Unit 3.4 The Urinary System Flashcards
What does the urinary system consist of?
Two kidneys, two ureters, one urinary bladder and one urethra.
What is urine produced by?
The kidneys which filter out harmful and unwanted waste products from the blood and balance the water and salt content from the body.
What do healthy kidneys filter the blood to remove?
Waste products (mainly urea from the breakdown of protein and other nitrogen rich compounds) and excess water and salts.
Proteins are essential for growth and repair but have to be used almost immediately as excess protein that has been eaten cannot be stored - where are the amino acids that make up proteins broken down and what do they produce?
They are broken down in the liver producing urea as a toxic waste product which must be removed from the body mostly through the kidneys.
As well as filtering blood what can the kindney’s help control and produce?
They help control blood pressure and produce hormones and chemicals which help the production of RBCs and maintain healthy bone.
Before blood returns to the heart what does it pass through?
The kidneys.
The kidneys are very important in homeostasis - what is this?
Maintaining a constant internal environment in the body.
Each day, how many litre of blood do the kidneys process, and through what system?
About 190 litres of blood through 225km of tubes and millions of tiny filtering systems called nephrons.
Where are the kidneys located?
High in the abdomen, towards the back of the abdominal cavity either side of the spine.
What protects the kidneys?
They receive some protection from the lower rib cage. They are encased in fat which also helps to protect them from damage.
Each kidney functions as a blood filter, how?
Retaining useful chemicals and removing the harmful or unneeded ones.
In addition, it regulates the loss of water and salts from the body and maintains the pH of the blood, how?
By adjusting the acid-base balance as well as regulating blood volume and pressure.
What hormones do the kidneys produce and what do these do?
Calcitrol is the active form of vitamin D and helps to regulate calcium in the body.
Erythropoietin stimulates the production of red blood cells.
The enzyme renin is also produced by the kidneys and helps to regulate the blood pressure.
Each kidney has 3 main functioning areas, what are these?
Cortex - the outer part of the kidney, it contains the functional units of the kidney called nephrons
Medulla - this is the region of the kidney which contains the loops of henle, where water and salts are reabsorbed back into the blood.
Pelvis - this is where all the collecting ducts combine into the ureter which carries urine down into the bladder.
What is the size of the kidney?
Each adult kidney is about 12cm long, 6cm wide and 3cm thick.
The kidneys have plentiful blood supply - what is the renal blood slow?
Approximately 1200cm3 per minute (about 25% of all the blood in the body)
Each kidney contains about one million microscopic filtration structures, what are these called?
nephrons
What do the kidneys bear the major responsibility for eliminating?
Nitrogenous wastes (urea) toxins (from the breakdown of many different substances in the liver) and drugs from the blood.
What is the tiny nephron?
The functional unit of the kidney and the site of urine production.
What does the blood supply to each nephron consist of?
An afferent arteriole coming in from the renal artery and an efferent arteriole going out of the renal vein.
What is the ball of delicate capillaries called in between the arterioles?
Golmerulus.
What does the golmerulus sit in and what are the two structures called together?
The golmerulus sits in the bowmans capsule and the 2 structures together are called the Malpighian body.
which tubule leaves the Bowmans capsule?
The renal tubule.
What are the three separate regions of the renal tubule?
The first coiled tubule (or proximal convoluted tuuble), the loop of Henle and the second coiled tubule (distil convoluted tuble)
What does the renal tubule finally join into?
The collecting duct.
What does the efferent arteriole which exits the glomerulus divide to form?
A second set of capillaries which surround the renal tubule - this is where substances are reabsorbed into the blood.
Which 4 processes are involved in the filtration of blood and the production of urine?
Filtration, secretion, re absorption and synthesis
In filtration why do small molecules move from the capillary into the bowmans capsule?
Blood in the afferent arteriole is under high pressure having come from the abdominal aorta and the renal artery. As a result small molecules such as water, glucose, amino acids and salts and waste products such as urea pass through the capillary wall into the Bowmans capsule.
In filtration why do larger plasma proteins and blood cells no appear in healthy urine?
Large molecules such as larger plasma proteins and blood cells do not pass through in healthy individuals and so protein and blood cells are not found in normal healthy urine
What is the liquid that arrives in the Bowmans capsule known as?
The glomerular filtrate and has the same concentration of most substances as blood plasma.
How many litres of fluid are filtered into the kidney tubles every day?
About 150-190 litres.
What is the process of secretion in the production of urine?
If the concentration of some substances in the efferent arteriole is too high even after filtration, they can be actively secreted into the renal tubule and removed form the body in the urine - In this way waste products such as urea, uric acid and creatinine can be excreted.
What occurs in the process of reabsorption?
As the glomerular filtrate passes through the tubules about 99% of the water, all glucose and most of he mineral ions (salts) are reabsorbed into the blood by processes which include diffusion and active uptake (which requires energy) This is a highly selective process and the actual quantity of substances reabsorbed is dependent on the body’s needs at any one time - most of the 150-190 glomerular filtrate is reabsorbed back into the blood which is why you produce only between 1-2 litres of urine per day.
What is the synthesis process of the filtration of blood and the production of urine?
Kidney tissue can also support the activity of the liver by making substances which inactivate some toxic chemicals, making them inactive and safe. In this way the kidney contributes to the detoxification process.
Which part of the kidney collects urine from the collecting ducts of the nephrons?
The pelvis.
Where does the urine drain from the pelvis into?
The two ureters.
What are the ureters?
They are muscular walled, narrow tubes each about 30cm long and 6mm in diameter. They connect the kidney with the bladder.
