Skin type - dermis, Biology

DERMIS (CORIUM) -

  • Mesodermal in origin. More developed part.
  • Leather is obtained from dermis by tanning. Thinnest in eye lid. Connective tissue present.
  • In it 4 types of cell are present -

(i) Fibroblast or fibrocyte - forms fibres attached to fibres.

(ii) Histocytes - Amoeba like, phagocytic in nature.

(iii) Plasma cells - formation of antibodies (g-globuline)

(iv) Mast cells - It forms matrix, heparine & serotonine.

  • Collagen & elastin fibres are present.
  • When elasticity of dermis is lost skin becomes wrinkeled.
  • Dermis consists of b.v., lymph, vessels, unstripped muscles, nerves etc.
  • Sensory papillae present in dermis (not in epidermis to avoid unnecessary stimulation).
  • These papillae are of following types -

(i) Genital corpusulses - On tip of penis & clitoris.

(ii) Vater pecinian corpusulses or baroreceptor - For pressure deeply placed. More in palm & sole.

(iii) Frigido receptor or end bulb of krausi - For cold.

(iv) Allgesi receptor - For pain. Attached to free nerve endings mainly.

(v) Endings of Ruffini or Calore receptor - For hot.

(vi) Tectile corpuscles or missnner's corpuscles or markle's disc - For touch. Markel's disc is diffterent from other in structure.

(vii) Vibreo receptor - For vibration. Basal part of dermis is peniculus adiposa present on hypodermis (not a part of skin). Fat is stored in it. Also helpfull in temp. regulation. This part is absent in eye lid, prepuce & scrotal sac.

  • Outer part of dermis is papillary part or pars papillaris in it dermal papullae present, fibres are dense, lines of langerhanse can be seen.
  • Inner part is reticulate part or pors reticularis, papullae are absent, fibres are scattered.
  • In dermis melanophage cells engulf melanin by phagocytosis.
  • In some area of dermis blood passes from artery to vein directly by shunt or arterioveinuous anastamoses.
Posted Date: 10/1/2012 6:22:08 AM | Location : United States







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