Wize High School Grade 11 Biology Textbook > Human Physiology: The Excretory System [Under construction]
The Excretory System & Connections to Other Organ Systems
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Water/Ion Balance
- this lesson will cover water and ions and their concentrations in our blood/plasma
- too much water = swelling = hypertension
- not enough water = shriveling = hypotension
- high ion concentrations will draw water to that area by osmosis (more water reabsorbed into our bodies)
- low ion concentrations will have a higher water concentration to begin with, but will need to gain more ions to be within the "normal" range for our body (more ions reabsorbed by our body
Wize Concept
The organ system of our body that is most important in regulating water and ion levels is the KIDNEY!
Two Main Hormones
- Vasopressin (ADH) - increases water in the blood
- Aldosterone - increases ions in the blood
Vasopressin (ADH)
- important for water reabsorption
- secreted from posterior pituitary, made by hypothalamus
- stimulated by receptors found in the walls of arteries that can tell when the walls are stretched or not.
- ADH released when there is not enough water in the blood ––> no stretch detected in artery walls
- binds to receptors on collecting tubule cells and causes aquaporin to be put into the membrane
- dysfunction results in diabetes
commons.wikimedia.org
Aldosterone
- important for ion reabsorption (Na+ and K+)
- secreted from the adrenal gland
- regulated by negative feedback
- also partly regulated by renin - a hormone made at the beginning of the nephron
Steps of ion Reabsorption using Aldosterone
- aldosterone binds to a receptor on a cell in the ascending loop of Henle
- receptor sends a signal to make more Na+ and K+ channels
- channels are made and put into the cells so more Na+ and K+ can return to the blood
Big Picture Summary
The posterior pituitary and the adrenal gland will release their respective hormones to act on the kidney. Under the influence of these hormones, the kidney will allow reabsorption of water and ions back into the blood stream. When ADH and Aldosterone are active, urine volume DECREASES and blood volume INCREASES. When these hormones are not present, the opposite occurs.
- ex. when you drink alcohol, the alcohol actually inhibits the function of ADH -–> less water is reabsorbed back into the body = more water in urine ––> thats why you have to pee all the time!
ar.wikipedia.org
Mark Yourself Question
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Mark Yourself Question
- Grab a piece of paper and try this problem yourself.
- When you're done, check the "I have answered this question" box below.
- View the solution and report whether you got it right or wrong.
Mark Yourself Question
- Grab a piece of paper and try this problem yourself.
- When you're done, check the "I have answered this question" box below.
- View the solution and report whether you got it right or wrong.