Diseases (1)

-Unprotected sex -Sharing needles -NB = infection from blood and from mother to foetus almost eliminated -Virus crosses protective mucous membrane and Structure Treatment and enters bloodstream Prevention -Integrase enzyme – ‘cut -Inhibitors of viral and paste’ viral DNA into enzymes to inhibit host’s reverse transcriptase -Reverse transcriptase – -No alcohol, smoking and produces viral DNA ‘healthy’ diet for -Two strands of RNA: viral individuals DNA Life Cycle -Safe2.Attached sex -Two protein coats – to CD4 receptor protein on cell -No successful vaccine protect RNA surface -Lipid envelope – fuses 3.Cell membranes fuse (endocytosis) 4.Coat breaks down and genes and enzymes with host cell membrane -Glycoprotein spikes – bind released 5.Reverse transcriptase transcribes RNA into to protein receptors on host cells DNA 6.Viral DNA integrated into host 7.Host cell ‘instructed’ to produce many copies

HI V

1) Depresses body’s normal immune response -T helper cells (co-ordinators of lymphocyte action) fall in number -Dendritic cells (display antigens) fall in number 5) Immune system does produce antibodies against HIV – HIV+ 7) Secondary infections by normally harmless organisms -Pneumocytis carinii (pneumonia) -Candida albicans (thrush) -Cytomegalovirus (kaposi’s sarcoma) 4) AIDS

Vector – female Anopheles Pathogen is Plasmodium which multiplies in stomach wall of mosquito and migrates to salivary glands

Parasites multiply rapidly in the liver Invade red blood cells and feed on haemoglobin and divide

MALAR IA Treatments Paludrin and Larium limit entry to liver and reduce multiplication Quinine from tonic water Vaccines limited – antigens evolve to avoid recognition

Saliva

skin Hydrochlori c acid in stomach

Nasal bones

Start with these useful words: Antigen

Any molecule which the body recognises as foreign eg. A bacterium, a virus, a dust particle

Antibody

A protein made by a lymphocyte that acts against a particular antigen

Pathogen

Any organism capable of producing disease

The Reds and The Whites White blood cell (granular)

Red Blood Cells

In an average healthy person, approximately 45 per cent of the blood volume is cells, among them red cells (the majority), white cells, and platelets.

A clear, yellowish fluid called plasma makes up the rest of blood. Plasma, 95 per cent of which is water, also contains nutrients such as glucose, fats, proteins, and the amino acids needed for protein synthesis, vitamins, and minerals.

The level of salt in plasma is about equal to that of sea water.

The cells that run the Immune System: Lymphocytes (B and T)

Phagocytes (Neutrophils, monocytes)

White Blood Cells: The Facts •WBCs are larger than Red Blood Cells •There are fewer WBCs than RBCs, about one white for every 600 red •Their main job is to protect the body against infection •Like RBCs, they are made in the bone marrow •Unlike RBCs, they contain a central nucleus and many can change shape •There are several kinds of WBCs

Broadly speaking, they can be divided into two categories: PHAGOCYTES

LYMPHOCYTES

•Destroy invading microorganisms by phagocytosis

•Smaller than phagocytes

•Recognised by granular cytoplasm and lobed nuclei

•Only small amount of cytoplasm

•Large round nucleus

•Destroy invaders by producing antibodies or by killing invaders directly.

Neutrophils

Macrophages

•Form 60% of all white blood cells

•Travel in blood as monocytes

•Patrol blood and lymph (squeeze through!)

•Become macrophages in organs

•Short lived

•Break up pathogens to expose recognisable antigens to lymphocytes

•Huge release during infection •Characteristic multilobed nucleus

•This initiates the IMMUNE RESPONSE

White Blood Cell

If the body is wounded, white blood cells pass through the walls of blood vessels where they attack and engulf invading bacteria

The Phagocytes……. • Neutrophils: Form about 60% of all WBCs. Patrol the circulation and the tissues by squeezing out of capillaries. Released in large numbers during an infection. Short lived. 2. Eosinophils: Respond to parasitic infections and allergic conditions 3. Monocytes: The precursors for macrophages. Once circulating monocytes enter tissues, they are converted into macrophages. Macrophages break up invaders to expose antigens to lymphocytes.

T Cells and the Immune Response

T killer cells

Search for invaded cells (antigens displayed on surface), attach and kill!

T Cells T helper cells Release CYTOKINES B cells  plasma cells antibody production

Stimulate macrophages  phagocytosis

T memory cells Remain in body ready for quick reaction at next exposure