2.75 Urine

recall that urine contains water, urea and salts.
-brain influences the function of the 2 kidneys.
-the 2 kidneys are filters our blood.
-the molecules which are removed which come down the ureter collects in the bladder and together these form urine.
-urine contains salts, water, urea.
-salt and water affects the composition of tissue fluid which is called osmoregulation.
-the removal of urea is part of the process of the excretion of metabolic waste.
-composition of urine (salts, water and urea) varies and depends on the condition which a person is operating.

2.74 ADH.

describe the role of ADH in regulating the water content of the blood.
-ADH- anti-diuretic hormone.
-ADH is produced in the region of the brain called the hypothalamus, it flows through the bloodstream and the target is the kidney.
-the effect of ADH is to control and alter the composition or the quantity of water in the blood.
-ADH can make the blood more or less concentrated- tissue fluid is isotonic to the cytoplasm of the cell.

-ADH targets the collecting duct- allows more water to come out of the collecting duct.
-collecting duct- where water is selectively reabsorbed into the blood.
-it is possible to increase the amount of water going into the blood by applying ADH.
-ADH makes the collecting duct balls have more pores- more water can escape from the collecting duct which goes back into the blood.
-the consequence of ADH secretion is that the urine coming from the collecting duct will be more concentrated and it will have a lower volume. (because of all the water escaping from the ADH)

 

2.73 Glucose reabsorption

understand that selective reabsorption of glucose occurs at the proximal convoluted tubule.
-selective- means that the molecule is selected (glucose)
-reabsorption- go from the glomerular filtrate and it will go back into the blood. remove the molecule from the blood and then put it back.
-filtration occurs in the bowman's capsule.
-items in the filtrate- glucose, water, salts and urea.
-water is removed back into the blood in the collecting duct.
-the end of the nephron is the urine and normally urine does not contain glucose.
-if you test urine for glucose and receive a positive test- indication of condition called diabetes.
-but yet there is glucose in the fluid at the start- in the bowman's capsule- this is because in the proximal convoluted tubule (proximal- first, convoluted- twisted, tubule- tube) section glucose is removed and is taken back into the blood.
-glucose is selectively reabsorbed into the blood in the proximal convoluted tubule.

2.72 Water re-absorption.

understand that water is reabsorbed into the blood from the collecting duct.
-the bowman's capsule- location of ultra filtration.
-blood comes into the kidney placed under high pressure and the dissolved content of the blood are forced into the bowman's capsule tube- glomerular filtrate (contains glucose, water, salts and urea)
-as the filtrate passes a long the tubular and when it reaches the collecting duct (vertical tube) water is removed from the filtrate. the water will go back into the bloodstream. water has been selected and reabsorbed into the blood- called selective reabsorption.
-selected reabsorption of water occurs in the collecting duct.

2.71 Ultrafiltration

describe ultrafiltration in the Bowman's capsule and the composition of the glomerular filtrate.
-nephron of the kidney- structure which carries out the filtration of the blood.
-results in filtered blood (clean blood) with waste products removed (urine)
-urine composed of water (the majority) salts and urea (molecule which contains nitrogen waste from body- toxic)
-urine comes out into the pelvic region and drains into the bladder.
-urine is produced at the beginning of the nephron called bowman's capsule (filtration process begins) known as ultra filtration.

-the filtration of blood begins with the blood arriving in the kidney in the nephron in the blood vessel called the afferent arteriole- the blood is coming in (high pressure blood from artery) (wide blood vessel)

-the twisted and coiled bit is called the glomerulus.

-the blood vessel that comes out of the bowman's capsule the diameter is smaller. (narrow blood vessel)

-the blood pressure increases in the glomerulus. the consequences is that the high pressure forces the liquid within the blood (plasma-component which dissolves in blood eg. water as solvent, salts, glucose, amino acids, urea.)- these things are all forced out of the blood vessel and into the space- inside of the bowman's capsule. 

-when the plasma is forced inside the bowman's capsule we change the name to filtrate. and because it is in the glamourous we call it the glomerula filtrate instead- contains water, salts, amino acids, glucose and urea.

-blood has been filtered by pressure due to the smaller restricted diameter of the blood vessel, generating a high pressure which forces the liquid to the tube.

2.70 Nephron Structure

describe the structure of the nephron to include the Bowman's capsule and the glomerulus converted tubules, Loop of Henle and the collecting duct.


-nephron- functional unit of the kidney. part that does the filtration and the controlling of the composition of the blood.
-branch of aorta- taking blood into the kidney is the renal artery.
-kidney filters the blood and the contents which are removed from the blood (excreted) are called urine which comes down the structure called the ureter and collects in the bladder for release.
-the filtered blood exits in the renal vein and returns to the vena cava.

-if we slice the kidney in half to show the internal structure we see different colour regions.
-lighter colour is called the cortex.
-darker colour is called the medulla.
-the space in the middle (lighter colour) is called the pelvic region. space is where the urine collects and drains down the ureter.

-the reason for the different colours is because the kidneys is made up of many million tubilar structures tubes.
-the tubes starts on the edge of the medulla and moves directly upwards through the medulla and out into the cortex and dips into the medulla again and back up and comes to a dead end.
-the dead end is called the bowman's capsule.
-the structure is called the nephron.

-above the dotted line is the cortex and below the dotted line is the medulla and the dotted line where the tube ends is the pelvic (where urine emerges).

-the tube is made up of twisted sections called the convoluted tubules.

-duct= tube.

-the dip is called the loop of Henle. (dips into the medulla)

-the dead end cup shape structure is called the bowman's capsule.

-the tight knot of blood vessels in the bowman's capsule is called the glomerulus.

-the first twisted section is called the proximal convoluted tubules (PCT)

-the second twisted section is called the distal convoluted tubules (DCT)

-the arrangement of this nephron structure which gives the different colour regions in the kidney.

-there are millions of nephrons in a single kidney.