- towards CNS - PNS: input - (sensory)

- away from CNS - PNS: output - (motor)

- 'between' - are confined to the CNS - they process, store, and retrieve info and ''make decisions" that determine how the body responds to stimuli

Lecture 15 Flashcards by Priscilla Gallardo

Two organ system are dedicated to maintaining internal coordination:
1. __________
2. __________ (divided into _____ & _____)

-both of these systems are __________ systems: it receives, integrates, and responds to information

Endocrine
Nervous system; CNS & PNS

-control

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Parts of the CNS & PNS

CENTRAL Nervous System:
- ________: central processing center
- ________: gateway between brain and trunk/limbs

PERIPHERAL Nervous System:
- ________: conducting wires (cordlike structures that conduct info; composed of ______(=nerve fibers) of neurons
- ________: knot-like swelling in a nerve where the ________ of neurons are concentrated

brain
spinal cord
nerves; axons
ganglia; cell bodies

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The CNS has various centers that integrate all of the information:
- __________ (incl. the spinal cord) that carry out essential body functions
- _________ that control more sophisticated information processing

lower centers
higher centers

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Afferent pathway

towards CNS
PNS: input
(sensory)

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Efferent pathway

away from CNS
PNS: output
(motor)

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mixed nerve

nerves that contain both sensory and motor fibers

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PNS: Sensory division
-somatic:
-visceral:

sensory info from the skin, skeletal muscles, bones, and joints
sensory info from viscera (organs in the thoracic and abdominal cavities)

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PNS: Motor division
-somatic:
-visceral:

voluntary muscle contractions; involuntary somatic reflexes; motor nerves that innervate skeletal muscles
Autonomic NS
controls:
cardiac muscle
smooth muscle
glands

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Ganglia (sing. ganglion):

collections of neuron cell bodies in the PNS

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Nerves:

Bundles of axons in the PNS

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Nuclei:

collections of neuron cell bodies in the interior of the CNS

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Tracts:

bundles of CNS axons that share a common origin, destination, and function

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Columns:

several tracts that form an anatomically distinct mass

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Sensory (afferent) neurons

conduct signals from receptors to the CNS

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Motor (efferent) neurons

conduct signals from the CNS to effectors such as muscles and glands

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Interneurons:

‘between’
are confined to the CNS
they process, store, and retrieve info and ‘‘make decisions” that determine how the body responds to stimuli

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3 parts of a neuron:
- _________: control center
- dendrites: _____________
-__________: conducting region

cell body
receptive or input regions
(they receive & convey incoming messages toward the cell body)
axon (generates and conducts nerve impulses away from the cell body)

Cell body= ______ or _____
contains
- ___________
- __________

soma; neurosoma
- nucleus
- nucleoli

Dendrites

their characteristic branching pattern allows for ______________
the more dendrites the more ________ it can receive
contains dendritic ______
_________ regulated ion gates respond to stimulation by NTs

integration of multiple input
info
spines
chemically

Axon= ________
- trigger zone: _______ + ______
- only the axon has _______ regulated ion gates- “the conducting region”
- the secretory region= __________ __________
- ____________: contain synaptic vesicles full of NTs

nerve fiber
- axon hillock + initial segment
- voltage
- terminal arborization
- terminal buttons

Neuron structures:
1.
2.
3.
4.

Multipolar
Bipolar
Unipolar
Anaxonic

Multipolar neurons
-_______ neurons of the CNS
- _____ dendrite(s)
- _____ axon(s)

most
multiple
one

Bipolar neurons:
- sensory neurons that are located in some ________ _______ organs
- _______ dendrite(s)
- _______ axon(s)

special sense
one
one

Unipolar
- the neurons that carry sensory signals to the _______ ______
- a _________ process leading away from the soma

spinal cord
single

4 types of CNS glial cells 1. 2. 3. 4.

1. Astrocytes 2. Ependymal Cells 3. Microglial cells 4. Oligodendrocytes

Astrocytes: - convert glucose to ______-; supply this to neurons - produce ________ factors - regulate the ________ _______ (chemical composition) - form the ______-_____ ______

- lactate - growth - extracellular environment - blood-brain barrier

Ependymal cells: - line _______ - produce _____________ (CSF)

- cavaties - cerebrospinal fluid

Microglia cells: (__________) - __________ cells (phagocytic) - they remove damaged neurons and microorganisms (infection)

(macrophages) - defensive

Oligodendrocytes: - their processes form _________ ________ around nerve fibers

- myelin sheaths

2 types of PNS glia cells 1. 2.

1. Schwann cell 2. Satellite cell

Schwann cell: - _________ certain axons in the PNS

- myelinate

Satellite cell: - surround and support _______ ________

- cell bodies

- insulation around the axon= ___% lipid - formed by plasma mb of glial cells: ___________ in CNS/ ____________ in PNS - myelin sheath _____ signal conduction - gaps between myelin-covered segments= __________ - myelin-covered segments= __________

- 80% - oligodendrocytes; Schwann cells - speeds - node of ranvier - internode

- __________= the outermost nucleated cytoplasmic layer of Schwann cells - _________= cytoplasm - _________= plasma mb - regeneration of damaged PNS nerve fiber (axon) can occur if.....

- neurilemma - axoplasm - axolemma - soma intact + at least some neurilemma remains

Local (or Graded) potential Event location= _______ and _________: - ______ distance (local)- typically within cell body to axon hillock - signals ______ with distance - REVERSIBLE Stimulus for opening ion channels: - chemical (________) or sensory stimulus (e.g. _____, ______, ______) Ion channels: - ______- gated Na+ channels Peak membrane potential: - excitatory= ________, moves toward 0 mV - inhibitory= _______, moves toward -90 mV

- cell body; dendrites - short - decay - NTs; light, pressure, temperature - ligand - depolarizes - hyperpolarizes

Action potential Event location: ______ and ______ - ______ distance- from trigger zone at axon hillock through entire length of axon - constitutes the nerve _________ - does NOT decay with distance (same strength) - IRREVERSIBLE: it can't be stopped once it begins Stimulus for opening ion channels: - _______ (depolarization, triggered by local potential reaching threshold) Ion channels: - _______- gated Peak membrane potential: - +30 to +50 mV - always begin with _________

- axon hillock; axon - long - impulse - voltage - voltage - depolarization

Local (or graded) potential: summation - stimulus responses can summate to increase amplitude of graded potential - ________: increased frequency of stimuli - ________: stimuli from multiple sources - ________: they vary in magnitude depending on the strength of the stimulus

- temporal - spatial - graded

Action potential: summation - does NOT occur - ____________: if a stimulus depolarizes the neuron to threshold, the neuron fires at its maximum voltage; if not reach= not AP

- All-or-none law

Propagation of Action Potential: - When the local current arrives at the ____ _______ it depolarizes the membrane at that point - If reaches the _________ voltage: the neuron now 'fires' (produces an AP)

- axon hillock - threshold

Nonmyelinated axons (__________ conduction) - uninterrupted ______ of electrical excitation all along the fiber

continuous - wave

Myelinated axons: - APs occur ONLY at the ___________, this mode of conductions creates a false impression that the nerve signal jumps from node to node - In the internodal segments, conduction is ____ _______, but decremental

- nodes of ranvier - very fast