Summary
Summary Transport in mammals
- Course
- Institution
- Book
Compiled and Summarised notes all based on the chapter Transport in Mammals and units falling under it, with diagrams included
[Show more]
Connected book
Book Title:
Author(s):
- Edition:
- ISBN:
- Edition:
More summaries for
-
PHOTOSYNTHESIS
-
Biology AS Best summary notes
-
Cell structure_ A level
Seller
Follow
raida
Content preview
AS Bio notes Raida 12DTransport in mammals
8.1 transport system in animals
Movement requires energy
This energy comes from glucose and other substances, which are broken down in
respiration inside each individual cell
The most efficient form of respiration which releases the most energy from a given
amount of glucose is aerobic respiration and this requires good supplies of oxygen
Supplying oxygen to respiring tissues is one of the most important functions of an
animal’s transport system
At the same time, waste products such as carbon dioxide can be removed
Very small animals may be able to get enough oxygen to their cells by diffusion,
especially if they are not particularly active
[In a jellyfish, for example, oxygen simply diffuses into its body from the seawater around it, and
then to the respiring cells. Carbon dioxide diffuses in the opposite direction. Because no cell is
very far from the surface, each cell gets an adequate amount of oxygen quickly enough for its
needs]
But in larger animals, diffusion is not sufficient
A transport system is needed to distribute oxygen quickly to all the body cells, and to
remove their waste products
Mammals have greater requirements for oxygen than most other animals because they
use respiration to generate heat inside their bodies to help keep their body temperature
constant
8.2 The mammalian circulatory system
The main transport system of mammals is the Circulatory system
It is made up of a pump (the heart) and a system of interconnecting tubes (the blood
vessels)
The blood always remains within these vessels, and so the system is known as a Closed
blood system
The blood travels twice through the heart on one complete ‘circuit’, this is called a
Double circulation
Blood is pumped out of the left ventricle into the aorta and travels from there to all parts
of the body except the lungs
It returns to the right side of the heart in the vena cava
This is called the Systemic circulation
The blood is then pumped out of the right ventricle into the pulmonary arteries, which
carry it to the lungs
The final part of the journey is along the pulmonary veins, which return it to the left side
of the heart
This is called the Pulmonary circulation
The pressure in the systemic circulation is considerably higher than in the pulmonary
circulation
Systemic circulation: the part of the circulatory system that carries blood from the heart
to all of the body except the gas exchange surface, and then back to the heart
, Pulmonary circulation: the part of the circulatory system that carries blood from the heart
to the gas exchange surface and then back to the heart
8.3 Blood vessels
There are three main types of vessel making up the circulatory system:
1. Vessels carrying blood away from the heart are known as Arteries
2. Carrying blood towards the heart are Veins
3. Linking arterioles and venules, taking blood close to almost every cell in the body are
called Capillaries
Small arteries are called arterioles and small veins are called venules
Artery: vessel with thick, strong walls that carries high-pressure blood away from the
heart
Vein: vessel with relatively thin walls that carries low-pressure blood back to the heart
Capillary: the smallest blood vessel, whose role is to deliver oxygen and nutrients to
body tissues, and to remove their waste products
, Arteries and arterioles
The function of arteries is to transport blood, swiftly and at high pressure to the tissues
Artery walls are very strong and elastic
Blood leaving the heart is at a very high pressure
Blood pressure in the human aorta may be around 120 mmHg/ 16 kPa
The thickness and composition of the artery wall enables it to withstand this pressure
Both arteries and veins have walls made up of 3 layers:
1. An inner layer, which is made up of a layer of endothelium (lining tissue) consisting of a
layer of flat cells (squamous epithelium) fitting together, plus a layer of elastic fibres; the
endothelium is very smooth, minimising friction with the moving blood
2. A middle layer containing smooth muscle, collagen and elastic fibres
3. An outer layer containing collagen fibres and elastic fibres
Endothelium: a tissue that lines the inner surface of a structure such as a blood vessel
Squamous epithelium: one or more layers of thin, flat cells forming the lining of some
hollow structures eg. blood vessels and alveoli
Smooth muscle: a type of muscle that can contract steadily over long periods of time
Arteries have the thickest walls of any blood vessel
The aorta, the largest artery, has an overall diameter of 2.5cm close to the heart, and a
wall thickness of about 2mm
The composition of the wall provides great strength and resilience
The middle layer, which is by far the thickest part of the wall, contains a large amount of
elastic fibres
These allow the wall to stretch as pulses of blood surge through at high pressure
Arteries further away from the heart have fewer elastic fibres in the middle layer but have
more muscle fibres
Arteries that have a lot of elastic tissue in their middle layer - such as the aorta - are
called elastic arteries
The function of an elastic artery is to carry blood from the heart on the first part of its
journey towards its final destination
The elasticity of these artery walls is important in allowing them to stretch, which reduces
the likelihood that they will burst
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 raida. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $11.99. You're not tied to anything after your purchase.
Can Stuvia be trusted?
4.6 stars on Google & Trustpilot (+1000 reviews)
78075 documents were sold in the last 30 days
Founded in 2010, the go-to place to buy study notes for 14 years now