The Integumentary System Flashcards
Epidermis
- made mostly of dead cells
- protects body from environment (water, sun, pathogens, etc.)
- contains cells that produce melanin
- cells filled with keratin
Dermis
- composed of living cells and specialized structures (sensory neurons, blood vessels, muscle fibres, hair follicles, glands)
- sense conditions and signals from environment (e.g. heat and pressure)
- regulate body temperature
- protect body from infectious diseases
Hypodermis
- made up of fat cells, which act as energy reserves
- protective, shock-absorbing layer
- insulate body against heat loss
Sweat pores
- allow sweat to leave the skin and evaporate
Hair shaft
- dead, keratin-filled cells
- protect and insulate body
Oil glands (sebaceous)
- found on face and scalp
- secrete fatty substance called sebum
- sebum prevents excess water loss, and lubricates and softens the skin and hair
Sweat glands
- release excess water, salts, and urea
- regulate body temperature by releasing sweat
Vascular region
- blood vessels provide nourishment to living cells, and help regulate body temperature
- arteries carry blood to cells
- veins carry blood away from cells
Nerve fibre
- sense conditions and signals from environment
Functions of the skin
- protective barrier
- retains body fluid
- protects against disease
- eliminates waste products
- regulates body temperature
Melanin
- determines skin colour
- absorbs harmful ultraviolet radiation
- amount produced depends on heredity and the length of time skin is exposed to UV radiation
- increased amounts occur in response to injury of the skin by UV radiation
Apocrine glands
- have about 2000
- inactive before puberty
- found in hair follicles, armpits, and the groin
Eccrine glands
- more abundant
- in palms, forehead, and foot soles, as well as everywhere else in the body that apocrine glands aren’t located
What layer of skin do tattoo needles need to hit?
Dermis
Explain why the concentration of melanin varies in populations who live closer to the equator compared to those who live in the northern hemisphere.
People who live close to the equator are exposed to more ultraviolet radiation and must produce more melanin to protect their skin, versus people who live in the northern hemisphere. Less melanin allows them to absorb enough rays to make more vitamin D.
