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Biology 201 Fundamentals of Biology II

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Biology 201 Fundamentals of Biology II Rob Mustard Adjunct Faculty PALOMAR COLLEGE PALOMAR COLLEGE PALOMAR COLLEGE Leukocytes & Immune Response Blood cells are one of ... – PowerPoint PPT presentation

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Title: Biology 201 Fundamentals of Biology II


1
Biology 201Fundamentals of Biology II
  • Rob Mustard
  • Adjunct Faculty

PALOMAR COLLEGE
2
Leukocytes Immune Response
  • Blood cells are one of the fluid Connective
    Tissues
  • Red blood cells (erythrocytes)
  • Mammalian RBCs lack nuclei and mitochondria
  • 7 ?m diameter
  • White blood cells(leukocytes)
  • Giemsa stain to differentiate WBCs

6-7 million erythrocytes / ml3 7,000 leukocytes /
ml3
3
Immune Response Modes
  • Innate Immunity
  • Rapid (and general) response to a broad range of
    microbial invasion
  • Acquired (Adaptive) Immunity
  • Secondary (and highly-specific) response to
    previously-encountered pathogens
  • Vertebrates have both forms of immune-response
    mechanisms

4
Innate Immunity
  • External defenses include
  • Skin impenetrable to most viruses bacteria
  • Mucous viscous fluid that traps microbes
  • Cellular secretions sebaceous (oil) sweat
    glands reduce skins pH to 3-5 lysozyme digests
    Gram cell walls
  • Internal defenses begin after bacteria invade,
    typically through a break in skin or other
    epidermal layer

5
Inflammatory Response
  • Tissue damage from physical injury leads to
    cascade of chemical signals
  • Histamine, stored in mast cells in connective
    tissue
  • Nearby capillaries become dilated and leaky,
    allowing passage of macrophages and increased
    blood flow
  • Increased local blood supply leads to redness,
    heat and swelling (inflammation)
  • Macrophages move out into damaged tissues, in
    interstitial spaces between cells
  • Nonspecific Inflammatory Response

6
Leukocytes Involved in Innate Immunity
Phagocytes
  • Neutrophils
  • 60-70 of all leukocytes, live only a few days
  • Big 12-15 ?m (2x erythrocytes)
  • Nucleus has 2-5 lobes (polymorphic)
  • Monocytes
  • 5 of all leukocytes
  • Biggest 20 ?m
  • Lighter, frothy horseshoe-shaped nucleus

Neutrophils are granular
Monocytes are agranular
7
Leukocytes Involved in Innate Immunity
Phagocytes
  • Eosinophils
  • Rare in blood smears (2-4)
  • Big 12-15 ?m (same size as Neutrophils)
  • Nucleus has 2 lobes
  • Dendritic Cells
  • Patrol interstitial spaces of skin mucosal
    membranes
  • Phagocytize invaders, process present antigen
    material (APCs)
  • Activate acquired immune system

Eosinophils are granular
8
Leukocytes Involved in Innate Immunity
Hypersensitivity
  • Basophils
  • Rarest of the leukocytes (lt0.5)
  • 10-12 ?m diameter
  • Respond to allergic reactions (e.g., bee wasp
    stings, pollen)
  • Very granular nucleus often obscured
  • Live for about 2 weeks

Basophils are very granular
9
Leukocytes Involved in Innate Immunity
Cytotoxicity
  • Natural Killer Cells
  • A specialized lymphocyte
  • Attack virus-infected cells
  • Attack cancer cells (tumors)
  • NK cells recognize infected/defective cells via
    surface features
  • Bind to target cells, release chemicals
    (perforins) that lead to apoptosis

An NK cell (N) attached to a "target" cell "T".
The NK cell will kill the now helpless target
cell quickly, by the injection of deadly perforin.
10
Leukocytes Involved in Acquired Immunity
  • Lymphocytes
  • Very common in blood 20-40 of WBCs
  • Slightly larger than RBCs (10 ?m)
  • Dark-staining, circular nucleus
  • Agranular cytoplasm is transparent

11
Lymphocyte Specialization
  • Vertebrate lymphocytes take on specialized roles
  • Circulate through blood lymph, concentrated in
    spleen lymph nodes
  • B T cells bear 100K antigen receptors (all the
    same)

Antigen- binding sites
IgM Receptors
V
V
Variable regions
V
Light chain
V
V
V
C
C
C
C
C
C
Constant regions
b chain
? chain
Heavy chains
T cell
B cell
12
Acquired Immunity Responses
  • Humoral Response
  • Dendritic cell (APC) engulfs pathogen, presents
    antibody via cell-surface protein (MHC class II)
  • Helper T cell binds to presented antigen
  • APC releases cytokines to stimulate production of
    more activated T cells
  • Activated B cells secrete antibodies, which
    immobilize pathogens, marking them for
    destruction by macrophages
  • Cellular Immune Response
  • A cell other than a leukocyte takes up and kills
    a microbe, presents antigen on surface (MHC class
    I)
  • Cytotoxic (activated) T cell binds to presented
    antigen, releases perforins, lyses infected cell

13
  • Questions??

PALOMAR COLLEGE
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