Renal System

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Renal System
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RemindersYou must sign up for lab this week! (Go
to vireo.biology.sjsu.edu) - Space is limited -
so dont wait!If you plan not to do this lab -
you do not have to sign upWhere do the sample
cups go?
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In preparation for lab

• Do not eat or drink anything for about 2 to 3
  hours prior to coming to lab.
• If you typically stop in the restroom before
  coming to lab wait! Youll appreciate this
  advice when you start lab
• You can bring a triple cappuccino into lab this
  week do not start to consume it until you
  arrive in lab (dont cheat if you can exercise
  some self-control, you will get great results).

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By the end of todays lecture, you should be able
to answer the following...
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• Imagine you are running the Bay to Breakers. Why
  would your body have a tougher time adjusting to
  physical exertion if you were drinking beer
  instead of water?

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An Introduction to The Urinary System (Flash
Animation)
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Urinary Systems Contribution to Homeostasis
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• Regulates body water levels
• Excess taken in is excreted
• Output varies from 1/2 liter/day to 1 liter/hour
• Regulates nitrogenous and other solute waste
• Nitrogen from amino acids made into urea as waste
• Others sodium, chloride, potassium, calcium,
  hydrogen ions, creatinine

Slide 15.1
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Urinary System Homeostasis
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• Maintaining balance between WATER and SOLUTES.
• What are SOLUTES? Essentially they are stuff in
  solution. Solutes you have known and loved...
• glucose
• sodium
• urea (ammonia uric acid)
• uric acid (due to breakdown of amino acids)
• vitamins

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How water is gained and lost
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• We gain water from
• ingested liquids solid foods
• metabolic reactions
• We lose water due to
• excretion in urine
• evaporation (lungs and skin)
• sweating
• elimination in feces

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How solutes are gained and lost
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• We get solutes from
• ingested liquids solid foods
• secretions from cells
• respiration
• metabolism
• We lose solutes due to
• excretion in urine (e.g., uric acid)
• respiration (CO2)
• sweating

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Deep thoughts for the day Why does beer make you
pee more often?
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And which will make you pee more frequently
coffee or water?
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Blame it on ADHAnti-diuretic hormone.

• A diuretic is something that makes you urinate.
  An anti-diuretic will make you reabsorb water so
  that you do not urinate (as much).
• When your body detects that your blood contains
  too little water (and therefore, causing a drop
  in blood pressure), ADH will kick in and your
  kidneys will work to conserve water.
• Secrete ADH Decrease in urine volume
• When your body detects that your blood has too
  much water, ADH will be inhibited and your
  kidneys will work to excrete the excess water.
• Inhibit ADH Increase in urine volume

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• If you inhibit ADH, what will happen?
• Whatever you are drinking becomes a diuretic.
• Alcohol inhibits ADH.
• Therefore, beer makes you pee more frequently
• Caffeine inhibits ADH.
• Therefore, coffee makes you pee more frequently

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Another deep thought for the day Why does
Chinese food make you retain water?
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Aldosterone
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• Sodium is a CRUCIAL solute!
• Sodium is vital in muscle and neural function.
• Sodium fluctuates in the body. For example
• we lose it when we sweat
• we keep it from being absorbed when we drink
  caffeine
• Where sodium goes, water follows...
• Aldosterone is a hormone that helps adjust sodium
  reabsorption.

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How is urine formed?
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• The kidneys first filter water and solutes from
  the blood.
• About 2/3rds of the water and solutes will be
  reabsorbed by the kidneys.
• The rest will be secreted via urine.

• Why we need to do this
• allows us to get rid of excess H and K ions
• prevents waste products such as uric acid from
  building up (kidney stones occur when this
  doesnt work very well)
• prevents substances such as pesticides and
  antibiotics from building up

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Kidneys
Regulate body water volume
Regulate body concentrations of inorganic ions
(esp. sodium)
Remove metabolic waste (primarily urea) from the
blood
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Kidneys
Help regulate blood volume and blood pressure
Help regulate acid-base balance and blood pH
Stimulate production of RBC (the kidneys secrete
erythropoietin)
Activate Vitamin D
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Ureters
Transport urine to the bladder
Urinary Bladder
Stores urine until elimination
Urethra
Transports urine to body surface
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Ureters
Transport urine to the bladder
Urinary Bladder
Stores urine until elimination
Urethra
Transports urine to body surface
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So, why is beer maybe not the best choice for
hydration during physical activity?
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