Theme 1: The Urinary System

Question 1

What is the urinary system responsible for?

Answer 1

The urinary system is responsible for the creation, storage and excretion of waste products. These waste products are excreted through urine

Question 2

What is the urinary system made up from?

Answer 2

1. The kidneys
2. The ureters
3. The bladder
4. The urethra

Question 3

What is the 5 function of the kidneys include?

Answer 3

Filtration of the blood to remove waste products considered toxic to the body.

Excretion of waste products such as urea and creatine in the form of urine.

Homeostatic regulation of blood pressure, electrolytes, acid-base balance and fluid volume in the blood.

Release of erythropoietin to trigger red blood cell production in the bone marrow.

Aids the production of vitamin D.

Question 4

Label the urinary system

Answer 4

A - kidney
B - inferior vena cava
C - abdominal aorta
D - renal artery
E - renal vein
F - bladder
G - ureter
H - urethra

Question 5

What are the kidneys?

Answer 5

Bean shaped organs at the middle of your back just underneath the rib cage

Question 6

What are the main function of the kidneys?

Answer 6

These organs are roughly the size of our fists, and are the major powerhouses of filtering our blood and removing waste products by producing urine.

Question 7

What are retroperitoneal organs?

Answer 7

Located in respect to the peritoneum, because of the position to the kidney, the right kidney sits slightly inferior to the left kidney

Question 8

The outer layer of the kidney

Answer 8

They are anchored into place with a combination of dense connective tissue and adipose tissue

1. First layer is the renal fascia > connective tissue and connects kidneys to adrenal gland and surrounding structures
2. Perirenal fat capsule layer of adipose tissue that provides protection from trauma and jolts
3. The final layer is the renal capsule which is another connective tissue layer that prevents infections spreading throughout kidney

Question 9

What are the three main structures inside the kidney

Answer 9

The renal cortex
The renal medulla
The renal pelvis

Question 10

What is the renal cortex?

Answer 10

is a reddish brown layer that has inward projections called renal columns that separate the renal pyramids within the renal medulla.

The nephrons will sit in both the renal cortex and the renal pyramids, with dedicated bundles of nephrons and collecting ducts organised depending on the positions of the renal pyramid

Question 11

What is the renal medulla

Answer 11

The renal medulla are inward structures that hold together bundles of conical shaped structures called renal pyramids. There can be from 8 to 18 renal pyramids in each medulla

Question 12

Label this

Answer 12

A - lobe
B - column
C - pyramid

Question 13

What is the renal pelvis

Answer 13

Consists of minor calyxes and major calyx,

Minor calyxes > connects the lower part of renal medulla and renal pelvis and allows urine to be drained from collecting ducts to enter major calyx

Major calyx > collects urine from a number of minor calyx and drains urine into the renal pelvis which will subsequently drain urine into the ureter

Sourounding by the smooth muscle that contracts and relaxes to create peristaltic action to proper urine into the ureter

Question 14

Label this

Answer 14

A - renal vein
B - renal artery
C - renal medulla
D - minor calyx
E - renal cortex
F - renal capsule
G - major calyx
H - ureter
I - renal pelvis

Question 15

How many nephrons are in the kidneys?

Answer 15

1 million nephrons - each one contributing to filtration, absorption and secretion related functions

Question 16

What are the four major comments of a nephron

Answer 16

The Bowman’s Capsule
The Proximal converted tubule
The Loop of Henle
The Distal Converted tubule

> > nephrons will be connected to collecting ducts that catch urine from the nephrons and drains it into the renal pelvis

Question 17

What is the bowman’s capsule

Answer 17

• contains the glomerulus > a capillary bundle that starts the process urine formation
• blood enters the bowman’s capsule via the afferent arteriolar, passes through the glomerulus and exits through the efferent arteriole
• the arterioles enter and leave capillaries that are designed to be more permeable than other capillaries to allow fluid and small particles to pass through
• made of 2 layers that maintain a capsular space for filtrate to drain into. The linings are called the visceral epithelium which lie across capillaries. This epithelium is made up of flattened squamous epithelium which is designed to allow fluid and small particles to pass through into the capsular space. The parietal epithelium lines the bowman’s capsule and helps maintain the capsular space.

