8 - Innate Immunity

Question 1

What is immunity?

Answer 1

resistance to disease

Question 2

What type of system is the immune system and why?

Answer 2

functional system not an organ system
- comprised of a vast array of molecules & cells
- involved in every body system

Question 3

Pathogen categories

Answer 3

• Bacteria
• Viruses
• Fungi
• Parasites

Question 4

What is lymphatic tissue?

Answer 4

special form of connective tissue containing lymphocytes

Question 5

primary vs secondary lymphoid organs/tissues
(name, basic function)

Answer 5

primary:
- red bone marrow + thymus
- immune cell production & !immunocompetence

secondary:
- lymph nodes, nodules/follicles & spleen
- where most immune responses occur

!immune cell maturation & education

Question 6

Red bone marrow
(where, purpose)

Answer 6

in flat bones & !epiphyses of long bones

• pluripotent stem cells divide & differentiate into:
  
  • immunocompetent B cells
  • pre-T cells (immature)

!inside the head

Question 7

Thymus
(where, purpose)

Answer 7

in anterior mediastinum
- pre-T cells develop into mature T cells

Question 8

Lymph nodes
(where, purpose)

Answer 8

throughout the body, couple centimeters large
- filters for lymph
- adaptive immune cells gather (get inflammed during sickness because immune cells multiply)

Question 9

Spleen
(where, purpose)

Answer 9

left, between stomach and diaphragm
- removes damaged & defective RBCs
- stores platelets
- also has the functions of a lymph node

Question 10

Lymphatic nodules
(where, purpose)

Answer 10

throughout the body (tonsils on each side of back of throat)
- not organs, organized masses of lymph tissue
- commonly associated with mucosal surfaces
- why they’re called !MALT

!Mucosal Associated Lymphoid Tissue

Question 11

Innate immune system vs Adaptive

Answer 11

Innate:
- defence: non-specific, 1st & 2nd line
- consists of: surface barriers, internal defenses (mechanisms & immune cells)

Adaptive:
- defence: highly specific, 3rd line
- consists of: immune cells, newly generated cell types + proteins
- has memory
- humoral (B cells) & cellular (T cells) immunity

Question 12

Skin
(innate or adaptive, why & how)

Answer 12

Innate (1st)
Epidermis:
- many layers of cells, hard for bacteria to get through
- sheds frequently, stuck bacteria will fall off
- slightly acidic (because of keratin) hostile environment to many pathogens

Question 13

Mucous membranes
(innate or adaptive, why & how)

Answer 13

Innate (1st)
- mucous (nose, throat…):
- viscous (traps things)
- can be ejected (coughing & sneezing)
- can be swallowed (killed in stomach)
- hairs (nose, ears…):
- trap and filter microbes
- cilia (respiratory tract…):
- hair like, move mucous

Question 14

Tears
(innate or adaptive, why & how)

Answer 14

Innate (1st)
made by lacrimal apparatus
- makes and drains tears in response to irritants
- flushes bacteria from the eye, prevents from collecting
- have lysozymes (enzymes) that break down cell wall of some bacteria

Question 15

Bodily fluids
(innate or adaptive, why & how)

Answer 15

Innate (1st)
Saliva:
- washes teeth & mouth
- contains enzymes

Urine:
- flow cleanses urinary system

Vaginal secretions:
- expel microbes (can be stimulated by toxins)
- slightly acidic

Sebum:
- oils form protective coating on skin
- acidic

Sweat:
- flushes microbes from skin
- contains lysozymes

Gastric juices:
- highly acidic, destroys most bacteria & bacterial toxins

Question 16

Microbiome
(innate or adaptive, why & how)

Answer 16

Innate (1st)
- crowd the skin (harder for bad bacteria to settle & grow)
- make compounds toxic to pathogens
- many other fun things :) little frens

Question 17

Antimicrobial proteins
(innate or adaptive, why & how)

Answer 17

Innate (2nd)
enhance innate defences by attacking or hindering reproduction of microorganisms:
- interferons: interfere with viral replication
- complement: assists other immune responses
- iron-binding proteins: steal iron from bacteria
- other antimicrobial proteins: kill or sound infection alarm

Question 18

Natural Killer cells
(innate or adaptive, why & how)

Answer 18

Innate (2nd)
- in blood and tissues
- spontaneously kill tumour or virally-infected cells:
- perforin: makes hole in cell
- granzyme: enters cell, causing apoptosis
- release cytokines: signal other immune responses

Question 19

How do natural killer cells identify problems?

Answer 19

by the amount of MHC class 1 molecules (flags that the cell belongs to the body)
- normal cells: enough MHC
- NK cells inhibited from killing
- tumour cells: often have reduced MHC
- NK cells not as inhibited from killing
- transformed/infected cells: can activate NK cell receptors
- flag NK cells to kill it, strong response

transformed = become cancerous

Question 20

Phagocytosis
(definition, stages)

goodnotes

Answer 20

engulfing of foreign microbes or debris by a cell via its membrane
5 stages:
1. chemotaxis (cells move to site of issue cuz of chemical stim)
2. adherence (attach to microbe)
3. ingestion (engulf microbe)
4. digestion (using digestive enzymes)
5. killing (microbe dead)

Question 21

Which cells can be phagocytes?
(innate or adaptive, name, info)

Answer 21

Innate (2nd)
Neutrophils:
- most abundant leukocyte
- become phagocytic near infectious material
- first to move from blood to tissues during inflammatory response
- major component of puss

Monocytes(MC)/Macrophages(MP):
- MCs: in blood –> MPs: matured MCs in tissues
- MCs recruited to infection sites to differentiate into MPs

Dendritic cells:
- highly specialized, tissue resident
- antigen presenting

Question 22

How do phagocytes recognize pathogens?

Question 23

Inflammation
(innate or adaptive, why & basic how)

Answer 23

Innate (2nd)
defensive response to any tissue damage
- helps deliver molecules & cells to infection
- prevent spread to other tissues
- prepare site for repair

Question 24

How does inflammation occur?
(full mechanism/feedback loop)

goodnotes flowchart

Answer 24

Step 1: signalling, vasodilation, permeability of blood vessels
- damaged cells signal issue: chemical ‘alarm’ & inflammatory mediators released
- nearby macrophages active: release cytokines & chemokines
- mast cells: also release inflammatory mediators

Step 2: phagocytes move from blood to infection
- more blood nearby, decreased velocity
- permeability allows immune cells to migrate

Step 3: Healing
- clots and such

Question 25

How to identify inflammation & why signals occur

Answer 25

• rubor & calor (redness & heat caused by increased localized blood flow)
• tumor (swelling caused by increased permeability fluid collects in tissues: edema)
• dolor (pain caused by swelling, notifies us to immobilize area)

Question 26

Fever
(innate or adaptive, why & how)

Answer 26

Innate (2nd)
is an abnormally high body temperature
- pyrogens (type of cytokine) alter hypothalamic thermostat
- increases metabolic rate (chem. rxns faster in heat)
- higher temp. helps steal minerals from bacteria (zinc, iron…)