AP Exam 4: Nervous System

Phagocytes of the CNS: 

Microglia

Form the myelin sheath of the PNS:

Schwann cells

Provide structure, clean up, and filtration in the PNS:

Satellite Cells

Secrete cerebral spinal fluid:

Ependymal cells

Form the blood brain barrier:

Astrocytes

Form the myelin sheath in the CNS:

Oligodendrocytes

What type of synapse uses gap junctions and only has one possible outcome?

Electrical

What synapse uses ligand gates ion channels and has multiple different outcomes?

Chemical

1 neuron can synapse with thousands of others to form:

a circuit

The three key regions of a neuron are:

• Receptive

• Conducting

• Secretory

What region of a neuron has receptors for NTs and dendrites (sometimes soma)?

Receptive

What region of a neuron is where AP forms and propagates?

Conducting

What region of a neuron is where NTs get released from the axon terminal?

Secretory

Where would you find VG Na+ and K+ channels on a neuron?

Nodes of Ranvier

What neurons carry info towards the CNS using the afferent pathway? 

Sensory

What neurons perform integration within the CNS and perform processing? 

Interneurons

What neurons carry information away from the CNS using the efferent pathway and activate an effector.

Motor neurons

What type of motor neuron controls skeletal muscle and is voluntary?

Somatic

What type of motor neuron is involuntary and controls smooth, cardiac, and glands?

Automatic

What is the most afferent neuron type?

unipolar

What is the rare type of neuron found in the eyes and ears? 

Bipolar

What is the most common type of neuron in the CNA and efferent - interneurons and motor neurons?

Multipolar

Stimulus: Vibration/pressure/distortion

Perception: Touch, hearing

Mechanoreceptors

Stimulus: Change in Temperature

Perception: Hot/Cold

Thermoreceptors

Stimulus: Light

Perception: Vision

Photoreceptors

Stimulus: Change in chemical levels or presence/absence

Perception: Taste/Smell

Chemoreceptors

Stimulus: Damage

Perception: Pain

Nocireceptor

Reponds to stimulus outside the body:

Exteroceptors

Responds to stimulus inside the body:

Interceptors

Responds to skeletal muscle stretch: 

Proprinoceptors

What is the conversion of stimulus into a graded potential (event in which membrane potential changes) ions move? 

Transduction

What is it called when many graded potentials happen over a short period of time:

Temporal Summation

What is it called when many graded potentials happen at the same time at different synapses?

Spatial summation

When can a VG channel be stimulated?

Closed

What two VG channels cannot be stimulated? 

Open and inactiviated

When a VG channel is closed what is happening? 

A GP causes the cell to depolarize to threshold

When a VG channel is open what is happening?

Membrane rapidly depolarizes -Na+ in

When a VG channel is inactivated what is happening?

• Gates are in the opposite orientation from rest

• Slow gate finally close, no more Na+ moves

Which refractory period is it when a second AP cannot form and VG Na+ channel is either open or inactivated? 

Absolute

Which refractory period is it when a second AP might form and VG channels are resetting inactivated → closed? 

Relative

AP propagation speed depends on two things which are:

1) Axon diameter: larger diameter = faster

2) Degree of Myelination: Myelination = faster

What type of conduction is it when AP continuously needs to reform (slow)?

Continuous

What type of conduction is it when AP jumps between myelin sheaths (fast)?

Saltatory

Chemical Synapse use:

Neurotransmitters

Electrical synapses use: 

Direct propagation through gap junctions

What happens if there is Excitatory Postsynaptic Potential (EPSP)?

Depolarization → closer to threshold (more +)

What happens if there is Inhibitory Post Synaptic Potential (IPSP)?

Hyperpolarization → away from threshold (more -)

A G protein coupled receptor is….

a receptor that links to a G protein inside the cell

A G-protein is inactive if its bound to:

GDP

A G-protein is active if its bound to: 

GTP

A serial processing circuit produces a _______.

Reflect, the stimulus causes a automatic response, and only requires neurons of the spinal cord

A parallel processing forms complex connections and consists of:

• Presynaptic neuron

• Discharge zone

• Facilitated zone

Why type of processing circuit is where one presynaptic neuron sends signals to multiple postsynaptic neurons?

Diverging circuit

Forming the myelin sheath in the CNS:

Oligodendrocytes

Surrounding the soma in the PNS to provide stability and filtration:

Satellite cells

Providing structure, filtration, clean up, and forming the blood brain barrier in the CNS:

Astrocytes

Offering immune system functions within the CNS:

Microglia

Lining spaces in the CNA and secreting cerebral spinal fluid:

Ependymal cells

Forming the myelin sheath in the PNS:

Schwann Cells

Ependymal cells have cilia on their apical surface. What’s the function of these? 

To circulate cerebrospinal fluid through open cavities (ventricles) in the CNS

Characteristics of a graded potential (GP) are: 

• Short lived

• Degrades with distance

• Measured as voltage change

Serial Processing steps in order:

Stimulus → Sensory Neurons → Interneuron → Motor Neuron → Effector