<span>The mineral crystals in obsidian are too small to see without a microscope. This is because the rock cools so rapidly from magma that crystals barely have time to form. Obsidian is a normally happening volcanic glass framed as an extrusive molten shake. It is delivered when felsic magma expelled from a well of lava cools quickly with negligible precious stone development.</span>
        
                    
             
        
        
        
Answer: In Stage 4 of the Demographic Transition Model birth rates and death rates are both low, stabilizing total population growth. The decline in both birth and death rates of most Stage 4 countries have been attributed to strong economies, highly educated citizens, ample healthcare systems, the migration of people from rural communities to cities (Bulgaria)
Explanation: i dont know if it's correct to them
 
        
             
        
        
        
True, just look at the weather channel on TV :)
        
                    
             
        
        
        
Cerebral cortex
1. Emotion can invoke an autonomic response.
2. Sexual thoughts or image which can increase blood flow to the genitals.
Hypothalamus.
1. It activates the flight or fight response.
2. It is the major control of ANS.
3. It is the integrating center for thermoregulation.
Brainstem.
1. It is integrating centers for reflexes which control heart rate and blood pressure.
2. It is the integrating center for pupillary reflex
Spinal cord
1. It is the integrating center for urination, erection, defecation and ejaculation reflexes.