Lecture 31 - Nervous System Introduction Flashcards
What are the 3 main functions of the nervous system?
- sensory input
- integration
- motor output
Functions that can be controlled voluntarily are referred to as _____ and those that are involuntary are referred to as _____
somatic; autonomic
What two parts is the nervous system divided into? what do they encompass?
- Central (CNS) - brain and spinal cord
- Peripheral (PNS) - cranial nerves, nerves extending away from CNS
What are the two functional divisions of the PNS
- sensory (afferent)
- motor (efferent)
what are the two divisions of the efferent PNS
- somatic
- autonomic
the sensory (afferent) division conducts impulses from ____ to ____
receptors; CNS
think “arriving”
the motor (efferent) division conducts impulses from ____ to ____
CNS; muscles/glands
think “exiting”
the somatic system conducts impulses to what kind of muscle
skeletal
the autonomic system conducts impulses to what kind of muscle
cardiac + smooth
T/F: the parasympathetic division conserves energy
TRUE
where are afferent neurons located in regard to the spinal cord
outside
where are efferent neurons located in regard to the spinal cord
within ventral horn
where is the enteric system found
within the walls of the entire gastrointestinal tract
Myenteric plexus
found in muscularis externa of GI
Submucosal plexus
found in submucosa of GI
What are the two types of principal cells
- Neuroglia
- Neurons
Neuroglia (glial cells)
small cells that surround and wrap delicate neurons
Neurons (nerve cells)
excitable cells that transmit electrical pulses
Astrocytes
most abundant
cling to neurons, synaptic endings, capillaries
summarize the functions of:
astrocytes
- support + brace neurons
- exchange between capillaries and neurons
- guide the migration of young neurons
- control chemical environment
- respond to nerve impulses
- influence neuronal functioning
- information processing
- maintain blood-brain barrier
Microglia
small ovoid cells with thorny processes that touch/monitor neurons
summarize the functions of:
microglia
- migrate towards injured neurons
- phagocytize neuronal debris
Ependymal cells
cuboidal to columnar
lines central cavities of brain and spinal column
summarize the functions of:
ependymal cells
- CSF production
- facilitate movement of CSF via cilia
Oligodendrocytes
branched cells, few processes, wrap nerve fibers (“fried egg”)
summarize the functions of:
oligodendrocytes
structural framework
produce myelin in CNS
Satellite cells
surround neuronal bodies
Schwann cells
surround nerve fibers
form myelin sheath in PNS
What are the neuroglia of the PNS
- Satellite cells
- Schwann cells
perineurium
thin connective tissue surrounding a cluster of axons (nerve fascicle)
epineurium
thick connective tissue binding fascicles together
what are the structural units of the nervous system
neurons
what are the special characteristics of neurons
- extreme longevity
- amitotic
- high metabolic rate
T/F: neuron dendrites convey messages as graded potentials over long distances
FALSE - short distances
What important activities take place in cell body (soma) of neurons
synthesize proteins, membranes, chemicals
contains nissl bodies (rough ER)
nuclei
clusters of neuron cell bodies in CNS
ganglia
clusters of neuron cell bodies in PNS
Neuron Axon Hillock
projection from cell body to axon
summation site of action potentials
EPSPs
excitatory post-synaptic action potential
increases chance
IPSPs
inhibitory post-synaptic action potential
decreases chance
What is the conducting region of the neuron
axon
what do myelin sheaths do
insulation of axon that speed up conduction
broken up by gaps (nodes of ranvier)
Multipolar
most abundant in body
major type in CNS
3 or more processes
Bipolar
rare
sensory
2 processes - one axon, one dendrite
Unipolar
PNS
T-like projection
T/F: the most neurons are classified as interneurons
TRUE
what is the main excitatory neurotransmitter of CNS
glutamatergic
what is the main inhibitory neurotransmitter of CNS
gabaergic
what is produced in the PNS and CNS by cholinergic cells
acetylcholine
what is produced mainly in the midbrain, hypothalamus, and olfactory bulb
dopamine
Which term is used to describe signals from internal organs?
visceral
After receiving a signal from another neuron, which outlines the path of an electrical impulse through a neuron?
dendrites –> cell body –> axon –> axon terminal
True or false: Ependymal cells use flagella to facilitate movement of CSF
FALSE
