Epidermis, Biology

Assignment Help:

EPIDERMIS -

  1. Ectodermal in origin. Outer part of skin. Made up of stratified epithelium.
  2. Branches of sensory nerves present. More branches on lips, tips of fingers.
  3. Blood vessels are absent. Get necessary miaterials from dermis.
  4. Porous in nature. Thickest in sole. Thinnest in cornea (conjuctiva).
  5. On palm grooves are known as sulcicutis & ridges are known as cristae cutis. Their study is dactyloscopy.
  6. Their arrangement on fingers & thumb are finger mark, i.e. dermatoglyphics.
  7. After the birth of babies, permanent linings on abdomen of women are linear gravidarum.
  8. In epidermis outer to inner following layers are clear -

1. Stratum corneum

2. Stratum lucidum

3. Stratum granulosum

4. Stratum spinosum

5. Stratum malpighi

 

 

1.      STRATUM CORNEUM -

  1. Outermost part of epidermis. 8-10 layers of cells present.
  2. Cells are flat, intercellular spaces absent, nucleus absent, cytoplasm negligible, more or less dead.
  3. Keratine protein present which is scleroprotein. It gives impermeability to skin.
  4. As on inner side new layer are formed by S. malpighi, outer layer of corneum is shed off. It is known as ecdysis.
  5. Free cholesterol and fat present in this layer.
  6. Claws, nails, horns hoofs in animals are formed by this layer.
  7. This layer is endocrine in nature. Hormon secreted by this layer reduces power of cell division in S. malpighi.
  8. If we remove this layer sensivity is increased.

 

2.      STRATUM LUCIDUM -

  1. Present inside S. corneum. 2-3 layers present. Cells are flat, intercellular spaces absent.
  2. Nucleus present, cytoplasm present, living cells eleidin present, that gives transparnacy to this layer.
  3. It is also known as clear zone, barrier layer.
  4. This layer checks water & other minerals to move out.

 

3.      STRATUM GRANULOSUM -

  1. In cytoplasm keratohyaline present which is made up of polysaccharide, Ca & RNA, basophillic in nature.
  2. Cornification or keratinization is common i.e. keratohyaline is converted first in to eleidin then in keratine.
  3. In this process malpighi cells first become cuboidal then squamous.

 

4.      STRATUM SPINOSUM -

  1. Situated inside S. granulosum. Cells are polygonal. Also known as prickle cells.
  2. Keratohyaline granules present little.

 

5.      STRATUM MALPIGHI -

  1. Also known as S. Germinativum.
  2. Inner most part of epidermis. 1-2 layers present. Capable of cell division.
  3. Cells are round in shape but columner type, so this layer is also known as S. Cylindricum.
  4. Complete epidermis is formed by it.
  5. S. Malpighi rests on basement membrane of dermis.
  6. S. Malpighi forms out growth as Rete pegs enter in dermis.
  7. Melanin pigment present, formed in melanasome part of melanocyte, dopa oxidase enzyme is needed for it.
  8. Colour of skin depends on quantity and shades of melanin.
  9. Melanin absent in palm & sole. Melanin maximum in areola mammary.
  10. Worm blooded animals of hot & humid area have abundent melanin pig. It is explained by Gloger's law.
  11. Melanin is under control of MSH & UV rays.
  12. Darking of skin after exposure to UV rays is common.
  13. In man complete absence of melanin is albinism due to recessive gene & absence of tyrosinase as melanin is derivative of tyrosine.
  14. Chromatophores absent. In frog present in dermis.
  15. In leucodermea melanin becomes absent at patches. Such skin is peibled skin.

158_mammalian skin.png


Related Discussions:- Epidermis

How inhibition might contribute to tumour formation, We now understand that...

We now understand that mutations that cause the inhibition of apoptosis are found in tumours. Because proliferation itself is not induced by the inhibition of apoptosis, explain ho

Can you explain the lichens, Q. What are the lichens? How fungi participate...

Q. What are the lichens? How fungi participate in this ecological interaction? Lichens are formed by mutualist ecological interaction between algae and fungi or between fungi a

Managing diarrhoea in children, Q. Managing diarrhoea in children? Mana...

Q. Managing diarrhoea in children? Managing diarrhoea in children is of great concern. The guidelines for the same are as follows: 1. The first objective is to rehydrate the

Explain gluconeogenesis, Explain Gluconeogenesis Gluconeogenesis (i.e...

Explain Gluconeogenesis Gluconeogenesis (i.e synthesis of  new  glucose)  is  the  synthesis of carbohydrate from  non-carbohydrate, source. The major  substrates for glucone

What is pulmonary edema, Q. What is Pulmonary Edema? When the capillary...

Q. What is Pulmonary Edema? When the capillary pressure exceeds the plasma osmotic pressure, fluid first accumulates in the interstitial spaces. The components of the interstit

Define the effect of scfa on sodium absorption, Define the effect of SCFA o...

Define the effect of SCFA on Sodium Absorption? SCFAs (short chain fatty acids) have a stimulatory effect on sodium absorption from colonic lumen. The unionized SCFA crosses th

Explain fats requirements during thyphoid, Explain fats requirements during...

Explain fats requirements during thyphoid Fats: Use of fats should be in moderation. This is because the typhoid patient has a compromised ability to digest and assimilate due

Do you know how ketoacidosis develops, Q. Do you know how ketoacidosis deve...

Q. Do you know how ketoacidosis develops? The chain of reaction begins with insufficient insulin to meet the needs of the body. Several factors then work together. These inclu

Digestive system - small intestine, SMAL L INTESTINE - A narrow tube 6...

SMAL L INTESTINE - A narrow tube 6 m long. In rabbit 4 m. long.Differentiated into duodenum, jejunum & Ileum. (i) Duodenum - 2.5 cm long. C-shaped (U-shaped in rabbit)

Is a viral infection treated with drug, Q. Is a viral infection treated wit...

Q. Is a viral infection treated with the same kind of drug that treats bacterial infections? The Antibacterial drugs, potent against a great variety of bacteria, are not effect

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd