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