Brain and Nervous System Chapter 4

Question 1

Central Nervous System

Answer 1

• the comprises of the brain and the spinal cord

Question 2

Peripheral Nervous System

Answer 2

• the first function of the PNS is to communicate information from organs to the CNS via sensory neurons
• second function is to communicate information from the CNS to the body’s organs via motor neurons

Question 3

two systems of the PNS

Answer 3

• Automatic Nervous System

- Somatic Nervous system

Question 4

two systems of the ANS

Answer 4

• Parasympathetic NS

- Sympathetic NS

Question 5

Parasympathetic NS

Answer 5

• this system is what keeps the body functioning efficiently and maintains a constant internal environment (homeostasis)
• operates in calm circumstances
• dominates the Sympathetic NS in this calm state
• the PNS maintains automatic functions (Digestion, heart rate and breathing)

Question 6

Sympathetic NS

Answer 6

• the Sympathetic NS is like an emergency system that activates when the organism perceives itself to be in an event of stress or danger
• essential in survival because it prepares the body for survival actions (flight/freeze)

Question 7

results of sympathetic NS activation

Answer 7

• Heart rate and blood pressure increase
  
  • Breathing rate increases
  • Sugar and fat are released to provide energy
  • Pupils dilate to enhance vision
  • Sweat glands increase the production of perspiration to cool the body
    
    • Digestion is slowed

Question 8

Motor Nerves

Answer 8

• Motor neurons carry information from the CNS to the particular muscles
that an organism intends to move.
• Efferent Nerves
These nerves carry motor information outward from the CNS to the
periphery of the body

Question 9

Sensory Nerves

Answer 9

• Sensory neurons carry information from receptors in the skin, muscles,
joints and tendons to the CNS where the information is processed.
• Afferent Nerves
• These nerves carry sensory information inward to the CNS from the
periphery of the body

Question 10

Neurons

Answer 10

• Neurons are the primary functional units of the nervous system
• their role is to:
  - receive information from other neurons
  - process this information
  - communicate the information to other neurons

Question 11

Dendrites

Answer 11

• Dendrites are the branch-like structures of the neuron
• they receive information from other neurons/sensory receptors (via synapses), and deliver this information to the cell body (of the neuron)

Question 12

Soma

Answer 12

• the soma controls the metabolism and maintenance of the cell
• it is the control centre of the cell

Question 13

axon

Answer 13

• the axon is the nerve fibre of the neuron
• the role is to carry information away from the soma and towards other cells
• the information is carried as an electrical impulse called action potential

Question 14

Neurotransmitter

Answer 14

• the end of each axon has terminal buttons that secrete a chemical called neurotransmitter whenever information is sent down the axon as an electrical impulse

Question 15

Glial Cells

Answer 15

• glial cells are no part of the neuron
• glial cells surround the neuron and hold them in place. They provide nourishment and oxygen to neurons.
• They also provide insulation for neurons to increase the speed of transmission of nerve impulses through the production of myelin
• glial cells remove dead neurons

Question 16

Myelin

Answer 16

• myelin is a fatty substance that covers the axon of the neuron and helps speed up messages passing through the axon
• it is produced in the brain and spinal cord by glial cells (myelination)
• the small gaps between myelin segments are called nodes of Ranvier. at each node, the axon is exposed and the action potential jumps from node to node at an increased speed.
• diseases that affect Myelin (Multiple Sclerosis)

Question 17

Synaptic Gap

Answer 17

• the synaptic gap is the space between two neurons.
• the gap is where the end of the axon (terminal buttons) comes into close proximity with receptor cites on the dendrites of the post-synaptic neuron

Question 18

Steps of Communication Between Neurons

Answer 18

1. The information is passed in the form of electrical impulses through the soma along the axon
   
   2. The neurotransmitter is secreted from the terminal buttons of the presynaptic neuron to a synapse shared with the dendrites of another neuron (chemical process).

Question 19

Vesicles

Answer 19

In a neuron, synaptic vesicles (or neurotransmitter vesicles) store various neurotransmitters released at the synapse.