Chapter 5 (copy)

The Integumentary System

Composed of skin and its derivatives

The Integumentary System

Produces Vitamin D in skin blood vessels

The Integumentary System

Reserves about 5% of the total blood

The Integumentary System

Covers the body

The Integumentary System

Protects underlying structures

The Integumentary System

Helps maintain body temp

Epidermis

Cell types include keratinocytes, melanocytes, Merkel cells, andLangerhans' cells

Keratinocytes

produce the fibrous protein keratin

Melanocytes

produce the brown pigment melanin

Langerhans' cells

epidermal macrophages that help activate theimmune system

Merkel cells

function as touch receptors

Stratum Corneum

Consists of 25-30 layers of dead, flat cells

Stratum Corneum

Cells are completely filled with Keratin

Stratum Lucidum

A prominent layer in the skin of palm and sole

Lucidum means

clear

Stratum Lucidum

Translucent layer

Stratum Lucidum

Consists of several layers of clear, dead, flat keratinocyte cells

Stratum Lucidum

Cells contain a clear substance called Eleidin

Eliedin changes into

keratin

Stratum Granulosum

Consists of a few layers of dead cells

Stratum Granulosum

Young cells are alive but eventually they die when the nuclei degenerat

Stratum Granulosum

Keratohyaline accumulate in the cells of this layer

Stratum Spinosum

8-10 layers of Polyhedral (many planes) cell

Stratum Spinosum

Cells are compact

Stratum Spinosum

Can divide to make new cells

Stratum Spinosum

Melanin granules and Langerhans' cells are abundant in this layer

Stratum Basale

Consists of a single layer of youngest keratinocytes

Stratum Basale

Cells are cuboidal to columnar

Stratum Basale

Cells divide very fast

Stratum Spinosum and Basale are collectively called

Stratum Germinativum because they germinate new cells to replace old dead skincells

Dermis

Consists of mainly collagen and elastin fibers

Dermis

Cell types include fibroblasts, macrophages, and occasionally mast cellsand white blood cells

Dermis

Very thick in the skin of palm and sol

Dermis

Very thin in the skin of eyelids, scrotum, etc

Dermis

Thicker on the dorsal side than the ventral side

Dermis

Thicker on the lateral side than on the medial side

Papillary Region

Upper part of the Dermis

Papillary Region

Consists of areolar fibrous tissue containing elastin and collagen fibers

Papillary Region

Contains peg-like projections called Dermal Papillae

Papillae contain

capillaries, nerve endings and touch receptors(Meissner's Corpuscles

Reticular Region

Located under the papillary region

Reticular Region

Makes about 80% of the skin.

Reticular Region

Consists of collagen and elastin fibers

Reticular Region

Provides strength and flexibility to the skin

Reticular Region

The spaces between the fibers are filled with blood vessels, skin glands,hair follicles, nerves, etc.

Hypodermis

Hypodermis

Hypodermis

Consists of adipose tissue and areolar tissue

Hypodermis

Contains pressure receptors (Pacican Corpuscles

Melanin

A pigment produced by Melanocyte cells

Melanin

Cells are present under or between the cells of Stratum Basale

Melanin

The number of melanocytes in different races is about the same

Melanocytes need

A hormone called Melanocyte Stimulating Hormone (MSH

Melanocytes need

Amino acids called Tyrosine

Melanocytes need

An enzyme called Tyrosinase

Melanin protects our body from

radiation

Carotene

Most obvious in the skin of palms and soles of the feet

Carotene

A prominent pigment in the skin of oriental people

Carotene

Accumulated in the Stratum Corneum and fatty areas of the dermis

Carotene plus melanin produce

yellow skin tone

Fetus has hair called

Lanugo

Several months following birth, a new set of hair grows called

vellus

Vellus is

the pale fine hairs in children and adults

Terminal hairs

are the coarse, long hair of eyebrows, scalp, axillary, andpubic regions

how many hairs on a human body

5 million

Scalp has how many hairs

100,000

Root

inside the skin

Shaft

projects outside the skin

Shaft consists of

dead, kertinized cells

Root has

Medulla,Cortex,Cuticle

Medulla is

the center of root with 2 rows of polyhedral cells

Cortex sorround the

medulla with several layers of pigment containingcells

Cuticle is

the outermost layer with one layer of dead keratinized cell

Hair grows from

Hair Follicle

Hair Follicle

These cells surround the root of the hair

Bulb contains

a papilla

Papilla contains

blood vessels

Around the follicle there are

Root Hair Plexus (touch sensors)

Bulb contains melanocytes for

hair color

Sebaceous (oil) Glands

Produce sebum (oil)

Sebaceous (oil) Glands

Larger glands are found in the skin of face, neck, and upper body

Sebum consists of

fats, cholesterol, salts, proteins, etc

Modified sebaceous glands are present in the eyelids and are called

Meibomian Glands

Sebaceous (oil) Glands function

Lubrication,Prevention of water loss,Keeps skin and hair soft

Sudo\=

Sweat

Ferre\=

to bear

Eccrine

Most of the sweat glands

Eccrine

Makes watery sweat

Eccrine

Numerous in the skin of palm and sole

Apocrine

Limited distribution

Apocrine

Found in the armpit and pubic areas

Apocrine

Produces viscous sweat

Apocrine

Becomes active at puberty

Sweat is made up of

water, salts, sugar, lactic acid, ascorbic acid, uric acid, andurea

Functions of sweat

Thermoregulation, Excretion

Cera\=

wax

Ceruminous Glands

Modified sweat glands found in the skin of ear canals

The combined secretion of these glands with the oil glands is the

Cerumen (ear wax)

Nail

Hard keratinized tissue of the epidermis

Nail fold

Skin fold on the lateral and proximal sides of the nail

Nail bed

Epidermal tissue under the nail