Anatomy & Physiology. Nervous Tissue & Homeostasis excitable characteristic of nervous tissue allows...
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- Slide 1
- Anatomy & Physiology
- Slide 2
- Nervous Tissue & Homeostasis excitable characteristic of
nervous tissue allows for generation of nerve impulses (action
potentials) that provide communication & regulation of most
body tissue. together with endocrine system: responsible for
maintaining homeostasis
- Slide 3
- Differences in Nervous & Endocrine Control of Homeostasis
NERVOUS ENDOCRINE rapid responder action potentials slow, prolonged
response releases hormones
- Slide 4
- Structures of the Nervous System total mass of 2 kg (~3% of
total body mass) Skull Spinal Cord Spinal Nerves Cranial Nerves
Ganglia Enteric Plexus Special Senses & other Sensory
Receptors
- Slide 5
- Major Structures of the Nervous System
- Slide 6
- Functions of the Nervous System 3 basic functions: 1. Sensory
2. Integrative 3. Motor
- Slide 7
- Sensory Function sensory receptors detect internal &
external stimuli sensory (afferent) neurons carry this sensory
information to spinal cord & brain thru cranial & spinal
nerves
- Slide 8
- Integrative Function integrate: process nervous system takes
information from sensory neurons & processes that information,
analyzes it, stores some of it & makes decisions for
appropriate responses served by interneurons (connect 1 neuron to
another neuron Perception : conscious awareness of sensory stimuli
occurs in brain
- Slide 9
- Motor Function served by motor (efferent) neurons carry info
from brain/spinal cord effectors (muscle or gland) thru cranial or
spinal nerves results in muscles contraction or gland
secreting
- Slide 10
- Quick Quiz What terms are given to neurons that carry input
spinal cord & brain? What terms are given to neurons that carry
output out of the brain & spinal cord?
- Slide 11
- Organization of the Nervous System
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- Histology of the Nervous System 2 cell types 1. Neurons 2.
Neuroglia
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- Neurons nerve cells that possess electrical excitability :
ability to respond to a stimulus & convert it into an action
potential stimulus: any change in environment that is strong enough
to initiate an action potential
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- Direction Action Potential Travels
- Slide 15
- Action Potential electrical signal that propagates along
surface of neurolema (membrane) begins & travels due to
movement of ions between interstitial fluid & inside of neuron
thru specific ion channels once begun it travels rapidly @ constant
strength
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- Parts of a Neuron
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- Parts of Neuron: Cell Body contains nucleus, cytoplasm, typical
organelles, + Nissl bodies clusters of RER make materials for:
growth of neuron regenerate damaged axons in PNS
- Slide 18
- Dendrites little trees input portion of neuron usually, short,
tapering, highly branched their cytoplasm contains Nissl bodies,
mitochondria
- Slide 19
- Axon propagates action potentials another neuron muscle fiber
gland cell
- Slide 20
- Parts of an Axon joins cell body @ cone-shaped elevation: axon
hillock part of axon closest to hillock = initial segment jct of
axon hillock & initial segment where action potential arises so
is called the trigger zone
- Slide 21
- Parts of an Axon axoplasm: cytoplasm of an axon axolemma:
plasma membrane of axon axon collaterals: side branches along
length of axon (most @ 90) axon terminals: axon divides into many
fine processes
- Slide 22
- Synapse site of communication between 2 neurons or between a
neuron & effector cell synaptic end bulbs: tips of some axon
terminals swell into bulb-shaped structures synaptic vesicles:
store neurotransmitter many neurons have >1 neurotransmitter,
each with different effects on postsynaptic cell
- Slide 23
- Slide 24
- Types of Neurons Functional Classification Structural
Classification Sensory Interneurons Motor use # processes extending
from cell body 1. Multipolar neurons 2. Bipolar neurons 3. Unipolar
neur ons
- Slide 25
- Multipolar Neurons several dendrites with 1 axon includes most
neurons in brain & spinal cord
- Slide 26
- Bipolar Neuron 1 main dendrite & 1 axon retina, inner ear,
olfactory area of brain
- Slide 27
- Unipolar Neuron are sensory neurons that begin in embryo as
bipolar during development axon & dendrite fuse then divide
into 2 branches (both have characteristic structure & function
of an axon) 1 branch ends with dendrites (out of CNS) 2 nd branch
ends in axon terminal (in CNS) cell bodies of most found in
ganglia
- Slide 28
- Unipolar Neuron
- Slide 29
- Purkinje Cells found in cerebellum
- Slide 30
- Pyramidal Cells in cerebral cortex of brain
- Slide 31
- Neuroglia (Glia) ~50% vol of CNS glue do not generate or
propagate action potentials multiply & divide in mature nervous
systems glioma : brain tumors derived from glial cells very
malignant, grow rapidly
- Slide 32
- Glial Cells of the CNS 1. ASTROCYTES 2. OLIGODENDROCYTES 3.
MICROGLIA 4. EPENDYMAL CELLS
- Slide 33
- Astrocytes star-shaped largest & most numerous of glial
cells functions: 1. physically support neurons 2. assist in
blood-brain-barrier (bbb) 3. in embryo: regulate growth, migration,
&interconnections between neurons 4. help maintain appropriate
chemical environment for propagation of action potentials
- Slide 34
- Slide 35
- Oligodendrocytes few trees smaller & fewer branches than
astrocytes Functions: 1. form & maintain myelin sheath on axons
in CNS 2. 1 oligo. myelinates many axons
- Slide 36
- Microglia small cells with slender processes giving off many
spine-like projections function: 1. phagocytes remove cellular
debris made during normal development remove microbes & damaged
nervous tissue
- Slide 37
- Ependymal Cells single layer of cuboidal to columnar cells
ciliated & have microvilli function: 1. line ventricles of
brain & central canal of spinal cord 2. produce, monitor, &
assist in circulation of cerebrospinal fluid (CSF) 3. form bbb
- Slide 38
- Slide 39
- Neuroglial Cells of the PNS Schwann cells Satellite cells
- Slide 40
- Schwann Cells functions: 1. myelinate axons in PNS 1 Schwann
cell myelinates 1 axon 2. participate in axon regeneration
- Slide 41
- Satellite Cells flat cells that surround cell bodies of neurons
in PNS ganglia functions: 1. structural support 2. regulate
exchange of materials between neuronal cell bodies &
interstitial fluid
- Slide 42
- Myelination myelin sheath: made up of multilayered lipid &
protein (plasma membrane) covering function: 1. electrically
insulates axon 2. increases speed of nerve impulses
- Slide 43
- Myelinated & Unmyelinated Axons
- Slide 44
- Nodes of Ranvier gaps in myelin sheath 1 Schwann cell wraps
axon between nodes of Ranvier
- Slide 45
- Myelin amount increases from birth to maturity infants
responses slower & less coordinated as older child or adult in
part because myelination is a work in progress thru infancy
- Slide 46
- Slide 47
- Demyelination loss of myelin sheath see in disorders: multiple
sclerosis Tay-Sachs side effect of radiation therapy &
chemotherapy
- Slide 48
- Gray Matter of the Nervous System contains: neuronal cell
bodies dendrites unmyelinated axons axon terminals neuroglia
- Slide 49
- White Matter of the Nervous System composed of: myelinated
axons
- Slide 50