THE DERMIS OF THE SKIN

The dermis is the layer of the skin beneath the epidermis. It  makes up about 90% of the skin's thickness. It has:

• Blood vessels
• Hair follicles - This is the tube that surrounds the hair and nourishes it.
• Lymphatic vessels - These drain the lymph in the skin. The lymph contains cells that fight infections. 
• Sebaceous glands - These glands produce sebum. This is the oily substance that lubricates the skin and keeps it waterproof. It keeps the skin smooth and supple. It also helps to fight off bacteria and fungal infections.
• Sweat glands - Produce sweat. There are two types: Apocrine and Eccrine sweat glands. Apocrine sweat glands are found in the armpit and pubic areas. They produce milky sweat that can encourage bacteria growth. Eccrine sweat glands are found in the other parts of the body. 
• Nerve endings - These include touch, pain, pressurs and temperature sensors.
• Collagen and Elastic fibers - These are connective tissues that help to keep the skin tough and elastic.

The dermis consist of two layers. The upper layer is called the papillary dermis and the lower one is called reticular dermis. The papillary layer is thinner than the reticular layer. The papillary layer contains a lot of blood vessels that help to nourish the epidermis and to regulate the body's temperature. The reticular layer has collagen fibers arranged parallel to the skin to help in stretching and maintenance of the strength of the skin. It supports the hair follicles, sweat and sebaceous glands. 

THE LAYERS OF THE EPIDERMIS OF THE SKIN

The epidermis of the skin refers to the topmost layer. It is composed of five layers. From the surface to the deep layers, the names are:

1. Stratum corneum
2. Stratum lucidum
3. Stratum granulosum
4. Stratum spinosum
5. Stratum basale or germinativum

STRATUM CORNEUM
This layer consists of dead cells with a hard protein envelope. These cells contain keratin surrounded by lipid. It is a tough water resistant layer. They are flat, anucleated  and cornified cells.

STRATUM LUCIDUM
This layer consists of dead cells containing dispersed keratohyalin granules. This layer is found in thick thick skins only such as the palm and soles.

STRATUM GRANULOSUM
This layer consists of cells that contain keratohyalin granules and lamellar bodies that have released lipids. They, therefore, look granular. The cells are covered by hard protein. They are polygonal cells with basophylic granules.

STRATUM SPINOSUM
This layer consists of cells that are accumulating keratin fibers and lamellar bodies. The are cuboidal like cells and desmosomes in between.

STRATUM BASALE
The cells in this layer undergo mitosis (cell division) to reproduce the top layers. The are columnar- like cells.

Here is a diagram illustrating the layers.

CHECKOUT "MEDSCAPE WEBSITE" TO REVIEW ANATOMY/PHYSIOLOGY

This is a great website with a comprehensive overview of anatomy and physiology. Click this link to visit the site.

In future, this website will also become a good resource to you in your medical practice. It gives you insight into various medical conditions and their treatments.

SOME POPULAR POSTS

Popular Posts

• WHAT ARE CATECHOLAMINES?

  The  nervous system consists of the central and the peripheral nervous systems. The central nervous system consist of the brain and spinal c...
• RELATIVE ATOMIC MASS/RELATIVE ABUNDANCE QUESTIONS

  Question 1: Calculate the relative atomic mass of silver if it occurs naturally as 51.84% silver-107 and 48.18% silver-109. Solution: Re...
• THE MASS SPECTROMETER

  The mass spectrometer is an instrument used for analyzing samples of elements and compounds. It consists of six basic stages:   Injection,  ...
• METABOLISM AND ENZYMES

  Metabolism is the building up (synthesis) or the breakdown of substances in the living organism. It consists of  anabolism  and  catabolism ...
• MAKING INFERENCES AND CONCLUSIONS

  You will be tested on your understanding of scientific experiments and your ability  to  make inferences and conclusions from various dat...
• FACTORS BEHIND MEDICAL SCHOOL ADMISSION

  Medical admissions committees always look at grades and MCAT test scores. But you can become a much stronger applicant by demonstrating your...
• REPRODUCTION IN MAMMALS

  Gametes  refers to the sperm and the egg. During sexual reproduction, the sperm and the egg unite to form the  zygote .                    ...
• WELCOME TO THE BEST HIGH YIELD MCAT SITE

  Welcome to the high yield MCAT site! I hope you will find useful information as you prepare or dream about entering into medical school. Thi...
• GOOD INFO ON MCAT

  Here is a link to a website that has a lot of information on MCAT and some practice test questions. Check it out by clicking on this link.

TYPES OF JOINTS

Joints occur at regions where two bones meet. They are classified as

• Immovable joints: Also known as fixed joints.  There is relatively no movement between the bones. There is no cartilage between the joints. Examples: Bones of the cranium and facial bones that articulate with the teeth
• Movable joints: Also known as synovial joints. The bones of this joints are capable of movements. The bones are separated by cartilage called articular cartilage. The movement may be partial or freely moveable.
• Partially moveable joints: Very limited range of movement.            Example: The joint between the vertebrae; The joints of the cranium; The joints of the hip bones.
• Freely moveable joints: There are free movements between the articulating bones. The articular surfaces are covered with cartilage. This articular cartilage reduces the friction between the two surfaces of bones making the joint. It is covered by a synovial membrane which forms a closed sac. This sac contains a fluid called synovial fluid. The synovial fluid helps in lubricating the joint to reduce friction. 

Types of freely moveable joints 

Classification is based on the degree of movement that they allow. 

• Hinge joints: These joints allow the backward and forward movement in only one plane. Examples: Elbow and knee joints
• Ball and Socket joints: These joints allow movements in multiple planes. Examples: Shoulder and hip joints
• Pivot joints:  Only rotational movements are possible in these joints. Examples: The joint between the first and second cervical (neck) bones.

WHAT TO KNOW IF YOU ARE PLANNING FOR MEDICAL SCHOOL

This is an article worth reading if you are planning to attend medical school. Click on this link to read more about it.

CONSIDER BECOMING A MEDICAL SCRIBE AHEAD OF MED SCHOOL

The US News and World Report, has under its educational section ten reasons why you should consider becoming a medical scribe ahead of medical school. It is a good read since medical schools look out for those who have experience, shadowing medical professions.
Read more by clicking here