Nervous System Flashcards
Functions of the Nervous System
SIM
Sensory input
Integration
Motor output
The function of NS is gathering information
This monitor changes happening inside and outside the body
Sensory input
The function of NS processes and interprets sensory input and decides whether action is needed
Integration
The function of NS is a response, or effect, activates muscles or glands
Motor output
Nervous system classifications are based on:
- Structures (structural classification)
* Activities (functional classification)
2 Levels of organization
Central nervous systems
Peripheral nervous systems
The organs of CNS are:
B & S
- Brain
* Spinal cord
One of the NS that function as integration; command center
One of the NS that interprets incoming s ensory information
One of the NS that issues outgoing instructions
The main control center
The one that decide and give order
Central nervous system (CNS)
Nervous system that is extending from the brain and spinal cord
Allow your central nervous system to communicate with the rest of your body
One of the NS that serve as communication lines among sensory organs, the brain and spinal cord, and glands or muscles
Peripheral nervous system (PNS)
The 2 nerves of PNS are:
S& C
Spinal & Cranial nerves
nerves that carry impulses to and from the spinal cord
Spinal nerves
carry impulses to and from the brain
Cranial nerves
2 division of nerve fibers of PNS:
S&M
Sensory division & Motor division
Nerve fibers that carry information to the central nervous system
(afferent)
Sensory division
2 sensory division (S&V)
Somatic & Visceral
sensory fibers carry information from the skin, skeletal muscles, and joints
Somatic
sensory fibers carry information from visceral organs
Visceral
Nerve fibers that carry impulses away from the central nervous system organs to effector organs (muscles and glands)
Sends directions from your brain to the muscles and glands
(efferent)
Motor division
2 motor subdivisions (S&A)
Somatic nervous system
Autonomic nervous system
voluntary
Consciously controls skeletal muscles
That rules your skeletal muscle movement
Somatic nervous system
involuntary
Automatically controls smooth and cardiac muscles and glands
Further divided into the sympathetic and parasympathetic nervous systems
That keeps your heart beating, and your lungs breathing, and your stomach churning
Autonomic nervous system
Support cells in the CNS are grouped together as neuroglia
Nervous Tissue
The type of cells ____ respond to stimuli and transmit signals
neurons, or nerve cells
Nervous Tissue Functions (SIP)
Support
Insulate
Protect neurons
2 principal cell types
Supporting cells
Neurons
Cells that also called neuroglia, or glial cells, or glia
Provide support, nutrition, insulation, and help with signal transmission in the nervous system
Resemble neurons
Unable to conduct nerve impulses
Never lose the ability to divide
Glue that held neurons together
Supporting cells
4 CNS glial cells:
A, M, EC, O
astrocytes
microglia
ependymal cells
oligodendrocytes
- Most Abundant glia cells
- star-shaped cells
- Brace and anchor neurons to blood capillaries
- Protect neurons from harmful substances in blood
- Control the chemical environment of the brain
- Support, regulate ions
- Exchange of materials between neurons and capillaries
astrocytes
- Spiderlike phagocytes
- Monitor health of nearby neurons
- Dispose of debris
- Defend
- Act as the main source of immune defense against invading microorganisms in the brain and spinal cord
microglia
- Line cavities of the brain and spinal cord
* Create, secrete, & circulate cerebrospinal fluid that fills those cavities and cushions those organs
ependymal cells
- produce myelin sheaths around axons of the CNS
- Lack a neurilemma
- Wrap and insulate around neurons
- Producing an insulating barrier (myelin sheath)
oligodendrocytes
2 PNS glial cells (S&S)
Schwann cells
Satellite cells
- Form myelin sheath around nerve fibers in the PNS
- Do mainly in the peripheral system what astrocyte cells do in the central system
- They surround and support neuron cell bodies
Schwann cells
- Protect and cushion neuron cell bodies
- Insulate, help form myelin sheath
- Similar to your oligodendrocytes
- Wrap around axons and make that insulating myelin sheath
Satellite cells
nerve cells
Cells specialized to transmit messages (nerve impulses)
Neurons
3 things in common in Neurons
Neurons are some of the longest-lived cells in your body.
