Micro Ch. 12

Susceptibility

Lack of resistance to a disease

Immunity

Ability to war off disease

Innate immunity

Defenses against any pathogen; rapid, present at birth

Adaptive immunity

Immunity or resistance to a specific pathogen; slower to respond, has memory component

Toll-like receptors (TRLs)

On host defensive cells attach to pathogen-associated molecular patterns (PAMPs)

Pathogen-associated molecular patterns (PAMPs)

Molecular structures common to pathogens

Cytokines

Cytokines small cell signaling proteins; regulate the intensity and duration of immune responses

Innate

Recruit defensive cells to isolate and destroy microbes as part of inflammatory response

Adaptive

Can activate cells involved in adaptive immunity

The First line of Defense (Physical Factors)

Skin and Mucous Membranes

Epidermis

Outer portion made of tightly packed epithelial cells containing keratin, a protective protein

Dermis

inner portion made of connective tissue

Epithelial layer lines

Gastrointestinal, respiratory, and genitourinary tracts

Mucous

Viscous glycoproteins that trap microbes and prevent tracts from drying out

Ciliary escalator

Transports microbes trapped in mucous away from the lungs; propels them upwards towards the throat

Lacrimal apparatus

Drains tears; washes eye

Other 1st line defense physical factors

Saliva, Peristalsis, Earwax, Urine, Vaginal secretions

1st line of defense of Chemical Factors

Sebum, Low pH, Lysozyme

4 things about Normal Microbiota

* Compete w/ pathogens via microbial antagonism
* Competitive advantage for space and nutrients
* Produce substances harmful to pathogens
* After conditions that affect pathogen survival

Probiotics

Live microbial cultures administered to exert a beneficial effect

Probiotics produce

Lactic acid and bacteriocins (toxic peptides) that inhibit pathogen growth

7Blood composition (2nd line of defense

Plasma (liquid portion)

Formed elements (cells and cell fragments in plasma)

Formed Elements in Blood

Erythrocytes (red blood cells)

Leukocytes (white blood cells)

Platelets

Where is blood created

red bone marrow stem cells by hematopoiesis

Hematopoiesis

Creation of cellular components of blood

All blood cells

Arise from stem cells

2 Leukocytes divided by appearance

Granulocytes and Agranulocytes

Granulocytes

Visual Granulocytes in cytoplasm

Agranulocytes

Granules in cytoplasm are not visible via light microscope

3 types of Granulocytes

Neutrophils, Basophils, Eosinophils

Neutrophils

Phagocytic; work in early stages of infection; can leave blood and enter infected tissue

Basophils

Release histamine; mediate inflammation and allergic responses

Eosinophils

Phagocytic; toxic against parasites and helminths; can leave blood

3 of types Agranulocytes

Monocytes, Dendritic cells. Lymphocytes

Monocytes

Leave blood, enter body tissues, and mature into macrophages (become Phagocytic)

Dendritic cells

Found in the skin, mucous membrane, and thymus; Phagocytic, initiate adaptive response

Lymphocytes

T cells, B cells, and NK cells; Play a role in adaptive immunity

Differential white blood cell (WBC) counts

Measure leukocytes in the blood and % per 100 counted cells

High WBC counts (leukocytosis) may

Indicate bacterial infections, autoimmune diseases, or side effects of medications

Low WBC counts (Leukopenia) may

Indicate viral infections, pneumonia, autoimmune disease, or cancers

Lymphatic System (2nd Line of defense)

Lymph- fluid

Lymph vessels- vessels, similar to circulatory system

Lymphoid tissue- structures and organs (thymus and lymph nodes)

Red bone marrow- Hematopoiesis

Overview 1st step of lymphatic system overview

Interstitial fluid (fluid between cells in tissues) flows into lymphatic capillaries (small lymphatic vessels)

Overview 2nd step of lymphatic system overview 

Fluid (now called lymph) flows in one direction and enter larger lymphatic vessels

Overview 3rd step of lymphatic system overview 

At interval along system, lymph flows through lymph nodes and nodes contain fibers to trap microbes, and defense cells to kill them by phagocytosis

Overview 4th step of lymphatic system overview 

Eventually all lymph passes through lymphatic ducts and enters bloodstream (lymph is now blood plasma)

Overview 5th step of lymphatic system overview 

Blood plasma moves through cardiovascular system and eventually becomes interstitial fluid again

Overview 6th step of lymphatic system overview 

The cycle repeats

Lymphatic Tissue is found

Scattered throughout mucous membranes that line GI, respiratory, urinary, and reproductive tracts

