Summary
Summary CCEA A21 Biology Exam notes
- Institution
- CCEA
CCEA A21 exam notes for Biology. Includes, -Succession -Plant coordination and control -Homeostasis -Food chains and Food webs
[Show more]
Seller
Follow
Content preview
Homeostasis.The maintenance of a constant or steady state within the body.
3 basic features of most homeostatic mechanisms:
1. Control system which has a sensor (receptor) - monitors the factor.
2. Corrective mechanism -brings about changes → regulating the factor which has deviated
from normal levels.
3. Negative feedback system- stops corrective mechanism from overcorrecting.
Communication between sensors, monitor and effectors can be hormonal or nervous.
e.g. Temp = nervous blood glucose=hormonal.
Homeostatic control of the mammalian body systems is essential for:
Providing the optimum conditions for enzyme reactions in terms of temp (H-bonds) and pH
(ionic bonds). → denatured enzymes = slower reactions.
Avoid osmotic problems in cells and body fluids.
The kidney (Homeostatic organ) and excretion:
1. Excretion: Removal of toxic waste products of metabolism e.g. urea and creatinine.
2. Osmoregulation: Control of water potential of body fluids (under influence of ADH.) helps
regulate amount of water in the blood by controlling both the volume and concentration of
urine produced.
, Urea- Nitrogen containing compound. Produced in breakdown of excess AA’s and nucleic acids in the
liver.
Creatinine- Waste product breakdown of creatine phosphate in muscles during synthesis of ATP.
Gross structure of the urinary (excretory system.)
Removes metabolic waste products.
Regulates chemical composition of body
fluids. Fluids.
Regulates water content of body fluids.
Regulates pH of body fluids.
Blood travelling through the aorta and renal artery reaches the kidneys at a high pressure
(required for filtration.)
The kidneys act as a complex filter (keeps useful products in the blood + eliminates excretory
products and water.)
Filtered blood leaves the kidney via the renal vein.
Excretory products and excess water pass through the ureter as urine.
Urine taken to the bladder for storage.
Sphincter muscles in base of the bladder control release urine.
Urine leaves the body through the urethra.
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 sadiekeenan10. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for £9.39. You're not tied to anything after your purchase.
Can Stuvia be trusted?
4.6 stars on Google & Trustpilot (+1000 reviews)
79271 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