W2 HBS: Body Defences

microorganism

tiny living organisms that can reproduce independently

prokaryotic cells properties

unicellular with no membrane bound organelle, asexual reproduction

eukaryotic cells properties

multicellular with membrane bound organelles, sexual reproduction

virus properties

non living, must infect host cells to survive, antibiotics are ineffective

bacteria properties

prokaryotic cells, able to reproduce independently, can be treated using antibiotics

protozoa properties

eukaryotic cells, unicellular

fungi properties

eukaryotic cells that reproduce through spores

helminths properties

eukaryotic cells that dont proliferate in the host

gram stains

technique used to visualise bacteria

gram positive

have thick cell walls and are capable of forming spores

gram negative

reinforced with a 2nd cell membrane and release endotoxins when damaged

benefits of microbiota

reduces ph, competes with pathogenic bacteria, secretes vitamins

modes of transmission

direct contact, indirect contact, vehicle, vector, vertical

chain of infection

reservoir, portal of entry, mode of transmission, portal of exit, susceptible host, infectious agent

sterilisation

destruction of all microbes

disinfection

elimination of most pathogens from inanimate objects

sanitation

disposal of body products

layers of skin

epidermis, dermis, hypodermis

epidermis composition

keratinised stratified squamous epithelial cells

avascular

no blood vessels

keratinocytes

produce keratin

melanocyte

produce melanin

langerhans cells

activate immune system

merkel cells

sensory receptors present at the epidermis dermis junction

strata of the epidermis

stratum basale, stratum spinosum, stratum granulosum, stratum lucida, stratum corneum

thin skin is missing the

stratum lucida

dermis composition

connective tissue, collagen and elastic tissue

layers of the dermis

papillary and reticular

hypodermis composition

subcutaneous layer that anchors skin to underlying structures

nail properties

densely packed epithelial cells containing fibres of hard keratin

gland properties

clusters of specialised epithelial cells that secrete a substance

chemical barrier of the skin

ph, chemical sin sebum prevent growth of bacteria

physical barrier

intact and hydrophobic prevents pathogens from entering

mechanoreceptors

pressure

thermoreceptors

temperature

nocireceptors

pain

lymphocyte

type of white blood cells

mast cell/basophil

release histamine in response to an allergen

neutrophil

phagocytosis of pathogens

eosinophil

releases toxic chemical mediators to destroy pathogens

macrophage

phagocytosis of pathogens and antigen presentation on MHC 2 markers

natural killer cell

destroys infected cells with insufficient MHC 1 markers

T lymphocyte

directly destroy infected cells

b lymphocyte

produce antibodies to target invading bacteria

lymph

fluid connective tissue containing lymphocytes and macrophages

interstitial fluid

fluid surrounding cells within tissue

red bone marrow

produces b and t cells, matures b cells

thymus gland

produces thymosin hormones to mature t cells

lymph nodes

filter lymphatic fluid using b and t cells

oedema

excessive accumulation of interstitial fluid

antigen

any molecule capable of inducing an immune response

innate immunity

general defence against all antigens that is present from birth

acquired immunity

targeted defence against a particular antigen that develops over time

first line of defence

prevention of entry of pathogen

first line of defence parts

intact skin, mucous membrane, fluid barriers, microbial barriers

second line of defence

attacks non specific pathogens and responds to tissue damage

interferon

prevents viral replication by blocking the virus

complement proteins

opsonisation, chemotaxis, lysis

chemotaxis

attract phagocytes

opsonisation

attach to pathogens to make them recognisable

lysis

form a membrane attack complex to create holes in the cell

phagocyte

antigen presenting cells

inflammation

vasodilation of blood vessels increases amount of phagocytes in response to localised tissue damage

fever

febrile temperature denatures the enzymes in pathogens

third line of defence

specific immunity that is developed through repeated exposure

properties of acquired immunity

specific, versatile, memory, tolerance

humoral immunity

destruction of extracellular pathogens through the production of antibodies

b cells properties

have antibodies on the surface that recognise one kind of antigen

b plasma cells

produces antibodies to destroy a specific pathogen

b memory cells

give rise to plasma cells upon recognition of its specific antigen

antibody

neutralize pathogens

helper t cells

recognise antigens on antigen presenting cells and stimulates b cells

cell mediated immunity

destruction of intracellular pathogens

memory t cells

hold memory of a specific antigen for future exposure

suppressor t cell

regulates t cell response at the end of an infection

cytotoxic t cells

kills virus infected cells by recognising both mhc 1 and 2 markers