Neurons are irreplaceable
Neurons have huge appetites
2 Major regions of all neurons
C&P
Cell body
Processes
nucleus and metabolic center of the cell
the metabolic center of the neuron
Cell body
Fibers that extend from the cell body
A projecting part of an organic structure
Processes
The cell body Rough endoplasmic reticulum
Nissl bodies
The cell body Intermediate filaments that maintain cell shape
Neurofibrils
(cell body)
Neuron’s life support
Soma
2 Specialized project of neurons:
D&A
Dendrites
Axons
Conduct impulses toward the cell body
The listeners
They pick up messages, news, gossip from other cells and convey that information to the cell body
Dendrites
Conduct impulses away from the cell body
The talker
Can be super short or run a full meter from your spine down to your ankle
Axons
Neurons have hundreds of ___ and have only one ____ arising from the cell body
Dendrites - axon
- End of an axon, which contain vesicles with neurotransmitters
- Axon terminals are separated from the next neuron by a gap
Axon terminals
gap between axon terminals and the next neuron
Synaptic cleft
functional junction between nerves where a nerve impulse is transmitted
Synapse
- White, fatty material covering axons
- Protects and insulates fibers
- Speeds nerve impulse transmission
Myelin
sleeves of fatty tissue that protect your nerve cells
carries messages back and forth between your brain and the rest of your body
Myelin sheaths
part of the Schwann cell external to the myelin sheath
Neurilemma
gaps in myelin sheath along the axon
Nodes of Ranvier
• clusters of cell bodies in the CNS
Nuclei
• collections of cell bodies outside the CNS in the PNS
Ganglia
• bundles of nerve fibers in the CNS (T)
Tracts
• bundles of nerve fibers in the PNS (N)
Nerves
• matter of collections of myelinated fibers (tracts)
White matter
• matter that is mostly unmyelinated fibers and cell bodies
Gray matter
- association neurons
- Cell bodies located in the CNS
- Connect sensory and motor neurons
- Transmit impulses between those sensory and motor neurons
- Most abundant of your body’s neurons
- Mostly multipolar
Interneurons
5 Sensory (afferent) neurons (FMLGM)
A. Free nerve endings B. Meissner’s corpuscle C. Lamellar corpuscle D. Golgi tendon organ E. Muscle spindle
Pain and temperature receptors
Free nerve endings
Touch receptor
Meissner’s corpuscle
Deep pressure receptor
Lamellar corpuscle
Proprioceptor
Golgi tendon organ & Muscle spindle
- one axon and a bunch of dendrites
- Most common structural type
- Many extensions from the cell body
- Where 99 percent of all your neurons found
Multipolar neurons
- one axon and one dendrite
- Located in special sense organs, such as nose and eye
- Rare in adults (found only in a special-sensory places)
Bipolar neurons
- Have a short single process leaving the cell body
- Sensory neurons found in PNS ganglia
- Conduct impulses both toward and away from the cell body
Unipolar neurons
2 Functional properties of neurons
Irritability and Conductivity
• Ability to respond to a stimulus and convert it to a nerve impulse
Irritability
• Ability to transmit the impulse to other neurons, muscles, or glands
Conductivity
1st Step that the plasma membrane at rest is inactive
In neuron’s plasma, there are fewer positive ions inside than outside
- Resting membrane is polarized
In Resting membrane is polarized, K+ is the major positive ion ___ the cell
inside
In Resting membrane is polarized, Na+ is the major positive ion ___ the cell
outside
As long as the inside of the membrane is more negative (fewer positive ions) than the outside, the cell remains ___
inactive
- 2nd step that stimulus changes the permeability of the neuron’s membrane to sodium ions
- Sodium channels now open
- Sodium diffuses into the neuron
- Changes the polarity of the membrane at that site
- Stimulus initiates local depolarization
- 3rd steps that graded potential exists (inside more positive – outside more negative/less positive)
- If the stimulus is strong enough and sodium influx great enough, local depolarization activates the neuron to conduct an action potential (nerve impulse)
- Depolarization and generation of an action potential
4th step that the depolarization of the 1st membrane patch causes permeability changes in adjacent membrane and events in step 2 are repeated
• If enough sodium enters the cell, the action potential (nerve impulse) starts and is propagated over the entire axon
• All-or-none response means the nerve impulse either is propagated or is not
• Fibers with myelin sheaths conduct nerve impulses more quickly
- Propagation of the action potential
- 5th step that the membrane permeability changes again becoming impermeable to sodium ions and permeable to potassium ions
- Potassium ions rapidly diffuse out of the neuron, repolarizing the membrane
- Involves restoring the inside of the membrane to a negative charge and the outer surface to a positive charge
- Occurs in the same direction as depolarization
- Repolarization
- 6th step that are restored using the sodium-potassium pump
- This pump, using ATP, restores the original configuration
- 3 sodium ions are ejected from the cell, 2 potassium ions are returned to the cell
- Until repolarization is complete, a neuron cannot conduct another nerve impulse
