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NERVOUS SYSTEM/ BIO 102/ Ari Lahtinen
Terms in this set (53)
What does the nervous system do?
1. Receiving: Detects info from the internal & external
2. Deciding: Makes decisions based on the info detected
3. Reacting: Stimulates muscles or glands to respond
The nervous system includes
Cellular Level: nerve cells (neurons) & neuroglia
General Level: organized into central & peripheral systems.
Organs of the N.S. are divided into 2 groups
Central Nervous System (CNS): brain & spinal cord
§ Peripheral Nervous System (PNS): cranial & spinal nerves
§ Connects CNS to other body parts.
N.S. can also be divided based on function
Receiving(Sensory):sensory receptors gather information
Deciding (Integrative): CNS integrates the information collected by the sensory receptors - interneurons
Reacting(Motor):motor responses carried out by effectors (muscles/glands)
Central Nervous System
(Sensory info received. sInformation is processed. Motor control is initiated.
Protected by skull, vertebrae, meninges, & spinal fluid.
Comprised of grey & white matter.)
Peripheral Nervous System
Structure of the Neuron
Cell Body: house nucleus & organelles
Dendrites: slim extensions around the cell body input information to the neuron.
Axon: conducts (sends) the impulse to other cells.
Myelin Sheath : lipid cells covering the axon (Schwann cells)
Nodes of Ranvier: gaps between myelin.
the gap between the dendrites of one neuron & the axon of another.
Types of Neurons
Sensory neurons: (throughout the body) Collect information about stimuli
Relay it to the spinal cord or brain.
Interneurons: (in brain & spinal cord) Receive & process sensory input
Send signals to other neurons.
Motor neurons: (throughout the body)
Relay signals from interneurons to muscles & glands (effectors) that carry out the response.
are the functional unit of the N.S.
pressure, touch, pain, temperature, chemicals, light
Send info to brain
Send signals from CNS to muscles & glands to carry out response
hormone secretion, etc.
are only in the brain & spinal cord.
Notice how the three types of neurons work together:
3 types of neurons:
Parts of each neuron
Interneurons are in the CNS.
Sensory & motor neurons are in the PNS.
cells that support the neurons.
They make up 50-90% of the nervous system.
Help maintain proper ion concentrations & provide insulation, protection, clean-up, physical support for the neurons, form myelin sheath.
In a resting neuron
Potassium & Sodium leak in & out by diffusion.
§ The Sodium Potassium Pump maintains correct levels
inside & outside by active transport.
Outside is more positive.
Inside is more negative.
resting membrane potential.
The difference in the inside charge & outside charge is the resting membrane potential.
This is depolarization
A strong enough electrical impulse (action potential) will send enough Na+ ions into the cell to turn the inside positive.
K+ ions rush out when the sodium ions rush in.
Sodium potassium pump immediately restores the concentrations.
Multiple Sclerosis: Attack on Myelin
Auto-immune inflammatory disease where fatty myelin is attacked & destroyed by abnormal proteins.
Result: axons cannot conduct signals
Causes: Genetics, infections, & environmental risk factors
Impulses travel from neuron to... neuron/ muscle/gland via
Remember: the synapse is the gap between neurons & other neurons, muscles, or glands.
The neurotransmitter diffuses across the synaptic cleft (the gap).
Then they bind with receptor proteins on the receiving cell.
Binding triggers ions to diffuse through the membrane of the receiving cell.
When the impulse gets to the synapse...
When the ions diffuse across the membrane of the receiving cell, the charge changes.
Therefore, the receiving cell becomes depolarized.
The receiving cell will repolarize immediately by returning the charge to it's resting potential.
What happens to the Neurotransmitter?
The neurotransmitters will be removed immediately by: Diffusion out of the gap
Broken down by enzymes
Getting pumped back into the vesicles
Some drugs work by blocking the reuptake of certain neurotransmitters....antidepressants block the uptake of serotonin.
Acetylcholine (Ach): in brain, spinal cord, muscles, glands
Epinephrine: prepare body to respond to stress
Norepinephrine: stress response, excites smooth muscle
Dopamine: fine motor control & learning, mood, organizes coordinated movements, reward circuits in brain
Serotonin: governs thermoregulation, sleep, emotions, & perception
Nitric oxide: not stored but manufactured Neuromodulators - can magnify or dampen the effects of a neurotransmitter....example: endorphins, Substance P
Neurotransmitters, Drugs, & Addiction
Increase neurotransmitters: Xanax, Valium
Prozac, Cymbalta, & Paxil allow norepinephrine & serotonin to linger in the synapse which works for depression
Decrease neurotransmitters: antipsychotic drugs treat schizophrenia & by decreasing dopamine
Mimic/Replace neurotransmitters: opiates bind to endorphin receptors to reduce pain & produce "high" Drug Abuse: dependence on drugs that artificially affect the reward circuit.
