integumentary system kaylee and jazzy. key terms apocrine sweat glands: glands that open into hair...
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Integumentary SystemKAYLEE AND JAZZY
Key Terms
Apocrine Sweat Glands: Glands that open into hair follicles
Arrector Pili: a bundle of smooth muscle cells attached to each hair follicle
Eponychium: the cuticle of the fingernail
Hair Shaft: Upper layer of dermis
Hypodermis: the subcutaneous layer
Keratin: tough, water repellant protein in epidermis
Melanocytes: Cells that produce a dark pigment called melanin
Papillary layer: the visible portion of the hair
Stratum Basale: mitotic skin layer of the epidermis
Stratum corneum: the outermost layer of the skin
What is it?
It provides a barrier against hazardous materials and pathogens
The skin and the glands, hair, nails, and other structures make up the system
Since the skin is on the outside of the body, this system is exposed to abuse in the form of bumps, cuts, scrapes, toxic chemicals, pollutants, wind, and sun.
The skin quickly repairs itself and continues to perform many functions
Structure of the Skin
Often called the cutaneous membrane
Consists of two distinct layers of tissues
The outer layer is called the epidermis
The inner layer is called the dermis
These are anchored to the underlying third layer called the subcutaneous tissue
Epidermis
The outer layer of the skin
No blood vessels
Cells receive nutrients from vessels in the underlying tissue
Cells on the bottom actively grow and divide from receiving adequate nutrients
As cells are pushed upward they receive less nutrients
By the time cells reach the top they are dead from lack of nutrients
Epidermis cont.
Stratum basale is the bottom layer, it is closest to the blood supply
Stratum spinosum is the next layer, it consists of several layers of cells
Stratum granulosum is a thin region that consists of 2 or 3 layers of flattened cells
Stratum lucidum consists of a few layers of flattened, anucleate cells. This region only appears in thick skin
Stratum corneum is the surface region, it consists of 20-30 layers of flattened, dead, completely keratinized cells
Dermis
Dense connective tissue that is deeper and thicker than the epidermis
Hair, nails, and certain glands are embedded in the dermis
Contains both collagenous and elastic fibers to give it strength and elasticity
If the skin is overstretched it could damage the dermis and leave whit scars called striae or “stretch marks”
Dermis is divided into 2 distinct layers called the papillary layer and the reticular layer
Papillary layer is the basis of finger prints and foot prints
Reticular layer is the deeper layer of the dermis that provides strength to the skin
Skin Color
Skin color is due to factors some genetic, some physiologic, and some environmental
Basic skin color is due to the dark pigment melanin produced by the melanocytes
Everyone has about the same number of melanocytes
The activity of melanocytes is genetically controlled
A larger number of melanin granules results in darker skin, a smaller amount of melanin granules results in lighter skin
Skin color cont.
Many genes are responsible for skin color
A single mutation can result in the inability to produce melanin which results in a condition called albinism
Albinism is when an individual have very light skin, white hair, and unpigmented irises in the eyes
Hair and Hair Follicles
Hair is found on almost all body surfaces
Hair is not found on the palms of the hands, soles of the feet, lips, nipples, certain external genitalia, and distal segments of the fingers and toes
All hair consists of a shaft and a root that are composed of dead cells
The shaft of a hair is the portion that extends beyond the epidermis
The shaft contains no nerves, therefore it can be cut with no feeling of pain
Hair and Hair follicles cont.
The root is the portion of hair that is below the surface of the skin
The shaft and root both make up the hair, which is produced by a hair follicle
The central core of the hair is the medulla
The root of a hair is enclosed in a tubular hair follicle
Nails
Thin plates of dead stratum corneum that contain a very hard type of keratin and cover the dorsal surfaces of the distal ends of the fingers and toes
Each nail has a free edge, nail body, and a nail root
The cuticle is a fold of stratum corneum that grows onto a portion of the nail body
Stratum basale grows under the nail body to form a nail bed
The nail matrix is responsible for nail growth
Nails appear pink because of the rich supply blood vessels in the underlying dermis
Glands: The two major glands associated with the skin are the sebaceous glands and the sweat glands
Sebaceous glands
generally associated with hair follicles
found in all areas of body with hair
Sebum- an oily secretion on the surface of the skin
Sebum keeps hair and skin soft and pliable
Sweat glands
Widely distributed around the body except for lips, nipples, and parts of external genitalia
There are more sweat glands in the palms and soles
An individual as about 2.5 mil. sweat glands
Recall
1. Cells that produce a dark pigment
2. Outermost layer of the skin
3. Actively mitotic layer of the epidermis
4. Subcutaneous layer
5. Visible portion of hair
6. Cuticle of fingernail
7. Glands that open into hair follicles
8. Muscle attatched to hair follicles
9. Tough, water repellant protein in epidermis
10. Upper layer of epidermis
A. Apocrine sweat glands
B. Arrector pili
C. Eponychium
D. Hair Shaft
E. Hypodermis
F. Keratin
G. Melanocytes
H. Papillary layer
I. Stratum basale
J. Stratum corneum
Answers
1. Cells that produce a dark pigment A. Melanocytes
2. Outermost layer of the skin B. Stratum Corneum
3. Actively mitotic layer of the epidermis C. Stratum Basale
4. Subcutaneous layer D. Hypodermis
5. Visible portion of hairE. Papillary layer
6. Cuticle of fingernail F. Eponychium
7. Glands that open into hair follicles G. Apocrine sweat glands
8. Muscle attatched to hair follicles H. Arrector pili
9. Tough, water repellant protein in epidermis I. Keratin
10. Upper layer of epidermis J. Hair shaft