Question 18

What is the proximal and distal convoluted tubule

Answer 18

The proximal convoluted tubule is the connection between the bowman’s capsule and the loop of Henle.

The lining of the tubule is lined with microvilli that are designed to enhance reabsorption of small molecules such as glucose and salts. The microvilli increases the surface area which allows the enhanced reabsorption to occur.

The distal convoluted tubule is the connection between the loop of Henle and the collecting ducts. The distal convoluted tubule lining is slightly different to the proximal tubule as the distal convoluted tubule has more secretion roles as well as reabsorption of water and ions.

Question 19

What is the loop of Henley?

Answer 19

connection between the two tubules, and it consists of an ascending and descending limb. The loop of Henle is involved in the secretion of salts and reabsorption of water.

Question 20

What are the two types of nephrons

Answer 20

The most abundant nephrons that are found are called cortical nephrons, 85% of nephrons. Other is juxtamedullary nephron

Cortical&raquo_space; shorter loop of Henle, found in renal cortex and do most of reabsorption and secretion

Juxtamedullary nephron&raquo_space; long loop of henle, responsible for collecting urine

Question 21

What is the blood supply to the kidney?

Answer 21

The abdominal aorta > renal artery > five segmental artery

They will divide into a number of lobar artery, which further into interlobar arteries

When inter-lobar arteries when reach renal cortex

Once blood goes through the glomerulus it will exit through the efferent arteriole > merge into peritubular capillaries and vasa recta

Further reabsorphtion and secretion will occur

Blood exits out the interlobular veins through the acruate vein > interlobar vein > renal vein > inferior vena cava

Question 22

What are the three stages of urine formation?

Answer 22

Glomerular filtration
Selective Reabsorption
Selective Secretion

Question 23

What is golmerular filtration

Answer 23

Urine filtration from the blood.

Blood enters the glomerulus via afferent arteriole to filter out smaller particles whilst maintains blood cells and plasma proteins.

Blood enters glomerulus as result of hyrdrostatic pressure after being squeezed

Because of hydrostatic pressure fluid and small particles/ molecules will pass through the selective-permeable membrane of the glomerulus lining into capsular space

Question 24

What is selective re absorption and secretion in the Proximal convoluted tubule (PCT)

Answer 24

When the filtrate drains into the capsular space within the Bowman’s Capsule, it will first arrive in the proximal convoluted tubule (PCT), where the majority of reabsorption occurs.

Question 25

What is reabsorbed in the proximal convoluted tubule?

Answer 25

Water and salts - 65% of water, sodium, potassium and chloride in the filtrate is reabsorbed.
Glucose - 100% of all glucose is reabsorbed.
Amino acids - 100% of amino acids are reabsorbed.
Bircarbonate - 85-90% of bicarbonate in the filtrate is reabsorbed.

A combination of osmosis, diffusion and active transport is used to aid process in the PCT

Question 26

What does the proximal convoluted tubule also has secretive properties

Answer 26

Hydrogen ions - this allows acid-base balance to be maintained as accumulation of hydrogen ions can make the blood acidic. Hydrogen ions are swapped with bicarbonate ions, with hydrogen ions being secreted in the filtrate, and the bicarbonate being reabsorbed into the blood.
Organic acids and bases - substances such as catacholamines and bile salts are excreted out through the proximal convoluted tubule.
Drugs/toxins - Secretion of broken down drugs and toxins are secreted through the proximal convoluted tubule.

Question 27

The loop of henle has a a key role in reabsorption of water and ions, it is effectively where urine is concentrated depending on the needs of the body….

What are the three parts to the loop of henle?

Answer 27

**The Thin Descending Limb ** - this is the part of the Loop of Henle that is highly permeable to water, which allows water to be reabsorbed back into the surrounding capillaries. Water moves across through osmosis and the osmotic gradient is influenced by the amount of sodium in the bloodstream. The higher the concentration of sodium there is, the more water will cross over.

