2.75 - Urine

- Role of brain influencing the kidneys 

- Filtration of blood in the kidneys 

- Resulting in the waste going into the bladder and coming out as urine 

Urine contains - Salt, H2O and Urea

- Salt and H2O affected the composition of the tissue fluid - Osmoregulation 

- Removal of urea - part of the process of excretion of metabolic waste

- composition of Urine varies - depends on the condition of which the person is operating

2.74 - ADH.

ADH - Anti Diuretic Hormone 

Produced in the Hypothalamus (a part in the brain) - flows through the blood stream to it's target (the kidney)

- ADH - controls and alter the composition of water in blood - more or less concentrated

- Tissue is isotonic with the cytoplasm of the cell

ADH - targets the collecting duct (more accurate then kidney) 

- It allows more water to come out of the collecting duct 

- Collecting Duct - where water is selectively reabsorbed into the blood 

- possible to increase the amount of water going into the blood by adding the hormone, ADH

- It makes the collecting duct walls more porous - so that more water can escape from the collecting duct - this water goes back into the blood 

- consequence of ADH secretion - Urine coming out will be more concentrated and will have a lower volume 

- ADH response to a hot day 

- ADH response to a cold day 

- ADH response to dehydration

2.73 - Glucose re-absorption

Selective re-absorbtion means the molecule is selected (glucose) and re-absorbtion means it will go from the glomereule filtrate back into the blood

- filtration occurs in Bowmans capsule - contains glucose (in the plasma, along with H2O, Salt and urea) 

- end of nephron is where the Urine comes out - does not contain glucose 

- If you have glucose in your urine - it means you have diabetes

- Proximal Convoluted Tubule - glucose is removed and taken back into the blood 

2.72 - Water re-absorption

- In the Bowmans capsule - Ultrafiltration takes place 

- When filtration occurs, it filters out too much water

- As filtrate passes along the tube and reaches Collecting Duct 

- As it passes through the Collecting Duct - water is removes from the filtrate. 

- It goes back into the blood stream 

- Water has been selected and reabsorbed into the blood - Selected reabsorption 

2.71 - Ultrafiltration

Nephron of the kidney (shown) - carries out filtration of blood 

two things : Filtered blood (clean blood) and waste blood, Urine

Urine emerges from bottom of tubule - Composed of H2O, Salts and Urea(nitrogen waste) - goes into pelvic region

Bowmans capsule - where filtration begins - Ultrafiltration 

Filtration begins when blood comes in the Afferent arteriole (high pressure - wide) 

- starts to branch into twists and coils - Glomerulus 

- Blood vessel coming out - Efferent arteiole (smaller diameter) - develops high pressure 

- High pressure forces the liquid in blood (Plasma) out of the blood vessel into the inside of the Bowmans capsule

Plasma - H2O - Salts - Amino Acids - Glucose - Urea

When it is the bowmans capsule it is called Glomerula filtrate (contains plasma) 

Blood has been filtered by pressure due to the smaller diameter arteriole, generating a high pressure in the glomerulus, forcing the liquid into the tube

2.70 - Nephron Structure

Branch of Aorta taking blood into the kidney is called the Renal Artery 

Kidney filters the blood

Contents which are removed are called Urine (through Ureter) - collects in Bladder

Filtered blood goes through the Renal Vein 

Out region - Cortex

Inner region - Medulla

The Space - Pelvic region - where the urine collects and drains down the ureter

Different colour because the kidney is made up of millions of tubes

Tube starts on the edge of the medulla and goes out into the cortex, then winds and then drops down to the medulla again, then winds and comes to a dead end. 

The dead end is called the Bowman's capsule. 

The tube structure is called a Nephron

Above the dotted line - Cortex 

Below the dotted line - Medulla

Twisted sections - Convoluted tubules 

The dip - loop of Henlé 

Dead end cup shape structure - Bowman's Capsule 

Tight knot of blood vessels - Glomeruloui

First twisted section - Proximal convoluted tubules (PCT) 

Second twisted section - Distal convoluted tubules (DCT)

This nephron structure is what gives the different colours - millions of them