THE URINARY SYSTEM COMPONENTS 2 Kidneys 2 ureters 1 urinary bladder 1 urethra FUNCTIONS Excretion and filtration Regulation of blood volume and pressure Regulation of blood solutes Regulation of pH ID: 283511
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Slide1
FORM AND FUNCTION
THE URINARY SYSTEMSlide2
COMPONENTS
2 Kidneys2
ureters
1 urinary bladder
1 urethraSlide3
FUNCTIONS:
Excretion and filtration
Regulation of blood volume and pressure
Regulation of blood solutes
Regulation of pHRegulation of Red Blood Cell synthesis
Vitamin D synthesisSlide4
Regulation of blood cell synthesis
Production of Erythropoietin (a glycoprotein hormone) by the kidneys controls manufacture of new RBC’s
EPO is banned from use by professional athletesSlide5
The kidneys and Vitamin D
The skin synthesizes inactive Vitamin D and the kidneys convert it to the active form.Slide6
KIDNEY STRUCTURE
Kidneys are fist sized organs
They are located on the posterior abdominal wall on either side of the vertebral columnSlide7
THE NEPHRON
Each kidney is composed of millions of microscopic filtering units known as
nephrons
The
nephron
is the functional unit of the kidney, doing all of the actual workSlide8Slide9
INTERNAL STRUCTURESlide10
NEPHRON STRUCTURESlide11
FILTRATION
21% of blood pumped by the heart each minute flows through the kidneys
19% of the blood plasma that flows through the capillary bed of the
glomerulus
passes through the filtration membrane into
Bowman’s Capsule, the first part of the
nephron
.
The liquid is called the
filtrate.Slide12
What is in the
filtrate?
The filtrate should contain water, salts, glucose, amino acids, wastes such as urea, vitamins, minerals, drug metabolites, and ions (H+, Na+, and K+)Slide13
FILTRATION
The filtrate
should not
contain blood cells, proteins, or glucose (after initial
rebsorbtion
).
Bowman’s Capsule
GlomerulusSlide14
REABSORPTION
180 liters of filtrate are produced daily!
Plasma volume is only 3 liters so how many times daily is the entire plasma volume filtered?
60 times!
Only 1-2 L of urine are produced daily
Almost all of the water and useful solutes are reabsorbedSlide15
THE PROXIMAL CONVOLUTED TUBULE
Absorbs 65% of water and
NaCl
that passes through
The Na+/K+ pump transports ions from the filtrate into the tubule cells (
simple
cuboidal
epithelium
)
Important substances such as amino acids, glucose, vitamins, and minerals are reabsorbed into the
peritubular
capillariesSlide16
MORE REABSORPTION
The
descending Loop of
Henle
concentrates the filtrate by removing water through
osmosis
This reduces the filtrate volume by another 15%
Urea
is removed by facilitated diffusion
In
the
acsending
loop, the Na+/K+ pump moves Na+ to the interstitial fluid surrounding the loop.Cl- and K+ are moved by
symport
This part of the loop is impermeable to water, so it cannot follow the ions passivelySlide17
LOOP OF HENLESlide18
THE DISTAL CONVOLUTED TUBULE
About 80% of water and 90% of solutes have been removed from the filtrate so far
Helps regulate pH by controlling H+ elimination and retention.
Works with PTH to reabsorb Ca
2+
ions
Further water
reabsorption
is under hormonal control
ADH
-
A
nti-diuretic
H
ormone causes water to leave the filtrate and enter the tubule cellsSlide19Slide20
When do you need ADH?
Dehydration
Sleeping
Sudden blood loss (aka,
hypovolemic
shock
Vampire
Not a vampireSlide21
NITROGENOUS WASTE
The metabolism of proteins produces nitrogen-based waste products such as ammonia and urea
These two substances can be toxic if they remain in the body.
The kidneys remove them in the distal convoluted tubuleSlide22Slide23
THE COLLECTING DUCT SYSTEM
It is controlled by hormones like ADH and
Aldosterone
The cells are impermeable to water, so any water in the filtrate remains and is excreted with other wastes as
urine
The Collecting Duct Slide24
What if your kidneys are not working?
DIALYSIS TREATMENTSlide25
The Kidneys at Work
http://www.youtube.com/watch?v=glu0dzK4dbU
http://
www.youtube.com/watch?v=aQZaNXNroVY&feature=related