Microbiology and Immunology Test 1

MDL 107

Label 1-5

1. Eyepiece/Ocular Lens

2. Diopter Adustment

3. Arm

4. Coarse Focus

5. Fine Focus

Label 6-10

6. on/off switch

7. base

8. light source/field diaphragm

9. iris diaphragm

10. condenser (w flip flop lens)

Label 11-14

11. Stage

12. Slide Holder

13. Objective Lens

14. Nose piece

Name the granular WBCs and their appearance

Neutrophil - light purple stain, multilobed nucleus

Eosinophil - Pink stain (from eosin stain), double-lobed nucleus

Basophils - dark purple stain, nucleus is obscured

Non-granular WBCs can be further divided into:

lymphocytes

monocytes

White blood cells (leukocytes) can be classified as

Granular (granulocytes)

Non-Granular

name the lymphocytes

B-cells

T-cells

natural killer (NK) cells

Monocytes in the blood become ___ or ___when they enter the tissues

macrophages, dentritic cells

What is the function of a neutrophil?

first cell at site of infection

phagocytosis

digestion done by hydrolase, myeloperoxidase, muramidase

What is the function of an eosinophil?

some phagocytosis (not its primary function)

control of parasitic infestations (releases enzymes extracellularly)

immediate hypersensitivity reactions

releases histaminase to inactivate IgE in allergic responses

What is the function of a basophil?

only in circulation for a few hours then migrate into tissues to become mast cells

some phagocytosis (not its primary function)

releases histamine in response to IgE binding to cell surface receptors

What is the function of a monocyte?

only in circulation for 8-10 hours before becoming macrophages

Antigen presenting cells (dendrites)

secrete proinflammatory cytokines and interleukins

express MHC II, complement, and antibody receptors (used in phagocytosis and antigen presenting cells)

What is the general function of B-lymphocytes?

antibody production in humoral immunity

What is the general function of T-lymphocytes?

regulates proliferation & differentiation of B and T lymphocytes

cell mediated immunity

Neutrophils make up ___% of circulating WBCs

50-70

Eosinophils make up ___% of circulating WBCs

2-5

Basophils make up ___% of circulating WBCs

1

Monocytes make up ___% of circulating WBCs

3-7

B cells mature in the ___ and localize in ___ ___ ___

bone marrow, peripheral lymphoid organs

The cell surface of B cells are lined with

antibodies (membrane bound)

T cells mature in the ___ and localize in the ___ ___ ___.

thymus; peripheral lymphoid organs

What is the function of natural killer cells?

Releases enzymes to lyse virally infected and defective (cancer) cells

natural killer (NK) cells are activated by

interferons

B and T cells can only be differentiated via

flow cytometry

lymphocytes account for ___% of circulating WBCs

20-30

What are the 2 main cell lines for leukocytes?

myeloid - neutrophils, eosinophils, basophils, monocytes/macrophages, red blood cells, platelets

lymphoid - T cells, B cells, NK cells

What is an interferon?

proteins produced by virally infected cells to induce viral resistance in surrounding cells; signal NK cells to destroy virally infected cells

Which factors affect immunity?

age, nutrition, stress

How does age affect immunity?

Young children do not have a completely developed immune system.

Elderly experience decline in immunologically competent lymphocytes

How does malnutrition affect the immune system?

decreased lymphocytes

decreased antibodies

decreased phagocytosis

Why are processed foods bad for immunity?

high fat diets promote action of carcinogens

lack vit. A needed to maintain physical barriers (e.g., skin)

lack vit. C needed for phagocytosis

How does stress affect immunity?

temporarily boosts immune system

longterm → reduces NK cell activity, lymphoid organs atrophy, fewer lymphocytes, phagocytosis reduced

saprophytic microorganisms

grow on dead, decaying matter (e.g., fungi)

symbiotic microorganisms

live with humans in a mutually beneficial relationship (e.g., gut microbiome)

commensal microorganism

depend on their host for support and nourishment

define phagocytosis and which immune cells perform this action

the process of ingesting and digesting foreign material

performed by neutrophils and monocytes

Explain the steps of phagocytosis

1. phagocytes are attracted via chemotaxis and make contact w foreign material

2. cellular cytoplasm flows around foreign particle to form pseudopods and engulf it (ingestion) → now a phagosome

