Lecture 15 Flashcards
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
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
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
Afferent pathway
- towards CNS
- PNS: input
- (sensory)
Efferent pathway
- away from CNS
- PNS: output
- (motor)
mixed nerve
nerves that contain both sensory and motor fibers
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)
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
Ganglia (sing. ganglion):
collections of neuron cell bodies in the PNS
Nerves:
Bundles of axons in the PNS
Nuclei:
collections of neuron cell bodies in the interior of the CNS
Tracts:
bundles of CNS axons that share a common origin, destination, and function
Columns:
several tracts that form an anatomically distinct mass
Sensory (afferent) neurons
conduct signals from receptors to the CNS
Motor (efferent) neurons
conduct signals from the CNS to effectors such as muscles and glands
Interneurons:
- ‘between’
- are confined to the CNS
- they process, store, and retrieve info and ‘‘make decisions” that determine how the body responds to stimuli
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.
- Astrocytes
- Ependymal Cells
- Microglial cells
- 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.
- Schwann cell
- 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
