The Integumentary System

- A Primary Skin Lesion
- A flat, circumscribed area that is a change in the colour of the skin; less than 1cm in diameter
- Examples: Freckles, flat moles (nevi), petechiae, measles, scarlet fever

- Primary skin lesion
- An elevated, firm, circumscribed area less than 1 cm in diameter
- Examples: wart (verruca), elevated moles, lichen planus

- Primary skin lesion
- A flat, nonpalpable, irregular-shaped macule more than 1cm in diameter
- Examples: Vitiligo, port-wine stains, mongolian spots, cafe au lait spot

- A primary skin lesion
- Elevated, firm, and rough lesion with flat top surface greater than 1 cm in diameter
- Examples: Psoriasis, seborrheic and actinic keratoses

- Primary skin lesion
- Elevated, irregular-shaped area of cutaneous edema; solid, transient; variable diameter
- Examples: Insect bites, urticaria, allergic reaction

- primary skin lesion
- Elevated, firm, circumscribed lesion deeper in dermis than a papule; 1-2cm in diameter
- Examples: Erythema nodosum, lipomas

- primary skin lesion
- Elevated, solid lesion; may be clearly demarcated; deeper in dermis; greater than 2 cm in diameter
- Examples: neoplasms, bengign tumor, lipoma, hemangioma

- Primary skin lesion
- Elevated, circumscribed, superficial, not into dermis; filled with serous fluid; less than 1cm in diameter
- Examples: Varicella (chickenpox), herpes zoster (shingles)

- primary skin lesion
- Vesicle greater than 1 cm in diameter
- Examples: blister, pemphigus vulgaris

- primary skin lesion
- Elevated, superficial lesion; similar to a vesicle but filled with purulent fluid
- Examples: Impetigo, acne

- primary skin lesion
- Elevated, circumscribed, encapsulated lesion; in dermis or subcutaneous layer; filled with liquid or semisolid material
- Examples: Sebaceous cyst, cystic acne

- primary skin lesion
- fine, irregular red lines produced by capillary dilation
- examples: telangiectasia in rosacea

- secondary skin lesion
- heaped-up, keratinized cells; flaky skin; irregular; thick or thin; dry or oily; variation in size
- examples: flaking of skin with seborrheic dermatitis following scarlet fever, or flaking of skin following a drug reaction; dry skin

- secondary skin lesion
- Rough, thickened epidermis secondary to persistent rubbing, itching, or skin irritation; often involves flexor surface of extremity
- examples: chronic dermatitis

- Secondary skin lesion
- Irregular-shaped, elevated, progressively enlarging scar; grows beyond the boundaries of the wound; caused by excessive collagen formation during healing
- Examples: Keloid formation following surgery

- Secondary skin lesion
- Thin to thick fibrous tissue that replaces normal skin following injury or laceration to the dermis
- Examples: Healed wound or surgical incision

- Secondary skin lesion
- Loss of the epidermis; linear, hollowed-out, crusted area
- Examples: Abrasion or scratch, scabies

- Secondary skin lesion
- Linear crack or break from the epidermis to the dermis; may be moist or dry
- Examples: Athlete's foot, cracks at the corner of the mouth

- Secondary skin lesion
- Loss of part of the epidermis; depressed, moist, glistening, follows rupture of a vesicle or bulla
- Examples: Varicella, variola after rupture

- Secondary skin lesion
- Loss of epidermis and dermis; concave; varies in size
- Examples: Decubiti, stasis ulcers

- help compete with pathogens such as Salmonella
- provide vitamins such as biotin and vitamin K
- aid in digestion and absorption of carbohydrates
- aid in absorption of ions such as iron, magnesium, and calcium
- contribute to immunity by stimulating lymphoid tissue associated with the gut mucosa to produce antibodies to pathogens

1. Escherichia coli (E coli)
2. Streptococcus species

- gram negative
- rod shaped
- commonly found in lower intestine

- spherical
- gram positive
- found within the gut

- meningitis
- bacterial pneumonia
- "flesh-eating" bacterial infections

- medically compromised immune system (AIDS)
- poor nutrition
- immunosuppressents
- renal failure
- long term antibiotic use

Salmonella

- invades the mucosa of the gut and causes the epithelial cells to synthesis and release various pro-inflammatory cytokines which evoke an acute inflammatory response
- may result in damage to the intestine
- after invading the epithelium, the salmonellae multiply intracelluarly and spread to the mesenteric lymph nodes and throughout the body via systemic circulation

- nausea
- vomiting
- pain
- diarrhoea

- rod-shaped
- endospore-forming
- aerobic or faculatively anaerobic
- gram-positive bacteria

- infection is caused by cutaneous inoculation, inhalation, or ingestion of the spores which make it easy to be used in biological warfare
- the spores are extremely virulent and resistant to heat, cold, radiation, desiccation, and disinfectants
- all they need for sporulation is oxygen

- bacteria have a cell wall of pepdioglycan whereas fungi have a cell wall of chitin
- bacteria may have other structural attachments such as flagella which are used for motility
- bacteria are prokaryotes and fungi are eukaryotes

1. gram positive: thick peptidoglycan layer

2. gram negative: outer lipopolysaccharide-containing membrane and a thin peptidoglycan layer

A prokaryote is a cell that does not contain a membrane bound nucleus or organelles

A eukaryote is a cell that does contain a membrane bound nucleus and organelles

As fungi are eukaryotic, treating a fungal infection may be difficult as the compositions of their cells are very similar to human cells. Therefore it is difficult to find treatments that will only kill the fungus and not the human cells.

Malaria

occurs via uninucleate sporozoites in the salivary glands of infected mosquitoes being injected into a human host when the mosquito feeds

- the sporozoites invade the liver parenchymal cells
- (in liver cells) they mature and burst to realease 10s of 1000s of uninucleate merozoites
- this causes hepatomegaly (increase in size of liver)
- merozoites can then infect the red blood cells
- this causes haemolysis (break down of RBCs)
- breaking down of RBCs causes the patient to have haemolytic anaemia

- fever
- chills
- sweating
- headache
- weakness
- other symptoms mimicking a "viral syndrome"

- abnormal level of consciousness
- severe anaemia
- renal failure
- multi-system failure

- stage 3 of its life cycle
- stage 3 is when the merozoites exit the liver cells and re-enter the blood stream
- (in the blood stream) they reproduce and invade red blood cells
- results in illness and complications

1. Protozoans
2. Helminths
3. Anthropods