lecture 2 Flashcards
skin defense physical barrier 1: epidermis
thin layer dead cells, keratin phagocytotic immune cells
skin defense physical barrier 2: dermis
thick layer of connective tissue
collagen
blood vessels
phagocytotic immune cells
skin defense chemical 1 : skin defensins
Antimicrobial peptides
Active against bacteria, fungi and viruses
Form pore holes in microbial membranes so microbes lose nutrients essential ions
skin defense chemical 2: lysozymes
enzyme from sweat glands and tears that breaks down bacterial cell walls
skin defense chemical 3: sebum
from sebaceous glands associated with hair follicles
low pH fluid prevents microbial growth colonisation
Skin defense chemical 4: salt
from sweat glands
creates hypertonic environment dehydrates pathogens
what are mucous membranes
1-2 layers of epithelium
Tightly packed live cells, renewed by stem cells Contains mucus-producing goblet cells
Lines body cavities body parts exposed to outside/air
Made of mucus layer, epithelium, fibrous connective tissue (lamina propria)
where are mucousal membranes
(line parts of the body that lead to the outside and are exposed to air) occular respiratory oral urogenital/rectal
1) the mucociliary escalator (respiratory)
mucus watery layer (traps dust particles and pathogens)
cilia synchronised beating motion (2-3 cm/hr)
goblet cell
columnar cell
basement membrane
- remove pathogens via coughing
2) gastrointestinal tract (oral)
stomach low pH (2-3)
gall bladder- bile secretion- breakdown lipid membrane
intestine - digestive enzymes
mucus (traps microbes)
Defensins (makes pores/holes) kill breakdown microorganisms inhibit growth
Diarrhoea and vomiting remove pathogens
3) tears (occular)
flushing action
lysozyme enzyme
wash away pathogens
4) urogenital tract
urine flow contains lysozyme low pH high osmolarity (hypertonic to bacteria) has cilia
number of cells layers (skin vs MM)
many, 1-few
tightly packed cells
yes, yes
cells dead or alive
outer dead inner alive, alive
mucus present
no, yes
lysosyme and defensins present
yes, some cases
sebum present
yes, no
cilia present?
no, in trachea and uterine tubes
how can physical chemical barriers be breached e.gs
e.g samonella rabies, drugs, penetration, mosquito
what increases chance of breached barriers
dry skin, exema, not so robust penetrate lack sebum
vulnerable and scratching
cells of innate immune system 3 blood cell lineages
bone marrow stem cells source, hematopoiesis
- Erythroid - RBC erythrocytes
- Myeloid - granulocytes, monocytes, dendritic cells, platelets (innate immune cells)
- Lymphoid- B and T lymphocytes ( adaptive immune cells)
granulocytes in blood
neutrophils, eosinophils, basophils
neutrophils (in blood)
75% of all leukocytes, highly phagocytic “eat and kill” numbers in blood increase during infection
