Ask Me Everything0

Handy guide

Although testosterone is the małe sex hormone, it is present in females, too. If you had a high level of testosterone before you were bom, your ring finger is usually longer than your index finger.

Index

finger

Ring

finger

04: Now relax your diaphragm so that it pushes up and the muscles between your ribs decrease the space in your chest cavity.

Air out

05: This forces your lungs to shrink and squeeze out the stale air containing the waste carbon dioxide.

Ribs

Hormones

01: Madę up of a number of different glands, the endocrine system releases Chemical messengers called hormones into your bloodstream.

02: Release of a hormone called melatonin peaks at night to make you drowsy; during the day, less is needed.

03: The endocrine system Controls morę than 30 hormones. Some of the activities that they help to control include:

■    How and when you grow

■    When you feel hungry

■    Glucose (sugar) levels in your bloodstream

■    Sleep

■    Dealing with stress

. Intercostal muscles

.Lungs . Diaphragm

i J?^HAT’S IW A WAME?

The word “hormone” comes from a Greek word meaning to excit_e ^or set in motion.

WEIRD°^r WHAT?

Temperaturę control

Humans are warm-blooded mammals, and several body systems are involved in maintalning a constant internal temperaturę of 98.6°F (37°C).

Nervous system

Nerves relay information about body temperaturę to the brain, which instructs the other systems to take action.

Integumentary system

Receptors in the skin detect changes in external temperaturę. If too hot, sweat glands release sweat, which evaporates on the skin’s surface to cool the body.

Cardiovascular system

Blood vessels near the surface of the skin widen to radiate heat from the body when hot or narrow to reduce heat lost through the skin when cold.

Endocrine system

If too cold, adrenal glands produce morę epinephrine and norepinephrine to speed up the ratę of Chemical reactions in cells to increase body heat.

Muscular system

If too cold, involuntary słiivering makes muscles contract and release heat to warm the body.

exercise

deve\op that you

which means

:an sometimes

n weight.

Lyc 11 iuouiuo inuvc

your eyeballs morę than 100,000 times per day.

Ten things you can’t do without a nervous system

Smell

Taste

See

Hear

Think

Remember

Dream

Touch

Move

Breathe

b Kindersley. Ali Rights Reserved.