Urinary system 1 - the kidneys

Question 1

Organs of the urinary system

Answer 1

oTwo kidneys oTwo ureters oOne urinary bladder oOne urethra

Question 2

The urinary system : the organs and their functions

Answer 2

oKidneys: • Regulate blood volume and composition •Regulate blood pressure, pH, and glucose levels •Produce two hormones: Calcitriol and erythropoietin •Excrete wastes in urine oUreters: •Transport urine from kidneys to urinary bladder. oUrinary Bladder: •Stores urine and expels it into urethra. oUrethra: •Discharges urine from body.

Question 3

The kidneys are an endocrine gland T/F

Answer 3

True - produces hormones

Question 4

Functions of the kidneys

Answer 4

oRegulation of blood ionic composition •Na+, K+, Ca2+, Cl-, and HPO42- oRegulation of blood pH, osmolarity and glucose oRegulation of blood volume •conserving or eliminating water oRegulation of blood pressure •secreting the enzyme renin •adjusting renal resistance oRelease of erythropoietin and calcitriol oExcretion of wastes and foreign substances

Question 5

External anatomy of the kidneys - how many layers and what are they?

Answer 5

o Three layers: surround each kidney: •The renal capsule: Innermost •The adipose capsule: Middle •The renal fascia: Outer oThe renal hilum/Hilus: an indentation near the centre of the concave border • For entry and exit of blood vessels, lymphatic vessels, and nerves.

Question 6

Internal anatomy of the kidneys - how many distinct regions and what are they ?

Answer 6

o Two distinct regions: •Renal medulla: a deep, darker reddish-brown inner region – divided into Renal pyramids At the end of each pyramid are renal papilla •Renal cortex: a superficial, light red area –Renal columns

Question 7

Explain blood supply of the kidneys

Answer 7

o2 Capillary beds. (Glomerular, Peritubular)

o2 Arteriolar beds (Afferent, Efferent)

o Capillary beds:

• Glomerular capillaries: filter blood
• Peritubular capillaries: carry away reabsorbed substances from filtrate

Question 8

The function of the Golmerular capillaries in the kidneys?

Answer 8

To filter blood

It’s a fenestrated capillary network that has lots and lots of holes in the epithelium allowing filtrate to be filtered through it

In each of the one million nephrons we have in each of our kidneys its where we filter the blood

Question 9

Function of the peritubular capillaries in the kidneys?

Answer 9

Function: to carry away reabsorbed substances from filtrate to go back into the blood supply

• It’s where we get back all our water and our nutrients once filtration has taken place

Question 10

Nerve supply of the kidney

Answer 10

oRenal plexus: the sympathetic division of ANS.

oSympathetic vasomotor nerves regulate blood flow and renal resistance by altering arterioles

o This causes vasodilation or vasoconstriction of renal arterioles

•Vasodilation / Vasoconstriction of afferent arteriole is an important response relating to regulating blood pressure

By controlling the diameter of the afferent and efferent arterioles we can change and regulate blood flow, Renal resistance and also how much the kidneys are filtering.

Question 11

Which area of the kidney does filteration take place?

Answer 11

The cortex area (outer layer) is where filteration of the blood takes place. This is due to the renal corpuscle of the nephron being in the cortex layer which contains the glomerular capillaries.

Question 12

What are the nephrons? what do they consist of?

Answer 12

They are the functional units of the kidneys

Each consists of:

• A renal corpuscle
• A renal tubule

Question 13

3 basic functions of nephrons

Answer 13

• Glomerular filtration
• Tubular reabsorption
• Tubular secretion

Question 14

Renal Corpuscle is the site of plasma filteration

1. What happens in the glomerulus? (nephrons)
2. What is the Glomerular (Bowman’s) capsule?

Answer 14

1. Capillary network where filteration occurs
2. Double-walled epithelial cup surrounding the glomerular capillaries that collects filtrate

Question 15

What is the order of events in the Nephron ?

Answer 15

•Renal Corpuscle

•Glomerular capillary & Glomerular Capsule

•Proximal Convoluted Tubule (PCT)

•Loop of Henle

‒Descending limb of the loop of Henle

‒Ascending limb of the loop of Henle

•Distal Convoluted Tubule (DCT)

Question 16

Order of events after the filtrate reaches the Distal convoluted tubule ? (path of urine drainage)

Answer 16

• Distal Convoluted Tubule (DCT)
• Collecting Ducts
• Papillary Ducts
• Minor Calyx
• Major Calyx
• Renal Pelvis
• Urteter

Question 17

How many types of nephrons are there? what are they?

Answer 17

oTwo types of nephrons: based on structure and function.

• Cortical Nephron: 80-85% of nephrons
• Juxtamedullary Nephron: 15-20% of nephrons

Have an important role in water reabsorption because of the length of their Loop of Henle into the medulla region

Question 18

What is the difference between the cortical nephrons and the juxtamedullary nephrons?

Answer 18

oA cortical nephron:

•Glomerulus:in the outer cortex

•Short Loop of Henle: penetrates only into the outer region of the medulla

•A juxtamedullary nephron:

• Glomerulus:in the deeper cortex close to the medulla
• Long Loop of Henle: stretches through the medulla

Question 19

What’s the primary function of the peritubular capillaries? (nephron)

Answer 19

This is where the blood supply is trying to get back all the nutrients and water and solutes from the filtrate that we have just filtered. Very extensive network wrapping around the loop of henle.

Question 20

Blood supply to the nephron - Explain what is involved

Answer 20

• Blood supply comes in via the afferent arteriole
• Supplies the glomerulus and exits via the efferent arteriole network
• It can then Circulate through an additional capillary network called the peritubular capillaries where we try to reclaim all that filtrate we filtered - trying to pick up all the aminos, glucose, sodium etc that we want back.
• Whatever is left flows down the distal convoluted tubule, collecting duct and then down into the papilla which is destined to become urine.

Question 21

How does filteration occur in the glomerular capsule of the nephron?

Answer 21

oFiltration (dialysis) membrane: Fenestrations ( little holes ) formed by the visceral and parietal epithelium act as a filtration membrane. Filtration occurs via the force of Blood Pressure.

Question 22

what enables the cells of the proximal convoluted tubule to reabsorb? (kidneys)

Answer 22

They are simple cuboidal epithelial cells with brush borders of microvilli

• the microvilli increases surface area thus increasing reabsorption

Question 23

The last part of the distal convoluted tubule and collecting duct consist of what type of cells ?

And what is their function?

Answer 23

Simple cuboidal epithelium cells consisting of principal cells and intercalated cells.

Principal cells: have receptors for ADH and aldosterone

Intercalated cells: play a role in the homeostasis of the blood PH

Question 24

What is the function of the Juxtaglomerular Apparatus (JGA)?

(nephron)

Answer 24

oJuxtaglomerular Apparatus (JGA):A structure where afferent arteriole makes contact with ascending limb of loop of Henle

oConstituted by:

• Macula densa:
• Juxtaglomerular cells

oFunction: Helps regulating blood pressure and the rate of blood filtration by the kidneys.

Question 25

What does surgical removal of a kidney stimulate?

Answer 25

Remaining kidney adapts as the loss of a kidney stimulates hypertrophy (enlargement) of the remaining kidney,

•able to filter blood at 80% of the rate of two normal kidneys.