ADVANCED RENAL ANATOMY
AND PHYSIOLOGY
Body
Fluids and Gross External
Anatomy
Internal Gross Anatomy of Kidney
BODY FLUIDS
Water is the major component of
the body
 Makes up 45-80% of the body
weight

DISTRIBUTION OF BODY WATER

Two major compartments
• Intracellular (Inside cells)
• 2/3 of total body water
• Extracellular (Outside cells)
• 1/3 of total body water
• Intravascular (within a blood vessel)
• 5% of body weight
• Interstitial (water between cells, organs, tissues)
• 15% of body weight
DISTRIBUTION OF BODY WATER

Solvent
• Any liquid in which a substance can be
dissolved

Solute

Solution
• Substance being dissolved
• Stable mixture of two or more substances in a
single phase
DISTRIBUTION OF BODY WATER

Colloid
• State of matter where large
molecules are suspended in a liquid

Colloid dispersion
• Substance with components of one
or two phases
DISTRIBUTION OF BODY WATER

Movement of water

Osmotic pressure
• Water diffuses freely
• Osmotic pressure
• Force produced by solvent particles of a solution as
•
they move through a semi-permeable membrane
Depends on the number of particles in a solution
• Inversely proportional to the volume of a solvent
• Varies directly with temperature
DISTRIBUTION OF BODY WATER

Osmosis
•
•


The movement from high
concentration to low
concentration across a
membrane
Equalize concentration on
either side
Isotonic 0.9%
Hypertonic > 0.9%
•
Will draw water out of cells or
tissues
http://chsweb.lr.k12.nj.us/mst
anley/outlines/Diffosm
osAP/image196.gif
WHAT
IS THIS
GARBAGE?!!!
OSMOTIC PRESSURE

Typical membranes restrict passage of
colloidal particles

Proteins account for plasma’s high
colloid osmotic pressure
• Albumins
• 60% of plasma proteins
• Most abundant protein for transporting
CONTROL OF WATER
MOVEMENT

Regulated by
• Thirst
• Low water intake-levels of sodium increase
• Kidneys decrease urine volume
• High sodium-body increases amount of retained water
• Kidneys secrete ADH
• Water excretion by the Kidneys
Water Loss

Sensible water loss
• Urine and GI tract
• Vomiting, diarrhea, suctioning from stomach

Insensible water loss

• Artificial airways
• Increased ventilation
Tracheostomy patient may lose an additional
700ml/day of water if humidification is
inadequate
• Skin (Fever)
• Lungs (Inadequate humidity)
KIDNEYS
http://cache.eb.com/eb/image?id=1398&rendTypeId=4

Kidneys are
Retroperitoneal
• Lie behind
(outside) the lining
of the abdominal
cavity
http://www.owensboro.kctcs.edu/gcaplan/anat2/notes/Image131.gif
KIDNEYS

Maintain the volume and
concentration of body fluids by
• Filtration and re-absorption of sodium
• Water secretion regulated by antidiuretic hormone (ADH)
• Any material that is filtered and not
reabsorbed will be lost in urine
FUNCTION OF THE URINARY
SYSTEM

Homeostasis of the body
• Controlling volume and concentration
of blood
• Removing and restoring select
amounts of water and solutes
• Excreting select amounts of wastes
FUNCTION OF THE KIDNEYS
 Excrete
end products of
metabolism
 Control concentration of body
fluids
FUNCTION OF THE KIDNEYS

Erythropoiesis
• Mechanism to speed up production of
RBC’s
• Stimulated by oxygen deficiency in
the kidney cells
EXTERNAL ANATOMY

Renal Cortex

Three layers of tissue around
kidney
• Outer region of kidney
• Renal capsule
• Adipose capsule
• Renal fascia
INTERNAL ANATOMY
http://medicalimages.allrefer.com/large/kidney-anatomy.jpg
INTERNAL ANATOMY

Parenchyma

Nephron
• Area of cortex that includes pyramids
• Functional unit
RENAL BLOODFLOW

20% of blood pumped by
the heart each minute
enters the kidneys
through the renal artery
SUBSTANCES CLEARED FROM
THE BLOOD

Excess ions
• Sodium is 90% of the positive ions in extracellular
fluid
• Increased sodium=increase extracellular osmotic
pressure
• Decreased sodium-decreased extracellular osmotic
pressure
• Kidney controls concentration of sodium by regulating
amount of water in the body
• Secretion of ADH and thirst
Anti Diuretic Hormone (ADH)



ADH affects the Reabsorption of water in the
distal convoluted tubule and collecting duct
Increased ADH = increased Reabsorption of
water
Released by posterior pituitary gland via
stimulation from the hypothalamus
SODIUM

Primary positive ion in extracellular fluid

Osmoreceptors in hypothalamus
• Fluids (blood plasma, i.e. intravascular)
• Responsible for maintaining optimal salt and
•
water balance in the body
Sense balance of sodium and water
concentration in extracellular fluid
SODIUM

Osmoreceptors in hypothalamus
(cont)
• Loss of body water
• Hypernatremia
• Excess body water
• Hyponatremia
SODIUM


Same system can be used in medical treatment to
regulate body fluids
•
Diuretic drug given
•
Osmoreceptors in blood
• Kidneys excrete sodium
• Additionally sense lower sodium concentration in the blood
Hypertension is an early sign of renal failure
POTASSIUM

