Nervous Tissue

A series of vocabulary flashcards related to the structure and function of nervous tissue, covering key concepts like types of neurons, characteristics of synapses, and the roles of neurotransmitters.

Nervous system

The system that includes the brain, spinal cord, sense organ receptors, and nerves connecting to other systems.

Neurons

Specialized cells in nervous tissue that are responsible for intercellular communication.

Neuroglia (glial cells)

Support and protect neurons and help preserve the structure of nervous tissue.

Central Nervous System (CNS)

Comprises the brain and spinal cord and is responsible for integrating sensory information and coordinating motor commands.

Peripheral Nervous System (PNS)

All nervous tissue outside the CNS that delivers sensory information to the CNS and carries motor commands to peripheral tissues.

Afferent Division

Part of the PNS that carries sensory information from receptors to the CNS.

Efferent Division

Part of the PNS responsible for carrying motor commands from the CNS to effectors like muscles and glands.

Somatic Nervous System (SNS)

Controls voluntary and involuntary (reflex) contractions of skeletal muscles.

Autonomic Nervous System (ANS)

Controls involuntary activities, such as the activity of smooth and cardiac muscles.

Dendrites

Short, branched processes of a neuron that receive information from other neurons.

Axon

A long, single cytoplasmic process of a neuron that propagates electrical signals.

Myelin sheath

A layer of fatty insulation around axons that increases the speed of action potential propagation.

Action Potential

A large depolarization that affects the entire excitable membrane and does not diminish with distance.

Refractory Period

The period during which the membrane cannot respond normally to additional stimuli.

Synapse

A specialized site where a neuron communicates with another cell, which could be electrical or chemical.

Neurotransmitter

Chemicals released at synapses that transmit signals between neurons.

Excitatory Neurotransmitters

Cause depolarization of postsynaptic membranes and promote the generation of action potentials.

Inhibitory Neurotransmitters

Cause hyperpolarization of postsynaptic membranes and inhibit the generation of action potentials.

Graded Potentials

Temporary localized changes in the resting membrane potential caused by the opening of gated channels.

Facilitation

Bringing the membrane potential of the initial segment closer to threshold, increasing the likelihood of firing an action potential.

What are the three fundamental functions of the nervous system?

To receive information from internal and external stimuli, process the information, and initiate responses.

What are Nissl Bodies, and what is their significance in a neuron?

Nissl Bodies are dense areas of Rough Endoplasmic Reticulum (RER) and ribosomes found in the neuron's perikaryon, responsible for protein synthesis and giving gray matter its color.

Describe the two directions of axonal transport and the proteins involved.

Anterograde transport moves materials from the cell body to axon terminals, facilitated by kinesin. Retrograde transport moves materials from axon terminals back to the cell body, facilitated by dynein.

What defines a Unipolar (Pseudounipolar) neuron, and where are they primarily found?

Unipolar neurons have continuous axon and dendrites with an off-centered soma. They are predominantly sensory neurons of the PNS.

Distinguish between a 'ganglion' and a 'nucleus' in the nervous system.

A ganglion is a collection of neuron cell bodies in the PNS, while a nucleus is a collection of neuron cell bodies in the CNS.

What specific type of sensory receptor monitors the position and movement of skeletal muscles and joints?

Proprioceptors.

What is the function of Satellite Cells in the PNS?

Satellite cells surround neuronal cell bodies in ganglia, regulating levels of O2, CO2, nutrients, and neurotransmitters.

What is Multiple Sclerosis (MS), and what part of the nervous system does it affect?

Multiple Sclerosis (MS) is an autoimmune disorder that destroys myelin in the CNS, leading to issues with speech, vision, balance, motor coordination, and bladder control.

Which specific ions are found in high concentrations in the Extracellular Fluid (ECF) and the Intracellular Fluid (Cytosol) at a neuron's resting state?

The ECF has high concentrations of Na+ and Ca2+. The Cytosol has high concentrations of K+ and negatively charged proteins.

Categorize three types of gated ion channels based on their opening mechanism.

Chemically gated (open when specific chemicals bind), Voltage-gated (respond to changes in membrane potential), and Mechanically gated (open in response to physical membrane distortion).

Describe the events that lead to repolarization during an action potential.

Repolarization occurs when voltage-gated sodium channels close and voltage-gated potassium channels open at approximately $+30 ext{ mV}$, allowing $K^+$ to exit the cell, making the membrane potential more negative.

Define the 'Absolute Refractory Period' of an action potential.

The Absolute Refractory Period is a time during which the membrane cannot respond to any further stimulation because sodium channels are either open or inactivated.

Compare Type A and Type C axon fibers regarding myelination, diameter, and transmission speed.

Type A fibers are myelinated, large diameter, and transmit signals rapidly. Type C fibers are unmyelinated, small diameter, and transmit signals slowly.

What causes 'synaptic delay' in chemical synapses?

Synaptic delay is primarily caused by the time required for Ca2+ influx into the axon terminal and the subsequent release of neurotransmitters.

What roles does dopamine play, and what conditions or substances is it implicated in?

Dopamine can be excitatory or inhibitory, crucial in various brain regions, and is implicated in Parkinson’s disease (deficiency) and cocaine effects (increased activity).