9.3 Your skin

• Biologie
• Middelbare school
• havo
• Leerjaar 3

9.3 Your skin

Planning

Learning objectives

• You will learn how your skin protects you and helps to keep your body at the right temperature.
  

• You will also learn how wounds heal and how cancer develops.

Discuss with your neighbour

- What are the functions of your skin?

Functions of the skin

1. Regulate your body temperature
2. Protection against dirt and pathogens
3. Protection against the sun

Anatomy of the skin

The epidermis: 

• Stratum corneum (dead skin cells). 
• Stratum basale (cell division). 

The dermis

Subcutaneous tissue

Regulation of body temperature

Temperature: around 37°

Senses of heat and senses of cold measure temperature and transmit impulses to your brain.

What are impulses? 

Cooling down

• Blood vessels in your skin become wider.
• Heat release to the environment.
• Skin is red
• Your sweat glands produce more sweat.

Warming up

• Blood vessels in your skin narrow.
• Skin is pale
• You're going to shiver.

Fat layer? Goosebumps?

Wound healing

1. Blood vessel narrows.
   
2. Clotting (clumping of platelets)
3. Platelets burst; fibrinogen is released.
   
4.  Formation of fibrin threads.
   
5. Blood clotting

Protection against sunlight

Ultraviolet radiation (uv-radiation) 

Cells in the stratum basale make small grains of brown colouring: pigment.

Pigment: ensures that UV radiation cannot penetrate your skin as deeply.

Development of cancer

What?	Make: 9.3 assignments 4-8, 10-12, 15, 16
How?	In your book. You may whisper.
Help?	Ask your neighbour first. Then raise your hand.
Time?	15 minutes
Finished?	Check your answers in teams!! Make a list of the bold words from 9.1 and 9.2 and their meaning.
	Well done!