A Level Advancing Biology for OCR Student Book (OCR B)
Summary notes for A-level Biology OCR B (Advancing Biology). Chapter 6 - Transport systems in mammals (2.2.2 on specification). In-depth detailed notes covering all required content.
Once organisms reach a certain size, diffusion is no longer sufficient to
Transport provide all body cells with the oxygen and nutrients they need.
systems in
mammals This is when a mass transport system is needed. In mammals this is
the circulatory system.
Unicellular organisms don't need a specialist transport system because
they have a high surface area : volume ratio. These cells use diffusion,
osmosis and active transport.
Mass transport = a system that transports all substances in the same
direction at the same speed.
A good transport system in humans has:
Large surface area
Pump to move substances
Fluid to suspend substances so they can be moved
Human circulatory system
Double circulation:
Pulmonary circuit – between the lungs and the heart
Systemic circuit – between the body and the heart.
Advantages
o Blood pressure maintained
o Oxygenated and deoxygenated blood does not mix
o Delivery of O and nutrients to tissues is more efficient
2
Closed system:
The blood in the human circulatory system always moves within
blood vessels, and can be maintained at pressure.
Advantages
o Blood pressure maintained
o Pressures can differ in pulmonary and systemic
systems
o Blood supply to organs can be varied due to functions
Blood vessels
Arteries:
Take blood away from the heart under high pressure
Narrow lumen
Thick wall, large amounts of smooth muscle and elastic fibres
Stretches during ventricular systole and recoils during diastole
Inner endothelium lining smooth to reduce friction
Veins:
Return blood to the heart
Thin walls, small amount of muscle and elastic tissue
Contain semilunar valves which prevent backflow
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 harryjking05. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $7.04. You're not tied to anything after your purchase.
