Summary
Summary AQA A Level Biology- Kidneys Notes
- Institution
- AQA
Summary of everything you need to know about kidneys for the AQA A Level Biology new specification.
[Show more]
Connected book
Book Title:
Author(s):
- Edition:
- ISBN:
- Edition:
Seller
Follow
Content preview
The Kidneys:Key Terminology:
★ Afferent arteriole: takes blood into glomerulus.
★ Efferent arteriole: take filtered blood away from glomerulus.
★ Glomerulus: bundle of capillaries looped inside a hollow ball called Bowman’s
capsule.
★ Bowman’s capsule: cup-like sac that performs the first step in ultrafiltration;
glomerulus enclosed in here.
★ Proximal convoluted tubule (PCT): convoluted portion of the nephron between
Bowman’s capsule and the loop of Henle; mainly involved in reabsorption.
★ Distal convoluted tubule (DCT): convoluted portion of the nephron between the
loop of Henle and the collecting duct; involved in secretion.
, ★ Loop of Henle: a long, hairpin loop that extends from the cortex into the medulla of
the kidney and back again; surrounded by blood capillaries; the longer the loop of
henle, the more glucose will be absorbed.
★ Ureter: tube that carries urine from the kidney to the urinary bladder.
★ Osmoregulation: control of water and salt.
Ultrafiltration:
➔ Blood enters the smaller arterioles in the cortex of the kidney from the renal artery.
➔ Blood is filtered in the glomerulus.
➔ Blood into glomerulus= afferent arteriole; blood away from glomerulus= efferent
arteriole
➔ Efferent arteriole has a smaller diameter than the afferent arteriole, therefore it
creates some resistance to blood flow and blood in the glomerulus is under high
pressure.
➔ Due to the high pressure, liquid and small molecules (e.g. glucose, some salt and
water) in the blood (a.k.a glomerular filtrate) are forced out of the capillary and into
the Bowman’s capsule. Large molecules like proteins and RBCs cannot be filtered
because they are too big to pass through the filter.
Bowman’s capsule:
➢ 1st layer: endothelium- has holes to let plasma pass
➢ Basement membrane: mesh-like structure that acts as a filter during
ultrafiltration.
➢ 2nd layer: wall of Bowman’s capsule- epithelial cells in this wall are called
podocytes. They have a foot-like structure and do not fit tightly together,
therefore the filtrate can pass because they have gaps between each other.
➔ Reabsorption is done by blood capillaries, which are closely wrapped around tubules.
Blood capillaries:
➢ Glomerular capillaries are within the Bowman’s capsule; plasma is filtered
here.
➢ The capillary bed reforms into an arteriole.
➢ Glomerular capillaries have afferent and efferent arteriolar ends.
➢ Glomerular capillaries are able to autoregulate blood flow so that here is a
constant flow over a wide range of blood pressure.
➔ The waste, consisting of water, some salt and urea is urine.
➔ The urine is collected by the collecting duct, taken to the ureters and then to the
blood.
Q: Describe the process of ultrafiltration. (5)
A: Blood enters the glomerulus under high pressure via the afferent arteriole and enters the
Bowman’s capsule. Small molecules like water, glucose and ions are able to leave the
capillaries as they are filtered via the podocytes in the basement membrane. Large
molecules like proteins and red blood cells stay behind because they are too large to pass
through the endothelium.
If proteins are in the urine, it means that the basement membrane would be damaged.
Selective Reabsorption:
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller anjalibhambra. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for £7.99. You're not tied to anything after your purchase.
Can Stuvia be trusted?
4.6 stars on Google & Trustpilot (+1000 reviews)
66579 documents were sold in the last 30 days
Founded in 2010, the go-to place to buy revision notes and other study material for 14 years now