3. oxygen consumption in the cell increases (respiratory burst) to form superoxide radicals (e.g., hypochlorite)

4. phagosome fuses with lysosomes → phagolysosome

5. pH of phagolysosome lowers to digest foreign material → now a residual body

6. wastes in residual body discharged via exocytosis

The immune system can be divided into

innate (natural) immunity

specific (adaptive) immunity

Innate immunity involves:

preventing entry of pathogens through barriers (e.g., skin)

counterattack if barriers breached (phagocytosis)

Specific immunity involves

recognition and disposal of specific pathogens

immunologic memory

amplification/enhancement of innate immunity

What are the differences between innate and specific immunity?

specific immunity discriminates between self and non-self; innate doesn’t

specific immunity is specific to the type of pathogen; innate deals with any foreign material

specific immunity has memory of previous pathogens; innate doesn’t

specific immunity takes days; innate takes minutes to hours

immunology

the study of the body’s response to foreign substances

antigen

a foreign substance that induces an immune response

Define innate immunity

the ability to resist infections by means of normally present body functions

innate immunity is ___ ___ ___ and the ___ ___ of defense

present from birth; first line

What are the 2 parts of innate immunity?

external defense system

internal defense system

What are the 3 components of the external defense system?

physical barriers

chemical barriers

microbiological barriers

Give 3 examples of physical barriers.

1. Intact skin sheds and prevents microorganisms from attaching to living cells

2. Mucous prevents microorganisms from attaching to underlying epithelium

3. Cilia epithelial cells move microorganisms and other particles out of respiratory tract

   (others: peristalsis of digestive tract, urine flushing out urethra, sneezing)

Give 3 examples of chemical barriers.

1. lysozymes in tears and saliva prevent infections.

2. low pH of stomach acid kills microorganisms

3. lactic acid on skin keeps pH at 5.6

   (others: low pH and lysozymes in urine)

Give 2 examples of microbiological barriers.

Gut microbiome and normal flora on skin use up space and nutrients, leaving little available for infectious microorganisms (crowd out the pathogens).

T or F: stomach acid can destroy microorganisms and toxins

F, stomach acid can’t destroy toxins

What are the 4 components of the internal defense system

WBCs

phagocytosis

complement proteins

acute phase reactants

define chemotaxis

the movement of cells in response to chemical stimuli

define opsonins

a substance which binds to foreign microorganisms making them more susceptible to phagocytosis.

give 3 examples of opsonins

c-reactive protein (CRP)

complement

antibodies

name the processes

a) opsonization

b) neutralization

c) agglutination

phagocytosis can lead to ___ of the phagocyte

apoptosis

what is the function of the complement system?

mediation of inflammation

define acute phase reactants (APRs) and list the 6 examples discussed in class

proteins in the blood that increase in concentration in response to injury/infection

1. c-reactive protein (CRP)

2. alpha-1 antitrypsin

3. haptoglobin

4. fibrinogen

5. ceruloplasmin

6. alpha-1 acid glycoprotein

where are APRs made?

liver

What causes CRP to rise?

bacterial/viral infections

malignancies

myocardial infarction (heart attack)

CRP is an …

early reliable indicator of acute inflammation.

How is CRP clinically useful?

indicates if healing is proceeding normally

rise in levels may indicate infection, organ rejection, or return of malignancy

Explain alpha-1 antitrypsin’s role in maintaining the elasticity of the lungs

• WBCs secrete elastase (a protease) to destroy bacteria and infected cells

• liver produces α-1 antitrypsin in response

• α-1 antitrypsin binds to elastase to prevent degradation of elastin and collagen in lungs

α-1 antitrypsin deficiencies can result in

COPD

emphysema

liver disease

What is the function of haptoglobin?

• binds free hemoglobin in blood from intravascular hemolysis

• prevents loss of iron by urinary excretion

• prevents kidney disease

What is the function of fibrinogen?

• forms fibrin clot when skin is cut (prevents spread of microorganisms)

• stimulates fibroblast proliferation and growth for healing

What is the function of cerulosplasmin?

