The Urniary System

Question 1

What is the urinary system composed of?

Answer 1

Two kidneys
Two ureters
One urinary bladder
One urethra

Question 2

Describe the location of the kidneys

Answer 2

Located in the abdominal cavity between the peritoneum and the posterior abdominal wall which makes them retroperitoneal organs
The kidneys extend from vertebrae T12 to L3, the right kidney is slightly lower than the left due to the liver

Question 3

Describe the external anatomy of the kidneys

Answer 3

Around 10-12cm and 5-7cm wide and 3cm thick
Near the centre of the concave border is a deep vertical feature called the renal hilum, through which the ureter emerges from the kidney along with blood vessels, lymphatic vessels and nerves

Question 4

Complete diagram 1 of the urinary system on notability

Answer 4

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Question 5

Describe the anatomy of the renal pelvis

Answer 5

Formed from the upper portion of the Ureter
Branches into cup like structures called major calyces and minor calyces
Each kidney has 2-3 major and 8-10 minor calyces
Major and minor calyces, blood vessels, nerves and adipose tissue are situated in a cavity inside the kidney called the renal sinus

Question 6

Describe the anatomy of the renal medulla

Answer 6

Consists of 8-10 cone shaped areas called renal pyramids

The apex of each pyramid ends in renal papillae that opens into a minor calyx

Question 7

Describe the anatomy of the renal cortex

Answer 7

Extends from the renal capsule to the bases of the renal pyramids and the spaces between them
The cortex is divided into two regions
The outer cortical region
The inner juxtamedullary region

The portion of renal cortex that extend between the Renal pyramids are called renal columns

Question 8

What is a renal lobe

Answer 8

A renal lobe consists of a single renal pyramid, it’s overlying cortex and one half of each adjacent column

Question 9

Describe the renal Parenchyma

Answer 9

The renal cortex and renal pyramids (medulla ) consistute the renal parenchyma (the functional portion) of the kidney
Within the renal parenchyma there are about one million microscopic structures called nephrons (the functional units of the kidney)

Question 10

Describe the blood supply of the kidney

Answer 10

Kidneys receive 20-25%of the resting cardiac output via the right and left renal arteries
In adults, renal blood flow rough both kidneys is about 1200ml/min

Question 11

Memorize blood flow chart on notability

Answer 11

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Question 12

Describe the anatomy of the nephron

Answer 12

Each nephron consists of two part:
Renal corpuscle (where blood plasma is filtered)
Renal tubule (a passage for the filtered fluids)

Each renal corpuscle consists of the glomerulus, the glomerular (Bowman’s) capsule (a double walled epithelial cup)
The renal tubules consist of;
The proximal convoluted tubules 
Loop of Henle
Distal convoluted tubules 

The renal corpuscle and both convoluted tubules lie within the renal cortex, the loop of Henle extends into the renal medulla

Question 13

What happens to the wate material in the distal convoluted tubules

Answer 13

The distal convoluted tubules of several nephrons empty into a single collecting duct.
Collecting tubules then unite to form a large papillary duct which go to the collecting ducts then to the renal pelvis and ureter

Question 14

Describe the anatomy of the loop of Henle

Answer 14

The loop of henle connects the prox and distal convoluted tubules and consists of two parts
The descending limb of the loop of Henle dips into the renal medulla, it then makes a hairpin turn to the cortex as the ascending limb of the loop of Henle

Question 15

What are cortical nephrons

Answer 15

About 80-85% of the nephrons are cortical nephrons meaning they have short loops of Henle that lie mainly in the cortex
The blood supply of the short loop of Henle is from the peritubular capillaries

Question 16

What are juxtamedullary nephrons

Answer 16

About 15-20% of the nephrons are juxtamedullary nephrons which have long loops of Henle that lie mainly in the medulla
The blood supply of the long loop of Henle is from the vas’s recta
The long loops of Henle have a thin descending limb and a thick ascending limb

Question 17

Describe the main renal physiology

Answer 17

Have a number of homeostatic functions including
Regulation of blood ionic composition including sodium ions (Na+), potassium ions (K+), calcium ions (Ca2+), chloride ions (Cl-) and phosphate ions (HPO42-).

Regulation of blood PH by excreting hydrogen ions (H+)and conserving bicarbonate ions (HCO3-)

Regulation of blood volume by conserving or excreting water

Regulation of blood pressure by excreting the enzyme renin

Maintenance of blood osmolarity by separately regulating loss of water and loss of solutes in the urine, the kidneys maintain a relatively constant blood osmolarity close to 300 milliosmoles per litre .

The kidneys also
Stimulate the production of red blood cells through the secretion of erythropoietin
Excrete waste and foreign substances in urine

Question 18

What are the three processes that take place to form urine

Answer 18

Glomerular filtration
Tubular reabsorption
Tubular Secretion

Question 19

Where does glomerular filtration take place and what is removed?

