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The Immune system. The Immune system is the body’s defense system Against: – Bacteria – Viruses – Protists – Other living invaders – Toxins – Foreign.

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Presentation on theme: "The Immune system. The Immune system is the body’s defense system Against: – Bacteria – Viruses – Protists – Other living invaders – Toxins – Foreign."— Presentation transcript:

1 The Immune system

2 The Immune system is the body’s defense system Against: – Bacteria – Viruses – Protists – Other living invaders – Toxins – Foreign debris – Cancerous cells The immune system is complex Defends against threats known and unknown

3 Elements of the Immune system Many lines of defense, for many kinds of threats Skin Blood Thymus Spleen Lymphatic system Mucous membranes Bone marrow

4 Innate vs. Adaptive immunity Innate Immunity Non-specific Defends against known invaders Skin, lysozyme Pre-existing Cannot adapt to changing threats Adaptive Immunity Mechanisms which fight specific invaders For unknown threats Responsive Requires time to build defense (days) Cannot anticipate threats Remembers previous threats

5 Humoral vs. Cell-mediated Immunity Cell- Mediated Immunity Live cells kill invaders Innate: Phagocytic cells (e.g. macrophages, neutrophils) Adaptive: B lymphocytes and T lymphocytes create specific responses to unique invaders Humoral immunity Proteins in blood (“humors”) Innate- complement system, clotting factors, cytokines, etc. Adaptive: Antibodies

6 Blood is a mixture of cells and plasma ~55% Plasma ~45% Red blood cells <1% White blood cells and platelets (“buffy coat”) Human Blood after centrifugation

7 Blood plasma Water Nutrients Solutes- Na+, Cl-, wastes, CO2, etc. Contains humoral immune elements Some innate immunity

8 All blood cells are part of the hematopoetic stem cell lineage

9 Hematopoetic stem cells differentiate into all blood cells Pluripotent- able to become any one of many cell types Includes T cells, B cells, macrophages, etc.

10 Red blood cells carry oxygen and CO2 Lose nucleus in development Short-lived, no repair Packed solid with hemoglobin Membranes designed to maximize surface area Facilitate gas transfer

11 Hemoglobin The oxygen-carrying protein Heterotetrameric protein 2 alpha subunits, 2 beta Each subunit holds a Heme group Each heme holds an Fe++ ion Each Fe++ can bind an O2

12 Hemoglobin binding curve In areas of High O2 (e.g., lungs)- binds O2 very well (picks up O2) In areas of Low O2 (e.g., muscles) binds O2 poorly (drops off O2) Myoglobin binds O2 in muscle & organ tissues

13 Platelets assist with blood clotting Recruit plasma protein fibrinogen to a cut They release clotting factors Clotting factors convert fibrinogen to fibrin Fibrin net prevents blood loss

14 The liquid part of blood is called A) water. B) plasma. C) serum. D) extrastitial fluid. E) anionic fluid.

15 White blood cells come in a great variety of types

16 Elements of Innate Immunity

17 Lysozyme- an innate enzymatic defense Enzyme that cuts bacterial cell walls Also cuts chitin, a constituent of fungal cell walls and arthropod exoskeleton Found in mucous, tears, egg whites

18 Complement- humoral defense against non-specific invaders A biochemical cascade Non-specific Signalling pathway to cause cell lysis Also Recruitable by adaptive immune system

19 Interferons are nonspecific anti-viral signalling molecules

20 Phagocytic white blood cells devour bacteria

21 Which of the following, produced by virus- infected cells, diffuses to neighboring cells to help them fight a viral infection? A) lysozyme B) interferon C) histamine D) antigen E) interleukin-2

22 The Inflammatory response

23 Keeping the body safe comes at a cost Inflammation implicated in heart disease, etc. Gum inflammation linked to heart attacks

24 The lymphatic system collects lymph and houses white blood cells in nodes

25 Adaptive Immunity contains humoral and cell-mediated components

26 Adaptive Immunity is learned, and has memory

27 Antibodies- the Key component of humoral adaptive immunity Two light chains, two heavy chains Each contains a variable region and a constant region

28

29 Antigen- anything which can be bound by an antibody

30 B Cells- the source of antibodies

31 Clonal selection musters B-cell defense forces against specific antigens

32 Adaptive Immunity is learned, and has memory

33 Immune cells are the only cells with different DNA VDJ recombination of light and heavy chains generate antibody diversity Change is permanent A form of Russian Roulette for the cell Successful recombination creates a binding antibody- cell survives Unsuccessful- cell is destroyed Finding a good cell takes time

34 Bound antibodies are the mark of death for invaders

35 Breast milk contains maternal antibodies Infants have no acquired immunity Mother’s acquired immunity is transferred to the baby through nursing Passive immunity Is not retained by the baby

36 Vaccination gives the body active immunity An antigen sample is given to a person Person’s immune system mounts a response to the antigen Antigen can be deactivated/destroyed virus particles, etc. No waiting time for body to develop 2 o immune response

37 Antibodies can be used as therapy Some growth factors are overactive in certain cancers Antibody binds to growth factors, or their receptors

38 Polyclonal Antibodies From multiple B cells Bind to different epitopes of an antigen

39 Monoclonal antibodies Obtained from a single B cell Bind to a single epitope A single B cell is fused to a myeloma cell Myeloma cells are immortal

40 Mouse antibodies can be humanized Constant regions of mouse antibody are gradually replaced with human sequences

41 Fluorescent antibodies can be used in scientific experiments Fluorescent molecules can be linked to antibodies Antibodies show us where proteins exist in vivo

42 In an ELISA, Horseradish Peroxidase is linked to a 2 o antibody

43 Indirect ELISA To detect the presence of an antibody Wash Block Wash Substrate Primary Antibody Secondary Antibody

44 Home pregnancy tests utilize antibodies

45 Antibodies are A) amino acids. B) lipids. C) carbohydrates. D) proteins. E) nucleic acids.

46 The transfer of antibodies from breast milk to an infant is an example of __________ immunity. A) nonspecific B) passive C) humoral D) active E) cell-mediated

47 T cells are the primary cell-mediated adaptive immune response

48 Major Histocompatibility Complex (MHC or HLA) MHCI Found on all cells, recognized by T C cells MHCII Found on B cells and Macrophages recognized by T H cells

49 When presented with antigen, Helper T cells recruit other immune cells

50 The basic function of T cells is to identify and destroy invaders in our A) blood or lymph. B) interstitial fluid. C) cells. D) immune system. E) brain.

51 CD4 on the surface of T H cells is the site of HIV binding

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53 Any known stage of the HIV life cycle is a potential point for therapy

54 Protease inhibitors prevent formation of HIV capsids

55 AZT is a nucleoside analog reverse transcriptase inhibitor AZTThymine

56 Cytotoxic T cells destroy infected body cells

57 In Autoimmune disease, the immune system attacks the self

58 Allergies are immune responses to harmless antigens

59 A substance that can elicit an immune response is called a(n) A) complement. B) interferon. C) histamine. D) antibody. E) antigen.

60 Which one of the following statements about HIV is false? A) The genome of HIV consists of RNA. B) HIV attacks helper T cells. C) New HIV are produced inside helper T cells. D) HIV is transmitted by body fluids transporting infected cells. E) Some antibiotics have proven effective in combating the spread of AIDS.

61 Which type of immune response is always disadvantageous to a person? A) cell-mediated B) inflammatory C) humoral-mediated D) autoimmune E) All immune responses are advantageous.


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