A&P II - Exam 3 - DEF NEED TO KNOW!!

Innate Defenses

First (surface barriers) and second line of defense (cells and chemicals)

First line of defense includes skin and mucous membranes

Second line of defense - innate system necessary if microorganisms invade deeper tissues

First Line of Defense

Skin and mucous membranes; physical barrier to most microorganisms; keratin resistant to acids and bases, bacterial enzymes and toxins; mucosae provides similar mechanical barriers

Produces protective chemicals that inhibit or destroy microorganisms

Acid

Inhibits growth (microbes) (acid mantle)

Enzymes

Lysozyme of saliva, many microorganisms killed, enzymes in stomach

Mucin

Sticky mucus lining digestive and respiratory tract, traps microorganisms

Defensins

Inhibit microbial growth

Second Line of Defense

Innate system necessary if microorganisms invade deeper tissues; many have a pattern (antigens on surface of microbe)

Phagocytes

WBC’s that ingest and digest foreign invaders

Neutrophils: Most abundant phagocytes, die fighting; become phagocytic on exposure to infectious material

Macrophages: Develop from monocytes, chief phagocytic cells; most robust phagocytic cell

Free macrophages: Wander through tissue spaces

Fixed macrophages: Permanent residents of some organs

Phagocytosis

1) Process starts when phagocyte recognizes and adheres to pathogen’s carbohydrate “signature”

-Opsonization: Immune system uses antibodies or complement proteins as opsonins that coat pathogens

-Act as “handles” for phagocytes to grab on to

2) Cytoplasmic extensions bind to and engulf phagosomes

3) Phagosome fuses with lysosome (Phagolysosome)

4) Phagolysosome acidified, lysosomal enzymes digest particles

5) Indigestible and residual waste exocytosed from phagocyte

Natural Killer Cells

Nonphagocytic, large granular lymphocytes that police blood and lymph; Can kill cancer and virus-infected cells before adaptive immune system is activated; attack cells that lack “self” cell-surface receptors; Kill by inducing APOPTOSIS

Inflammation

Innate 2nd line of defense; triggered whenever body tissues injured

Benefits: Prevents spread of damaging agents, disposes of cell debris and pathogens, alerts adaptive immune system, sets the stage for repair

Cardinal Signs: Redness, heat, swelling, pain

Stages:

-Chemical Release; released into ECF by injured tissues, immune cells, or blood proteins; histamine released by basophils and mast cells is the key chemical

-Vasodilation and increased vascular permeability; vasodilation causes hyperemia; results in local swelling, resulting in pain

-Phagocyte mobilization; Neutrophils flood area first, macrophages follow; if it’s due to pathogens, complement is activated

Juxtaglomerular Complex

Involves modified portions of: Distal proportion of ascending limb of nephron loop; afferent (sometimes efferent) arteriole

Important in regulating rate of filtrate formation and blood pressure

1) Rate of filtrate formation and 2) Systemic blood pressure, affecting the glomerular hydrostatic blood pressure

Three cell populations seen in JGC: Macula Densa, Granular Cells, Extraglomerular Mesangial Cells

Macula Densa

Tall, closely packed cells of ascending limb; contain chemoreceptors that sense NaCl content of filtrate

Granular Cells

Enlarged, smooth muscle cells of arteriole; Act as mechanoreceptors to sense blood pressure in afferent arteriole; contain secretory granules that contain enzyme renin

Extraglomerular Mesangial Cells

Located between arteriole and tubule cells; interconnected with gap junctions; may pass signals between macula densa and granular cells

Filtrate Flow

Glomerulus, Proximal Convoluted Tubule, Descending Nephron Loop, Ascending Nephron Loop, Distal Tubule, Collecting Duct

Urine Flow

Renal Pyramid, Minor Calyx, Major Calyx, Renal Pelvis, Ureter, Urinary Bladder, Urethra