** The Thin Ascending Limb ** - this part and the Thick Ascending Limb is impermeable to water, which means that water is not allowed to cross over into the bloodstream. However, sodium is reabsorbed thanks to active sodium channels that will only let sodium through without water following.

** The Thick Ascending Limb ** - like the Thin Ascending Limb, this part is impermeable to water, and more progressive sodium reabsorption occurs to reduce the osmolality of the filtrate to a hypotonic solution.

Question 28

What are the osmolatity changes that occur in the loop of henle?

Answer 28

The osmolality changes that occur can be shown in the diagram below. When water is reabsorbed in the Thin Descending Limb just below the proximal convoluted tubule, the osmolality increases because there is less water and a higher concentration of ions, meaning the filtrate is highly concentrated. Then, when it turns up the thin and thick Ascending Limb, the sodium is then reabsorbed without taking any more water out which reduces the osmolality once again.

Question 29

Whats the distal convoluted tubule responsible for?

Answer 29

responsible for the reabsorption of ions such as sodium, calcium and chloride, as well as the secretion of excess electrolytes such as potassium. It is also important for further acid-base balance.

Question 30

What is the role of the early distal convoluted tubule?

Answer 30

is the location where sodium, calcium and chloride ions are reabsorbed which will further reduce the osmolality of the filtrate ready for the collecting duct.

Question 31

What are the two functions of the late distal convoluted tubule?

Answer 31

Principal cells exchange the reabsorption of sodium with the excretion of potassium ions. This is in response to accumulation of potassium levels in the blood that could interfere with nerve and heart function.
Intercalated cells reabsorb bicarbonate in response to blood acidity, whilst secreting free hydrogen ions into the tubule where it binds with either phosphate or ammonia molecules to be excreted. However, in response to blood alkalosis (when pH is higher), intercalated can secrete bicarbonate ions and reabsorb hydrogen ions into the blood to neutralise the blood.

Question 32

What is the filtered/waste products like

Answer 32

Hypotonic

Question 33

What is the collecting duct?

Answer 33

The collecting duct is the final place for water to be reabsorbed if blood osmolality is high.

Question 34

What do osmoreceptors do?

Answer 34

Osmoreceptors detect blood osmolality in the hypothalamus and trigger the release of anti-diuretic hormone (ADH) from the posterior pituitary gland which works on the collecting duct to reabsorb more water, further concentrating the urine more.

Question 35

Why is the filtrate prepared to be hypotonic

Answer 35

Because the filtrate is hypotonic and the blood is more hypertonic, a concentration gradient is created. With assistance from ADH, it means that water can easily pass through into the blood stream to help rehydrate the blood.

Question 36

What are the ureter?

Answer 36

The two ureters connect from the renal pelvis of each kidney to the bladder. They are a pair of muscular tubes that use peristalsis to transfer urine into the bladder, in which they enter the bladder at an oblique angle to prevent backflow of urine back to the kidneys.

Question 37

What is the bladder?

Answer 37

The bladder is a reservoir for urine that has drained from the ureters. The structure of the bladder is designed to expand when urine collects inside the bladder.

Question 38

What are the four layers of the bladder

Answer 38

The bladder lining has four layers:

A mucosa layer - this mucosa has folds called rugae which allows for the bladder to stretch.
The Lamina propria - connective tissue layer that connects the mucosa epithelial tissue to the muscle layer.
Submucosa layer - another layer of connective tissue that connects the mucosa layer to the muscle layer.
Detrusor muscle - a circular muscular layer that is able to change length and shape depending on how full the bladder is.

Question 39

Whats the anatomy of the bladder?

Answer 39

Question 40

What is the urethra?

Answer 40

The urethra is a muscular tube that expels urine out of the body from the bladder. The urethra has two different sphincter muscles, one internal that is made up of detrusor muscle, and one external. The internal sphincter muscle is under involuntary control whilst the external sphincter muscle can be under voluntary control.

Question 41

What is the length of the female urethra?

Answer 41

4cm

Question 42

What is the length of the male urethra?

Answer 42

20cm