Lesson 10 - Removing Waste

The Kidneys perform two key roles in the body. What are they?

Remove waste products, such as urea from the blood

Regulate the water content of the blood stream (osmoregulation)

Does Pure Water have a high or low Water Potential

High, if you add solutes, the potential becomes lower

What is Water Potential

The number of free water molecules in a cell or fluid

What is the start of the Nephron, and what is it

Glomerulus - A ball of capillaries

How has the Glomerulus adapted for ultrafiltration

The capillaries have a small lumen size, increasing blood pressure which squeezes water, urea, ions and glucose out of the blood and into the Bowmans Capsule

What makes up the Glomerular filtrate

Water, Urea, Glucose, Ions (WUGI)

Where does this filtrate go?

To the Bowman’s Capsule through the partially permeable membrane

What is the significance of this membrane being partially permeable

So large molecules like proteins and blood cells are not squeezed out

Finish this sentence - As the … flows along the Nephron, useful substances are … … back into the blood

filtrate / selectively reabsorbed

What takes place at the Proximal Convoluted Tubule

All glucose is reabsorbed to be used for respiration, using active transport

How has the PCT adapted for Selective Reabsorption

It has a lot of mitochondria for energy for active transport

It has a large surface area which increases the rate of active transport

What is the Loop of Henle

The site of Water Reabsorption by Osmosis

What is the Distal Convoluted Tubule

More selective reabsorption

By the time the filtrate gets to the collecting duct, what molecules/components remain and are excreted as urine?

Excess salts, urea, excess water

What is Osmoregulation

Osmoregulation is the control of the water content and mineral ion (salt) concentration of the body fluids to maintain a constant internal environment (homeostasis).

What is Homeostasis

The maintenance of constant internal conditions (temperature, pH, water potential) despite changes in the external environment

Which structure in the brain has osmoreceptors

Hypothalamus

What Hormone is secreted from the Pituitary Gland which is involved in Osmoregulation

Anti diuretic hormone (ADH)

Where in the Kidney does ADH have an effect

The collecting duct

What is the effect of ADH

ADH increases the reabsorption of water back into the blood

If someone dehydrated, describe the process of osmoregulation

The decreased water potential of blood is detected by osmoreceptors

More ADH is produced by the Pituitary gland

It travels in the blood to the collecting duct

Collecting duct becomes more permeable to water

More water is reabsorbed

Lower volume of concentrated urine is produced

In the Nephron, what is the role of the Capillary Network

As the filtered fluid flows along the nephron, these capillaries allow useful substances to be reabsorbed back into the bloodstream