Ch. 43 notes

Ch. 43 notes - Ch.43TheImmunesystem 16:25 Immune system...

Info iconThis preview shows pages 1–4. Sign up to view the full content.

View Full Document Right Arrow Icon
Ch. 43 The Immune system 16:25 Immune system – responses to infection which enable an animal to avoid or limit many infections Examples Macrophages engulf foreign cell Proteins punch holes in bacterial membrane Block viruses from entering body cells 2 types Innate immunity – defense that is activated immediately upon infection and is the same whether or not the pathogen has been encountered previously Barrier defenses Outer covering that provides a significant barrier to entry by microbes Skin Mucous membranes secretions Internal defenses Distinguishing self from nonself (molecular recognition – receptor molecules bind specifically to molecules from foreign cells or viruses), Bind to molecules or structures unique to viruses/bacteria Phagocytic cells Natural killer cells Antimicrobial proteins Inflammatory response Adaptive immunity – defense found only in vertebrates, produce a vast arsenal of receptors, each of which recognizes a feature typically found only on a particular part of a particular molecule on a particular pathogen super specific Also known as “acquired immune response”
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Activated after innate immune response, develops more slowly, include synthesis of proteins that inactivate a bacterial toxin/targeted killing of a virus-infected body cell Humoral response Antibodies defend against infection in body fluids Cell-mediated response Cytotoxic cells defend against infection in body cells Innate immunity: traits common to groups of pathogens Invertebrates Exoskeleton = first line of defense (made of chitin) Lysozyme – enzyme that breaks down bacterial cell walls, more protection for the insect digestive system Hemocytes – second line of defense, travel throughout body in hemolymph Phagocytosis Trigger production of chemicals that kill pathogens and help entrap large parasites Secrete antimicrobial peptides, which inactivate/kill fungi and bacteria by disrupting their plasma membranes Fungal cell walls – certain unique polysaccharides Bacterial cell walls – combinations of sugars and amino acids not found in animal cells Vertebrates Barrier defenses Epithelial tissues block the entry of many pathogens Skin Mucous membranes lining the digestive,, respiratory, urinary, and reproductive tracts Mucus – viscous fluid that enhances defenses by trapping microbes and other particles
Background image of page 2
In the trachea, ciliated epithelial cells sweep mucus + microbes upward = help prevent infection of lungs Inhibit colonization by fungi and bacteria + lysozyme destroy cell walls Saliva Tears Mucous secretions Acidic environment of stomach destroys most microbes before they can enter intestines Secretions from oil and sweat glands: pH = 3 – 5, acidic enough to prevent the growth of many bacteria Cellular innate defenses Phagocytosis Toll-like receptor (TLR) – similar to that of insects, binds to fragments of molecules characteristic of a set of pathogens Ex) TLR3 – on the inner surface of vesicles formed by endocytosis, sensor for double-stranded
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 4
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 17

Ch. 43 notes - Ch.43TheImmunesystem 16:25 Immune system...

This preview shows document pages 1 - 4. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online