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Structure of the nervous system and neurones

Homeostasis and response • The human nervous system

Key concepts

What you'll likely be quizzed about

  • The central nervous system consists of the brain and spinal cord, acting as the main coordinator of nervous activity.
  • It receives electrical impulses from receptors, processes this information, and sends signals to effectors to elicit responses.
  • The brain manages higher functions such as memory and decision-making, while the spinal cord supports rapid reflex pathways, allowing quicker responses.

Flashcards

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Why do reflex actions bypass the brain initially?

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Reflex actions bypass the brain to produce immediate responses, preventing damage and saving time.

Key notes

Important points to keep in mind

CNS equals brain plus spinal cord; only relay neurones are inside the CNS.

Pathway sequence: stimulus → receptor → coordinator (CNS) → effector → response; motor neurones transmit impulses to effectors.

Sensory neurones send impulses to the CNS; motor neurones send impulses away to muscles or glands.

Myelin sheath increases conduction speed; long axons transmit signals quickly across the body.

Synapses use neurotransmitters for one-way signal transfer; enzymes breakdown neurotransmitters to stop continuous firing.

Reflex arcs produce automatic, rapid responses by routing impulses through the spinal cord without initial brain involvement.

Specific brain regions have specialized functions: cerebrum for consciousness and memory, cerebellum for muscle coordination, medulla for automatic life functions.

Effectors produce movement (muscles) or chemical release (glands); the CNS selects between reflex and processed routes to balance speed and control.

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