Lesson 11: Nervous Tissue and Nervous System Flashcards
What is the basic function of the NS?
To send and receive electrical and chemical signals/ communicating system of the body(sensory input, integration, and motor output)
Explain the structural and functional divisions of the nervous system
Central NS: Structural: Brain and Spinal Cord
Peripheral NS: Structural: Cranial and spinal nerves/ Functional- Sensory Division and Motor Division
Motor Division: Somatic and Autonomic
Autonomic: Sympathetic and Parasympathetic
What are the components of the neuron and its functions?
Cell body(soma): Contains nucleus; biosynthetic center and receptive regions
Dendrites: Receptive regions
Axon: Impulse generating and conducting region
What are the functional classifications of neurons?
- Sensory: sends a message to ANS
- Motor: away from ANS to effectors
- Interneurons: interpretation by ANS
What are the neuroglia cells of the CNS?
- Astrocytes
- Microglial cells
- Ependymal cells
- Oligodendrocytes
What are the neuroglial cells of the PNS?
- Satellite cells
2. Schwann cells
What is the function of astrocytes?
Most abundant; functions include playing a role in exchanging b/w capillaries and neurons, supporting neurons, responding to nerve impulses, controlling the chemical environment around neurons, and interpretation
What is the function of microglial cells?
Function as immune cells, phagocytosis, and trap debris
What is the function of ependymal cells?
Produce and circulate cerebrospinal fluid, line the ventricles
What is the function of oligodendrocytes?
Myelinate–>insulate and protect signals neurons are sending
What is the function of satellite cells?
Function similar to astrocytes
What is the function of Schwann cells?
Function similar to oligodendrocytes
Define neuron
A nerve cell designed to transmit info to other nerve cells
Define ganglion
A group of neuron cells in the periphery
What is resting membrane potential?
Approximately -70 mv; caused by the cytoplasmic side of the membrane being negatively charged relative to the outside; the membrane is said to be polarized
What is action potential?
A large transient depolarization event that is generated along the membrane of a muscle cell or an axon of a neuron
What is saltatory conduction?
Transmission of an action potential along a myelinated fiber in which the action potentials appears to leap from gap to gap.
What is the absolute refractory period?
Period following stimulation during which no additional action potential can be evoked; enforces one-way transmission of nerve impulses
What is the purpose of the myelin sheath?
- Protect and electrically insulate axon
- Increase the speed of nerve impulse transmission
How is the myelin sheath both formed in the CNS and PNS?
In the PNS: Wrapped by Schwann cells, one cell forms one segment of the axon
In the CNS: Wrapped by oligodendrocytes, each cell can wrap up to 60 axons
What is the difference between gray and white matter?
White matter is a region in the brain or spinal cord with dense myelinated fibers, while gray matter contains non-myelinated fibers
How are action potentials generated?
- Resting state: All Na+ and K+ channels are closed, only leakage channels are open
- Depolarization: Na+ channels open and Na+ goes into the cell, as a result, ICF becomes less negative. At threshold(-55 mv to -50 mv), positive feedback causes opening of all channels
- Repolarization: Na+ channels are inactivating and K+ channels open. Membrane returns resting membrane potential.
- Hyperpolarization is caused by K+ continuing to leave the cell
What is a synapse?
Functional junction or point of close contact between two neurons or between a neuron and an effector cell.
What are neurotransmitters?
Chemical messenger released by neurons that, upon binding to receptors of neurons or effector cells, stimulate or inhibit those neurons or effector cells