Specific organs and aggregations of lymphoid tissues

Spleen, Thymus, Tonsils, Peyer’s patches (in small intestine)

Phagocytosis

Ingestion of microbes or other substances by a cell performed by phagocytes

1st step of Phagocytosis

Chemotaxis

2nd step of Phagocytosis

Adherence

3rd step of Phagocytosis

Ingestion

4th and final step of phagocytosis

Digestion

At start of infection

Granulocytes (mostly neutrophils) and monocytes move to infected area

At start of infection neutrophils

Dominate initial response

At start of infection Monocytes

Mature into macrophages

Fixed macrophages

Are residents in tissues and organs

Free (wandering) macrophages

Roam tissues and gather at sites of infection

As infection progresses

Macrophages become predominant cell type

Chemotaxis

Chemical signal attract phagocytes to microorganisms

Adherence

Attachment of phagocyte to microbe surface (TRLs and PAMPs) and enhanced by opsonization: microbial antigens are marked with serum proteins (antibodies)

Ingestion

Pseudopods (plasma membrane extension) engulf microbe, fuse and form phagosome which pinches off membrane and enters cytoplasm

Digestion

Phagosome fuses w/ lysosome (contains digestive enzyme and bactericidal substances; forms phagolysosme which digest microorganisms and release indigestible material outside cell

Inflammation

Local defensive response triggered by injury to body tissue

Signs and Symptoms of PRISH

Pain, redness, immobility, swelling, heat

In PRISH pain

Release of chemical

In PRISH redness

Increased blood flow

In PRISH immobility

Loss of function

In PRISH swelling

Fluid accumulation

In PRISH heat

Increased blood flow

Functions of Inflammation

Destroys injurious agent; removes it and by-products

Limits its effects on the body; isolating/walling off it and by-products

Repairs and replaces tissue damaged by the injurious agent and by products

2 Types of inflammation

Acute and chronic

Acute inflammation

Rapid development of signs and symptoms; last days to weeks

Mild and self-limiting

Primarily neutrophils

Examples of acute inflammation

Appendicitis, cold flu, sore throat, minor cuts/scratches

Chronic inflammation

Slow development of signs and symptoms; last months to years

More severe and progressive

Primarily monocytes and macrophages

Examples of chronic inflammation

Peptic ulcers, tuberculosis, rheumatoid arthritis

3 steps of inflammation

1. Vasodilation and increased permeability of blood vessels
2. Phagocyte migration and phagocytosis
3. Tissue repair

Acute inflammatory begins

When TLRs on phagocytes, neutrophils and macrophages recognize PAMPs and release cytokines

Liver responses to cytokines in

Blood and activities acute-phase- proteins

Serum proteins increase or decrease in

Concentration by less than 25% in response to cytokines

Increase serum proteins

Play role in immune response like complement proteins

Decrease Serum Proteins

Are reduced to save amino acids for producing additional plus proteins

Vasodilation

Dilation (Widening) of blood vessels

1st step of inflammation involves

Vasodilation (causes redness) and increase permeability (defensive substances leave blood vessels and enter injured area which causes edema) blood vessels which occurs immediately following tissue damage

Edema

Fluid accumulation

In the 1st step of inflammation after chemical release

Blood clots form and prevent spread of microbes or toxins which causes abscess to from and contains pus

Abscess

Cavity created by breakdown of tissue

Pus

Mixture of dead cells and body fluids

In 2nd stage of inflammation a

Margination occurs as blood flow decreases, phagocytes (neutrophils and monocytes) stick to inner surface of blood vessels

In 2nd step of inflammation after the margination

Diapedesis then occurs which is when phagocytes squeeze between endothelial cells of blood vessels and phagocytosis of microbes

The 3rd step of inflammation begins

During active inflammation but cannot be complete until all harmful substances are removed or neutralized

In the 3rd step of inflammation Tissue

Is repaired when stroke or parenchyma produce new cells

Parenchyma

Functioning part of the tissue

Stroma

Supporting connective tissue

In 3rd step of inflammation repair involving

Only Parenchyma cells equal near perfect repair and only stromal cells equal scar tissue

In the 3rd step of inflammation in chronic inflammation

Cytokines released by macrophages cause stromal cells to synthesize connective tissue (fibrosis)

Fibrosis

Accumulation of connective tissue resulting in scar tissue

Fever

Abnormally high body temp

3 characteristics of a fever

1. Systemic response to infection
2. Typically caused by bacterial or viral infection
3. Defense against disease to a certain point