Nervous System

Question 1

What is the nervous system?

Answer 1

-Allows us to receive info from the environment and react to it
~Receive signals through light, touch, and smell
- Allows info processing (determines what you are seeing)
- Causes appropriate responses (NS is very fast)

Question 2

In what ways do we sense and react to stimuli?

Answer 2

• Info is received by sensory cells
  ~Stimuli is received by sensory cells which are modified sensory neurons
• This info is then converted to electrical signals and then transmitted and processed by neurons
  ~The info is communicated to effectors like the muscles and glands and causes behavioral or physiological responses
• This entire process happens over long distance (bc it runs through the entire body) and is extremely fast

Question 3

What are the cells involved ands what are their functions?

Answer 3

• Neurons
  ~Receive, encode and transmit info
  ~Use electrical impulses (action potentials)
  ~ Chemicals (neurotransmitters)
• Glial cells
  ~Protect, support, insulate and nourish neurons
  ~Are support cells; if killed, the neurons will die; for every neuron, there are 10 glial cells

Question 4

How is the neuron structured?

Answer 4

• Cell body
  ~contains the nucleus and most of the cell’s organelles

-Dendrites
~receive info from other neurons or sensory cells
~The amount of dendrites will be dependent on what type of neuron it is and its function

-Axon
~The tail of the neuron
~Conducts electrical impulses away from the cell body and towards the target cell (postsynaptic cell)
~ The beginning of the axon is called the axon hillock, where the action potential is generated and contains voltage
~The end of the axon is the axon terminal where there is swelling at the tip of the nerve endings, where it is close to the target cell, and where it branches into 5 nerve endings where the synaptic terminals release neurotransmitters into the synapse

Question 5

What are some of the neuronal networks?

Answer 5

• Nervous system process info in three stages: sensory input, integration, and motor output
• Sensory neurons: transmit info about external stimuli such as light touch, or smell
  ~When sensory neurons receive stimuli, they send it to the CNS where the interneurons determine what it is and what to do with it
• Interneurons: integrate (analyze and interpret) the info
• Motor neurons: transmit signals to muscle cells, causing them to contract

Question 6

How is the neuronal networks complex?

Answer 6

• Neurons and synapses are divided into distinct yet interacting networks that function in parallel
• Human brain has an estimated 10^11 neurons and 10^14 synapses

Question 7

How is the nervous system organized?

Answer 7

• CNS: includes the brain and spinal cord; the sites of most info processing, storage, and retrieval
• PNS: includes sensory and effector neurons and support cells found outside the CNS

Question 8

What are action potentials and how do they help with communication between action potentials?

Answer 8

• Action potential: electrical impulses that neurons use to communicate with
  ~info that is received turns into electrical signals that are set to the CNS
• Neurons are capable of transduction going info
• Long distance -> electrical signals (action potentials)

-Short distance -> neurotransmitters (chemical signals)
~Happens across synapses