Exam 3 Flashcards
What are the three divisions of the nervous system?
Peripheral nervous systems (PNS)
Central nervous system (CNS)
Enteric nervous system
The CNS consists of ________
Brain and spinal cord
Describe the general overview of the nervous system
Receptors send stimulators information to the efferent division of the PNS which is then sent to the CNS for processing in the brain then the CNS sends signals to the efferent division of the PNS for motor commands stimulating the SNS or the ANS
The PNS consists of ________
All the nervous tissue outside the CNS and ENS
What are the two subdivisions of the PNS?
Somatic nervous system (SNS)
Autonomic nervous system (ANS)
Define Peripheral nerves ______
Nerves with associated blood vessels and connective tissue
Define cranial nerves
Nerves connected to the brain
Define spinal nerves
Nerves attached to the spinal cord
The afferent division of the PNS is responsible for _________
Bringing sensory information to the CNS
The efferent division of the PNS is responsible for _____
Carrying motor commands from CNS to target tissue
The somatic nervous system controls _______
Voluntary contractions of skeletal muscles
The autonomic nervous system controls ______
Involuntary regulation of smooth muscle and heart
The ANS has what two divisions, what do they do?
Parasympathetic - negative feedback, slows response
Sympathetic- positive feedback, enhances response
What is the function of the perikaryon (cytoplasm of a neuron cell body)
Provide energy and synthesize organic material
The axon of a neuron is responsible for _____
Creating action potentials
What is the purpose of afferent neurons/sensory neurons?
Deliver information from sensory receptors to CNS
What is the function of motor neurons or efferent neurons?
Carry motor instructions from CNS to target tissue
Neuroglia in the PNS consists of _____ and ______
Satellite cells and Schwann cells
Neuroglia in the CNS consists of ______ (there are 4)
Astrocytes, Ependymal cells, oligodendrocytes, microglia
What is the function of Astrocytes in the CNS?
Largest Neuroglia
Maintain blood brain barrier, provide structural support, regulate ion nutrient and dissolved gas levels, absorb and recycle neurotransmitters, form scar tissue after injury, neuron development in the embryonic phase
What are the functions of Ependymal cells found in the CNS?
Line ventricles of the brain, and the spinal cord, assist in the production, circulation and regulation of cerebral spinal fluid
What is the function of Oligodendrocytes in the CNS?
Myelinate CNS axons and provide structural support
What is the function of Microglia in the CNS?
Smallest Neuroglia
Remove waste by phagocytosis
Define gray matter
Great concentration of neuron cell bodies in an integrated region
Define white matter
Lots of myelinated axons
What is the function of Satellite cells found in the PNS?
Surround neuron cell bodies in ganglia, regulates O2 and CO2 and nutrient levels around ganglia
What are the functions of Schwann cells found in the PNS?
Surround all axons in PNS with myelin sheath , responsible for myeilnation and repair
What is the threshold for an action potential to begin in a neuron?
-60 to -55 mV
What are the steps of activating an action potential?
1) depolarize to threshold
2) activation of voltage gated sodium channels and rapid depolarization
3) inactivation of sodium channels and activation of potassium ion channel, repolarization occurs
4) turning off potassium gated channels return to resting potential
What is the refractory period?
The time between the start of an action potential and the return to resting potential, during this time the plasma membrane doesn’t respond normally to additional depolarizing stimuli
Define continuous propagation
Action potential moves down the axon
Define saltatory propagation
Action potential jumps from node to node
What are type A axon fibers
Are the largest myelinated axons with VERY fast action potentials
Carries sensory information, as well as skin sensations to the CNS as well as carry motor commands
What are type B fibers?
Smaller myelinated axons
Carry information to and from CNS, delivering temperature, pain, pressure sensations and control smooth and cardiac muscle
What are C type Fibers?
Small unmyelinated axons
Carries information to and from CNS
Deliver information regarding temp, pain and carry signals to smooth muscles, cardiac muscles, and glands
Define synapse
A specialized site where the neuron communicates with another cell
Define electrical synapses
Direct physical contact between the presynaptic and postsynaptic membranes through gap junctions
Rare in body
Define chemical synapses
One neuron sends chemical signals to another neuron
Define cholinergic synapses
Synapses that releases ACh, ACh is the most widespread neurotransmitter
How do Cholinergic synapses release ACh?
Action potential-> depolarization Ca channels open and calcium enters -> ACh released from synaptic vesicles by exocytosis -> ACh diffuse across the synaptic cleft and binds to the postynaptic membrane-> Depolarization ends ACh is broken down
Define synaptic delay
Time between the arrival of a signal at the presynaptic membrane and the initiation of the action potential in the postsynaptic membrane
What is synaptic fatigue
Under intensive stimulation resynthesis and transport of ACh may not keep up with the demand and the response of the synapse weakens until ACh has been replenished
What are Excitatory neurotransmitters?
Cause depolarization and promote the generation of action potentials
What are inhibitory neurotransmitters?
Cause hyperpolarization and suppress the generation of action potentials
What are the Biogenic Amines
Norepinephrine
Dopamine
Serotonin
What Amino acids are involved neurotransmitters
Gamma-aminobutyric GABA
Define neuromodulators
Typically neuropeptides that alter the rate of neurotransmitter release by presynaptic neurons or change the response of postsynaptic neurons
What are the opioid neuromodulators?
