Summary
Summary 16 Homeostasis
- Course
- Institution
- Book
Concise homeostasis summary notes for the new linear A-level biology 7401/7402
[Show more]
Connected book
Book Title:
Author(s):
- Edition:
- ISBN:
- Edition:
More summaries for
-
Carbohydrates
-
Carbohydrates - Mono/Di-Saccharides
-
AQA A-Level Biology Summary Notes: 3.1.3 Lipids
Seller
Follow
biostudent_
Content preview
16 HomeostasisHomeostasis is the maintenance of a constant internal environment.
What is maintained?
® Temperature
® Water levels
® Blood pH levels
® Blood glucose concentration
Homeostasis ensures body cells get what they need to function, despite external changes.
® Temperature – too high and enzymes will denature, too low and chemical reactions
will be too slow
® Water content – not in equilibrium could cause cells to burst (lysis) or shrivel up
(crenation)
Control mechanisms
1. Set point (optimum condition) is monitored by receptor
2. Receptor detects changes in set point and tells controller
3. Controller relays message to effector
4. Effector carries out appropriate changes, creating a feedback loop
5. Feedback loop tells receptor what changes were made
Control mechanisms are mostly negative feedback systems
® Negative feedback: when feedback causes the corrective measures to be turned off
® Positive feedback: when feedback causes corrective measures to remain turned on
Thermoregulation
® To warm the body:
1. Vasoconstriction
If temperature falls, blood vessel constricts so less heat is lost from the
surface of the skin
2. Shivering
3. Increased metabolic rate
4. Decrease sweating
5. Behaviour mechanisms e.g. huddling
6. Raising of hair / piloerection
Hairs trap a layer of air next to the skin – insulating layer
® To cool the body:
1. Vasodilation
Diameter of arteries become larger near skin surface, brings blood closer
so more heat can be lost
2. Sweating
Liquid sweat turns into a gas (evaporates) using heat from the skin
3. Lowering body hair
4. Behaviour mechanisms e.g. sitting in shade
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 or Stuvia-credit 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 biostudent_. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $4.50. You're not tied to anything after your purchase.
Can Stuvia be trusted?
4.6 stars on Google & Trustpilot (+1000 reviews)
67474 documents were sold in the last 30 days
Founded in 2010, the go-to place to buy study notes for 14 years now