Excretory System

Hormonal Controls Dysfunction

Water Balance

Urine output depends on water input and water use An increase in water intake will increase water

output Exercise, or a decrease in water will cause a

decrease in water output Water balance is dependent on two systems:

(1) Nervous system

(2) Endocrine system

Regulating ADH

ADH (antidiuretic hormone) helps regulate the osmotic pressure of body fluids by acting on the kidneys to increase water reabsorption

When ADH is released, a more concentrated urine is produced, therefore conserving body water

ADH is produced when your brain receives a signal that tells it water is low

Osmoreceptors Osmotic pressure can:

(1) Increase when you decrease water intake or increase water loss

(2) Decrease when water intake increases

– Osmoreceptors are specialized nerve cells located in your brain that detect changes water pressure.

– When water levels drop in your blood, water moves out of your cells in your brain into the blood stream, causing the cells to shrink

– When the cells shrink, ADH is released

– This causes the kidneys to reabsorb more water, thus producing a more concentrated urine

Aldosterone

Works to increase water intake INDIRECTLY Causes sodium retention and therefore water follows

Released in response to decreased blood volume (large loss of body fluid – diarrhea or hemmorhage)

Kidney Disease or Problems

Diabetes Mellitus

– Inadequate secretion of insulin from pancreas (type I) or resistance to insulin by body cells (type II)

– Blood glucose levels rise

– Excess glucose remains in nephron and is excreted in urine

– Water remains in nephron – large volumes of urine

– Always thirsty Diabetes Insipidus

– Defect in ADH

– Large volumes of very dilute urine

Kidney Disease or Problems

Kidney Stones

– Precipitation of mineral solutes from the blood (most commonly too much calcium is absorbed from food)

– Causes:

• Dehydration

• Urinary tract infection (blockage of urine output)

Nephritis

Inflammation of the nephron Damage to blood vessels of glomerulus Proteins/RBC in nephron High osmotic pressure in nephron – water in Increased urine output (containing RBC and proteins)

http://www.youtube.com/watch?v=4UM90RxVbno&feature=relatedhttp://www.youtube.com/watch?v=16ewFJ-iQtw

http://www.youtube.com/watch?v=C2OdyEoE41I&NR=1

Dialysis

Hemodialysis

– Machine connects to vein

– Dialysis tubes with varying concentration gradients

– Removal of wastes/addition of important solutes and hormones

Peritoneal Dialysis

– Dialysis fluid pumped into peritoneal cavity (abdomen)

– Waste diffuses into cavity (fluid replaced several times daily)

Urinalysis

What is it? What information can be obtained from a urinalysis?