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Cells

Cell recognition and the immune system

Defence mechanisms

NON- Specific

Phagocytosis Process

SKIN (acts as Organ barrier)

1) cell surface membrane of phagocyte attach its receptors to the chemicals of the pathogen down a Conc Grad

2) Phagocute engulfs to from a vesicle /phagosome around pathogen

3) Lysosomes release lyzozymes to hydrolyse pathogen break down cell walls/membrane

4) hydrolysed products are amino acids/ glucose and are absorbed into the cytoplasm of cell

SPECIFIC

T Lymphocytes

Mature in Thymus Gland and Cell mediated - immune response carried out in body cells

Cell mediated Process

1) Antigen of pathogen is presented by phagocyte/cell representing cell

2) Receptors in T help cells recognise antigen as foreign cell, the multiply through mitosis makes genetically identical cells

3) Cloned T cells function as

Memory cells

stimulate B lymphocytes and secrete antibodies

Stimulate Phagocytosis

Activate Cytotoxic cells

- Produce perforin protein - makes holes in the cell surface so its completely permeable - stops virus replication - kills body cell

B lymphocytes (Makes antibodies)

Matures in the Bone marrow and Humoral immune response, only in the tissue fluid

Humoral Immunity Process

2) Mitotic division of B cell creates monoclonal antibodies

1) B cell presents antigen. Helper Tc attach to antigen and activate B cell.

Memory cells will recognise antigen and secrete plasma cells that secrete specific antibodies in future infections

Plasma cells secrete antibodies and attach to antigen (Primary response)

Antibodies- prepares Antigen for phagocyte

.Aggulination: 1) formation of Antigen-antibody complex 2) Antibody aggulinate antigen into clump clumps of bacterial cells too easy for phagocyte to locate

Structure of Antibody: - Variable region- complementary to antigen,(antigen-antibody complex) 3d shape. Constant region - receptors bind. i.e b cells. 4 polypeptide chains - light and heavy chains