Urine

2.75 Recall that urine contain water, urea and salts.

Urine contains salt and water and urea.

Salt and water affects the concentration of the tissue fluid.
Which is called Osmoregulation.

The removal of the urea is part of the process of the excretion of metabolic waste.

The excretion of salt, water and urea, varies and depends on the condition of which a person is working.

ADH

Describe the role of ADH in regulating the water content of the blood.

Anti Diuretic hormone is produced in a region of the brain know as the hypothalamus. Like all hormones in flow through the blood stream and it's target is the kidney.

It controls and alters the quantity of water in blood. So ADH has the ability to make the blood more or less concentrated.

ADH targets the collecting duct. It allows more water to come out of the collecting duct. It makes the collecting duct more porous.  the consequence is that the urine becomes more concentrated.

Glucose reabsorption

2.73 understand that selective re-absorption of glucose at the proximal convoluted tubule.

The same process for water, happens for glucose.
Except Urine does/should not contain glucose

If glucose is tested positive in Urine, this is a condition called Diabetes.

This is because in the proximal convoluted tubual, glucose is removed and is taken back into blood.

2.72 Water re-absorption

2.72 Understand that water is reabsorbed into the blood from the collecting duct.

When ultrafiltration occurs it tends to filter out more water and as the filtrate passes along the tubule, when i reaches the collecting duct, water is removed from the filtrate and returned back to blood vessels (blood stream)

The water is selected and it's been re-absorbed.

this is selective re-absorption of water. This occurs in the collecting duct.

Ultrfiltration

2.71 Describe ultrafiltration in the browmam's capsule and the composition of the glomerular filtrate.

Nephron - filtration of blood
results in filtered blood and urine

Urine is composed largely of water, salts and urea (n)

Ultrafiltration = the filtration of molecules

in the bowman's capsule, blood comes in through the afferent arteriole (wide) at high pressure, and leaves through the efferent arteriole (Narrow). This process develops a high pressure in the glomerulous.

The high pressure of blood forces the liquid (Plasma, contents dissolved in blood) out of the blood vessel, into the bowman's capsule, plasma turns into glomerula filtrate (H2O, Salts, A.A., Glucose and urea)

Nephron Structure

2.70 describe the structure of a nephron, to include Bowman's capsule and glomerulus, convoluted tubules, loop of Henle and collecting duct.

The outer lighter colored region is known as the cortex.

The darker inner region is the medulla.

In the middle, there is a space called the pelvic region. this is where the urine collects and drains down the ureter.

The different colours are cause by the millions of tubular structures in the kidney.

The tube starts on the edge of the medulla and moves directly upwards and out into the cortex. It then winds before dipping down into the medulla and then back up and then another short twisted section before hitting a dead end.

The "dead end" is called the bowman's capsule.

The tubular structure is known as the Nephron.

The tube is made up of twisted sections known as the convoluted tubules. The tube going through the cortex and medulla is known as the collecting duct.

The loop knot of blood vessels is known as the Glomerulous.

The first twisted section is know as the proximal (DCT)

There are millions of these Nephrons in a single kidney.

Urinary system

2.69 Describe the structure of the urinary system, including the kidneys, ureters, bladder and urethra.

The urinary system has two kidneys (right and left)
each has it's own separate blood supply.

They carry out the process of excretion, filtration and osmoregulation.

Each kidney has a ureter which leads to the bladder (carries urine).

There is a common bladder or simply 1 bladder for both ureters

Then then urine is conducted to the outside of the body to be excreted down the urethra which travels down through the vagina or penis.

Osmoregulation

2.68b Understand how the kidney carries out it's role of osmoregulation. 

Osmo referring to osmosis
Regulation referring to control

The tissue fluid which surrounds the cells in our body must be isotonic whith the cytoplasm of these cells. This means that the amount of water going into and out of these cells is equal and the cells will remain the same size, shape and maintain their function.

The danger to the tissue is that blood curculating into the tissue, would be concentrated causing a hypertonic (remove too much water) tissue fluid or very dilute cause a Hypotonic(add too much water) tissue fluid.

To maintain an isotonic, the composition of blood must be controlled.
Blood forms the tissue fluid.

The role of the kidney, is to control the composition of our blood.
Excess water and salts can be removed and excreted down through the ureter.

By controlling the content of water and salts in the blood, the kidney keeps the blood and therefore tissue fluid isotonic with the cell cytoplasm which maintains the function of the cells.

Excretion

2.68a Understand how the kidney carries out it's roles of excretion and osmoregulation.

Note: Urea contains Nitrogen, which is toxic in the body and cannot be stored.

The original form of Nitrogen and potentially toxic to the body are amino acids (normally used for growth). When they are in excess, they are toxic and must be removed.
This is the role of both the liver and the kidneys.

Stage 1: blood circulates to the liver and the amino acids are broken down and converted into the molecule we call Urea, which then circulates to both kidneys.

Stage 2: The kidneys will filter the urea from the blood and the urea will be added to water to form urine which drains down the ureters and collects in the bladder

Stage 3: the Urea is now removed from the body as Urine (through the bladder)

Stage 4: The filtered blood returns to the circulation in the veins with the toxic amino acids removed.

Excretion in plants and Humans

2.67a Recall the origin of carbon dioxide and oxygen as waste products of metabolism and their loss from the stomata of a leaf.

1. Photosynthesis = Co2 + H2O ---> C6H12O6 + O2 (the oxygen is an example of excretion


2. Respiration = C6H12O6 + O2 ---> ATP + CO2 + H2O (The carbon dioxide is given off by the plant as a waste. Another form of excretion).

2.67b Recall that the lungs, kidneys and skin are organs of excretion

1. The lungs excrete Carbon dioxide waste from respiration.

2.The kidneys excrete excess water, Urea (Nitrogen waste from amino acids) and Salts


3. The Skins excretes water and salts (Sweating) and a little bit of Urea (Not much)

The Excretion comes out through the sweat gland