The Sympathomedullary Pathway

Question 1

A description of the body’s response to acute stress….

Answer 1

Immediate (acute) stressors arouse the autonomic nervous system (ANS). The ANS is one part of the nervous system. It is called autonomic because it governs itself. The ANS is divided into the Sympathetic Nervous system and the Parasympathetic Nervous system. The SNS arouses an animal to be ready for Fight or Flight, the parasympathetic returns the animal to a state of relaxation.
The SNS is part of the autonomic nervous system that controls our internal organs such as glands, heart and circulation. The nerve pathways of the SNS originates in the brainstem and travel via the spinal cord and spinal nerves to various body organs. One of the pathways runs to the Adrenal Medulla, which, along with the Adrenal Cortex, makes up the Adrenal Gland. When activated the SNS Stimulates the Adrenal Medulla to release the hormones adrenaline and noradrenaline into the blood stream.

Question 2

What are the effects on the body of activating the sympathetic nervous system?

Answer 2

• increased pupil size lets in more light for better vision
• increase in heart rate allows for greater flow of blood flow to skeletal muscles
• Glycogen stored in the liver is converted into glucose for energy
• Bronchial tubes in lungs dilate for greater oxygen intake
• Sweat glands stimulated to produce more sweat
• Adrenal Medulla stimulated to release adrenaline

Question 3

What type of stress does the Sympathomedullary pathway respond to?

Answer 3

Acute stressors

Question 4

What are the 6 steps of SAM (Sympathodmedullary pathway)?

Answer 4

1. STRESSOR
2. Hypothalamus activated
3. Sympathetic branch of ANS activated
4. Adrenal Medulla releases adrenaline and noradrenaline
5. Fight or flight response = Physiological signs including increased heart rate and blood pressure
   6a. Stressor goes and parasympathetic branch returns the body to its usual state
   OR
   6b. Stressor stays (prolonged stress) = Pituitary Adrenal system