Anatomy and Physiology Unit Three - Nervous System

Central Nervous System (CNS)

The part of the nervous system that includes the brain and brain stem and spinal cord; responsible for coordinating information and activities across the body.

Peripheral Nervous System (PNS)

The part of the nervous system that connects the central nervous system to the limbs and organs, consisting of sensory and motor neurons.

Neuron cell

A specialized cell transmitting nerve impulses, fundamental to the nervous system's function.

Neuroglial cell

Supportive cells in the nervous system that provide protection, nutrition, and insulation to neurons. They play a crucial role in maintaining homeostasis and facilitating signal transmission.

Nerve action potential

The rapid rise and fall in voltage across a neuronal membrane that occurs when a neuron sends information down an axon, essential for signal transmission.

Cell body

The central part of a neuron that contains the nucleus and organelles, responsible for maintaining the cell's health and metabolic functions.

Dendrites

A short branched extension of a nerve cell, along which impulses received from other cells at synapses are transmitted to the cell body

Axon

the long threadlike part of a nerve cell along which impulses are conducted from the cell body to other cells

Nucleus (of neuron)

Where DNA is stored - the central part of the neuron located in the body of the cell.

Nucleolus 

a dense structure within the nucleus of a nerve cell (neuron), that is primarily involved in ribosome synthesis to produce the proteins essential for neuronal growth, maintenance, and function

Nissl bodies

Free floating endoplasmic reticulum and ribosomes, tasked with producing proteins in order to maintain the function of the neuron.

Axon hillock

Connects cell body to axon

Axon terminals

Axons end in these - they send out neurotransmitters to other cells

Sensory neurons

send nerve impulses to central nervous system (CNS)

motor neurons

send nerve impulses away from central nervous system (CNS)

interneurons

mainly located in central nervous system (CNS); send nerve impulses between sensory and motor neurons

Myelin sheath

formed by different typed of neuroglial cells - surrounds axons of most neurons

Olidodendrocutes (CNS)

the cells that make myelin in the central nervous system 

Schwann cells (PNS)

The cells that make myelin in the peripheral nervous system

Nodes of ranvier

The naked areas of the axons located between adjacent myelin internodes

Ganglia

Clusters of neuronal cell bodies in the peripheral nervous system (PNS)

Nucleus 

Clusters of neuronal cell bodies in the central nervous system (CNS)

Nerve

Bundles of axons in the peripheral nervous system (PNS)

Tracts

Bundles of nerves in the central nervous system (CNS)

White matter

contains mostly myelinated axons

Gray matter

contains neuronal cell bodies, dendrites, unmyelinated axons

action potential

a rapid sequence of changes in the voltage across a membrane - allow for communication over short AND long distances

graded potential (local potential)

a localized and variable change in a cell's membrane voltage, meaning its strength is proportional to the stimulus that caused it - allow for communication over short distances only

resting membrane potential 

the stable, negative electrical charge across a cell membrane when the cell is not excited, established by uneven ion distribution and selective membrane permeability

leakage channels

randomly alternate between open/closed; allowing for ions to flow down their electrochemical gradients. found in ALL parts of neurons

ligand-gated channels

ion channels that open or close in response to the binding of a specific ligand and other chemical stimuli. occurs in dendrites in pain receptors, and dendrites/cell bodies of motor neurons/interneurons

mechanically-gated channells

respond to mechanical stimuli or pressure stimuli. found in auditory receptors, receptors that monitor stretching of internal organs, and in touch/pressure receptors in skin

voltage-gated channels

respond to direct changes in membrane potential. responsible for generation and conduction of nerve impulses in the axons of all types of neurons

resting membrane potential

buildup of negative ions in the cytosol along the inside of the membrane and an equal buildup of positive ions in the extracellular fluid along the outside surface of the membrane 

sodium-potassium ATPase pump

maintains resting membrane potential by actively transporting Na+ out of the cell and K+ into the cell

polarized

inside cell is more negatively charged than outside

hyperpolarized

inside of cell becomes MORE negative 

depolarized

inside cell becomes LESS negative