Unit 3 - Nervous System Flashcards
Neurons
A specialized cell transmitting nerve impulses
Aka a nerve cell
Astrocytes
Specialized glial cells that outnumber neurons by over fivefold
Many essential complex functions in healthy central nervous system
Ependymal cells
Simple cuboidal cells that line the ventricles in the brain and the central canal in the spinal cord
Microglia
Macrophages that are found in the cns.
They remove damaged neurons and infections
Oligodendrocytes
glial cell similar to astrocytes but with fewer protuberances. Produces myelin in the cns
Schwann cells
Glial cells that wrap around axons of motor and sensory neurons to form myelin sheaths
Two parts of CNS
Neurons or nerve cells and glial cells
Three parts of the neuron
Dendrites
Cel body
axon
What are the supporting cells of the CNS and PNS called?
Neuroglial cells
The only neuroglial cell found outside the CNS
Aka in the PNS
Schwann cells
What structure of a neuron is covered in myelin to increase speed of nerve impulse transmission?
Axon
Axon
Long threadlike part of a nerve cell along which impulses are conducted
Some are mylinated and some are not
Dendrites
Short branched extension of a nerve cell
Impulses received from other cells at synapses are transmitted to the cell body
Cell body
Nucleus containing central prt of a neuron
Depolarization
Na+ entering axon and voltage changes from -70mV to +30mV
Repolarization
K+ leaving axon and voltage changes from +30 mV to -70mV
Local or continuous Conduction
Occurs in the axons that do not have myelin
Saltatory conduction
Occurs in axons that do have myelin (faster than local)
4 stages of action potential transmission
- Reaches axon
- Ca2+ channels open
- Ca2+ binds to sensor protein in cytoplasm
- Ca2+ stimulates fusion and exocytosis of neurotransmitters
Four regions of neuron
Receptive segment
Initial segment
Conductive segment
Transmissive segment
What do neurotransmitters do?
- they are Chemicals found in axon terminal
- removed from synaptic cleft by reuptake or by enzymatic breakdown
- carry the nerve message on postsynaptic neuron
Acetylcholine
- Major excitatory or depolarizing neurotransmitter in the PNS
- can be excitatory or inhibitory
- Parasympathetic
Norepinephrine
- Can either be excitatory or inhibitory (sympathetic stimulation)
- in PNS
- fight or flight
Serotonin
- Inhibitory neurotransmitter in CNS
- Sleep, anxiety, mood and thermoregulation
- Too low in those with depression
Dopamine
- excitatory neurotransmitter in CNS basal gaglia area of brain
- initiation and termination of voluntary motor movements
- low levels cause Parkinson’s
Gamma-aminobutyric acid (GABA)
Inhibitory in CNS, controls localized motor sensory and cognitive functions
Glycine
Inhibitory amino acid in CNS to control localized motor functions
Endorphins
- inhibitory neurotransmitter in CNS and PNS
- down regulating pain
- Runners high chemical
Classification of neuron : Multipolar
- in CNS and in motor neurons
- have many dendrites and one axon
Neuron classification: Bipolar
- Have one dendrite and one axon
- Found in photoreceptor layer of the retina of the eye and in nasal cavity
Neuron classification: Unipolar
- one process from the cell body that divides into 2 processes
- seen in most sensory neurons
Afferent
Conduct action potential in CNS (sensory)
Interneuron
Once action potential reaches CNS, it is processed by interneurons within the CNS itself
Efferent
Motor
- motor neurons will conduct action potentials away from the CNS
Sensory input
Brain constantly receiving input from various sensory receptors throughout the body
These provide info back to the brain (from receptors to brain or spinal cord)
Integration
The brain and spinal cord integrates the info it receives from sensory input and determines what type of output or info it will send to muscles glands or organs
(Occurs in brain)
Motor output
After integration, brain sends motor info to the muscles glands or organs
A. CNS
Brain and spinal cord
- brain: Cerebrum, diencephalin, cerebellum and brain stem
- Spinal cord: Cylinder of nervous tissues that extends from the base of the brain down the vertebral cavity
PNS
Peripheral nervous system
Brings info to and from the cns
- Contains sensory (afferent) and motor (efferent) components of pns
Function and two parts of Sensory (afferent) Nervous system
- take info from sensory receptors to the CNS
- Somatic: Signals from the skin, muscles, joints and special systems (closer to surface)
- Visceral: Carry signals from body organs and are located mire deep in the body
Function and two parts of Motor (efferent) nervous system
- Carry info from CNS to their effectors
Somatic: send signals to skeletal muscles (voluntary)
Autonomic: Signals to smooth muscle, cardiac and glands, involuntary
Sympathetic nervous system
In the autonomic nervous system apart of motor or efferent NS
Fight or flight (heart rate, respiratory and metabolism)
Parasympathetic nervous system
In the autonomic nervous system apart if motor or efferent NS
Rest and digest mode, salvation, urination and defecation/digestion
Nerve
A nerve is made up of many axons of neurons wrapped up in connective tissue
- nerves are in PNS
- cell bodies are in CNS
Cns tracts
- bundles of axons found in the CNS
- axons have similar function and a common origin
Cocaine produces what neurotransmitters
Dopamine and norepinephrine
