Question

MCAT Mini-Tutorial: The Integumentary System

Answer 1

\({\bf{Functions:}}\)
- protection against physical damage, infection, water loss, UV radiation
- thermoregulation via capillary constriction and dilation, sweating
- osmoregulation via sweating and other excretions
- sensory reception via tactile cells, touch receptors, pressure receptors, hair follicles
- vitamin D synthesis (synthesis starts in the skin and is completed in the liver/kidneys/macrophages)

\({\bf{Structure:}}\)
- epidermis (outer layer, keratin)
> contains keratinocytes which make keratin
> outer layer is the older cells, continuously replaced/pushed upward by newer cells
> melanocytes: produce melanin
> Langerhan's cells: macrophages
> Tactile cells: sensory receptors

- dermis: connective tissue
> provides blood for nerves, glands, receptors, muscles, and hair/nails
> collagen and elastin
> sebaceous glands: make sebum (protects skin)
> sudoriferous/sweat glands: secrete sweat, cools the body, balances electrolyte levels

- hypodermis: adipose tissue (technically not part of the skin but provides support/thermoregulation)

- hair: keratin shaft, detects touch/temperature
> arrector pili: muscle at the base of the air, causes contraction and hair movement

- nails: flattened structures on the surface of fingers, also made of keratin

Answer 2

Anyway, that's the end of my tutorial, I hope it was a helpful resource. Source material is the 2nd Edition Barron's Prep book for the new MCAT