Essential Knowledge 3.E.2

Animals have nervous systems that detect external and internal signals, transmit and integrate information, and produce responses.

The neuron is the basic structure of the nervous system that reflects function. A typical neuron has a cell body, axon and dendrites. Many axons have a myelin sheath that acts as an electrical insulator. The structure of the neuron allows for the detection, generation, transmission

and integration of signal information. Schwann cells, which form the myelin sheath, are separated by gaps of unsheathed axon over which the impulse travels as the signal propagates along the neuron.

Action potentials propagate impulses along neurons. Membranes of neurons are polarized by the establishment of electrical

potentials across the membranes. In response to a stimulus, Na+ and K+ gated channels sequentially open and cause the membrane to become locally depolarized. Na+/K+ pumps, powered by ATP, work to maintain membrane potential.

Transmission of information between neurons occurs across synapses. In most animals, transmission across synapses involves chemical messengers called neurotransmitters. Examples include:

• Acetylcholine
• Epinephrine
• Norepinephrine
• Dopamine
• Serotonin
• GABA

Transmission of information along neurons and synapses results in a response. The response can be stimulatory or inhibitory.

Different regions of the vertebrate brain have different functions. Examples include:

• Vision
• Hearing
• Muscle movement
• Abstract thought and emotions
• Neuro-hormone production
• Forebrain (cerebrum), midbrain (brainstem) and hindbrain (cerebellum)
• Right and left cerebral hemispheres in humans

NOTE: The types of nervous systems, development of the human nervous system, details of the various structures and features of the brain parts, and details of specific neurologic processes are beyond the scope of the course and the AP Exam.

Students should be able to:

LO 3.43 Construct an explanation, based on scientific theories and models, about how nervous systems detect external and internal signals, transmit and integrate information, and produce responses.

LO 3.44 Describe how nervous systems detect external and internal signals.

LO 3.45 Describe how nervous systems transmit information.

LO 3.46 Describe how the vertebrate brain integrates information to produce a response.

LO 3.47 Create a visual representation of complex nervous systems to describe/explain how these systems detect external and internal signals, transmit and integrate information, and produce responses.

LO 3.48 Create a visual representation to describe how nervous systems detect external and internal signals.

LO 3.49 Create a visual representation to describe how nervous systems transmit information.

LO 3.50 Create a visual representation to describe how the vertebrate brain integrates information to produce a response.