skin !

Question 1

human skin !

Answer 1

epidermis : cornified layer, granular layer, malpighian layer

dermis

hair : hair papilla, hair erector muscles

sweat glands : richly surrounded by blood capillaries

nerve endings : sensory receptors -> sense pain, pressure & temperature changes in external environment

sub-cutaneous fat : consists of adipose cells -> store fats

Question 2

thermoregulation !

Answer 2

helps maintain human body temperature of 37 degrees celsius

• body temperature increases : body will reduce further heat gain + promote heart loss
• body temperature decreases : body will reduce further heat loss + promote heat gain

Question 3

heat gain !

Answer 3

blood & skin temperature increases -> temperature receptors in skin & hypothalamus of brain is stimulated

arterioles in skin undergo vasodilation : more blood sent to skin through blood capillaries -> increases heart loss by radiation, convection & conduction

• sweat glands : more active -> increased production of sweat -> more latent heat removed when sweat evaporates
• increased rate of breathing
• decreases metabolic rate -> decreases heat production

relaxation of hair erector muscles
- lie flat : allowing air to circulate over skin -> trap less air -> reduced insulation -> more heat lost by conduction, convection & radiation

body temperature decreases -> blood & skin temperature returns to normal

Question 4

heat decrease !

Answer 4

blood & skin temperature decreases -> temperature receptors in skin & hypothalamus of brain is stimulated

aterioles undergo vasoconstriction : less blood sent to skin through blood capillaries -> lesser heat loss from skin by radiation, convection & conduction

• swat glands : less active -> decreased production of sweat -> lesser latent heat removed when sweat evaporates
• increased metabolic rate : more heat produced within the body
• shivering : reflex contraction of body muscles to generate heat

contraction of hair erector muscles
- stand up : trapping air -> act as insulating layer -> less heat is lost by conduction, convection & radiation

body temperature increases -> blood & skin temperature return to normal