Skin

Question 1

what is skin?

Answer 1

its an organ ! - group of tissues working together to perform a specific function

Question 2

what are some important functions of the skin?

Answer 2

1) thermoregulation : blood conducts heat from the core of the body to the skin. Skin has both warm and cold receptors
2) protection : physical barrier to abrasion, bacteria, dehydration, many chemicals and UV
3) Environment sensory input: gathers info from env like sensing temp, pressure, pain and touch
4) excretion: water and salts are excreted thru the skin
5) immunity: besides being a physical barrier to bacteria. specialized cells of the epidermis are components of the immune system
6) blood reservoir: vessels of the dermis hold up to 10% of the blood of resting adult
7) vitamin D synthesis

Question 3

what are the two principal parts of the skin?

Answer 3

1) epidermis and the dermis
beneath the skin is a subcutaneous tissue called the superficial fascia or hypodermis. the fat of this subcut layer is an important heat insulator for the body

Question 4

Epidermis

Answer 4

epidermis is avascular ( no blood vessels) epithelial tissue. it has 4 major cells types

Question 5

What are the 4 major cell types of the epidermis?

Answer 5

1) keratinocytes: 90% of epidermis is made up of this- these make the protein keratin that helps to waterproof the skin
2) melanocytes transfer melanin (skin pigment) to keratinocytes
3) langerhan cells interact with the other helper T cells of the immune system
4) Merkel cells attach to sensory neutrons and function in the sensation of touch

Question 6

what does exposure to friction and pressure stimulate the epidermis to do?

Answer 6

thicken and form a callus

Question 7

what do we know about the dermis?

Answer 7

its a connective tissue, its embedded by blood vessels, nerves, glands and hair follicles. collagen and elastic fibres in the dermis provide skin with strength , extensibility and elasticity.