UNIT FIVE: THE INTEGUMENTARY SYSTEM Flashcards
NAME THE CELLS THAT MAKE UP THE EPIDERMIS AND BRIEFLY DESCRIBE THEIR FUNCTION, DESCRIBE CHANGES THAT OCCUR AS THEY MIGRATE IN THE EPIDERMIS
→ keratinocytes: are the most abundant cell in the epidermis. They create keratin which gives skin its protective characteristics. Keratinocytes are connected with one another using tight junctions and desmosomes to prevent water movement and loss in the skin. Cells will begin to die as they move up the epidermis, this is called apoptosis
→ melanocytes: are spider shaped cells that produce a pigment called melanin, which protects from UV rays. Melanocytes are located in the stratum basale, melanocytes will also transfer to keratinocytes to protect nuclei from UV rays.
→ dendritic cells: are star shaped cells located in the stratum spinosum. They are key activators in the immune system and are also macrophages. They are produced in the bone marrow and migrate up into the epidermis.
→ tactile cells: are located in the dermal papillae of the dermis. Are sensory receptors that detect light touch. Are associated with nerve endings.
NAME THE TYPES OF TISSUES FOUND IN THE DERMIS AND EPIDERMIS, ALSO DESCRIBE MAJOR LAYERS OF EACH.
Epidermis: is the superficial layer of the skin and is NOT vascularized. Is composed of many layers
→ stratum basale: is the deepest layer of the epidermis. Is composed of stem cells that make 2 daughter cells. One moves up into the epidermis and another stays and becomes another stem cell, contains melanocytes and is one layer.
→ stratum spinosum: is often referred to as the prickly layer because the tight junctions and desmosomes between the keratinocytes appear prickly. Extensions of melanocytes can be found here alongside dendritic cells. Is 2-3 layers.
→ stratum granulosum: is the middle layer of the skin, keratinization occurs here. This means the cells start filling up with keratin causing organelles and nuclei to die. As a result the cells become flat. Is 4-6 layers.
→ stratum lucidum: this layer is only found in thick skin, like the palms of the hands and feet. Contains 2-3 layers of dead clear keratinocytes.
→ stratum corneum: is the most superficial layer of the epidermis. All the cells are dead here. Functions include protection from abrasion, UV lights, acts as a physical and chemical barrier, and also prevents water loss in the skin. Is 20-30 layers.
Dermis: is the vascularized portion of the skin, containing 2 major layers.
→ papillary layer: is composed of loose areolar tissue and immune cells, is also the superficial layer of the dermis.
The papillary layer has extensions that go into the deeper reticular layer called dermal papillae. This is where tactile cells are located
→ reticular layer: is composed of dense irregular connective tissue. It is also the largest layer of the dermis.
There is also the hypodermis which is located beneath the dermis. It is not considered part of the skin and contains loose adipose tissue. Its major functions are insulation, shock absorption, and connecting skin to underlying structures like the muscles.
COMPARE THE STRUCTURES OF SWEAT AND SEBACEOUS OIL GLANDS
There are 2 types of sweat glands.
→ eccrine (merocrine) glands: these sweat glands are located throughout the body and are most abundant on the palms of the hands, feet, and forehead. This type of sweat is 99% water based.
→ apocrine glands: these glands contain a yellow-ish sweat which is used to excrete wastes such as fatty acids and proteins. Bacteria feed off of this sweat which makes it smell. Located in the axillary and pubic regions of the body. Activated during puberty.
^^ nervous system stimulation forces sweat into sweat glands.
Sebaceous sweats release through holocrine methods, basically the gland gets rid of all the product at once, kind of exploding.
→ are located everywhere except the palms of the hands and feet. Release sebum which softens skin. These glands are relatively inactive until puberty.
NAME THE 6 FUNCTIONS OF SKIN
→ protection: protects from abrasion, bacteria, UV rays, etc.
→ excretion of wastes: releases waste via sweat glands, waste is often nitrogen based like urea, uric acid, and ammonia.
→ metabolic functions: synthesis of vitamin D, some keratinocytes can aid in hormone activation.
→ blood reservoir: the skin holds 5% of the body’s blood.
→ temperature regulation: done through constriction and dilation of blood vessels in the skin and activation of sweat glands, etc.
→ cutaneous skin sensation: tactile cells allow us to feel skin sensations and temperature change.
