫الطبقة‬ ‫او‬ ‫الوسطى‬ ‫الطبقة‬ -
.‫المثانة‬ ‫الى‬ ‫البول‬ ‫لدفع‬ ‫التموجية‬ ‫بالحركات‬ ‫تقوم‬ ‫للخارج‬ ‫ودائرية‬ ‫للداخل‬
•
3
‫الجسم‬ ‫بأنسجة‬ ‫الحالبين‬ ‫ربط‬ ‫على‬ ‫تساعد‬ ‫ليفية‬ ‫طبقة‬ ‫وهي‬ : ‫الخارجية‬ ‫الطبقة‬ -
. ‫مكانهما‬ ‫في‬ ‫لبقائهما‬
•
‫البولية‬ ‫والمثانه‬ ‫الحالبين‬ ‫بين‬ ‫الفتحة‬ ‫تحرس‬ ‫صمامات‬ ‫اى‬ ‫توجد‬ ‫ال‬

Urinary Bladder
•
.‫للخارج‬ ‫طرح‬ ‫قبل‬ ‫للبول‬ ‫كمخزن‬ ‫تعمل‬ ، ‫مطاطي‬ ‫عضلي‬ ‫كيس‬ ‫عن‬ ‫عبارة‬ ‫البولية‬ ‫المثانة‬
•
‫اسفل‬ ‫عند‬ ‫فهى‬ ‫الطفل‬ ‫عند‬ ‫اما‬ ‫البطن‬ ‫اسفل‬ ‫الى‬ ‫تصل‬ ‫تمتلئ‬ ‫وعندما‬ ‫الحوض‬ ‫داخل‬ ‫في‬ ‫توجد‬
.‫فارغة‬ ‫وهب‬ ‫حتى‬ ‫البطن‬
•
‫ثم‬ ‫الشكل‬ ‫كروية‬ ‫تبدو‬ ‫البول‬ ‫وصول‬ ‫عندما‬ ‫ولكن‬ ‫مثلثة‬ ‫هيئة‬ ‫على‬ ‫تبدو‬ ‫سميك‬ ‫جدار‬ ‫ذات‬ ‫فهي‬
. ‫امتالئها‬ ‫عند‬ ‫الشكل‬ ‫كمثرية‬
•
: ‫طبقات‬ ‫اربع‬ ‫من‬ ‫المثانه‬ ‫جدار‬ ‫يتركب‬
•
1
‫مادة‬ ‫وتفرز‬ ‫التمدد‬ ‫على‬ ‫قادرة‬ ‫انتقالية‬ ‫طالئية‬ ‫خاليا‬ ‫وهي‬ ) ‫(الداخلية‬ ‫المخاطية‬ ‫الطبقة‬ -
‫للحماية‬ ‫المخاط‬
•
2
‫والطبقة‬ ‫المخاطية‬ ‫الطبقة‬ ‫بين‬ ‫ما‬ ‫تصل‬ ‫ضامه‬ ‫انسجة‬ ‫عن‬ ‫عبارة‬ : ‫المخاطية‬ ‫تحت‬ ‫الطبقة‬-
‫العضلية‬ ‫الثالثة‬
•
3
‫الخارج‬ ‫في‬ ‫وطولية‬ ‫الوسط‬ ‫في‬ ‫ودائرية‬ ‫للداخل‬ ‫طولية‬ ‫عضالت‬ ‫من‬ ‫وتتكون‬ ‫العضلية‬ ‫الطبقة‬ -
‫الداخلية‬ ‫بالعاصرة‬ ‫يعرف‬ ‫ما‬ ‫الدائرية‬ ‫االلياف‬ ‫تكون‬ ‫البولي‬ ‫المجرى‬ ‫وعند‬.
(
Internal sphinchtor
)
‫هيكلية‬ ‫عضالت‬ ‫من‬ ‫تتكون‬ ‫والتي‬ ‫الخارجية‬ ‫العاصرة‬ ‫توجد‬ ‫العاصرة‬ ‫هذه‬ ‫وتحت‬
•
4
. ‫للمثانة‬ ‫العلوي‬ ‫السطح‬ ‫يغطي‬ ‫الذي‬ ‫البريتونيوم‬ ‫غشاء‬ ‫امتداد‬ ‫من‬ ‫تتكون‬ ‫المصلية‬ ‫الطبقة‬ -

