18Class 11 Biology

Neural Control and Coordination short notes

Short notes on neurons, nerve impulses, synapses and the human brain. Know the sequence of an action potential and what each brain part controls.

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Neurons and impulses

Neurons have dendrites, a cell body and an axon. Myelinated fibres conduct faster, jumping between nodes of Ranvier.
Resting potential is about −70 mV, with more K⁺ inside and more Na⁺ outside.
The Na⁺/K⁺ pump moves 3 Na⁺ out and 2 K⁺ in.
Depolarisation: Na⁺ rushes in. Repolarisation: K⁺ moves out.

Electrical synapses pass impulses directly, and they're fast and rare.
Chemical synapses use neurotransmitters such as acetylcholine released into a cleft.

Forebrain: the cerebrum, thalamus and hypothalamus.
The corpus callosum connects the two cerebral hemispheres.
The hypothalamus controls temperature, hunger and thirst, and it controls the pituitary.
Midbrain: includes the corpora quadrigemina.
Hindbrain: pons, cerebellum and medulla.
The cerebellum handles balance and coordination, and the medulla handles breathing, heart rate and reflexes such as swallowing.
The midbrain and hindbrain form the brain stem.

Reversing the ions in the action potential, since Na⁺ moves in first.
Saying the cerebellum controls breathing. That's the medulla.
Thinking impulses can pass backward across a chemical synapse. They only go one way.

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