A&P I Lecture exam #3 review Part 1

What is the primary function of the myelin sheath? How does the diameter of an axon alter the speed of signal conduction?

• Primary function of the myelin sheath is to insulate the axon which increases the speed of nerve impulse conduction along the axon via the process of saltatory conduction. • The larger the diameter of the axon the faster it will transmit electrical impulses.

What is the value of a resting membrane potential in a neuron? what is the value of threshold in the neuron

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1.These neurons are responsible for integration of information: they process, store, and retrieve information for the purposes of decision making. 2.These neurons carry signals from the central nervous system to the bodies effectors. 3.These neurons detect signals and carry environmental information to the central nervous system. 4.These neurons are the only neurons to live fully within the central nervous system: the axons of the other neurons formed the nerves of the peripheral nervous system.

1.Interneurons 2.Motor (efferent ) 3.Sensory (afferent) 4. Interneurons

The refractory period has two phases: During this refractory period, another action potential cannot occur no matter how strong the stimulus During this refractory period, strong stimuli may result in another action potential

Absolute refractory period Relative refractory period

Which region of the neuron possesses the myelin sheath?

Axon (nerve fiber)

Match the type of neuron to the correct function

Bipolar - rare sensory neurons (i.e., ear, nose). Multi polar - all motor and interneurons. Unipolar (pseudounipolar) - most common type of sensory neuron. Anaxonic - participate in local communication, can't produce action potentials.

List neuroglial cells that belong to the central and peripheral division of the nervous tissue

CNS: astrocytes, oligodendrocytes, microglial cell, epindymal cells PNS: Schwan cells, satellite cells

Structurally, the nervous system is divided into two divisions: The ______ nervous system division, which consists of the brain and spinal cord. The ______ nervous system division, which consist of the nerves and ganglia.

Central Peripheral

During this synapses , the pre-and post-synaptic cells are separated by a synaptic cleft During this synapses , two cells are joined at their plasma membrane via gap junctions.

Chemical Electrical

• _____ - gated channels open in response to the binding of a ligand like a neurotransmitter. • _____ - Gated channels open in response to a change in voltage inside the neuron.

Chemically Voltage

In unmyelinated axons, nerve signals (impulse) travel via _____ conduction, which is slower In myelinated axons, nerve signals (impulses) travel via _____ conduction, which is faster

Continues Saltatory

• The movement of charged particles is referred to as_____, and this is an example of kinetic energy. • What is the opposition to the movement of charged particles?

Current Resistance

List to characteristics of local potentials

Decremental-local potential weekends was distance traveled, ions are lost out of the leak channels, or the movement is stopped due to resistance. Graded - means strength of the stimulus results in strong response in membrane potential by opening gated channels and allowing greater ion flow

Neurons typically have two different kinds of processes. • One or more highly branched ____, which bind neurotransmitter and receives signals from other cells. • Only ever one long _____, which produces and conducts action potentials, permitting stimulation of other cells.

Dendrites Axons

Match the electrical events to the best description

Depolarization - neuron becomes less negative than addressed due to entry of cations Hyper polarization-neuron becomes more negative than addressed due to loss of cations Summation -this is not a phase of the action potential, it brings neuron to threshold so action potential can be generated. Repolarization-neuron returns towards RMP due to loss of cations

What is defined as a difference in the concentration of charged particles between two locations? The potential difference described above can also be referred to as ______, which is typically measured in millivolts

Electrical potential Voltage

List and describe two characteristics of neurons.

Excitability-response to environmental changes such as stimuli Conductivity - generate and conduct electrical signals, occurs within axon.

A Local potential occurring at the synapse that makes a neuron more likely to produce an action potential is referred to as an ________ -potential A local potential occurring at synapse that makes a neuron less likely to produce an action potential is referred to as _____ -potential

Excitatory post-synaptic Inhibitory post-synaptic

Are the following statements is true or false? • Neurotransmitters are always small, organic molecules. • Chemical synapses are more common in the nervous system than electrical synapses. • Unmyelinated axon's conduct signals faster than myelinated axons. • The terms repolarization and hyperpolarization can be used interchangeably. • The effect that a neurotransmitter has on the postsynaptic cell is partially influenced by which receptors are present, not just the type of neurotransmitter itself.

False True Falls Falls True

What is the definition of ganglia? What is the definition of nerve?

Ganglia are clusters of cell bodies that lie outline the central nervous system, and are protected by satellite cells. Nerve are in bundles of axons (nerve fibers) that carry information to and from the brain and spinal cord.

Ion can enter or exit the cell through the use of channel proteins. • What channels are usually closed, and only open in response to a specific stimulus? • What channels are always open?

