Anatomy & Physiology 2Unit 1

Called the integument (meaning “covering”) It is essential in keeping water and other

important molecules in the body It is also important in keeping out bacteria

Functions include:◦ Protect (bacteria, UV radiation, chemicals, etc)◦ Insulate◦ Cushion◦ Regulates thermal energy◦ Manufactures Vitamin D◦ Helps get rid of wastes◦ Sensory organ

Two kinds of tissue◦ Epidermis (outer layer)◦ Dermis (inner layer)

The epidermis is harder and tough to protect from the environment

The dermis is dense and made of connective tissue

Has 5 zones called strata Has no blood supply (that is

why some cuts don’t bleed) Varies in levels of thickness

depending on area of the body

These cells constantly undergo cell division (millions are lost daily and re-grown daily)

Melanin is found in this layer – it gives skin its color

Areas of dense melanin forms moles or freckles

Leather products are treated dermis of animals because it is dense and strong

Also varies in thickness depending on area of body (hands and feet are thicker than eyelids)

Where fingerprints form Helps regulate body

temperature The reticular layer is the

deepest skin layer◦ Contains blood vessels, sweat

and oil glands and hair follicles

Fingerprints are uneven, fingerlike projections from the dermis region

They create indentions in the epidermis layer

They often send nutrients to the epidermis and house touch receptors

Palms, hands, fingers, soles of feet and toes all have definite patterns of looped and whorled ridges

The patterns are genetically determined that is why they are unique to individuals

These ridges are also well supplied with sweat pores this is why fingerprints are left on almost anything touched.

Tattoos are made by inserting colored pigments into the dermis layer using a needle

Since the dermis layer contains the blood glands it is important to have sterile needles

Sebaceous glands Sweat glands Hair Nails

There are millions of hairs scattered across the body

Hair is all over the body expect on palms of hands, soles of feet, nipples and lips

Hair is the fastest growing tissue in the body

It’s main role is to provide minor protection Guards the head against bumps

and heat loss Eyelashes shield the eye Nasal hairs trap foreign

particles

Hair is all most entirely dead epidermis and proteins

The central core is the medulla, which is surrounded by a bulky cortex, which is further covered by a cuticle

The cuticle is formed by a single layer of cells that overlap one another like shingles on a roof

The cuticle is the most heavily keratinized (proteins) part of the hair to provide strength

As the hair lengthens the cuticle begins to wear away allowing the inner hair region to “frizz” out – this is known as a split end

Arrector pili are small bands of smooth muscles on each side of the hair root

When these muscles contract (as in cold or frightened) the hair is pulled upright

This phenomenon can especially be seen in a frightened cat

Hair comes in a variety of sizes and shapes Short and stiff in the

eyebrows Long and flexible on the head Nearly transparent in some

areas Hair pigment is made by

melanocytes in the hair bulb Varying types and amounts

of melanin account for all types of hair colors from pale blond to pitch black

Sebaceous glands◦ Oil glands◦ Found everywhere

except hands and soles of feet

◦ Release sebum (a mixture of oily substances and fragmented cells

◦ Hydrates skin and keeps bacteria balance

Sweat glands◦ Helps regulate body

temperature through evaporation of sweat

◦ On a hot day you could lose up to 7 liters of body water through sweat

A scale-like modification (corresponds to a hoof or claw)

Parts◦ Free edge◦ Body ◦ Cuticle◦ Root◦ Matirx

Nails are transparent and nearly colorless, but appear pink because of nail bed blood supply

Like hair nails are nonliving tissues

Athlete’s foot◦ Caused by a fungus

Cold sores◦ Caused by a virus

Psoriasis◦ Chronic condition

Burns◦ 1st degree, 2nd degree and

3rd degree

Skin cancer◦ Basal cell carcinoma◦ Squamous cell carcinoma ◦ Malignant Melanoma