2.22.10 - The two fundamental control systems in animals:...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
The two fundamental control systems in animals: Hormones : slow, long-lasting, specificity based on target cells with correct receptors. Nervous system: fast, very short duration, specificity based on delivering message precisely to the target cell only. Today we cover: how information moves within nerve cells how information moves from nerve cells to target cells Neurons and synapses Nervous systems are based on a characteristic cell type highly specialized for sending and receiving messages: neurons . Neurons have a cell body (soma) with nucleus and basic cell functions Dendrites specialized to receive information -- may be very extensive! Axon specialized to transmit information; can be very long! often shielded by Schwann cells; these increase transmission speed by electrically insulating axon; wrapped around axon: myelin sheath axon terminus (‘bouton’) sends information to target cell Node of Ranvier Neurons and synapses Variations on basic neuron structure: “plain” branched axon soma connected very elaborate branching to axon only Neurons and synapses Information flow in a neuron is usually in one direction only: information enters cell in dendrites information passes through cell body to base of axon information moves along axon to axon terminus information moves to target cell from axon terminus
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Neurons send information by combined electrical and chemical means: passive transmission through dendrites and soma active transmission in axons: they generate self- propagated electrical impulses moving from axon base to axon terminal. This depends on the distribution of charged molecules across the nerve cell membrane, and the neuron's ability to rapidly change that distribution. Message transmission in neurons Neurons send information by combined electrical and chemical means. Important electrical principles and terms: Voltage (or potential ): measure of the driving force for moving electrical charges. Always measured as a difference between two areas -- i.e., between inside and outside of a neuron. Analogous to water pressure in a pipe. Ions : molecules or atoms carrying electric charge (they have 'missing' or 'extra' electrons, as in K + , Na + , Ca +2 , or Cl - ). Current : amount of electric charge moving. In a nerve cell, this means the number of ions moving. Analogous to the amount of water flowing in a pipe. Like electrical charges repel each other Unlike charges (+ and -) attract.
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 7

2.22.10 - The two fundamental control systems in animals:...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online