Answer 19

Takes place in through the semi-permeable walls of the glomerulus and glomerular capsule
Water and a large number of small molecules pass through.
Blood cells, plasma proteins and other large molecules are unable to filter through and remain in the capillaries
The filtrate is the glomerulus is very similar in composition to plasma with the exception plasma proteins

Question 20

What are the three forces that glomerular filtration depends on?

Answer 20

Glomerular blood hydrostatic pressure (GBHP )
Capsular hydrostatic pressure (CHP)
Blood colloid osmotic pressure (BCOP)

Question 21

What is GBHP an d what causes it

Answer 21

Glomerular blood hydrostatic pressure,
Caused by the pressure in the glomerular capillaries, generallythe GBHP is around 55mmHg
It promotes filtrating by forcing water and solutes in the blood plasma through the the filtration membrane

Question 22

What is CHP and what causes it

Answer 22

Capsular hydrostatic pressure,
Caused by
The pressure exerted against the filtration membrane by fluid already in the capsular space and renal tube
CHP opposes the filtration and represents back pressure of about 15mmHg

Question 23

What is BCOP and what causes it

Answer 23

Blood colloid osmotic pressure
Caused by
The presence of proteins in blood plasma
It too opposes filtration and is about 30mmHg

Question 24

What is a healthy glomerular filtration rate in an adult?

Answer 24

Calculated by adding both kidneys filtrate volume together

Healthy GFR is about 125ml/min I.E 180L of dilute filtrate are formed each day by both kidneys
Most is absorbed with only 1-1.5 bing excreted as urine

Question 25

What substance does the body want to regain in tubular reabsorption

Answer 25

Water Sodium ions Glucose Amino acids

Question 26

What two types of transport are used in tubular reabsorption

Answer 26

``` Active transport (to transport substances against there conc gradient Passive transport (moves molecules down conc gradient without energy) ```

Question 27

What is the function of ADH and where is produce

Answer 27

Produced in the posterior lobe of the pit gland and increases permeability if the distal convoluted tubules increasing water absorption

Question 28

What is the function of aldosterone hormone and where is produced ?

Answer 28

Aldosterone hormone secreted by the adrenal cortex increases the reabsorption of sodium and water and the excretion of potassium

Question 29

What is atrial natriuretic peptide (ANP) and where is produced

Answer 29

Released in the atria of the heart as a response of stretching of the atrial wall It inhibits reabsoption of NA+ and water in the prox convoluted tubule and collecting duct This increases the excretion of Na+ in urine (natriuresis) and increase urine output (diuresis)

Question 30

What is parathyroid hormone (PTH)

Answer 30

It is secreted from the parathyroid glands and together with the hormone calcitonin, from the thyroid gland regulates the reabsorption of calcium from the distal collecting tubes. PTH increases the blood calcium level and calcitonin lowers it

Question 31

What happens in Tubular secretion

Answer 31

Substances not required and foreign materials (e.g. drugs may not be cleared from the body by filtration because of the short time it remains in the glomerulus) are cleared by secretion into the convoluted tubules and are excreted from the body in the urine

Question 32

Describe the external anatomy of the ureters

Answer 32

Carry urine from the kidneys to the bladder About 25-30cm with a diameter of 3mm Passes downwards through the abdominal cavity into the pelvic cavity to pass obliquely through the posterior wall of the bladder Because of this arrangement as the urine vol increases the United’s are compressed and the openings of the bladder are blocked This prevents the back flow of urine into the ureters towards the kidneys

Question 33

What are the three layers of the ureter wall

Answer 33

An outer covering of fibrous tissue A middle muscular layer consisting of interlacing smooth muscle fibers An inner layer of mucosa consists of transitional epithelium Peristalsis of the smooth muscle propels urine along the ureter, occurring several times per min

Question 34

Describe the external anatomy of the urinary bladder

Answer 34

A hollow, distensible muscular organ situated in the pelvic cavity posterior to the pubic symphysis. In males, it is anterior to the rectum, in females anterior to the vagina and inferior to the uterus It has an average capacity of 700-800ml Although it is smaller in females

Question 35

Describe the internal anatomy of the urinary bladder

Answer 35

Wall composed of three layers Outer layer of loose connective tissue containing blood and lymphatic vessels and nerves Middle layer consists of interlacing smooth muscle fibers and elastic tissue The inner mucosa consists of transitional epithelium The internal urethral sphincter controls outflow of urine and is not under voluntary control

Question 36

Describe the anatomy of the urethra

Answer 36

Extends from the neck of the bladder at the internal urethral orifice to the exterior at the external urethral orifice The female urethra is about 4cm and 6mm in diameter, it runs posteriorly to the pubic symphysis and opens at the external urethral orifice just in front of the vagina It is controlled by the external urethral sphincter which is under voluntary control The male urethra is 20cm passing through the prostate then through the deep muscles of the peritoneum and finally though the penis The urethra consists of 2 layers An inner mucosa -continuous with that of the bladder and is made up of smooth muscle fibers which autonomic The outer mucosa is made up of striated muscle fibers which is under voluntary control