Wayne State BIO 2870 Exam 2

central nervous system consists of

brain and spinal cord

peripheral nervous system consists of

cranial and spinal nerves

the peripheral nervous system is divided into

afferent division and efferent division

afferent division

brings sensory information to the CNS from receptors in body tissues and organs

efferent division

carries information away from the CNS to effectors

effectors

muscles and glands that respond to motor commands

the efferent division is divided into 2 parts

somatic nervous system
autonomic nervous system

somatic nervous system (SNS)

voluntary controls skeletal muscle

autonomic nervous system (ANS)

involuntary controls smooth and cardiac muscle, glands and adipose tissue

autonomic nervous system is also called

visceral motor system

autonomic nervous system includes 2 parts

sympathetic division
parasympathetic division

sympathetic division

increases heart rate

parasympathetic division

decreases heart rate

neural tissue consists of two kinds of cells

neurons and neuroglia

neurons

the basic units of the nervous system
communication of neurons with one another and with other cells

neuroglia act as

phagocytes

phagocytes

clean up waste

neuroglia

regulate environment around neurons
provide a supporting framework for neural tissue

neuroglia are much

smaller cells and outnumber neurons

neuroglia retain the ability to

divide

a multipolar neuron consists of

cell body
dendrites
axon
axon terminals

dendrites

receive incoming signals into the cell body

axon terminals

form a synapse with the next cell

free ribosomes and RER form

nissl bodies giving a gray color to areas with many cell bodies

most neurons lack centrioles, as a result

typical CNS neurons cannot divide

CNS neurons cannot

be replaced if lost to injury or disease

neural stem cells

are present in the adult nervous system, but are typically inactive

multipolar neuron

all motor neurons that control skeletal muscles
efferent

unipolar neuron

most sensory neurons of the PNS
afferent

bipolar neurons

small and rare, occur in special sense organs
afferent

sensory neurons are

afferent
unipolar and bipolar

sensory neurons

receive information from sensory receptors monitoring the external and internal environment

somatic sensory receptors are divided into

external receptors and proprioceptors

external receptors

monitor the external environment

proprioceptors

monitor the position and movement of skeletal muscles and joints

visceral receptors are also called

internal receptors

visceral receptors

monitor activities of internal organs and provide sensations of distension, deep pressure and pain

motor neurons are

efferent
multipolar

motor neurons

total about half a million
carry instructions away from CNS

somatic motor neurons

innervate skeletal muscles

visceral motor neurons

innervate cardiac muscle, smooth muscle, and glands

interneurons are

association neurons
most numerous about 20 billion

interneurons

function as links between sensory and motor neurons

interneurons are located

entirely within the CNS

interneurons play a role

in all higher functions

neuroglia make up

about half of all neural tissue

4 types of neuroglia

astrocytes, oligodendrocytes, microglia, ependymal cells

astrocytes are

the largest and most numerous

astrocytes maintain

the blood brain barrier that isolates the CNS from the bodys general circulation

astrocytes secrete

chemicals that cause the capillaries to become impermeable to many compounds

astrocytes create

structural framework for CNS neurons and perform repairs in damaged neural tissues (scabs)

oligodendrocytes

produce an insulating membranous wrapping around CNS axons called myelin

myelin

increases speed of action potential

internodes

areas covered in myelin

Nodes of Ranvier

gaps in the myelin sheath

white matter

regions inside the CNS that are dominated by myelinated axons

gray matter

areas in CNS dominated by neuron bodies, glial cells, and unmyelinated axons

Oligodendrocytes can wrap

around multiple axons

microglia size

smallest and least numerous of neuroglia

microglia

perform protective functions such as engulfing cellular waste and pathogens

microglia act as

phagocytic cells

phagocytic cells

derived from white blood cells that migrated into the CNS as the nervous system formed

ependymal cells are

simple cuboidal epithelial that have microvilli

ependymal cells

line cavities in the CNS filled with cerebrospinal fluid

ependymal lines

central canal of the spinal cord
ventricles of the brain

Ependyma

involved in producing and circulating cerebrospinal fluid around the CNS

ependyma lacks

basement membrane

2 types of neuroglia found in PNS

satellite cells
schwann cells

satellite cells

surround and support neuron cell bodies in PNS

schwann cells cover

every axon in the PNS

outer surface of schwann cells is called

neurilemma

neurilemma

outer surface of schwann cells

myelinated axons in PNS have one

schwann cell per segment

one schwann cell can encircle

several unmyelinated axons

gray matter consists of

neuron cell bodies

white matter consists of

bundles of axons