Normal 3.5-5 mEq/L
• Primary intracellular cation
• Important in maintaining fluid
and electrolyte balance in
body

Muscle contraction and
sending nerve impulses
• Action potential
POTASSIUM


Hypokalemia
•
•
•
Potentially fatal
Accompanies diarrhea/vomiting/increased diuresis
Symptoms include
• Muscle weakness
• Paralytic ileus
• ECG abnormalities (Arrhythmia, Cardiac arrest)
• Decreases reflexes
• Respiratory paralysis
• Alkalosis
May need to replace K whenever diuretics
are given
POTASSIUM

Increased potassium
• Metabolic acidosis
• Direct stimulation of kidney to transport
•
potassium into urine
Indirect stimulation of adrenal cortex to
produce aldosterone
• Kidney cells transport potassium into urine
CALCIUM

Deficit

Too much

Long term defect

Adults need 100-1300 mg calcium daily
• Affect bone and tooth formation
• Kidney stones
• Osteoporosis
RENAL FAILURE

Decrease in glomerular filtration rate

Chronic renal failure

Acute renal failure
• Increased serum creatinine
• Develops slowly w/ few symptoms
• Kidney diseases
• Rapidly progresses
• Characterized by oliguria
NEPHRON


Functional unit of the
kidney
Regulates water and
soluable substances
•
•
•
Filtering blood
Reabsorbing what is
needed
Excreting the rest as
urine
http://faculty.etsu.edu/currie/images/kidney1.jpg
NEPHRON





Eliminate waste
Regulate blood volume and pressure
Control levels of electrolytes and metabolites
Regulate blood Ph
Function regulated by endocrine system
•
•
•
ADH
Aldosterone
•
Hormone that governs Na+ Reabsorption in the kidneys
Parathyroid hormone
NEPHRON

Nephron composed of 2 sections
• Renal corpuscle
• Initial filtering component
• Filters out large solutes
• Delivers water and small solutes to renal
tubules
• Renal tubule
• Specializes in reabsorption and secretion
NEPHRON



Controls blood concentration and volume
•
Removing selected amounts of water and electrolytes
Regulate blood pH
•
Regulates secretion of H+ and reabsorption of HCO3-
Remove toxic wastes from blood
•
•
•
Remove materials from the blood
Return materials the body requires
Eliminate anything left over
NEPHRON FUNCTION


Filtration
•
Reabsorption
•
•
•

Filters a large portion of plasma through glomerular membrane to
nephron tubules
Movement of substances out of the renal tubules into the blood
capillaries
Fluid flows into tubules
•
Unwanted substances pass to urine
Substances needed by body reabsorbed back into plasma
(capillaries)
Secretion
•
Substances in plasma directly secreted into epithelial cells lining
tubules
•
Into tubular fluid
***Urine formed by three processes: Filtration ,Reabsorption, secretion
NEPHRON ANATOMY


Kidney composed of approximately
1,000,000 nephrons
Nephron composed of renal tubule and
vascular supply
• Renal corpuscle
• Cortex of kidney
• Renal tubule
• Dips into medulla
RENAL CORPUSCLE

Renal corpuscle contains

Glomerular filtrate
• Bowman’s capsule
• Glomerulus inside Bowman's capsule
• Site of initial urine formation
•
•

Fluid from the glomerulus to Bowman’s capsule
• Composition of fluid almost same as plasma
•
No significant amount of protein
Fluids further processed along the nephron to form urine
In the average adult, approximately 125 mL/min
(180 L/day) of fluid is filtered across the glomerulus
PROXIMAL CONVOLUTED
TUBULE

Fluid leaves the
Bowman’s capsule
and flows into the
proximal convoluted
tubule.
LOOP OF HENLE


Leaves the
proximal
convoluted tubule
and flows into the
loop of Henle.
Loop of Henle is
part of the nephron
and is found in the
medulla of the
kidney
DISTAL CONVOLUTED TUBULE


Cells lining the tubule have numerous mitochondria
• Allows active transport to take place
Ion transport regulated by the endocrine system
• Parathyroid hormone
• Reabsorbs more calcium
• Excretes more phosphate
• Aldosterone
• Reabsorbs sodium
• Excretes more potassium
COLLECTING DUCTS



Begins in the renal cortex
Extends deep into medulla
•
•
Urine passes by medullary interstitium
hypertonic
Collecting duct will become permeable to water
in presence of ADH
•
Can reabsorb as much as ¾ water by osmosis
*** Collecting duct not considered part of the full nephron
THE JOURNEY CONTINUES


Lower portions of collecting duct permeable to
urea
Urine leaves through the renal papilla
•
•
•
•
•
Into the renal calyces
Renal pelvis
Ureter
Bladder
Urethra
Start to Finish








Glomerulus
Proximal convoluted tubule
Loop of Henle
Distal convoluted tubule
Collecting tubule
Ureter
Urinary bladder
Urethra
FORCES CONTROLLING FLUID
EXCHANGE

Glomerular filtration rate (GFR)
• Quantity of glomerular filtrate formed each
minute in all nephrons of both kidneys
• Normal is 125 mL/min (180 liters/day)
FORCES CONTROLLING FLUID
EXCHANGE
http://blog.lib.umn.edu/trite001/humananatomy/glomerulus.jpg
http://www.gcrweb.com/HeartDSS/charts/fig4.jpg