Defense mechanisms

Question 1

Immunity

Answer 1

If the body’s defence se mechanisms manage to overwhelm, the pathogen, the body is better prepared for a second infection and can kill it before an infection.

Question 2

Defence mechanisms

Answer 2

Immediate defences
Skin
Phagocytosis

Long lasting
cell mediated T lymphocytes
Humoral responses involving B lymphocytes

Question 3

Recognising your own cells
Clonal selection

Answer 3

Body’s cell- self
Foreign- non-self

+Each types of cell have specific molecules on its surface to identify it. Most significantly, proteins.
+The proteins allow the immune system to identify
-pathogens
-Non-self materials
-Toxins
-abnormal cells like cancer

To minimise the effect of cell rejection of prosthetics, donor tissues are closely matched to the host, like relatives.

Due to the high amount of Lymphocytes, there might be one who complements it.
Then that lymphocyte stimulates to divide its numbers,= Clonal selection

Question 4

How Lymphocytes recognise cells belonging to the body
From fetus

Answer 4

+Around 10 000 000 different lymphocytes with a specific chemical shape.
+In the fetus, lymphocytes are constantly colliding with each other.
+ Infection in the fetus is rare because it’s protected by the placenta.
+∴, L will only collide with self cells.
+Some L will have receptors that recog own cells and are killed or suppressed.
+The only ones remaining will be L that might recognise non-self.
+In adults, L are produces in bone marrow only recog self-antigens
+Any L that respond to self antigens undergo cell death=Apoptosis before they can be differentiated into mature lymphocytes.
+Only clones of non-self L are in blood