Skin Flashcards
Outline the functions of skin and relate these to its structural
organization
Protection: The epidermis, the outermost layer of the skin, is composed of tightly packed cells called keratinocytes that are constantly being shed and replaced. This layer acts as a barrier, preventing harmful substances from entering the body. The skin also contains melanocytes, which produce the pigment melanin that protects the skin from harmful UV radiation.
Sensation: Sensory receptors that detect temperature, pressure, pain, and touch. These receptors are located in the dermis, which is the middle layer of the skin. The dermis also contains blood vessels that supply nutrients and oxygen to the skin cells.
Thermoregulation: Maintaining the body’s temperature. When the body is too warm, sweat glands in the skin produce sweat, which evaporates and cools the skin. When the body is too cold, blood vessels in the skin constrict to conserve heat.
Excretion: Sweat glands in the skin produce sweat, which contains salt and other waste products that are eliminated from the body through the skin.
The epidermis is composed of keratinocytes that provide a barrier against harmful substances. The dermis contains blood vessels and sensory receptors that allow the skin to detect changes in the environment and regulate temperature. The hypodermis contains adipose tissue that insulates the body and provides cushioning.
Describe the organization of skin at the light microscope level, and appreciate its subdivision into epidermis, dermis and hypodermis
The epidermis is the outermost layer of the skin and is composed of keratinocytes. The cells at the topmost layer of the epidermis are dead and flattened, forming a protective barrier against environmental factors. The deepest layer of the epidermis contains cells that are responsible for producing new cells that migrate towards the surface to replace the dead cells. The epidermis also contains melanocytes, which produce the pigment melanin that gives the skin its color.
The dermis is the layer beneath the epidermis and is composed of dense connective tissue. It contains blood vessels, lymphatic vessels, nerves, and various types of cells, including fibroblasts that produce collagen and elastin, which provide the skin with its elasticity and strength. The dermis also contains hair follicles, sweat glands, and sebaceous glands.
The hypodermis, also known as the subcutaneous tissue, is the deepest layer of the skin. It is composed of adipose tissue and loose connective tissue and serves as a cushioning layer that protects the body from trauma and helps regulate body temperature.
Overall, the organization of the skin into these three layers allows it to perform its various functions, including protection, sensation, and thermoregulation.
give an account of the biology of the epidermis and its cell
populations: keratinocytes (including the concept of the epidermal stem cell); melanocytes, Langerhans cells and Merkel cells
The epidermis is the outermost layer of the skin and is composed of several cell types, including keratinocytes, melanocytes, Langerhans cells, and Merkel cells.
Keratinocytes are the most abundant cells in the epidermis, and they are responsible for producing the protein keratin, which provides strength and protection to the skin. These cells are continuously produced in the basal layer of the epidermis, and as they mature and move upwards towards the surface, they undergo a process of differentiation and eventually become dead, flattened cells that form the outermost layer of the epidermis.
The epidermal stem cells, which are a type of keratinocyte, are found in the basal layer of the epidermis and are responsible for the continuous production of new keratinocytes. These cells have the ability to divide and differentiate into all the different types of cells that make up the epidermis.
Melanocytes are another type of cell found in the epidermis, and they are responsible for producing the pigment melanin, which gives the skin its color. These cells are located in the basal layer of the epidermis, and they transfer their pigment to nearby keratinocytes.
Langerhans cells are a type of immune cell that are found in the epidermis and play a role in defending the skin against infection. These cells have long dendrites that extend throughout the epidermis, allowing them to detect and respond to foreign invaders.
Merkel cells are specialized cells that are involved in the sensation of touch. These cells are found in the basal layer of the epidermis and are closely associated with nerve endings.
Appreciate the importance of the vascular organization and
sensory innervation of the dermis, and recognize the appearance
of the special sensory receptors (Pacinian and Meissner’s
corpuscles)
Two types of special sensory receptors found within the dermis are Pacinian and Meissner’s corpuscles. Pacinian corpuscles are specialized receptors that detect pressure and vibration, while Meissner’s corpuscles are responsible for sensing light touch and texture. Both types of receptors are highly sensitive and are able to detect even subtle changes in the skin’s environment.
Outline the structure and function of sweat glands (merocrine and apocrine) and sebaceous glands
Merocrine glands:
These are the most common type of sweat glands and are distributed throughout the body. They are also called eccrine glands. They produce a watery secretion that is composed of electrolytes, water, and urea. The secretion is released onto the surface of the skin through a duct and helps to regulate body temperature by cooling the skin through evaporation.
Apocrine glands:
These glands are found in the armpits, groin, and nipple areas. They produce a thicker, milky secretion that contains fatty acids and proteins. This secretion is released into a hair follicle and is broken down by bacteria on the skin, causing body odor. Apocrine glands are activated during puberty and are thought to play a role in sexual attraction and communication.
Sebaceous glands:
These glands are found in hair follicles throughout the body, except for the palms and soles of the feet. They produce an oily substance called sebum, which helps to moisturize and protect the skin and hair. Sebum also helps to lubricate the skin and prevent it from drying out. Overactive sebaceous glands can lead to oily skin and acne. Sebaceous glands are also involved in the production of pheromones, which are chemical signals that play a role in sexual attraction and communication.
