Anatomy & Physiology 2 Unit 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 ◦ 1 st degree, 2 nd degree and 3 rd degree
Skin cancer ◦ Basal cell carcinoma ◦ Squamous cell carcinoma ◦ Malignant Melanoma