U3.4 Integumentary System

Temperature Regulation & Sensation

1. Unit 3 The Integumentary System Chapter 5 in Textbook 3.4 Temperature Regulation & Sensation

2. Body Temperature Normal body temperature ranges from 97 ºF to 100 ºF (average is 98.6 ºF) Body temperature fluctuates throughout the day lower in the morning higher in the afternoon Core temperature (cranial, thoracic and abdominal cavities) Shell temperature (skin and mouth)

3. Body Temperature Body temperature is maintained by balancing heat production and heat loss (remember homeostasis?) Heat is produced by the millions of chemical reactions occurring in the body and is affected by food consumption, hormone secretion, and physical activity 80% of heat is lost through the skin, the rest through the respiratory tract and excretion of wastes This balance is known as thermoregulation Excessive changes in body temperature can be severe, even fatal (hyperthermia vs hypothermia)

4. Body Temperature The skin helps to regulate the homeostasis of body temperature through a negative feedback system Perspiration from sweat glands and dilation of the superficial blood vessels help to remove excess heat from the body Constriction of the blood vessels in the skin aids in conserving heat when body temperature drops; also, hair stands up, trapping insulating air YOU can help thermoregulate by stretching out when hot and curling up when cold!

5. Body Temperature

6. Body Temperature Thermoregulation is difficult for newborns Large surface area increases heat loss Thin layer of subcutaneous fat Neonates cannot shiver Neonates have brown adipose tissue (BAT) which produces a large amount of heat when metabolized; this is called non-shivering thermogenesis

7. Sensation The skin acts as a sensory organ. There are receptors located throughout the dermis and the epidermis. Free nerve endings found in the dermal papillae and possibly in the stratum basale and stratum spinosum detect itch, pain, hot, and cold.

8. Sensation Touch is a skin sensation that results from an active or passive contact between a person's skin and an object. Pressure applied onto the skin is the primary stimulus for the sense of touch. Another stimulus, vibration, emerges when there is a rapid and regular change in pressure. Fine (discriminative) touch Touch that is subtle but easily located Crude (non-discriminative) touch Touch that is more easily identified, but more difficult to locate (tends to spread)

9. Sensation Meissner corpuscle (AKA: tactile corpuscle) Receptor that mediates sensations of discriminative touch such as light versus deep pressure, as well as low-frequency vibration. (dermal papillae of the fingertips, lips, eyelids, nipples, and genitalia)

10. Sensation Pacinian corpuscle Receptor that responds to crude and deep pressure, vibration, and stretch; perceives proprioceptive information about joint positions. (inner dermis/subcutaneous layers of fingertips, breast, and genitalia)

11. Sensation Ruffini corpuscle Receptor that mediates deep or continuous, pressure. They adapt slowly and permit the body to stay in contact with grasped objects. May also detect heat.

12. Sensation Merkel cells have spiked appearance sensory receptors for touch & pressure (palms, soles, and lips) Root hair plexuses respond to the movement of hair shafts