chapter 12 key terms from book

neurons

basic functional units of the nervous system

neuroglia

supporting cells, functions essential to survival and functionality of neurons and to preserve the physical and biochemical structure of neural tissue

central nervous system (cns)

brain and spinal cord, also has neural tissue, blood vessels and various connective tissues that support and protect

peripheral nervous system (pns)

all the neural tissue outside the cns, delivers sensory info to the cns and carries motor commands to peripheral tissues and systems

nerves

bundles associated with blood vessels and connective tissues

cranial nerves

nerves connected to the brain

spinal nerves

nerves connected to the spinal cord

2 sections of pns

afferent and efferent

afferent division

brings sensory info to the cns from receptors in peripheral tissues and organs

3 afferent receptory

special sensory, visceral sensory and somatic sensory

receptors

sensory structures that either detect changes in the environment or respond to specific stimuli

efferent division

carries motor commands from the cns to muscles, glands and adipose tissue

effectors

target organs that respond by doing something

somatic nervous system (sns)

controls skeletal muscle contractions, both voluntary and involuntary

autonomic nervous system (ans)

also called visceral motor system, automatically regulates smooth muscle, cardiac muscle, glandular secretions and adipose tissue at the subconscious level

has a sympathetic and parasympathetic division (opposites)

effectors of somatic nervous system

skeletal muscle

effectors or parasympathetic ans

smooth muscle, cardiac muscle and glands

effectors of sympathetic ans

smooth muscle, cardiac muscle, glands and adipose tissue

perikaryon

cytoplasm surrounding the nucleus of a neuron

cytoskeleton of the perikaryon components

neurofilaments and neurotubules

dendrites

slender, sensitive processes, extend out from the cell body, play a key role in intercellular communication

axon

long cytoplasmic process capable of propagating an electrical impulse called action potential

synapse

site of intercellular communications

structural classifications of neurons

anaxonic, bipolar, unipolar and multipolar

anaxonic neuron

small and have numerous dendrites but no axon, located in the brain and in special sense organs

bipolar neurons

rare, 2 distinct processes (one dendrite and one axon), occur in special sense organs to relay sensory info, small

unipolar neurons

dendrites and axons are basically fused, found in most sensory neurons of the pns, long

multipolar neurons

two or more dendrites and a single axon, most common neurons in the cns

functional classifications of neurons

sensory, motor or interneurons

sensory neurons

form the afferent division in the pns, deliver info from sensory receptors to the pns

motor neurons

efferent neurons, carry info from cns to peripheral effectors in a peripheral tissue, organ or organ system

interneurons

always located in cns, distribute sensory inputs and coordinate motor outputs

4 types of neuroglia in the cns

ependymal cells, astrocytes, oligodendrocytes and microglia

ependymal cells

line ventricles and central canal, assist in producing, circulating and monitoring cerebrospinal fluid

astrocytes

maintain blood-brain barrier, provide structural support, regulate ion, nutrient and dissolved gas concentrations, absorb and recycle neurotransmitters, form scar tissue after injury

oligodendrocytes

myelinate cns axons, provide structural framework

microglia

remove cell debris, wastes and pathogens by phagocytosis

2 types of neuroglia in the pns

satellite cells and schwann cells

satellite cells

surround neuron cell bodies in ganglia, regulate o2 and co2, nutrient and neurotransmitter levels around neurons in ganglia

schwann cells

surround all axons in pns, responsible for myelination of peripheral axons, participate in repair process after injury