Chapter 11: The Nervous System

Question 1

Steps involved in a short-term stress response (include hormones & their function, glands, organs, symptoms, effects, involuntary/voluntary responses)

Answer 1

Short-Term Stress Response (Fight-or-Flight Reaction)

1. Stress is Detected:
   
   • The brain, specifically the hypothalamus, detects a stressor (e.g., danger, threat) and activates the stress response.
2. Hormones are Released:
   
   • Adrenaline (epinephrine) and Noradrenaline (norepinephrine) are released by the adrenal glands (specifically the adrenal medulla).
     
     • Function:
     • Breaks down glycogen into glucose, raising blood sugar and giving a burst of energy.
     • Increases heart rate, breathing rate, and cell activity.
     • Expands blood vessels to send more oxygen and nutrients to muscles.
     • Dilates the pupils to improve vision.
     • affects attention center of the brain (norepinephrine)
   • Cortisol is also released from the adrenal cortex.
     
     • Function: Cortisol reduces inflammation, keeps blood sugar high by suppressing insulin, boosts glucagon for more glucose, and breaks down fats and proteins for energy and repair.
3. Body Changes:
   
   • Heart: Beats faster to pump more blood and oxygen to vital organs and muscles.
   • Lungs: Breathe faster to supply more oxygen to the body.
   • Muscles: Get more blood (and thus oxygen) to be ready for quick action.
   • Digestive System: Slows down since digestion is not a priority during a stress response.
4. Symptoms:
   
   • increase in respiratory rate
   • increase in heart rate
   • muscle tension
   • sweating
   • frequent urination
   • irritability
   • tiredness
   • trouble sleeping
   • upset stomach
   • headaches
   • tremors (shakiness)
5. Involuntary Responses:
   
   • Heart rate increases automatically.
   • Breathing rate increases without conscious control.
6. Voluntary Responses:
   
   • Fighting or fleeing: These actions are under voluntary control. You can choose to defend yourself or run away from the stressor.

Question 2

Neuron

Answer 2

A neuron is a special type of nerve cell that helps the body receive and react to signals from inside or outside the body. It is the basic working unit of the nervous system.

Question 3

Direction of nerve impulse

Answer 3

The nerve impulse moves in this order:

1. Dendrites: Receive the signal.
2. Cell Body: Processes the signal.
3. Axon: Sends the signal away from the cell body.
4. Axon Terminals: Pass the signal to the next cell (neuron, muscle, or gland).

So, the impulse travels from the dendrites → cell body → axon → axon terminals.

Question 4

Function of adrenaline (epinephrine)

Answer 4

• epinephrine has the following effects:
• glycogen breakdown into glucose -> increases blood sugar level and results in a sudden burst of energy
• increases heart rate and respiratory rate and cell metabolism
• vasodilation -> increases blood supply oxygen and nutrients to tissues (i.e., muscle)
• retinal dilation -> enhanced visual percepti