animal defenses against pathogens

What are the 3 physical barriers in animal defence

Skin

Mucus membranes

Lysosomes

How is skin a barrier

Sebum

Inhibits growth of pathogens

What is contained in mucus membrane

Phagocytes - remove remaining pathogens

Traps microorganisms

Lyssyomes - kill pathogen cell wall (bacteria/fungi)

Where is lysosomes

Urine

Tears

Stomach acid

What is another barrier to do with vomiting

Expulsion reflexes

Coughing sneezing vomiting

What doe mast cells release

Histamines

Cytokines

What do histamines do in terms of vasodilation

Cause blood vessels to dilate - localised heat + redness - increase temp and redness helps prevent pathogens reproducing

What do histamines do in terms of tissue fluid

Cause blood vessel walls to leaky - blood plasma forced out = tissue fluid - causes swelling and pain

Where is mast cells activated

In damaged tissues

What do cytokines do (3)

Attract WBC

Dispose pathogens

PHAGOCYTOSIS

CELL SIGNALLING MOL WHEN CELL UNDER ATTACK

INCREASE BODY TEMP

What are opsonins

Make pathogens recognisable

Phagocytosis bind to opsonins to allow engulfing

Tag phagocytes

Why do phagocytes bind to opsonins

To allow engulfing

What are cytokines for

Cell signaling molecules when cells under attack

Increase body temp

How do or body get rid of pathogens (2 ways)

Phagocytosis

Fever

How do fevers work to get rid of pathogens?

How do cytokines work?

Pathogens work best at or below 37 degrees

Cytokines cause hypothalamus to increase temperature - this inhibit pathogen reproduction + immune system works best at this temp

What are the 4 stages of phagocytosis

• pathogens chemicals attract phagocytes

• P.c recognise proteins pathogen as non self

• P.c engulfs pathogen - enters phagososome inside

• Phagososome + lysosome = phagolysosome

• Enzymes from p.l.s digest +destroy pathogens

What are the 2 cells that are apart of phagocytosis

Macrophages

Neutrophils

Where do phagocytes build up

Give examples

Phagocytes build up at infection + attack

Cut / puss/ wound

What dos puss consist of

Puss consists of dead neutrophils and pathogens

How do macrophages differ to neutrophils

Macrophages take longe than neutrophils when it comes to phagocytosis

Ho do macrophages work?

Digests pathogen

Combines antigen + major histocompatibility complex

MHC takes pathogen antigens - macrophages own surfaces membrane = antigen presenting cell (stimulate other cells in immune response)