Neurotransmitters: Parkinson's Disease
Death of neurons (in thalamus) which make dopamine, epinephrine, & norepinephrine.
Affects movement-control center. ?Causes: genetic & multifactorial
Progressive, but not fatal
Effects: motor control, tremors, executive function, muscle weakness
Treatment: meds to replace neurotransmitters
Central Nervous System contains:
Brain & spinal cord
Contains interneurons only
Peripheral Nervous System contains:
Nerves throughout the rest of the body § Carry impulses to & from the CNS
Cell bodies & short, non-myelinated fibers, synapses (connections, integrations)
Myelinated axons arranged in tracts.
Neurons connecting & synapsing with each other
Connective tissue membranes layered between the skull & brain.
Protect & cover the brain.
Continuous with the spinal
cavities of cerebrospinal fluid (4).
Infection of Meninges: Meningitis
Bacterial or viral infection of the meninges.
Viral: less severe
a medical emergency
Symptoms: headache, rash, neck stiffness, high fever
the least permeable in the body.
Substances pass through the cells, so it's very specific.
Helps control substances reaching the brain.
Helps maintain homeostasis of CSF.
Glucose passes easily.
Caffeine, nicotine, alcohol, barbiturates, heroin, anesthetics can pass through & effect the
CNS: The Spinal Cord
From base of brain through foramen magnum.
Function: communication b/w the brain & peripheral nerves (the information highway)
Protected by vertebrae & meninges (membranes)
Control center forre flexes!!
Reflex Arc of the Somatic System
Reflex: an automatic response.
Reflex Arc: the nerve pathway in an automatic response.
Includes: sensory neuron, motor neuron & usually interneuron in spinal cord. Can involve glands, muscles, organs.
Skips the brain!
No decisions, just reactions!
Sulci: Grooves that make the wrinkles
̈ Gyri: The ridges between the grooves (sulci).
̈ Fissure: Deep sulcus
CNS: The Brain
Cerebrum: Cerebral cortex, motor & sensory areas, association & processing areas
Cerebellum: Coordination, motor control, balance ̈ Brainstem: Midbrain,
pons, medulla oblongata
Diencephalon: Thalamus, hypothalamus &
Limbic System: Amygdala & hippocampus
The Cerebrum: Two Hemispheres
Speech, analytical skills, math. Usually dominant.
Visual-spatial relationships, music, and creativity.
Corpus Collosum: between the two hemispheres. Connects them, & carries signals between them.
Lobes & Association Functions
Frontal:Concentration & decisions
Interpret sensory info
Reading, storing memories
Cerebral Cortex: thin outer layer of gray matter
Full of gyri & sulci
1 billion cell bodies
Association Area ¤ Processing Are
Interprets info from sensory § receptors of skin & skeletal
Temperature, touch, pain, pressure...
Voluntary skeletal movement
Swallowing, expression, vocalization, hand movements...
Visual, auditory, & somatosensory information is sorted & relayed to appropriate brain center.
sRegulates hunger, sleep, temperature,
Controls pituitary gland, so it links nerves & endocrine glands
Midbrain: Relay center between cerebrum & spinal cord or cerebellum. Reflex centers for visual, auditory, & tactile responses.Pons:signals traffic between cerebellum & forebrain
Medulla Oblongata: circulation & breathing. Reflex center for hiccupping, vomiting, coughing, sneezing, swallowing...
Reticular Formation: masses of gray matter in the brainstem that work to arouse the RAS.
gives emotional overtones to experiences. Creates sensation of fear!
Can trigger the stress response.
& memory, determines
what info is sent into memory.
Sensory & pre-frontal areas are used. Similar to circuits & patterns. Temporary! Only 7 items for 20-30 sec.
stored in bits/pieces in various sensory association areas. Hippocampus bridges sensory association area (memory storage) with prefrontal cortex (memory usage). Emotionally charged memories = amygdala involved.
The Teenage Brain
2nd most dramatic period of - completes at age 25!
Matures from back of brain (most primitive) to front of brain.
Faster developing Limbic System (amygdala) causes: intense emotions, risk-taking, pleasure-seeking, egocentric behavior, reward system.
Slower developing Pre-frontal Cortex causes: reason, decision making, impulse control, long-term perspective.
Shift in Circadian Rhythms: sleep patterns change
Hormone & Neurotransmitters: dopamine (more sensitive to drugs), oxytocin (egocentric behavior)
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