Bio 226 Unit 4 (Nervous System Cells)

Identify the three basic parts/regions of a neuron.

3 basic parts: body (soma), dendrites, axons

Describe how polar substances cross the blood-brain barrier: polar: (two main transport mechanisms)

Active and facilitated transport

Classify neurons into three groups based on their locations and the directions in which they send signals relative to the CNS.

Afferent: Sensory (receptor → neuron → CNS) Efferent: Motor (CNS → neuron → effector organ) Interneurons: connect other neurons; located in CNS

What type of glial cell contributes to formation of the blood-brain barrier?

Astrocytes

Which type of glial cell supports neurons and brain blood vessels and contributes to forming the blood-brain-barrier?

Astrocytes

What makes the blood-brain barrier important and how does it differ structurally from other capillaries?

Astrocytes use their appendages to create a secondary layer of cells. Astrocytes are able to chemically talk to squamous cells during development of brain blood vessels and instruct these squamous cells of the capillary walls to create tight junctions which make barriers leak proof. Capillaries, which are one cell thick, retain small gaps between squamous cells to facilitate rapid exchange between blood and the surrounding tissue spaces. A permeability barrier with tight junctions is important because neural tissues are sensitive to fluctuations, therefore we want to select the substances that are exposed to brain and spinal cord cells.

Describe the location of presynaptic terminals.

At the end of an axon where signals are sent

What cellular processes of neurons allow them to receive increased numbers of inputs from other neurons?

Axons

Which part of a neuron sends signals to other cells?

Axons

Describe the structure of those Ependymal Cells that synthesize cerebrospinal fluid and contrast this with the structure of those that help it circulate.

Cells in the choroid plexus will consist of microvilli and cilia. Due to the elongated structure of the microvilli mixed in with cilia this would increase surface area for secretion of CSF.

Describe how these cells contribute to the blood-CSF barrier, and why this is important.

Cells in the ventricle walls will consist of true cilia which aid in the circulation in the correct pattern.

Which part of a neuron is responsible for increasing the number of possible incoming signals from other cells by increasing surface area?

Dendrites

Describe how the synaptic cleft communicates.

Electrical current will travel down the axon , upon reaching the axon terminus chemical messaging will take place in the form of neurotransmitter molecules, the neurotransmitter molecules will then diffuse through the synaptic cleft that separated the two cells, chemical signaling will take place due to the signaling molecule binding to a receptor protein on the target cell.

Which type of glial cell lines the ventricles?

Ependymal Cells

Which type of glial cell acts as a phagocyte?

Microglia

Which type of glial cell is phagocytic?

Microglia

Define presynaptic and postsynaptic cells in relation to the flow of information relative to a synapse.

Neurotransmitter molecules are released from a presynaptic neuron, diffuse through the synaptic cleft, and bind to receptors on the postsynaptic cell

Which types of glial cells help form myelin sheaths in the CNS versus the PNS?

Oligodendrocytes

If an axon of a neuron were damaged, is the axon more likely to be capable of repair if it is located in the CNS or in the PNS?

PNS Neuroglia

What are the other basic functions of Astrocytes?

Promote development of neurons and blood vessels Attach to and cover blood vessels and neurons. Stimulate formation of tight-junctions at blood-brain barrier Help wall of sites of injury and limit spreading of inflammation.

Which other type of glial cell protects the cell bodies of neurons in the sensory ganglia?

Satellite Cells

Which type of glial cell helps protect neurons from toxins in the PNS?

Satellite Cells

For the 6 types of neuroglia, describe the location with respect to the CNS or PNS.

Satellite Cells: PNS Schwann cells: PNS Microglia: CNS Oligodendrocytes: CNS Astrocytes: CNS Ependymal Cells: CNS

Which type of glial cell forms myelin sheaths in the PNS?

Schwann cell

What type of glial cell is responsible for aiding repair of an injured axon?

Schwann cells

Which one of these cells is more effective at aiding the repair of damaged axons?

Schwann cells

What is the body of a neuron called?

Soma

Describe the synaptic cleft.

The synaptic cleft is the space in between the axon and dendrite separating both cells and filled with interstitial fluid.

Define synapse

a junction between two nerve cells, consisting of a minute gap across which impulses pass by diffusion of a neurotransmitter.

What cellular processes of neurons allow them to send signals to other cells?

axon

Define Postsynaptic.

cell receiving a message

Define presynaptic.

cell sending a message

Which type of glial cell makes up the walls of the ventricles and produces CSF?

ependymal cell

What is the plasma membrane of a neuron called?

neurolemma

Of the two basic types of nervous system cells, which functions to send and receive signals via electric impulses?

neuron

Which one is responsible for communication between the nervous system and other tissues of the body?

neurons