lecture 6 Flashcards
the components and primary functions of the integumentary system
- Protection – gives the barrier to protect the body from water loss, invading pathogens, UV radiation, and physical issues
- Temperature regulation – if too cold, the body’s temp is maintained through skin and hair. If too hot the body releases sweat
- Sensory reception – allows us to feel things
- Vitamin D synthesis
the process and importance of vitamin D synthesis
- When sunlight hits the skin, modified cholesterol molecules are converted to a vitamin D receptor.
- Vitamin D is necessary for calcium absorption
- Lack of vitamin D during development can cause rickers
the two main layers of the skin, and the one just deep to skin
- Epidermis – superficial -> the thin wavy base. Is stratified squamous
- Dermis – the deeper layer -> where we see the nerves, follicles, and parts.
- Hypodermis – the subcutaneous layer -> in charge of insulation, energy storage, and adipose tissues
the tissue types of the epidermis
stratified squamous epithelium
the tissue type of the dermis
dense irregular connective tissue
the tissue type of the hypodermis
loose connective tissue and adipose tissue (fat cells)
the functions of the four main cell types in the epidermis
- Keratinocytes – the most abundant cell type, produce keratin and a tough fibrous protein. (as cells fill with keratin they die)
- Melanocytes – found in the deepest layer of the epidermis and produce melanin. When in contact with the skin more melanin is produced to protect the lower skin tissues
- Dendritic (Langerhans) cells – like macrophages; help fight of pathogens, has pathogens that help kill things by invading the skin
- Tactile (merkel) cells – they are between the epidermis and dermis, allows you to feel light touches on the skin. Fingertips are an area with a lot of these
the 5 layers of the epidermis
- Stratum corneum – the top layer made of dead keratinocytes (is the thickest)
- Stratum lucidum – (only found in thick skin), the clear layer, is 2-3 layers, and is on the hands and feet
- Stratum granulosum – has 1-5 layers, is where keratin building begins
- Stratum spinosum – the spiny layer – living keratinocytes (has desmosomes). This is where squamous cell carcinoma occurs.
- Stratum basale – is the bottom layer. The layer of the base of the dermis. Where stem cells rapidly divide and create new ones. This layer is avascular and relies on capillaries (where the keratinocytes of the epidermis are generated)
cell types of the epidermis
keratinocytes
melanocytes
dendritic (langerhans) cells
tactile (merkel) cells
cell types of the dermis
The primary cell type in the dermis is the fibroblast, which produces collagen and elastin, while other cell types present include macrophages, mast cells, adipocytes, Schwann cells, and occasional immune cells like lymphocytes and dendritic cells
cell types of the hypodermis
adipocytes (fat cells)
fibroblasts
macrophages
describe the changes in cells chapes and function that occur as cells travel through the layers
As cells move through different layers of a tissue, their shape and function often change significantly due to variations in their environment, signaling molecules, and interactions with neighboring cells, leading to specialization and adaptation to the specific role required in that layer; this process is called cellular differentiation, where a cell’s gene expression is altered to produce different proteins and structures, ultimately modifying its shape and function.
basal cell carcinoma
makes up about 80% of cases, is most commonly seen on the face, is a proliferation of the stratum basale cells, is the least malignant and most common one, 99% of these can be surgically removed
squamous cell carcinoma
on the head, face; and nails. Is proliferation of keratinocytes in the stratum spinosum. The 2nd most common form, can metastasize if not treated in time
melanoma
the most dangerous type and is 2-3% of all cases. The proliferation of melanocytes is highly metastatic and resistant to chemo. Early detection is key
describe the function and structural characteristics of the two dermal layers
- Papillary dermis
- Areolar connective tissue where the fine interlacing collage and elastic fibers form a loosely woven may with many small blood vessels.
- Allows phagocytes and other defensive cells to wander freely as they patrol the area for bacteria that may have penetrated the skin.
- Has dermal papillae on the surface, which house capillary loops and/or nerve endings and touch receptors.
- Friction ridges -> may enhance our ability to grip certain kinds of surfaces
- Reticular dermis
- Accounts for about 80% of the thickness of the dermis, and is coarse, dense irregular connective tissue. The blood vessels nourish this layer
- Reticular = network
- Has cleavage (tension) lines -> externally visible lines that tend to run longitudinally in the skin of the limbs and in circular patterns around the neck and trunk.
- Has flexure lines -> dermal folds that occur at or near joints, where the dermis is tightly secured to deeper structures.
hemoglobin
is localized in the dermis
sebaceous glands
microscopic exocrine glands found in the skin that produce and secrete an oily substance called sebum, primarily functioning to lubricate the skin and hair by creating a protective barrier against drying out; they are most concentrated on the face and scalp, and are typically associated with hair follicles, with the exception of certain areas like the eyelids where they open directly onto the skin surface.
sweat glands
also known as sudoriferous glands, are small tubular structures located in the skin that produce sweat, primarily functioning to regulate body temperature through evaporative cooling by releasing water onto the skin’s surface
apocrine
eccrine
apocrine sweat glands
secretes a viscous milky or yellowish sweat
begins functioning at puberty (may act as a sexual scent glands)
eccrine sweat glands
secretes sweat, which helps regulate body temperature (thermoregulation) and disposes of metabolic wastes
sweat glands
in the sweat glands are epidermal ridges and sweat pores that are primarily responsible for fingerprints
melanin
dark pigment formed by cells called melanocytes; imparts color to the skin and hair
carotene
yellow to orange pigment that accumulates in the stratum corneum epidermal layer and in fatty tissue of the subcutaneous tissue
