SM 1.501 The Cell: Brain and Nervous System

Flashcards about the brain and nervous system.

Why is a nervous system needed?

Why organisms need a nervous system to communicate between different areas in order to control function, regulate responses to conditions, and maintain homeostasis.

Neuron (Nerve Cell)

The basic unit of the nervous system; excitable cells that produce and transmit electrical impulses.

Action Potential

Transient change in the potential difference or voltage across the membrane of a neuron; sweeps down the membrane and is the basic unit of communication across the nervous system.

Soma

The cell body of a neuron containing the nucleus, responsible for protein synthesis and integrating incoming signals.

Dendrites

Branches from the soma that receive incoming inputs from other neurons.

Axon

A single projection from the soma that carries the impulse away to other neurons, characterized by branching into terminal boutons.

Myelin Sheath

An insulating, fatty coating that covers the axon, increasing the efficiency of electrical impulse conduction.

Synapses

Connections between neurons where axons synapse with dendrites, allowing impulse conduction through a brief change from an electrical to a chemical signal.

Presynaptic Cell

The nerve cell before the synapse

Postsynaptic Cell

The nerve cell after the synapse

Vesicles

Synaptic vesicles that contain neurotransmitters

Neurotransmitters

Chemicals contained in synaptic vesicles that bind to specific receptors on the postsynaptic cell, causing changes in the postsynaptic cell.

Synaptic Cleft

Space between the presynaptic cell and the postsynaptic cell.

Synaptic Transmission Reset

Mechanisms used to reset the synapse by neurotransmitter reuptake via transport pumps, enzymatic breakdown, and washout into the bloodstream.

Divergent Pathway

Synapses that expand signals throughout the nervous system; the presynaptic numbers are smaller than the postsynaptic numbers.

Convergent Pathway

Synapses where many signals channel down into a small number of nerve cells; presynaptic neurons are more numerous than postsynaptic neurons.

Afferent Neurons

Incoming neurons that carry sensory information from the periphery into the central nervous system.

Efferent Neurons

Outgoing neurons that carry commands from the nervous system to effector organs.

Interneurons

Neurons, also called relay neurons that form connections and establish circuits between afferent and efferent neurons, storing and integrating information.

Reflexes

Simple reflexes like the withdrawal reflex, involving an afferent neuron, an interneuron, and an efferent neuron that operates at the level of the spinal cord.

Nerve Net

A loose connection of neurons that form the basis of neuronal networks, seen in organisms like the C anemone.

Ganglia

Collections or groupings of neurons in certain regions.

Central Nervous System

The brain and spinal cord encased in bone.

Peripheral Nervous System

Communicates from the periphery to the center and in the opposite direction.