Renal pathophysiology

Question 1

What are the functions of the renal system?

Answer 1

Balancing of bodily fluids and acidity, removal of waste, control of blood volume and blood pressure

Question 2

What happens during waste filtration?

Answer 2

Kidneys remove waste products (e.g., urea, creatinine) and toxins from the blood. Blood enters the kidneys through the renal artery, where nephrons filter it, removing these by-products of cellular metabolism. The clean blood exits back into circulation while the waste forms urine.

Question 3

How do the kidneys maintain fluid balance?

Answer 3

Hormones such as ADH signal kidneys to retain water during dehydration while excess fluid prompts increased urination

Question 4

How is blood pressure regulated?

Answer 4

Through the renin-angiotensin-aldosterone system (RAAS) kidneys detect changes in blood flow and secret renin which triggers a cascade of reactions that constrict blood vessels and increase fluid retention, therefore raising blood pressure

Question 5

How do the kidneys regulate pH?

Answer 5

By excreting hydrogen ions and reabsorbing bicarbonate ions, this buffer System ensures that blood pH remains between 7.35 and 7.45 preventing harmful shifts toward acidosis and alkalosis

Question 6

What does the renal system consist of?

Answer 6

2 kidneys, 2 ureters, bladder and urethra

Question 7

Where are the kidneys located in the body?

Answer 7

Around the 12th rib, in the retroperitoneal space on either side of the spine right kidney is slightly lower due to liver

Question 8

What does the ureter do?

Answer 8

Carries urine from the kidneys to the bladder via peristaltic waves in preparation for excretion to the body. they have one way valves ensuring urine does not return to the kidneys

Question 9

What does the bladder do?

Answer 9

holds urine prior to excretion through the urethra, holds between 300-500ml before the urge to empty occurs but can hold significantly more

Question 10

What is the functional unit of the kidney?

Answer 10

Nephron

Question 11

What is the outer layer of the kidney?

Answer 11

Renal cortex

Question 12

What does the renal cortex do?

Answer 12

Contains the glomeruli and is responsible for initial blood filtration

Question 13

What does the medulla in the kidneys do?

Answer 13

Contains tubules that modify the filtrate into urine

Question 14

What do nephrons do?

Answer 14

Filter blood, remove waste and balance fluid and electrolytes through a series of filtration and reabsorption processes

Question 15

What are the 2 main parts of a nephron?

Answer 15

Renal corpuscle (for filtration) and renal tubule (for modification of filtrate)

Question 16

How is blood supplied to the kidney?

Answer 16

Blood flows into each kidney through the renal artery, which branches off from the aorta. Within the kidney, the artery further branches into smaller arterioles that deliver blood to the nephrons. After filtration, the blood exits via the renal vein, which connects to the inferior vena cava, returning clean blood to circulation.

Question 17

What is the renal corpuscle composed of?

Answer 17

Glomerulus (a network of capillaries) and Bowman’s capsule which captures the filtrate that becomes urine.

Question 18

How does blood enter the glomerulus?

Answer 18

Through the afferent arteriole, where pressure forces plasma out filtering out large proteins and cells

Question 19

What is the renal tubule composed of?

Answer 19

Proximal convoluted tubule, loop of henle, distal convoluted tubule and collecting duct. Each segment plays a role in selectively reabsorbing water, ions and nutrients while excreting waste products, this process refines the initial filtrate into urine

Question 20

How is blood supplied to the nephron?

Answer 20

Blood enters via the afferent arteriole and is filtered in the glomerulus. Post-filtration, the blood exits though the efferent arteriole and travels through the peritubular capillaries allowing for the reabsorption and secretion of various substances along the tubule

Question 21

What are podocytes?

Answer 21

Specialised cells in Bowman’s capsule that wrap around the capillaries of the glomerulus, forming filtration slits that control what passes into the nephron.

Question 22

What does the collecting duct do?

Answer 22

Receives filtrate from the distal convoluted tubule and conveys it to the minor calyces

Question 23

What does the afferent arteriole do?

Answer 23

Carries unfiltered blood from the renal artery to the glomerulus. The pressure in this arteriole facilitates filtration as blood floes into the capillary bed

Question 24

What happens in the peritubular capillaries surrounding the nephron tubules?

Answer 24

Reabsorption of water, nutrients and ions occurs before blood returns to circulation via the renal vein

Question 25

What do podocytes do?

Answer 25

They play a critical role in filtering plasma, ensuring only the correct substances enter the nephron. They adjust the size of filtration slits in response to changes in blood pressure of kidney function, allowing for fine control of filtration

Question 26

What happens if podocytes become damaged?

Answer 26

Can lead to proteinuria, a sign of kidney dysfunction

Question 27

What are the 3 steps of filtration?

Answer 27

Filtration in the glomerulus, selective reabsorption in the tubules and secretion of excess ions and waste

Question 28

What is the process of filtration?

Answer 28

Filtration at the glomerulus - blood enters the glomerulus under high pressure forcing water, ions and small molecules through the filtration membrane into Bowman's capsule. Selective reabsorption - as filtrate passes through the nephron tubules, essential substances like glucose, ions and water are reabsorbed back into the blood stream based on the body's needs. Tubular secretion - final adjustments occur, where additional waste products e.g excess hydrogen or potassium are secreted into the filtrate before it exits as urine

Question 29

What is the glomerular filtration rate (GFR)

Answer 29

The volume of filtrate produced by both kidneys each minute, a key indicator of renal function. It reflects how efficiently kidneys filter blood and is used to assess kidney health

Question 30

What is selective reabsorption?

Answer 30

The process of molecules being specifically reabsorbed into the blood based on the body's needs

Question 31

Where does selective reabsorption take place?

Answer 31

Most selective reabsorption takes place in the proximal convoluted tubule - some is passive and some larger molecules such as glucose need actively transporting

Question 32

What does ADH do?

Answer 32

Increases water reabsorption in the distal tubule. Secreted by the posterior pituitary

Question 33

What does Atrial Natriuretic Peptide (ANP) do ?

Answer 33

Lowers blood pressure by promoting sodium and water excretion. Secreted by the atria of the heart

Question 34

What does Aldosterone do?

Answer 34

Boosts sodium and water reabsorption, and potassium excretion. Secreted by the adrenal cortex

Question 35

Why is tubular secretion essential?

Answer 35

Because some substances that are not required and foreign materials may not be entirely filtered out of of the blood because of the short amount of time in the glomerulus and require additional filtering

Question 36

What does the juxtaglomerular complex do?

Answer 36

Regulates blood pressure and GFR. It consists of macula dense cells, extraglomerular mesangial cells and juxtaglomerular cells

Question 37

Where is the juxtaglomerular complex located?

Answer 37

Between the distal convoluted tubule and the afferent arteriole

Question 38

What is the process of urination?

Answer 38

Urine forms in the nephron, flows out via the collecting duct, through the renal pelvis, and down the ureter by peristalsis. Bladder stretch signals the brain, triggering the urge to urinate.