2.9.4 Kidney Structure & Function Flashcards
Where are kidneys located
in the back of the abdomen
What are the kidneys two important functions in the body
1. They regulate the water content of the blood (vital for maintaining blood pressure)
Name the 7 waste substances that need to removed from the blood
#1. Urea #2. Creatinine #3. Ammonia #4. Excess Hormones #5. Excess Water #6. Uric Acid #7. Excess Salt/Ions
There are three regions of the kidney, what are they?
1. Cortex – the outermost region
Each kidney contains around a million tiny structures called, what?
nephrons, also known as kidney tubules or renal tubules
Where are Nephrons located
Nephrons start in the cortex of the kidney, loop down into the medulla and back up to the cortex
The contents of the nephrons drain into the, what?
the renal pelvis and the urine collects there before it flows into the ureter to be carried to the bladder for storage
The nephron is made up of a kidney tubule which has several sections, what are they?
1. Bowman’s capsule
What surrounds the tubule
a network of capillaries with a knotted section which sits inside the Bowman’s capsule
In the kidney, before the key substances are reabsorbed back into the blood, what happens
blood is filtered (ultrafiltration)
Explain the process of ultrafiltration
1. Arterioles branch off the renal artery and lead to each nephron, where they form a knot of capillaries (the glomerulus) sitting inside the cup-shaped Bowman’s capsule
(Components of Filtrate Table) Where is water reabsorbed at?
Loop of henle and collecting duct
(Components of Filtrate Table) Where is Salts reabsorbed at
Loop of henle
(Components of Filtrate Table) Where is Glucose reabsorbed at?
Proxminal convoluted tubule
(Components of Filtrate Table) Where is Urea reabsorbed at?
Not Reabsorbed
After the glomerular filtrate enters the Bowman’s Capsule, glucose is the first substance to be reabsorbed, where?
at the proximal (first) convoluted tubule
- This takes place by active transport
The nephron is adapted for this by having many mitochondria to provide energy for, what?
the active transport of glucose molecules
Reabsorption of glucose cannot take place anywhere else in the nephron, why?
the gates that facilitate the active transport of glucose are only found in the proximal convoluted tubule
In a person with a normal blood glucose level, there are enough gates present to remove, what?
all of the glucose from the filtrate back into the blood
People with diabetes cannot control their blood glucose levels and they are often very high, what does that mean?
that not all of the glucose filtered out can be reabsorbed into the blood in the proximal convoluted tubule
- As there is nowhere else for the glucose to be reabsorbed, it continues in the filtrate and ends up in the urine
What is one of the first tests a doctor may do to check is someone is diabetic
to test their urine for the presence of glucose
As the filtrate drips through the Loop of Henle necessary salts are reabsorbed back into the blood by, what?
diffusion
As salts are reabsorbed back into the blood, water follows by, what?
osmosis
How is water also reabsorbed
from the collecting duct in different amounts depending on how much water the body needs at that time
Exam Tip
Take care to describe clearly where substances are moving from and to in the kidneys (ie. glucose moves from the filtrate into the bloodstream when it is selectively reabsorbed. Using your technical terminology incorrectly here could lose you marks.
Also – small substances such as urea are forced out of the blood during filtration as a result of high-pressure mass flow, they don’t diffuse out of the blood.