• transports copper in plasma (blood) to cytochrome C oxidase to meet energy requirements of phagocytosis and wound healing

• removes superoxide radicals generated from phagocytosis

what is the function of α-1 acid glycoprotein?

• unknown

• thought to transport and metabolize progesterone

• binds and inactivates some drugs

Define inflammation

the overall reaction of the body to injury or invasion by an infectious agent

Describe the process of inflammation.

1. mast cells in damaged tissues release histamines, causing vasodilation → causes redness and heat

2. histamines cause endothelial cells of capillaries to contract, making them “leaky” → fluid leaks into tissues to cause swelling

3. neutrophils, clotting factors, and APRs, can now pass through leaky capillaries into damaged tissues → phagocytosis of microorganisms, amplification of coagulation system

4. monocytes migrate to area (now macrophages) a few hours later to clear the area

why is prolonged/chronic inflammation bad?

causes tissue damage and loss of function

If the body’s innate system gets overwhelmed, the body responds with

adaptive immunity

adaptive immunity consists of:

humoral response - production of antibodies (humoral immunity)

cellular response - activation of antigen-specific lymphocytes (cell mediated immunity)

MHC stands for

major histocompatibility complex

• cell surface protein

• type I on all nucleated cells

• type II on macrophages, monocytes, B cells

How do antigen presenting cells (APCs) function?

• APCs (e.g., dendrites) recognize pathogens, engulf and digest them (phagocytosis), and display the antigen on MHCII on cell surface

• APC travels to lymphatic tissue (this is where the B and T cells are)

• presents antigen to T cells until there is a match

• Matching T cells are now active, adaptive immunity has been activated

Once activated by dendrites, T cells become

helper T cells - present antigens to B cells to activate them

cytotoxic T cells - destroy infected/defective cells

suppressor T cells - limits/controls immune response

memory T cells - retain the memory of the pathogen

Once activated by helper T cells, B cells become

plasma cells - secrete antibodies

memory b cells - retain the memory of the pathogen

Why are memory B and T cells important?

so an immediate, specific, and enhanced response can be launched in response to subsequent exposures

Describe the function of platelets

involved in clotting mechanism

change shape when activated to form a platelet plug

release cytokines to attract WBCs

Define reticula/reticular tissue

a type of connective tissue composed of reticular fibers (type III collagen) that creates a mesh-like structure to support other tissues and organs

What is the reticuloendothelial system (RES)?

phagocytic cells (primarily monocytes and macrophages) located in reticular connective tissues to filter and trap antigens

I which organs/tissues is the RES found?

spleen

lymph nodes

bone marrow

liver

lungs

What are the primary lymphoid organs?

bone marrow

fetal liver

thymus

What are the secondary lymphoid organs?

spleen

lymph nodes

mucosal associated lymphoid tissue (MALT)

the spleen and lymph nodes are ___ organs

encapsulated

What do secondary lymphoid organs do?

trap antigens

provide network for lymphocyte-antigen interaction (to activate lymphocytes)

what is the role of bone marrow in the immune system?

-blood cell production

-pluripotent hematopoetic stem cells can turn into various blood cells

-B cells maturation

RBCs and WBCs are produced in the ___ bone marrow

red

When is the thymus biggest

at puberty, then begins to shrink

T cell maturation occurs in the ___ and ___ of the thymus

cortex, medulla

mature T cells are found in the ___ of the thymus

medulla

adaptive immunity begins in the ___ lymphoid organs

secondary

what are the common features of all secondary lymphoid organs?

• specialized port of entry

• areas where B&T cells migrate

• structure maximizes trapping of antigens and lymphocyte-antigen interactions

What do lymph nodes do?

drain and filter fluid from extracellular spaces of tissue

Antigens get trapped in the ___ ___ and phagocytosed by ___. The antigens are then presented to the ___.

lymph nodes, macrophages, lymphocytes

the largest lymphoid organ is the ___ and it ___ ___

spleen, filters blood

The inside of the spleen is split into ___ ___ and ___ ___

red pulp, white pulp

What is the function of the spleen’s red pulp?

destroys old and abnormal RBCs

What is the function of the spleen’s white pulp

provide an area for antigens and  antigen presenting cells to activate lymphocytes