5.2 The skin (and nose and tongue)

• Biologie
• Middelbare school
• havo
• Leerjaar 1

5.2 The skin
& taste/smell

Read page. 94-95

- Difficult words? write them on the board

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The nervous system

• Central nervous system (brain and spinal cord) 
  
  
• Seperate nerves 

Perceiving and reacting to the environment

stimuli - (impuls)->   Perception   -(impuls)->    Reaction    

(effect)      

 

How well do you understand 5.4, 5.7 nervous system and
5.1 perceiving your environment (senses)?

010

How do you perceive when someone smiles to you? And how do you react?
Give 6 steps using key words

1. Senses receive stimuli (=something from environment)
2. Sensory cells produce impulses (=little electrical shock)
    
3. Impulses travel trough nerves to the spinal cord and then the brain  (*above neck directly to the brain)
    
4. The brain processes these impulses to perceive the environment, (conscience = bewustzijn) 
    
5. Impulses are sent down to the muscles and glands. 
6. Muscles and glands react (effect)
   
   "contract arm muscles and produce saliva"  

Nervous system in action

Basic 5.2 The skin

Succes criteria: 

- Know the three different layers of the skin and what lies underneath

- Can name the different parts of each layer and their function  ----->

- You can determine with an experiment where on your body the skin is most sensitive

What are things you
can feel with your skin?

Senses in the skin

• Heat (hotter than skin)
• Cold (colder than skin)
• Pressure (hard contact)
• Touch (gentle contact) 
  *how many receptors differs over the body ---> experiment
  
  
• Pain (skin, but also in deeper organs)

* fun fact: skin = largest organ

sensory cells

Experiment touch receptors

Pincers

Read page 153. 

Practical 2 page 153

What is skin?

1. Cell
2. Tissue
3. Organ system
4. Organ

The skin

Which is the part of the skin that consists of dead cells?

1. Basal layers
2. Dermis
3. Corneal layer
4. Subcutaneous connective tissue

Where are most new skin cells formed?

1. At skin underneath the feet
2. Basal layer
3. Corneal layer
4. Dermis

Tattoo

Where is the tattoo ink
injected in the skin?

1. Epidermis, corneal layer
2. Epidermis, basal layer
3. Dermis
4. Subcutaneous connective tissue

Tattoo

Wanneer de inkt de lederhuid (dermis) bereikt, gebeurt er iets geks. Je lichaam schrikt van de onbekende stof en wil het eigenlijk meteen zoveel mogelijk afvoeren. De pigmentdeeltjes zijn te groot om door ‘lichaamseigen opruimcellen’ afgevoerd te worden.

Om je toch te ‘beschermen’ kapselt de lederhuid de inkt in.

Door deze beschermingsreactie ontstaan er letterlijk bolletjes

inkt, die verder geen schade kunnen aanrichten en waardoor

de kleuren mooi en permanent in je huid blijven zitten.

Experiment methol gum

Read 5.2 Taste and smell 
on page 95-96

What are you perceiving?

Tasting

Taste buds

Smell

            Smell

* Er zijn wel duizenden verschillende soorten stofjes (moleculen) die we kunnen ruiken, voor elk stofje is een nét ander soort reukreceptorcel. Veel geuren bestaan uit een combinatie van geurstofjes.

Denk aan: 

citrus, houtachtig, nootachtig, leer, bloemig, oriëntaals, kaneel, rokerig, dennengeur, zwavel/rotte eieren, muntig, fruitig, grondachtig, zoet, metalig... etc.

Experiment 

tasting chocolate: describe in detail to your neighbour what sensations you experience   ('What do you perceive') 

Try to describe at least 5 different sensations

Smaak & Reuk

Read 5.2 Taste and smell page 95-96
Make assignments: 

3, 4 and 7 t/m 9. 

olfactory system = reukzintuig

nasal cavity = neusholte

scent = geur

Discuss test results