Excretion Powerpoint

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Excretion Powerpoint
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Urinary System
Based on Mader, S., Inquiry Into Life,
McGraw-Hill
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Anatomy of the Kidney
Based on Mader, S., Inquiry Into Life,
McGraw-Hill
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The Human Kidney Nephron
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Urine Formation in the Nephron

• Urine formation in the nephron is a continuous
  process starting in the glomerulus and bowmans
  capsule followed by the proximal convoluted
  tubules, loop of henle, distal convoluted tubules
  and finally ending in the collecting duct.

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Glomerulus and Bowmans Capsule

• Process Pressure filtration
• High blood pressure in afferent arteriole
• Small soluble molecules pushed out of blood
  through capillaries of glomerulus and collected
  in Bowmans capsule

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Filterable - small and soluble (pass from blood into Bowmans Capsule) Filterable - small and soluble (pass from blood into Bowmans Capsule) Non-Filterable large (remain in blood) Non-Filterable large (remain in blood)
Good stuff Bad Stuff Good Stuff Bad Stuff

Loss of all these permanently would result in dehydration, low blood pressure, starvation and death. Loss of all these permanently would result in dehydration, low blood pressure, starvation and death. Loss of all these permanently would result in dehydration, low blood pressure, starvation and death. Loss of all these permanently would result in dehydration, low blood pressure, starvation and death.
Water Glucose Salts Amino acids vitamins
Urea Uric acid
Blood cells Platelets Proteins
Histamines Penicillin
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Proximal Convoluted Tubules

• Selective Reabsorption
• Movement of good stuff from the filtrate to the
  proximal convoluted tubules into bloodstream of
  the peritubular capillary network.
• Glucose, amino acids, vitamins, minerals
• Accomplished by passive transport (diffusion,
  osmosis, and facilitated transport) and by active
  transport

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• Water is reabsorbed due to osmotic pressure
  caused by plasma proteins and ions in the blood
• Step 1 Na ions actively reabsorbed
• Step 2 Cl- ions follow passively
• Step 3 water moves passively into bloodstream
• Threshold levels Reabsorption occurs only
  until this is reached. For example, glucose has a
  high threshold level where as urea has a low
  threshold level

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Summary of Selective Reabsorption
Reabsorbed Filtrate components (move back into bloodstream) Nonreabsorbed Filtrate Components (remain in nephron tubules)

Mostly water Nutrients (glucose, amino
acids) Required salt (ions)
Some water Nitrogenous waste Excess salts (ions)
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Distal Convoluted Tubule

• Tubular Secretion
• Active transport of any unfilterable waste
  molecules or foreign substances (because they
  were too large to be originally filtered) from
  the blood into the distal convoluted tubules, so
  that these materials will become part of the urine

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Substance actively added to the filtrate in the
distal convoluted tubules

• Hydrogen ions
• Cretinine
• Drugs penicillin, histamines

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Loop of Henle and Collecting Duct

• Maintaining water-salt balance
• Counter-current exchange
• Excretion of hypertonic urine is dependent upon
  the reabosption of water from loop of henle
  collecting duct
• Loop of Henle, which descends into the renal
  medulla, is made up of two limbs the descending
  limb and the ascending limb

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Loop of Henle

• NaCl diffuses out of lower portion of ascending
  limb
• Na is actively pumped out of upper portion of
  ascending limb, Cl- follow passively
• Ascending limb is impermeable to water, therefore
  water cannot move through it
• As a result, osmotic gradient is set up within
  tissues of renal medulla. The concentration of
  salt is greater in the direction of the inner
  medulla.

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• Due to osmotic gradient between renal medulla and
  nephron tubules, water moves by osmosis out of
  both descending limb of loop of Henle and
  collecting duct.
• This movement of water out of filtrate is
  responsible for concentrating the urine into
  hypertonic solution

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NaCl out actively
Descending Limb
H2O
Increase of solute
Ascending Limb
Water comes out due to high Salinity
NaCl out passively
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Nephron
Video
Based on Mader, S., Inquiry Into Life,
McGraw-Hill
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Urine moves from the collecting ducts through the
kidney pelvis to the ureter
Based on Mader, S., Inquiry Into Life,
McGraw-Hill
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Incontinence (urine leakage)

• More than 10 million Americans experience
  incontinence
• Most do not seek treatment
• Treatment can improve or eliminate the problem
  90 of the time

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Causes of Incontinence
Stress incontinence leaking small amounts of
urine when coughing, lifting, or exercising Urge
incontinence the bladder suddenly and
unexpectedly contracts and expels urine Overflow
incontinence bladder cannot completely empty so
urine dribbles
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Treatments for Incontinence

• Kegel exercises to strengthen the urinary
  sphincter
• Medicines that increase the sphincters ability
  to contract
• Surgery to strengthen the pelvic muscles or to
  lift the bladder
• Retrain the bladder to increase its storage
  capacity (allowing 3-4 hours between urinating)
• Drugs to prevent urge incontinence
• Surgery to remove part of prostate gland if
  responsible for overflow incontinence

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Kidney stones form in the kidney pelvis. There
are types of stones.

• Calcium stones
• (most common)
• Uric acid stones
• Bacteria caused stones
• Cystein stones

Based on Mayo Clinic Health Letter
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Urinary Tract Infection (UTI)

• Second most common infection following
  respiratory infections
• UTI occur when bacteria (E. coli) from the
  digestive tract get into the opening of the
  urinary tract and multiply
• Bacteria first infect the urethra, then move to
  the bladder and finally to the kidneys
• UTI tend to occur more in women than men

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• Women may have more UTIs than men because
• they have a shorter urethra, allowing quicker
  access to the bladder
• the urethral opening is nearer the anus
• intercourse may result in UTIs in women

Based on Harvard Medical School Family Health
Guide
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Symptoms of UTIs

• Urge to urinate but only small amount of urine
  produced
• Pain and burning sensation in bladder
• Fever
• Blood in urine

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Diagnosis and Treatment

• Doctors check urine for white and red blood cells
  and bacteria
• Bacteria grown in culture to determine which
  antibiotic will work the best
• UTIs are treated with antibiotics and are often
  cured within 1 or 2 days

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Kidney Disease and Ethnicity

• Kidney disease 26 million Americans
• African Americans five times likely to require
  dialysis or kidney transplant
• Possible reasons
• Lack of health care
• Genetic component
• Diabetes
• Hypertension

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Alcohol Effects

• Alcohol suppresses ADH production by the
  pituitary
• Without ADH, higher amounts of water stay in the
  urine
• Urine with high concentrations of water leaves
  the body