Ohne Titel

Cells

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

Thymus Gland 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)

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

HIV Replication

1) Viral glycoprotein binds to receptor CD4 on Tc helper

2) Capsid fuses with cell surface membrane

3) HIV Reverse transciptase converts RNA to DNA and is inserted in the host cell

4) Transcription and translation of the viral DNA occurs viral protein then assemble into nonliving viral particlesnto the Tc and then inside the host celundergo protein synthesis

ELISA TEST: Test for Antigen HIV

1) use antigen sticking surface, remove unattched antigens

2) add antibody complementary to antigen

3) Add second antibody with enzyme attached. Formation of antigen antibody complexes.

4) Colourless substrate is turned into coloured due to the enzyme attached antibody forming antigen-antobody complexes as the intensity of colour show the intensity of enzyme

Herd Immunity: Large propotion of populaion are vaccinated

Consider: - not everyone can be vaccinated, babies immune system not functional - make immunodeficeny inidvidual more ill

Limitation:

- Defective immune systems

- antigenic varability

- disease development - pathogen variety

-pathogen hides

- religious reasons

Cell recognition and the immune system

3.2.3 Transport across cell membranes

Structure Of cell surface membrane

Glycoprotein

Phospholipid Biplayer

Cholestrol

Glycolipds

Proteins

Hydrophobic/Hydrophillic: repel and attack water. F: FLexible, allow lipid and water

-forming of tissiue, receptors for hormones. Carbohydarte and lipid

Carrier: act as receptors with glycolipids. Carrier: active transport of glucose glucose/amino acid Channel: allow water to diffuse

Strength. - prevent water leaking. less fluid high temp

Extrinsic proteins and crabohydrate. - form tissue. cell recoginition

Fluid Mosiac Model

- Proteins are embedded vary in shape/pattern size. - phospholipids move Relatively

Facilitated Diffusion

Osmosis

Active Transport

Diffusion

Carrier Proteins

High to low Concentration

Water potential: high to low concentration. Water follows solute

Use of ATP - Co transport, Sodium potassium pump acid/glucose