12. Disturbances in the metabolism and accumulation of proteinogenic (tyrosine, tryptophan) and lipidogenic native pigment Flashcards
What is the Proteinogenic Pigment?
Melanin
What is Melanin?
Normal Pigment
Found in Form of FINE BROWN Granules
IN Skin / Choroids of Eye / Adrenal Medulla / Hair / Meninges / Intestine
Describe the Synthesis of Melanin
1) UV Radiation STIMULATES Melanin Synthesis
2) Tyrosine GETS OXIDISED in the Melanocytes
3) AFTER SECRETION, Melanin is taken up by ADJACENT EPIDERMIAL CELLS + PHAGOCYTIC MELANOSPHORES in Underlying Dermis
What are the 2 Types of Melanin Disorders?
- Generalised Hypo / Hyper-Pigmentation
2. Localised Hypo / Hyper-Pigmentation
1| What are the Causes of Generalised Melanin Pigmentations?
(i) Addison’s Disease
(ii) Adrenocortical Insufficiency
(iii) Cholasma (During Pregnancy)
(iv) Chronic Arsenic Poisoning
2a| What are the Types of Localised HYPO-Pigmentation?
(i) Leucoderma = Partial Albinism
(ii) Vitiligo (Genetic)
(iii) Acquired Focal Hypopigmentation = DUE to Leprosy / Wound Healing / Syphilis / Radiation Dermatitis
2a| What is Albinism?
Inherited Generalised Disorder of Melanin Metabolism
DECREASE / ABSENCE of Pigment in Skin / Choroid of Eye
Blonde Hair, Poor Vision + SEVERE Photophobia
HIGH SENSITIVITY to Sunlight
2b| What are the Types of Localised HYPER-Pigmentation?
FOCAL Hyperpigmentation = Malignant Melanoma / Nevus / Melanosis Coli / Lentigo
2b| What is Malignant Melanoma?
HIGHLY Malignant
Invades Normal Tissues EARLY + WIDELY
With HIGH CHANCE of MORTALITY
2b| What is a Nevus?
A Benign Tumour
2b| What is a Harmatoma?
CONSISTS of Nevus Cells
Presents FREQUENTLY at Birth
GROWS SLOWLY in Puberty
What are the 2 Lipopigments?
- Lipofuscin
2. Lipochrome
1| What is Lipofuscin?
Type of Lipochrome
Associated with Cell Membrane Deposition
Insoluble
Fine Granule of YELLOW-BROWN Intracellular Pigment
Aka “Aging” or “Wear and Tear” Pigment
1| Where is Lipofuscin Located?
Cells of ELDERLY People
People Suffering from Malnutrition / Chronic Wasting Diseases
Organs = Liver / Kidneys / Heart Muscles / Retina / Adrenals / Nerve + Ganglion Cells
E.g. LARGE Amounts are DEEP BROWN; Heart (Brown Atrophy)
2| What is Lipochrome?
A Naturally Occurring
Fat-Soluble Pigment