Gated channels Leak channels

• When a cell becomes more negative than at rest, this is referred to as a ____ • When a cell becomes less negative that at rest, this is referred to as a _____

Hyperpolarization Depolarization

What part of the cell is the greater concentration of potassium ions K+? What part of the cell is the greater concentration of sodium ions Na+?

Inside the cell (ICF) Outside the cell (ECF)

Which potential typically begin in the dendrites and flow towards the axon? Which potential only occur within the axon of a neuron?

Local Action

Which of the following statements is true of neuroglial cells, but not neurons?

Mitotic - They are capable of mitosis

Match the category of neurotransmitter to the best description

Monoamines - produced from amino acids, can also act as hormones. Neuropeptides - chains of amino acids, can also act as hormones or neuromodulators. Acetylcholine- primary neurotransmitter associated with muscle contraction. Purines Dashgroup associated with amino acids, includes ATP. Amino acids-plain amino acids behaving as neurotransmitters. Gases - inorganic, move into and out of the cells via diffusion.

The nervous system can be divided functionally. The ______ division carries information from the central nervous system to the effectors (muscles, glands, etc.). The ______ division carries information from receptors to the central nervous system.

Motor (efferent) Sensory (afferent)

Match the structural classification of neuron to the best description

Multi polar neurons have multiple dendrites, one axon, most common neurons shape. Bipolar neurons have one dendrite, one axon, and their uncommon Unipolar (pseudounipolar) neurons - single process connected to neurosoma by stalk and they are common. Anaxonic neurons - Lack an axon and rare

• Myelinated axon's always have on myelinated areas referred to as_____ • The process of adding mile into an axon is referred to as _____

Myelin sheath gaps or node of Ranvier Myelination

Why is conduction faster in myelinated axon compared to on myelinated axon's? Why are neurotransmitters required at chemical, but not electrical, synopsis?

Myelination of an axon provides insulation that prevents ions to leak and speeds ip AP Neurotransmitters are chemical messengers. In electrical synapse ions flow through gap junctions which does not exist in chemical synapse and ions cannot cross the cleft therefore they rely on neurotransmitters to send signal.

The depolarization face is a result of ____ ions _____ these the neuron The repolarization and hyper polarization phases of the action potential are due to ___ ions ____ the neuron

Na+, entering K+, exiting

The inside of a neuron is relatively _____ The outside of a neuron is relatively _____

Negative Positive

A _____ is a successive series of action potentials occurring along the length of the axon. The _____ is a period of time in which an action potential either cannot occur, or will not occur without strong stimulus

Nerve signal Refractory period

How do neuroglial cells differ from neurons? List two ways

Neuroglial cells bind neurons together and provide strong framework for nervous tissue, and facilitates the function of the communication network. Neuroglial cells do not conduct nerve impulses, but instead Support, nourish, and protect neurons. Unlike neurons they are capable of mitosis.

What cells that make up the functional units of the nerve tissue and produce action potentials? What cells protect the above cells and fulfill a number of other important functions and nerve tissue?

Neurons Glial, neuroglial

Where does the nucleus of the neuron is housed? Projecting of the above are two different types of slender ______ , which have different functions.

Neurosoma Processes

Defined the term neurotransmitter Chemical synapses are slower, unidirectional, and possible to fatigue. What advantages do they have over electrical synapses?

Neurotransmitters are any molecules produced by neurons, released in response to a nerve signals, enable to affect the physiology of the postsynaptic cell. The advantage of chemical synapses over electrical synapses is they can integrate information.

Select the correct covering for each structure of the nerve and axon (nerve fiber). -Covers an individual fasicle in a nerve. -Covers the entire nerve. -Covers individual axons and their neuroglial cells. -Formed of the plasma membrane of Schwann cells, covers individual axons

Perineurium Epineurium Endoneurium Myelin sheath

Match the function to the correct neuroglial cells

Phagocytosis of dangerous or unwanted materials - Microglial cell Numerous functions: forms blood brain barrier, nourishes neurons, regulates blood flow, etc. - Astrocytes Protects cell bodies of neurons in ganglia - satellite sell Produces and circulate cerebrospinal fluid - Ependymal cell

The plasma membrane is _____, meaning that it has an electrical potential When the cell is at rest, this electrical potential is referred to as the _____

Polarized Resting membrane potential RMP

In a chemical synapse, there are two cells. This cell releases neurotransmitters and lies before the synaptic cleft This cell bind neurotransmitter, and lies after the synaptic cleft

Presynaptic Postsynaptic

Are the following statements is true of a local potentials or action potentials ?