- Initial Ionic conditions restored
Are rapid, predictable, and involuntary responses to stimuli
Reflexes
neural pathways in reflexes
Reflex arcs
2 types of reflexes
S&A
Somatic reflexes
Autonomic reflexes
Type of reflexes that stimulate the skeletal muscles
Involuntary
Example: pulling your hand away from a hot object
Somatic reflexes
Regulate the activity of smooth muscles, the heart, and glands
Example: regulation of smooth muscles, heart and blood pressure, glands, digestive system
Autonomic reflexes
Five elements of a reflex arc
Sr, Sn, Ic, Mn, Eo
Sensory receptor Sensory neuron Integration center Motor neuron Effector organ
reacts to a stimulus
Sensory receptor
carries message to the integration center
Sensory neuron
processes information and directs motor output
Integration center (CNS)
carries message to an effector
Motor neuron
is the muscle or gland to be stimulated
Effector organ
- Simplest type
* Example: patellar (knee-jerk) reflex
Two-neuron reflex arcs
- Consists of 5 elements: receptor, sensory neuron, interneuron, motor neuron, and effector
- Example: flexor (withdrawal) reflex
Three-neuron reflex arcs
5 elements
R,I,M,E,S
Receptor Interneuron Motor neuron Effector Sensory neuron
• Functional anatomy of the brain
Central Nervous System (CNS)
4 Brain regions (C,C,B,D)
Cerebral hemispheres
Cerebellum
Brain stem
Diencephalon
- Are paired (sagittal) superior parts of the brain
- Include more than half of the brain mass
- The surface is made of ridges and grooves
Cerebral hemispheres
are named for the cranial bones that lie over them
Lobes
Other term of ridges
gyri
Other term of grooves
sulci
Deeper grooves
Fissures
3 main regions of cerebral hemisphere
CIB
Cerebral cortex (gray matter)
Internal white matter
Basal nuclei
are deep pockets of gray matter
Basal nuclei
Functions of Major Brain Region (CCDB)
Cerebellum
Cerebral hemispheres
Diencephalon
Brain stem
- Located in parietal lobe posterior to central sulcus
- Receives impulses from the body’s sensory receptors
- Pain, temperature, light touch (except for special senses)
- Sensory homunculus is a spatial map
Primary somatic sensory area
Cerebral areas involved in special senses
OVA
Visual area, Auditory area, and Olfactory area
The lobe called in Visual area
occipital lobe
The lobe called in Auditory area & Olfactory area
temporal lobe
- Located anterior to the central sulcus in the frontal lobe
- Allows us to consciously move skeletal muscles
- Motor neurons form pyramidal (corticospinal) tract, which descends to spinal cord
- Motor homunculus is a spatial map
Primary motor area
(motor speech area)
Broca’s area
- Composed of fiber tracts deep to the gray matter
- Association fiber tracts connect areas within a hemisphere
- Projection fiber tracts connect the cerebrum with lower CNS centers
Cerebral white matter
Tracts are known as
commissures
Localizes and interprets sensory inputs
Controls voluntary and skilled muscle activity
Acts in intellectual and emotional processing
Cortex: Gray Matter
“Islands” of gray matter buried deep within the white matter of the cerebrum
Subcortical motor centers help control skeletal muscle movements
Basal nuclei
Sits on top of the brain stem
Enclosed by the cerebral hemispheres
Regulate things like homeostasis, alertness, and reproductive activity
Diencephalon
3 structures of Diencephalon (THE)
Thalamus, Epithalamus, and Hypothalamus
- Encloses the 3rd ventricle
- Relay station for sensory impulses passing upward to the cerebral cortex
- Transfers impulses to the correct part of the cortex for localization and interpretation
- Relays sensory impulses to cerebral cortex
- Relays impulses between cerebral motor cortex and lower motor centers
- Involved in memory
Thalamus
- Chief integration center of autonomic (involuntary) nervous system
- Regulates body temperature, food intake, water balance, and thirst
- Regulates hormonal output of anterior pituitary gland and acts as an endocrine organ (producing ADH and oxytocin)
- Makes up the floor of the diencephalon
- Important autonomic nervous system center
- Houses the limbic center for emotions
- Houses mammillary bodies for olfaction (smell)
Hypothalamus
- Forms the roof of the third ventricle
- Houses the pineal body (an endocrine gland)
- Includes the choroid plexus that forms cerebrospinal fluid
Epithalamus
• Attaches to the spinal cord
Brain stem
3 Parts of the brain stem (MMP)
Midbrain, Pons, and Medulla oblongata
- Extends from the mammillary bodies to the pons inferiorly
- Cerebral aqueduct (tiny canal) connects the third and fourth ventricles
- Two bulging fiber tracts, cerebral peduncles, convey ascending and descending impulses
- Contains visual and auditory reflex centers
- Contains subcortical motor centers
Midbrain
- Relays information front the cerebrum to the cerebellum
- Cooperates with the medullary centers to control respiratory rate and depth
- Contains nuclei of cranial nerves V-VII; contains projection fibers
- Mostly composed of fiber tracts
- Includes nuclei involved in the control of breathing
Pons
- Relays ascending sensory pathway impulses from • skin and proprioceptors
- Contains nuclei controlling heart rate, blood vessel diameter, respiratory rate, vomiting, etc.
