neurons

nervous system

receives information, processes information, and sends out signals to the muscles and glands to elicit an appropriate response from the body

• can be divided into 2: central and peripheral

nervous tissue

responsible for communication between the cells of the body by forming a system of electrical impulses that communicate very rapidly

• are like the wiring of the body

central nervous system

includes the brain and spinal cord

the skull protects the brain and the vertebrae protect the spinal cord

• can send signals or impulses to and receive impulses from the perihperal nervous system

nuclei

collections of cell bodies inside the central nervous system

tracts

the collection of nerve axons in the central nervous system

peripheral nervousy system

Includes all nerves not in the brain or spinal cord

• includes cranial nerves and spinal nerves

• connects all parts of the body to the central nervous system can be divided into 2 sections

brainstem

region includes the midbrain, pons and medulla

ganglia

collections of cell bodies inside the perihperal nervous system

nerves

collection of nerve axons in the peripheral nervous system

sensory nervous system

branch of the peripheral nervous system

• afferent division

motor nervous system

branch of the peripheral nervous system

• efferent division

sensory organs

the peripheral nervous system receives impulses from sensory organs via the afferent division

• then relays signals or impulses from hte central nervous system to the muscles and glands via the efferent division

somatic nervous system

a branch of the efferent division

• are generally under conscious control, control the movements of skeletal muscles, skin and joints

autonomic nervous system

branch of the efferent division

• controls the glands and smooth muscles of the internal organs. generally not under conscious control

• can be divided into 2: sympathetic and parasympathetic

sympathetic nervous system

activates and prepares the body for vigorous muscular activity, stress and emergencies

parasympathetic nervous system

generally operates during normal situations, permits digestion and conserves energy

neurons

are nerve cells tha conduct electrical impulses and relay infromation throughout the body

• contains three parts

  • do not undergo mitosis, can survive a person’s entire lifetime, which is why brain and spinal damage is so serious

• neurons can only survive minutes without oxygen

dendrites

the receiving end of a neuron

• are numerous short extensions that emanate from the cell body

• which receive information from other neurons

  • conduct those nerve impulses towards the cell body to its axon terminals

cell body

synthesizes all nerve cell products

• consists of a large nucleus with surrounding cytoplasm containins the normal organelles

• information is recevied and sent in the same direction within a neuron

  • contains the nucleus and other organelles typically found in cells, except for centrioles, which aid in mitosis

axon

conducts nerve impulses away from the cell body to its axon terminals

can vary in length, being very short to very long, up to three feet

• are composed of cell componenets like the cell body but lack rough endoplasmic reticulum.

  • the axon depends upon the neuron’s cell body to send the necessary proteins down the length of the axon

axon terminals

store neurotransmitters inside secretory vesicles at the end of the axon terminals

when neurotransmitters are releaseed from axon terminals, vesciles carry the nerve impulse from one neuron to the next

neurotransmitters

one of the main functions of the cell body is to manufacture neurotransmitters

• are chemicals stored inside secretory vesicles (axon terminal vesicles) at the end of the axon terminals

  • When neurotransmitters are released by the axon terminal vesicles, they carry the transmission of the nerve impulse from one neuron to another

• presynaptic neuron is before the synapse, postsynaptic neuron is after the synapse

synapse

neurotransmitters are emited across this to the dendrite of another neuron

• is a gap between two neurons, as neurons do not physcially touch eachother

multipolar neuron

a neuron that has three or more extensions from the cell body

• have one axon and many dendrites. they can be called motor neurons

bipolar neurons

have a central cell body with two extensions

• are found within the body as special receptor cells in the visual and olfactory systems

unipolar neurons

pseudounipolar

• have one extension off the cell body that branches into two:

  • one central process running to the CNS

  • another peripheral process running to the sensory receptor

sensory neurons

are afferent, unipolar and function to carry information from the PNS to the CNS

• most of these carry impulses from the skin or internal organs to the CNS

interneurons

are association neurons, are found only in the CNS

• are typically multipolar neurons and transmit impulses within different parts of the central nervous system

motor neurons

efferent, send messages from the CNS to the PNS