MYTUTOR SUBJECT ANSWERS

642 views

What is the second line of defence?

What is the second line of defence?

Before we start let’s re-cap some key terminology:

-pathogen: a microorganism causing disease or illness to its host

-lymphocyte: a small white blood cell involved in immunity. There are two major types; B and T.

-phagocyte: a large white blood cell that ingests foreign particles

-inflammation: a response to tissue injury characterised by swelling, heat, pain and redness

-lysosomes: vesicles containing digestive enzymes

Description: http://www.nature.com/nrd/journal/v7/n9/images/nrd2673-i1.jpg

The three-pronged fork

The second-line of defence is like this fork. There are three mechanisms that work together to produce this response. We will cover the first step.

1)      Inflammation

‘Alarm’ signals are sent which does two things; (i) makes the blood vessels vasodilate which means they get bigger as they fill with blood. As more blood pools to this area of tissue damage there will be redness and swelling (ii) makes the capillary walls ‘leaky’ which allows the white blood cells to move out of the blood, through the walls and into the tissue

The advantage of inflammation is that it allows the needed white blood cells to pool into this area.

2)      Phagocytosis

There are two important phagocytes that you should be familiar with; neutrophils and macrophages. Phagocytosis is the process in which the phagocyte, after leaving the bloodstream and entering the infected tissue site, will digest the pathogen (think of it as a pacman!)

-the bacteria are attracted to the surface of the phagocyte

-the phagocyte will engulf the bacterium

-the engulfed bacterium is now called a phagosome

-lysosomes fuse with the phagosome and digest it

-the bacteria has been killed and digested

3)      Macrophages

They also promote the destruction of pathogens ‘from a distance’ by making proteins:

-they can punch holes into the cell wall of pathogens causing them to die by osmolysis

-they can make proteins which stick to the pathogens and acts as signals attracting more white blood cells to come and destroy them

 

Although the second line of defence is a much needed response, can you think of any flaws to the system?

-is it able to remember past infections?

-are some pathogens able to escape this response?

Tumbi O. A Level -Personal Statements- tutor, GCSE Biology tutor, A L...

2 years ago

Answered by Tumbi, an A Level Biology tutor with MyTutor


Still stuck? Get one-to-one help from a personally interviewed subject specialist

164 SUBJECT SPECIALISTS

£22 /hr

Shreya G.

Degree: Biochemistry with molecular medicine (Bachelors) - Nottingham University

Subjects offered:Biology, Maths+ 1 more

Biology
Maths
-Personal Statements-

“I am a first year undergraduate student at The University Of Nottingham, currently studying Biochemistry with molecular medicine. ”

£24 /hr

Pooja D.

Degree: Medicine (Bachelors) - Birmingham University

Subjects offered:Biology, Science+ 6 more

Biology
Science
Physics
Maths
Chemistry
.UKCAT.
-Personal Statements-
-Medical School Preparation-

“I have tutored for the past 4 years and have gathered many ways of teaching concepts to students in a way that is easily-digestible and understandable. ”

Nehemie M. A Level Biology tutor, GCSE Biology tutor, IB French tutor...
£20 /hr

Nehemie M.

Degree: Biochemistry with a Professional Placement (Bachelors) - Bath University

Subjects offered:Biology, French

Biology
French

“I am university student passionate about Biology and Chemistry who also speaks French!!!”

About the author

£20 /hr

Tumbi O.

Degree: Medicine with Medical French (Bachelors) - Manchester University

Subjects offered:Biology, Maths+ 2 more

Biology
Maths
French
Chemistry

“Top tutor from the renowned Russell university group, ready to help you improve your grades.”

MyTutor guarantee

You may also like...

Other A Level Biology questions

In genetics, what does co-dominance mean?

What is the difference between competitive and non-competitive inhibition of enzymes?

What is the difference between competitive and non-competitive enzyme inhibition?

What are the differences between prokaryotic and eukaryotic cells?

View A Level Biology tutors

We use cookies to improve your site experience. By continuing to use this website, we'll assume that you're OK with this. Dismiss

mtw:mercury1:status:ok