Urinary Bladder
: ‫المثانه‬ ‫من‬ ‫البول‬ ‫خروج‬ ‫في‬ ‫التحكم‬
•
‫فتحة‬ ‫بينما‬ ‫العريضة‬ ‫العلوية‬ ‫الناحية‬ ‫من‬ ‫المثانة‬ ‫قاعدة‬ ‫عند‬ ‫الحالبان‬ ‫يفتح‬
. ‫السفلية‬ ‫الناحية‬ ‫من‬ ‫المثانة‬ ‫مثلث‬ ‫قمة‬ ‫في‬ ‫توجد‬ ‫اإلحليل‬
•
‫التبول‬ ‫طريق‬ ‫عن‬ ‫البول‬ ‫طرد‬ ‫يتم‬
(
urination
)
‫عصبية‬ ‫تحفيزات‬ ‫طريق‬ ‫عن‬
( ‫وذاتية‬ ‫ودية‬ ‫حركية‬
Voluntary and involentary
)
•
‫حوالي‬ ‫المثانة‬ ‫سعة‬ ‫تبلغ‬
700
-
800
‫تبلغ‬ ‫وعندما‬ ‫مل‬
350
-
400
‫مل‬
‫السفلي‬ ‫الجزء‬ ‫الى‬ ‫التحفيزات‬ ‫بنقل‬ ‫المثانه‬ ‫جدار‬ ‫في‬ ‫التمدد‬ ‫مستقبالت‬ ‫تبدأ‬
‫الحركية‬ ‫االعصاب‬ ‫يرسل‬ ‫بدورة‬ ‫والذي‬ ‫للمخ‬ ‫اشارة‬ ‫ليرسل‬ ‫الشوكي‬ ‫للحبل‬
‫يندف‬ ‫ثم‬ ‫ومن‬ ‫لترتخي‬ ‫للعاصرة‬ ‫ثم‬ ‫المثانة‬ ‫جدار‬ ‫في‬ ‫العضالت‬ ‫تنبه‬ ‫لكي‬
.‫اإلحليل‬ ‫او‬ ‫البولي‬ ‫المجري‬ ‫الى‬ ‫البول‬

Urethra

‫الجسم‬ ‫بخارج‬ ‫البولية‬ ‫المثانه‬ ‫قاع‬ ‫تصل‬ ‫طولية‬ ‫قناة‬ ‫عن‬ ‫عبارة‬ ‫اإلحليل‬

‫الرجل‬ ‫في‬ ‫طولها‬
20
‫المرأة‬ ‫وفي‬ ‫سم‬
4
‫وقطره‬ ‫سم‬
6
‫عنق‬ ‫من‬ ‫مم‬
. ‫الخارجية‬ ‫او‬ ‫األمامية‬ ‫اإلحليل‬ ‫فتحة‬ ‫الى‬ ‫المثانة‬

‫للرجل‬ ‫القضيب‬ ‫وسط‬ ‫تمر‬ ‫التناسلية‬ ‫البولية‬ ‫القناة‬ ‫هو‬ ‫يكون‬ ‫الرجل‬ ‫عند‬
، ‫البروستاتا‬ ‫غدة‬ ‫في‬ ‫االحليل‬ ‫يمر‬ ‫ذلك‬ ‫وقبل‬ ،‫األسفنجية‬ ‫باألنسجة‬ ‫وتحاط‬
.‫للمرأة‬ ‫الفرج‬ ‫اعلى‬ ‫مستقلة‬ ‫بفتح‬ ‫اإلحليل‬ ‫قناة‬ ‫تفتح‬ ‫المرأة‬ ‫في‬ ‫بينما‬

: ‫طبقات‬ ‫ثالث‬ ‫من‬ ‫اإلحليل‬ ‫جدار‬ ‫يتركب‬

1
‫ثم‬ ‫للداخل‬ ‫المخاطية‬ ‫الطبقة‬ -

2
‫ثم‬ ‫الوسط‬ ‫في‬ ‫الدموية‬ ‫بالشعيرات‬ ‫غنية‬ ‫رقيقة‬ ‫اسفنجية‬ ‫طبقة‬ -

3
‫الملساء‬ ‫العضلية‬ ‫الطبقات‬ ‫لتلك‬ ‫امتداد‬ ‫وهي‬ ‫للخارج‬ ‫العضلية‬ ‫الطبقة‬ -
‫المثانة‬ ‫في‬

Micturition
Once urine enters the renal pelvis, it flows through the ureters
and enters the bladder, where urine is stored.
Micturition is the process of emptying the urinary
bladder.
Two processes are involved:
(1) The bladder fills progressively until the tension in its wall
reses above a threshold level, and then
(2) A nervous reflex called the micturition reflex occurs that
empties the bladder.
The micturition reflex is an automatic spinal cord reflex;
however, it can be inhibited or facilitated by centers in the
brainstem and cerebral cortex.

Parasympathic S2-4
Plexus pelvicus (detrusor
contractility)
Sympathic Th10-L2
Nn.Hypogastrici (Bladder
neck relaxant)
Somatic S2-4 N.Pudendus
(external sphincter)

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