- Contains nuclei of cranial nerves VIII-XII; contains projection fibers
- The most inferior part of the brain stem that merges into the spinal cord
- Includes important fiber tracts
Medulla oblongata
Medulla oblongata contains 5 important centers that control:
- Heart rate
- Blood pressure
- Breathing
- Swallowing
- Vomiting
4th ventricle lies posterior to: (P&M)
pons and medulla
Diffuse mass of gray matter along the brain stem
Involved in motor control of visceral organs
Reticular formation
Plays a role in awake/sleep cycles and consciousness
• Filter for incoming sensory information
Reticular activating system (RAS)
- Two hemispheres with convoluted surfaces
- Outer cortex of gray matter and inner region of white matter
- Controls balance
- Provides “instructions” to cerebral motor cortex and subcortical motor centers resulting in smooth, coordinated skeletal muscle movements
- Responsible for proper balance and posture
Cerebrum
3 Protection of the Central Nervous System (M, TC, CSF)
Meninges, Tentorium cerebelli, & Cerebrospinal fluid
Outermost leathery layer
Double-layered external covering
Folds inward in several areas
Dura mater
Cerebral falx also known as
Falx cerebri
attached to inner surface of the skull
Periosteum
outer covering of the brain
Meningeal layer
- Middle layer
- Weblike extensions span the subarachnoid space to attach it to the pia mater
- Subarachnoid space is filled with cerebrospinal fluid
- Arachnoid granulations protrude through the dura mater and absorb cerebrospinal fluid into venous blood
Arachnoid layer
Internal layer
Clings to the surface of the brain and spinal cord
Pia mater
- Similar to blood plasma in composition
- Formed continually by the choroid plexuses
- Forms a watery cushion to protect the brain and spinal cord
- Circulated in the arachnoid space, ventricles, and central canal of the spinal cord
Cerebrospinal fluid (CSF)
capillaries in the ventricles of the brain
Choroid plexuses
CSF Circulation
- CSF flows through the ventricles and into the subarachnoid space via the median and lateral apertures. Some CSF flows through the central canal of the spinal cord
- CSF flows through the subarachnoid space
- CSF is absorbed into the dural venous sinuses via the arachnoid villi
- CSF is produced by the choroid plexus of each ventricle
4, 1, 3, 2
- Includes the least permeable capillaries of the body
- Allows water, glucose, and amino acids to pass through the capillary walls
- Excludes many potentially harmful substances from entering the brain, such as wastes
- Useless as a barrier against some substances
Blood-brain barrier
• Traumatic brain injuries
Brain Dysfunctions
- Slight brain injury
* Little permanent brain damage occurs
Concussion
- Marked nervous tissue destruction occurs
* Coma may occur
Contusion
Death may occur after head blows due to:
Intracranial hemorrhage
Cerebral edema
- Also called stroke
- Results when blood circulation to a brain area is blocked and brain tissue dies
- Loss of some functions or death may result
Cerebrovascular accident (CVA)
one-sided paralysis
Hemiplegia
damage to speech center in left hemisphere
Aphasia
- Temporary brain ischemia
* Numbness, temporary paralysis, impaired speech
Transient ischemic attack (TIA)
