Physio Block 4 Nervous Flashcards
The Main Function of the Nervous System
Coordinate Activity to maintain homeostasis
What are the two cell types in Nervous Tissue?
Neurons and Neuroglia
Role of Neurons
*fxnl unit of nervous system
-excitability (respond to stimuli)
-conductivity (stim via elec signaling)
-secretion (elec signal –> secretion of signaling molecules)
Role of Neuroglia
*Support Cells (physical and regulatory)
*10x as many of these as neurons
*Communicate with Neurons
Oligodendrocytes
*CNS
cytoplasmic extension that wrap around axons- myelin sheath
-insulates axon
-increases speed of elec signals
-key part of white matter
Ependymal Cells
CNS
*Lines brain cavities and central canal of spinal cord
*separates fluid cavities filled with CSF
*Branched extensions monitor and adjust composition of CSF
Microglia
CNS
*Smallest of glial cells
*SECURITY FORCE!
Macrophage
destroys debris, waste, pathogens
Astrocytes
CNS
*largest and most of
*cytoplasmic extension
-regulates interstitium
-blood-brain barrier
-structural framework
-repair damaged tissue
-neuron development
Satellite Cells Roles
PNS
-Support neurosomas in ganglia
Ganglia (plural)
Ganglion (individual)
nucleus of the PNS basically
*Cluster of nerve cell bodies in PNS
Schwann
*Cover all PNS neurons
*Forms Myelin Sheath
*Secrete neurotrophic factors to direct growth and connections
Myelin
Protects and insulates axons
-increases transmission speed
-minimizes ion leakage by minimizing contact with ECF
-increases thickness by 100x
notable features of neurons
extreme longevity (>100 yrs)
amitotic- lose the ability to divide
High Metabolic Rate- requires continuous supply of glucose and O2
Dendrites
found on neurons
-thin branched extensions
-contain most types of organelles but not a nucleus
-it is a point of connection with other neurons
-receives signals-pass along to neurosoma
Neurosoma
AKA soma
contains nucleus, mitochondria, lysosomes, golgi, rough ER, and ribosomes
-1/10 or less of cell volume
-extensive cytoskeleton
Axon structure and functions
AKA Nerve Fiber
*Axon Hillock (origin point)
*vary in length 1 meter-1micrometer
*Transmits signal from cell body to axon terminal
*extensive cytoskeleton
Terminal Arborization
*multiple branches that end in axon terminals
*each axon terminal forms a synapse with a target cell
*can use varicosities instead of synaptic vesicles?
Actual Proportion examples for a neuron
Somatic Motor Neuron:
neurosoma: tennis ball
Dendrites: bushy mass filling whole classroom
Axon= 1 mile long and narrower than a garden hose
The CNS consists of
Brain and Spinal Cord
The PNS consists of
Nerves and Ganglia
Two functional Divisions of the PNS
Sensory (afferent) division
Motor (efferent division)
Sensory (afferent) division 2 types
somatic sensory-carry signals from skin or muscles that are consciously perceived
visceral sensory- INTERNAL sensitivity- such as fullness or blood pressure
afferent division general fxn
neurons conduct signals from sensory receptors TOWARDS CNS.
Stimuli such as light, temperature, smell, pressure, etc.
Bipolar or unipolar
Motor (efferent) 2 types
Somatic Nervous System- Voluntary- directs skeleton for walking etc.
Autonomic Nervous System- involuntary fxns such as heart rate, digestion, gland secretion
Efferent division general fxn
Carry info AWAY from CNS
*synapse with effectors/target tissues
*enlarged axon terminals/varicosities generate response
*multipolar
Interneurons
CNS (completely within)
Most numerous (90%) class of neuron
CONNECTS the sensory and motor pathway
1) receive info
2) integrate info
3) dictate motor response by stimulating motor neurons
*multipolar
subdivisions of Autonomic (involuntary) system
Sympathetic: prepares body for intense physical activity (fight or flight)
Parasympathetic: promotes rest and recovery (rest and digest)
