THE URINARY SYSTEM. FORM AND FUNCTION. 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 Regulation of Red Blood Cell synthesis Vitamin D synthesis. - PowerPoint PPT Presentation
THE URINARY SYSTEM
FORM AND FUNCTIONTHE URINARY SYSTEM
COMPONENTS2 Kidneys2 ureters1 urinary bladder1 urethra
FUNCTIONS:Excretion and filtrationRegulation of blood volume and
pressureRegulation of blood solutesRegulation of pHRegulation of
Red Blood Cell synthesisVitamin D synthesisRegulation of blood cell
synthesisProduction of Erythropoietin (a glycoprotein hormone) by
the kidneys controls manufacture of new RBCs
EPO is banned from use by professional athletesThe kidneys and
Vitamin D
The skin synthesizes inactive Vitamin D and the kidneys convert
it to the active form.KIDNEY STRUCTUREKidneys are fist sized organs
They are located on the posterior abdominal wall on either side of
the vertebral column
THE NEPHRONEach kidney is composed of millions of microscopic
filtering units known as nephronsThe nephron is the functional unit
of the kidney, doing all of the actual work
INTERNAL STRUCTURE
NEPHRON STRUCTURE
FILTRATION21% of blood pumped by the heart each minute flows
through the kidneys19% of the blood plasma that flows through the
capillary bed of the glomerulus passes through the filtration
membrane into Bowmans Capsule, the first part of the nephron.The
liquid is called the filtrate.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+)
FILTRATION
The filtrate should not contain blood cells, proteins, or
glucose (after initial rebsorbtion).Bowmans
CapsuleGlomerulus13REABSORPTION180 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 dailyAlmost all of the water and useful solutes are
reabsorbedTHE PROXIMAL CONVOLUTED TUBULEAbsorbs 65% of water and
NaCl that passes throughThe 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 capillariesMORE
REABSORPTIONThe descending Loop of Henle concentrates the filtrate
by removing water through osmosisThis reduces the filtrate volume
by another 15%Urea is removed by facilitated diffusionIn the
acsending loop, the Na+/K+ pump moves Na+ to the interstitial fluid
surrounding the loop.Cl- and K+ are moved by symportThis part of
the loop is impermeable to water, so it cannot follow the ions
passivelyLOOP OF HENLE
THE DISTAL CONVOLUTED TUBULEAbout 80% of water and 90% of
solutes have been removed from the filtrate so farHelps regulate pH
by controlling H+ elimination and retention.Works with PTH to
reabsorb Ca2+ ionsFurther water reabsorption is under hormonal
controlADH- Anti-diuretic Hormone causes water to leave the
filtrate and enter the tubule cells
When do you need ADH?
DehydrationSleepingSudden blood loss (aka, hypovolemic
shockVampireNot a vampireNITROGENOUS WASTEThe metabolism of
proteins produces nitrogen-based waste products such as ammonia and
ureaThese two substances can be toxic if they remain in the
body.The kidneys remove them in the distal convoluted tubule
THE COLLECTING DUCT SYSTEMIt is controlled by hormones like ADH
and AldosteroneThe cells are impermeable to water, so any water in
the filtrate remains and is excreted with other wastes as urine
The Collecting Duct What if your kidneys are not working?
DIALYSIS TREATMENTThe Kidneys at
Workhttp://www.youtube.com/watch?v=glu0dzK4dbUhttp://www.youtube.com/watch?v=aQZaNXNroVY&feature=related
