Download Chapter 4 – Integumentary System Skin is the largest organ that we

Chapter 4 – Integumentary System
Skin is the largest organ that we have.
Skin has stratified squamous epithelium supported by connective tissue. The blood
vessels are located in the connective tissue.
Arrector Pili – Smooth muscle that contracts and pulls skin down causes the hair to stick
up causing goose bumps.
Skin has motor neurons that goes to the muscle and sensory neurons as well.
Epidermis (pg. 88)
Layer
Stratum germinativum
Stratum spinosum
Stratum granulosum
Stratum lucidum
Stratum corneum
Characteristics
Innermost, basal layer
Attached to basal lamina
Contains epidermal stem cells,
melanocytes, and Merkel cells
Keratinocytes are bound together by
desmosomes attached to tonofibrils of the
cytoskeleton.
Some keratinocytes divide in this layer
Langerhans cells and melanocytes are often
present
Keratinocytes produce keratohyalin and
keratin
Keratin fibers develop as cells become
thinner and flatter
Gradually the cell membranes thicken, the
organelles disintegrate, and the cells die.
Appears as a “glassy” layer in thick skin
only
Multiple layers of flattened, dead,
interlocking keratinocytes
Typically relatively dry
Water resistant, but not waterproof
Permits slow water loss by insensible
perspiration.
Dermis is underneath epidermis. It is a mixture of connective tissue with some cells that
are part of the epithelial cells.
Stratum corneum is the most external layer. It is the one that gets shed. It has no nuclei,
they are dead. They are like a callous. Usually found in thicker areas such as the heel of
foot, palm of hand and elbow. It is mainly for protection.
Stratum lucidum is very fine and appears glassy and only found in thick skin
Stratum granulosum – has granules made of kerotine. Kerotinocytes are going to create
kerotine fibers. Kerotine fibers are made of strong protein that is going to contribute to
the hardness of the skin. That is why skin is tough.
Stratum spinosum – kerotinocytes are going to start dividing and multiplying by mitosis.
Melanine present in this layer as well. Melanocytes are stimulated by MSH.
Stratum germinativum – basal layer that is going to germinate and sprout and give other
layers above it.
Skin is the largest component of the integumentary system.
Hair follicles, exocrine glands (sweat glands and sebaceous glands) and nails are also part
of integumentary system.
All of the components of the integumentary system are basically all dead things. (cut hair,
cut nails, scrub your skin)
Exocrine glands has 2 purposes:
1. assist in thermoregulation
2. excrete waste
3. lubricate epidermis (sebaceous glands cause lubricration for greasy skin)
a. when you get older, glands don’t secrete as much therefore you need to
apply lotion.
Integumentary system is also considered part of excretory system.
Aging and Integumentary System
Porphyria (purple) – condition in blood which changes the biochemical pathway.
Patient with porphyria has conditions with skin. They cannot be exposed to sunlight
(photo sensitive)
Porphyria 5 P’s
1. Puberty (approximate time when symptoms appear
2. Psychiatric abnormality
3. Pain (abdominal pain)
4. Polyneuropothy (neurological problems)
5. Photosensitive
Symptoms tend to come and go and are aggravated by many drugs including garlic.