ESSENTIAL QUESTION

HOW DOES WATER CONSUMPTION

AFFECTTHE

KIDNEY FUNCTION AND

EXCRETION?

UNIT QUESTION

1) WHY IS WATER IMPORTANT TO THE KIDNEY? http://www.abpischools.org.uk/page/modules/homeostasis_kidneys/kidneys4.cfm?age=Age%20range%2014-16&subject=Biology

Humans have two kidneys. They are complexorgans that are vital for life. The kidneys produceurine which is made up of waste products, excess mineral ions and excess water from the body

The main job of your kidneys is to regulate the amount of water in the body and

balance the concentration of mineral ions in the blood. They also get rid of waste

products, especially a nitrogen-containing compound called urea. At the same time

they hold on to useful substances such as glucose and protein so none is lost from

the body. Our kidneys are complex organs. They regulate the amount of water lost

from the body and get rid of waste products, especially urea. Urea is made when any

excess amino acids are broken down in your liver. The amino acids come from

protein you have eaten.

About 180 litres of water filters through your kidneys every day, but only about 1.5

litres finally leaves your body asurine.

Where are the kidneys?Your kidneys are just under your ribcage above the small of your back. The blood

arrives through the renal arteryand leaves in the renal vein. The kidneys produce

urine which is carried to the bladder along the ureter. The urine is kept in the bladder

until you urinate. The muscular sphincters relax and let urine out of the body through

the urethra. The diagram below shows the structure of the kidneys and their position

in your body.

A)HOMEOSTATISOur body is made up of millions of cells. For them to work properly, the conditions

inside our body need to be as constant as possible. However everything we do tend

to change our internal conditions. We take millions of new molecules into our body

when we eat and digest food, we release heat energy every time we move about, the

amount of water we take into and lose from our body varies all the time and our cells

are constantly producing poisonous waste.

Homeostasis describes the functions of our body which work to keep our internal

environment constant within a very narrow range. One of your most important organs

of homeostasis is the kidney. The kidney's most important work is keeping 

homeostasis. Homeostasis means that the body keeps a stable environment inside

itself. The body wants to have the consistent and proper amount of water, salt,

and acid in the blood. This makes the body work better. The kidney keeps these

things constant. If there is too much water, the kidney puts more water in the urine. If

there is not enough water, the kidney puts less water in the urine.

b) OSMOTIC PRESSURE AND FORMATION OF URINEThe water balance is so important in homeostasis as substances are moving in and

out of the cells of our body all the time and these concern diffusion, osmosis

and active transport.

Diffusion is the spreading out of the particles of a gas or any substance in solution. It

is caused by the random movement of the particles. The higher the temperature, the

faster the particles move and the faster diffusion takes place. Diffusion results in the

overall (net) movement of particles from an area of high concentration to an area of

low concentration down a concentration gradient. If there is a big concentration

difference diffusion will take place more rapidly than if there is only a small

concentration difference. The difference in concentration is known as the

concentration gradient.

Diffusion is very important in the body for the movement of substances eg the

movement of oxygen from the air into the blood and carbon dioxide out of the blood

into the air in the lungs, or the movement of glucose from the blood to the cells.

Osmosis takes place when two solutions are separated by a partially permeable

membrane. A partially permeable membrane lets some particles through but not

others. Cell membranes are partially permeable. Water can move freely through

them but other particles, such as sugar molecules, cannot.

Osmosis is the movement of water through a partially permeable membrane down a

concentration gradient from a dilute solution (where there is a high concentration of

water) to a concentrated solution (where there is a relatively low concentration of

water).

The movement of water by osmosis is the main reason why it is so important to

control the water balance of the body.

Active transport uses energy to move substances against (up) a concentration

gradient or across a partially permeable membrane. In active transport a special

transport protein in the cell membrane picks up the useful particle on one side of the

membrane. The transport protein then rotates through the membrane and releases

the particle on the other side of the membrane. This uses energy from cellular

respiration.

Active transport is used to move substances into cells and out of cells. Cells which

carry out a lot of active transport often have lots of mitochondria to give them the

energy they need. Active transport is important in the kidney for hanging on to the

substances needed by the body such as glucose and some sodium ions. According to Pratt et all,(2001),osmotic pressure is the pressure which needs to be

applied to a solution to prevent the inward flow of water across a semipermeable

membrane.[1] It is also defined as the minimum pressure needed to nullify osmosis.

The phenomenon of osmotic pressure arises from the tendency of a pure solvent to

move through a semi-permeable membrane and into a solution containing a solute to

which the membrane isimpermeable.And the osmotic pressure determines the flow of

water in urine filtration - the water will follow the direction of solute flow.

Each cell in your body is effectively a bag of chemicals contained in a partially

permeable membrane. Water and small particles such as some mineral ions can

pass in and out of the membrane freely down concentration gradients. However

many chemicals such as glucose, amino acids and proteins cannot pass through the

membrane at all - they are too big.

The cells of your body are bathed in tissue fluid. This is also a solution of salts,

sugars and other chemicals in water. It is important that the concentration of

dissolved substances in the tissue fluid is the same as the concentration of the cell

contents (an isotonic solution). If the solution outside the cell is more concentrated

than the cell contents (a hypertonic solution), water will move out of the cell by

osmosis. If the solution outside the cell is less concentrated that the cell contents

(a hypotonic solution), then water will move into the cell by osmosis.

National Kidney Foundation

Beside the water-timer gadgets, we also invited the lectures from National Kidney Foundation to give up a speech to the students in our school. They are mainly take about the roles of kidney in our body, symptoms of kidney diseases and awareness of kidney.

photo: students is pay attention for the speech of kidney.

Photo: lecture from national kidney foundation is giving a speech.

The main roles of kidney in our body is to filter the waste in blood such as sodium, chloride, potassium, and urea and remove them in the form of urine out from our body.

The symptoms of the kidney diseases is swelling of face and legs, dull skin, moon face and others. We also learn the knowledge to appreciate our kidney to damage. The lectures had tells us to do not eat too much food that high concentration of salt like junk food, drink more water and go to toilet regularly .We have to drink at least 2000ml water a day. Moreover, they also give

the quiz for the students to answer, this will test how many is the students understanding.

Through this speech, we gain many knowledge of our kidney and how to appreciate our kidney in the well condition.