Tract
bundle of axons in CNS
Nerve
bundle of axons in PNS
Gray Matter
neurosomas,dendrites,synapses
White Matter
Axon bundles
Cranial Meninges roles
*protects underlying neural tissue
*Anchors brain in the cranial cavity
3 Layers!!
Dura, Arachnoid, and Pia Mater
cerebrospinal fluid
physical+chemical protection
Blood-Brain Barrier
protects brain from harmful particles in blood
Dura Mater
*Most Superficial
*periosteal and meningeal layer (Periosteum does not continue to spinal cord)
*Dural Sinuses form when space increases for blood collection
3 separation regions of meningeal layer folds
Falx Cerebri (btwn R and L cerebral hemispheres)
Falx Cerebelli (btwn R and L cerebellar hemispheres)
Tentorium cerebelli (between cerebellum and cerebrum)
Arachnoid Mater
subarachnoid space- filled with CSF
Contains space for blood vessels
Pia Mater
*Thin, protective layer of tissue
*Directly Covers nerves and neuroglia
CSF
100-160 ml in ventricles and canals of CNS
-blood plasma, glucose, Na+, Cl, Mg, and other ions
FXNS: shock+cushion, chemical protection, exchange nutrients+waste
Brain Ventricles
-Where CSF is formed
-fluid-filled chambers within the brain
-numbered according to CSF flow (4th Ventricles CSF empties into central canal of spinal cord)
5 Steps of CSF formation/flow
1) CSF secreted by Choroid plexus in ventricles 1 and 2
2) Flows into 3rd ventricle
3) cerebral aqueduct to 4th ventricle
4) flows out lateral apertures to fill subarachnoid space
5) reabsorbed through Arachnoid villi into venous sinuses
the BBB
least permeable capillaries in the body
maintain stable environment for brain
protects from hormones, neurotransmitters, and foreign substances
Astrocyte and endothelial cell role in the BBB
endothelial cells form tight junction
Astrocytes extend foot process around endothelial cells to form a second barrier
What can and cannot cross the blood barrier
small, lipid soluble can cross (o2, co2, etc.) and Large lipids can move slowly
- charged mlcls cannot cross
glucose, amino acids, etc. must be transported
cerebral hemisphere made up of thesee 3 things
2 hemispheres connected by corpus callosum
how many lobes in each hemisphere
5 lobes
Frontial, parietal, Temporal, Occipital, Insula
what is each lobe known for
occipital- vision
temporal- auditory stimuli and memory
parietal- stimuli related to touch, pressure, temperature, pain
Frontal- reasoning, speech motor, emotions, problem solving
Insula- visceral function, autonomic info
Cerebral Grey Matter
Cerebral cortex and Basal Nuclei
-superficial -deep
-initiate movement -cognition
-perception -emotion
cerebral white matter
axons and bundles of fibers (tracts)
3 tract types and their roles
Projection Tracts
-connection btwn brain and spine
Commissural tracts
-connection between cerebral hemispheres
Association Tracts
-Connection in same cerebral hemisphere
sensory info has both a ____ and a _____ area
primary sensory cortex and sensory association area
Multimodal Association
Combines info from multiple senses- complex interpretation
Multimodal Association Areas
Prefrontal Cortex- cognition, personality, recall
Posterior- language, pattern recognition, position in space
Limbic- emotional impact
Motor Division is part of what division of the Nervous system
Efferent
cerebral cortex voluntary motor areas
primary motor cortex, premotor cortex, Broca’s (speech), frontal eye field
the two planners and coordinators of complex patterns
cerebellum and Basal nuclei
Aphasia
Inability to process language normally
Wernicke’s = fluent aphasia
Broca’s= non fluent aphasia
Categorical Left or right in hemisphere for right handed?
Left
Representational Left or right in hemisphere for Left handed?
70% right hemisphere
Categorical (left)
Reasoning, numbers, spoken and written language
Representational (left)
Imagination, music, creativity
Is diencephalon grey or white matter?
grey matter core of forebrain
Thalamus
key relay and processing center
contains nuclei that handle all afferent input
sensory, motor, emotion, learning, memory
hypothalamus
links nervous and endocrine system
key for homeostasis
thirst and temp, circadian rhythms, emotions
Epithalamus
superior and posterior to thalamus
-pineal gland- uses visual info to help regulate light and dark cycles (sleeping!)
-Habenular nuclei- emotional response to odor (smells like home)
Midbrain
auditory and visual reflexes (superior and inferior colliculi)
controls eye movement
superior colliculi role
visual
inferior colliculi role
auditory
Pons
-relay between cerebrum and cerebellum (where cerebellum attaches to brain stem)
-includes 4 cranial nerves thst control functions of the face
-breathing, sleep, posture
Medulla
transition between brain and spinal
INVOLUNTARY
-vomit
-swallow
-cardiovascular
-respiratory
limbic- system
emotional brain- memory and learning
Reticular Formation??
runs whole length of brain stem- projects to cerebral cortex
key for- cardio
sleep
muscle tone
pain
habituation
