Nervous System Flashcards
Functions of the NS
- sensory receptors monitor changes in and out of the body
- processes and interprets sensory input
- dictates a response by activating effector organs
Afferent vs efferent
A- sensory signals picked up by sensory receptors
E- motor signals are carried away from the CNS
Somatic body region vs visceral
S- structures external to the ventral body cavity
V- viscera within the ventral body cavity
4 subdivisions of the PNS
somatic sensory
visceral sensory
somatic motor
visceral motor
What are the general somatic senses? (somatic sensory division)
receptors are widely spread throughout
-touch, pain, temp, proprioceptive senses
What are the special somatic senses? (somatic sensory division)
receptors are confined to small area
-hearing, balance, vision
What are the general visceral senses? (visceral sensory)
- stretch, pain, temp, nausea, hunger
- felt in digestive and urinary tracts and reproductive organs
What are the special visceral senses? (visceral sensory)
-taste, smell
What is the role of the somatic motor division?
signals contraction of skeletal muscle
-voluntary control
What is the role of the visceral motor division?
- regulates contraction of smooth and cardiac muscle
- controls function of visceral organs
What makes up the ANS?
the visceral motor division of the NS
What are the 2 cell types that make up nervous tissue?
neurons- transmit electrical signals
neuroglia- support cells (4 in CNS, 2 in PNS)
What are the special characteristics of a nerve cell/ neuron?
Longevity
Do not divide- neural stem cells are an exception
High metabolic rate- require abundant O2 and glucose
How long does it take a neuron to die without O2?
5 minutes
Role of dendrites?
- increase SA for receiving synaptic communication
- transmit electrical signal towards the cell body
Axons transmit impulses _______ the cell body
away from
How does axon diameter affect the conduction of impulses?
larger diameter= faster impulses
smaller diameter= more resistance= slower impulses
What are the most abundant type of neuron?
multipolar
What neurons make up majority of sensory neurons?
unipolar
Sensory (afferent) neurons transmit impulses _______ the CNS
toward
Motor (efferent) neurons transmit impulses _______ the CNS ____ the effector organ
away from
to
Most motor neurons are _____polar
multi
What are interneurons?
association neurons
- multipolar
- btwn. sensory and motor
- confined to CNS
Satellite cells vs. schwann cells
surround neuron cell bodies within ganglia
surrounds axons in the PNS to form myelin sheaths
What cells wrap multiple cell processes around different axons in the CNS to produce myelin sheaths?
Oligodendrocytes
Function of bear cilia?
help circulate CSF
-located on ependymal cells
What cells increase blood flow to active regions of the brain and take up/ release ions to control environment?
Astrocytes
MS is when the immune system attacks __________ in the ______
myelin sheaths
CNS
Endoneurium? Perineurium? Epineurium?
endo- surrounds axon
peri- surrounds fascicle of axons
epi- surrounds whole nerve
Afferent PNS fibres (nerves) respond to ______ and carry info ______ the CNS
sensory stimuli
to
Efferent PNS fibres (nerves) transmit _______ from the CNS to ______ and _______
motor stimuli
glands and muscles
Nerves of the CNS are composed of ________
interneurons
Monosynaptic reflex
- simplest and fastest
- knee jerk
Polysynaptic reflex
-withdrawal reflex
single interneuron btwn. motor and sensory
How does neuronal regeneration occur?
- in the PNS, macrophages invade and destroy the axon distal to the injury
- axon filaments grow peripherally from the injury site
- in the CNS, neuroglia never form bands to guide regrowing axons
- no effective regeneration to spinal cord and brain
Where are sensory, motor, and interneurons located?
dorsal
ventral
central
