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Unit 19: Biology Part 2 Page 30 of 137
Hair and nails are made of keratin. The Skeletal System
Keratin is a tough, waterproof
protein. Hair color comes from What makes us so human-shaped?
melanin—the same pigment that Answer: Our bones! Without them
acts as a sun-block in the skin. we would be a blob of tissue. Our
Luckily, they do not have nerves— skeletal system—our bones,
otherwise it would be pretty painful ligaments, and cartilage—give us
to get a hair cut or clip your nails! our structure.
Nails act as protective plates on Maintaining a healthy skeletal
the fingers, while hair serves system is important. We must
several purposes. Hair can keep make sure we get the right
use warm, although it’s mostly nutrients—especially while we’re
used this way by other mammals. still growing.
The melanin protects us from the
sun. Hair can even act as filters— If our bones get broken, it’s
filtering the air that comes up our important to see a health-care
noses. professional; if not correctly
treated, bones may not heal
Keeping your skin, hair, and nails properly.
clean is an important part of
keeping them healthy. Poor Vertebrate (animals with
hygiene can lead to offensive body backbones) skeletons (the bones)
odor—a bad smell that comes off are connected to each other by
your skin, hair, and nails. Good protein fibers called ligaments.
skin hygiene can help fight both Where two bones meet, there’s a
body odor and acne. layer of cartilage to create a
smooth movement-surface.
Sunlight is a double-edged sword.
On the one hand, your skin makes The main functions of bones are:
vitamin D when exposed to
sunlight. On the other, sunlight can Support: Bones give the
damage skin and even lead to skin body its structure—its shape.
cancer. It’s important to get It holds up the tissue against
sunlight, but to do so safely; using the pressure of gravity.
a sun block that blocks UV rays. Protection: The bones protect
certain tissues. For example,
the skull protects the brain,
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