Reversible - Local potential Non-decremental-Action potential Graded - Local potential Consist of depolarization followed by repolarization-Action potential

In the peripheral nervous division, axons are myelinated by _______ In the central nervous division, axons are myelinated by _____

Schwan cells (Neurolemmocytes) Oligodendrocytes

What cells myelinate the axon of the peripheral nervous system? What kind of cells myelinate the axons of the central nervous system?

Schwann cells (neurolemmocyte) Oligodendrocytes

What is the role of the sodium/potassium pump in maintaining the resting membrane potential? Why is this role necessary?

Sodium/potassium pump prevents equilibrium from occurring. ATP is spent in order to move sodium back outside of the cell and potassium back into the cell.The sodium/potassium pump moves these ions against their concentration gradients.

When dividing the nervous system: What term refers to the muscle, joints, bones, and skin? What term refers to the internal organs of the thoracic and abdominal cavities?

Somatic Visceral or viscera

In the trigger zone, summation occurs in order to bring the neuron to threshold. • During this summation, multiple neurons in close proximity fire at the same time, bringing the postsynaptic cell to threshold. • During this summation, a single neuron fires repeatedly in quick succession, bringing the postsynaptic cell to threshold.

Spatial Temporal

When classifying nerves structurally: ______ nerves connect to the spinal cord? ______ nerves connect to the brain?

Spinal Cranial

The autonomic (visceral efferent) division of the nervous system is divided into two branches. The ______division prepares the body for action in response to physical, emotional, or mental stress. The ______ division services to maintain homeostasis at rest, and increases activity of the digestive and urinary systems.

Sympathetic Parasympathetic

• A _____ is a junction between a neuron and another cell, though they may not be physically in contact. • _____ Are chemical messengers released at some of these junctions, which stimulate or inhibit the next cell.

Synapse Neurotransmitters

Are the following statements is true or false?

Synapsis lend to the nervous system's plasticity: they can be added or removed, strengthened or weakend. True The binding between a neurotransmitter and its receptor is permanent, the NT must be removed by an outside force. False Action potentials can only occur within the trigger zone: they don't occur anywhere else along the axon. False According to the all or none law, weak stimuli produce weaker action potential's. False Summation combines the affects of multiple post-synaptic potential's, making it easier to reach threshold. True

What process or processes accounts for synaptic delay? How do you end stimulation of the postsynaptic neuron?

Synaptic delay is a result of the time required for neurotransmitter to be released from the presynaptic cell, for it to bind to the receptors of the postsynaptic cell, and the resulting generation of another action potential in the postsynaptic cell. In order to end synaptic signaling, you must first stop the release of neurotransmitter. Then, all present neurotransmitter must be removed from the cleft.

At the end of the neuron, the axon splits into a highly branched region called the _____ At the tip of these branches, there are swollen areas called ______ which form synapses

Terminal arborization Axon terminals

What is the function of the central nervous system? What is the function of the peripheral nervous system?

The function of the central nervous system is to integrate and process information, coordinate bodily functions, and perform at a high-level functions. The function of the peripheral nervous system is to relay information to and from the central nervous system. It connects receptors and effectors to the brain and spinal cord.

What is the benefit of the refractory period as it applies to signal conduction? What does that all-or-none Law state regarding threshold and action potentials?

The refractory period prevents the nerve signal from traveling backwards along the axon. Any sodium ions that travel away from the terminal arborization cannot stimulate the inactivated sodium channels, and therefore another action potential can't be generated in the region in the refractory period. All-or-none law means that once threshold is reached, an action potential will always occur, and it cannot be stopped at this point. Nerve signal fires no matter the level of strength of the stimulus.

• Action potentials can only occur if a specific internal voltage is reached, referred to as _____. Any stimulation below this point will not result in an action potential. • The above is part of a set of "rules" defining the behavior of action potentials referred to as the _______ law

Threshold All-or-none

Action potentials always begin in this region of the axon The action potential continues along the axon until it reaches the _____, which stores neurotransmitter

Trigger zone Axon terminals

• Action potentials begin in a specific region of the axon known as the ______ • During _______, the neuron returns to its resting membrane potential.

Trigger zone Repolarization

What is relationship between resistance and current? What provides resistance in a neuron? How can these resistance be changed?

• Resistance and current are inversely proportional: increasing resistance lowers current, while decreasing resistance raises current. This is what Ohm's law states: V=IR • Plasma membrane provides resistance in the wrong. It is changed by opening and closing ion channels.

List to characteristics of action potentials

• They are non-decremental which means they don't we can by distance they travel • All-or-none law the strength of the stimuli does not affect the strength of the response