Enkephalins
Endorphins
Dynorphins
What are the dissolved gas neurotransmitters?
Nitric oxide
Carbon monoxide
What are direct effecting neurotransmitters?
Compounds that have a direct effect on membrane potential such as ACh, glutamate, aspartame
What neurotransmitters have both direct and indirect effects on membrane potentials?
Glutamate
GABA
Norepinephrine
Serotonin
What are the indirect effects on membrane potential?
A neurotransmitter binds as a first messenger signaling the the second messenger usually a G protein which are produced or released into the cell
Indirect effects on membrane potentials
Include nitric oxide and carbon monoxide
Define Postsynaptic potentials
Graded potentials that develop in the postsynaptic membrane in response to a neurotransmitter
Define excitatory postsynaptic potential
Graded depolarization caused by the arrival of a neurotransmitter at the postsynaptic membrane
Define inhibitory postsynaptic potential
Graded hyperpolarization of the postsynaptic membrane
What is summation
Process in which EPSP and IPSPscombine to produce one graded potential
Define temporal summation
Rapid additions of stimuli one after another until an action potential can occur
Define spatial summation
Many stimuli stimulate different locations at the same time producing a cumulative effect on the membrane potential
The posterior horns contain ______
Somatic and visceral sensory nuclei
The lateral horns located in the thoracic and lumbar region contain ______
Visceral motor nuclei
The anterior horns contain _____
Somatic motor nuclei
Short tracts carry sensory or motor information to the ______
Between segments of the spinal cord
Long tracts carry sensory and motor information between the _____ and _____
Spinal cord and brain
What is the function of ascending tracts?
Carry sensory information towards the brain
What is the function of descending tracts?
Convey motor commands to the spinal cord
What is the function of sensory nuclei?
Receive and relay sensory information from peripheral receptors
What is the function of motor nuclei
Issue motor commands to peripheral effectors
Describe the layers of a nerve
Epineurium- outermost layer
Perineurium- mid layer
Endoneurium- innermost
Define dermatome
Specific bilateral region of the skin monitored by a single pair of nerves
Define Divergence Neural circuits
Spread information from one neuron to many
Define convergence neural circuits
Several neurons signaling one neuron
Define serial processing
A circuit in which neurons or pools work in a sequence
Define parallel processing
Neurons or pools process the same information simultaneously
Define reverberation
A positive feedback circuit
What is the function of the cerebrum
Conscious thought process
Memory storage and processing
Conscious and unconscious skeletal muscle contractions
What is the function of the Diencephalon?
Relays and processes sensory information
What is the function of the midbrain?
Process visual and auditory information
Define first order neuron
Delivers sensation directly to CNS
What is the function of the cerebrum?
Conscious thought processes, intellectual function, memory, regulation of skeletal muscle contractions
Largest portion of brain
What make up the diencephalon, what is its function?
Made up of:
Thalamus-relay and process sensory information between
Hypothalamus- controls emotion, autonomic function, hormone production
What is the function of the Midbrain (Brainstem)
Process visual and auditory, generate reflexive somatic motor response, maintain consciousness
What is the function of Pons?
Relay sensory information to the cerebellum and thalamus, subconscious somatic and visceral motor centers
What is the function of the Medulla Oblongata?
Relay sensory information to the thalamus, regulation of cardiovascular, respiratory and digestive
What is the function of the cerebellum?
Coordinate complex somatic motor patterns
What is the function of the Falx cerebri?
Separates cerebral hemispheres
What is the function of the tentorium cerebelli?
Seperate cerebral hemispheres from cerebellum
What is the function of the Falx Cerebelli?
Divides the two cerebral hemispheres
In embryonic development the prosencephalon develops into the ______
Telencephalon (cerebrum and lateral ventricles) and Diencephalon (thalamus and third ventricle)
In embryonic development the Rhombencephalon forms the _____
Metencephalon (cerebellum and pons) and the myelencephalon (medulla oblongata)
Cerebrospinal fluid is responsible for ____
Supporting the brain
Cushioning
Transport of nutrients, chemicals, waste, and messages
Where is CSF produced?
Leaks from capillaries in the Choroid plexus, secretion into ventricles by Ependymal cells
Define descending tracts
Carry motor commands from higher centers to cranial or spinal nerve nuclei
Define ascending tracts
Carry sensory information from brainstem nuclei to the thalamus
What are the three major Somatic sensory pathways
Spinothalamic
Posterior column
Spinocerebellar
The spinothalamic pathway carries what type of signals?
Touch, pressure, pain, and temperature
The posterior column pathway carries what type of information?
Fine touch, pressure, vibration
The spinocerebellar pathway carries what type of information?
Proprioceptive (perception of position) information
What is the function of cranial nerves 5-10?
Carry sensory information from mouth, larynx, trachea to target tissue
What is the function of spinal nerves T1-L2?
Carry sensory information from organs between diaphragm and pelvic cavity
What is the function of spinal nerves S2-S4?
Carry sensory information from organs in lower pelvic cavity
What is the function of the corticospinal pathway?
Provides voluntary control over skeletal muscles
