Nervous System Flashcards
What are the two major divisions of the nervous system?
Central nervous system and peripheral nervous system
What major structures does the central nervous system consist of?
Brain and spinal cord
What are the two nervous system divisions of the peripheral nervous system that controls voluntary and involuntary motor activity
Somatic nervous system (voluntary) and autonomic nervous system (involuntary)
What are the two divisions of the peripheral nervous system that sends sensory and motor information to and from the body and the central nervous system?
Afferent(sensory) and efferent(motor)
What type of information does the afferent division of the peripheral nervous system send
Sensory information from the body to the central nervous system includes visual, receptors, auditory receptors, chemo, receptors, and somatosensory or touch receptors
What type of information does the efferent division of the peripheral nervous system send
Motor information from the central nervous system to the body through the somatic and autonomic nervous system’s
What efferent information is sent via the somatic nervous system?
Voluntary and involuntary contraction of skeletal muscle, for stability and mobility of the body
What efferent information is sent via the autonomic nervous system?
Involuntary activation of smooth muscles for functioning of the internal organs
What are the two main types of cells in the nervous system?
Neurons and glial cells
What is the end of the axon that meets the dendrites at the synapse called?
Axon terminal
What is the electrical signal sent down the axon of a neuron called
Action potential
Are motor neurons typically unipolar multipolar and what does that mean?
Multi polar, they have two or more dendrites, and a single axon
What is myelin?
A Phatty protective sheets wrapped around the axons of some neurons that help to speed up electrical signals, known as action potential’s
What type of cell form is Myelin in the central nervous system?
Oligodendrocytes
What type of cell forms myelin in the peripheral nervous system?
Schwann cells
What is the name for bundles of axons within the central nervous system?
Tract
What is the function of the blood brain barrier?
It is a highly selective membrane lining the capillaries in the brain that lets in water, oxygen glucose and other smaller molecules, while keeping most others out to protect the brain from foreign invaders
What is the function of the two cerebral hemispheres of the brain?
The right cerebral hemisphere receives sensory fibers and sends motor fibers to the left side of your body
The left cerebral hemisphere receives sensory fibers and sends motor fibers to the right side of your body
What is the gray matter in the brain made of
Neuron cell bodies
What is the white matter in the brain made of?
Axons of neuron cell bodies
What is the function of the hypothalamus?
It is a small region that does a variety of things like regulate the body temperature for sleep, and wake cycle and eating and drinking by regulating the release of the major endocrine hormones
What is the function of the pituitary gland?
Produce and secrete hormones, when it receives signals from the hypothalamus
What is the function of the cerebellum?
It helps with coordinating movement, precision and balance
What is the function of the brain stem?
It controls, vital life functions like blood pressure, breathing consciousness, sleep wake, cycles, postural, control, facial expressions, blood pressure, swallowing, coughing, vomiting, and digestion
What is the function of the spinal cord?
It is a long ride of nervous tissue that extends down from the brainstem to the lumbar region of the vertebral column. Information travels up through sensory fibers and down through motor fibers.
What are the three gray matter paired horns that are seen in a cross-section of the spinal cord?
Anterior or ventral horn’s posterior, or dorsal horns and lateral horns
What is the function of the anterior or ventral horns of the spinal cord?
They receive information from the motor cortex of the brain and then send it to the skeletal muscle to trigger voluntary movement
What is the function of the posterior or dorsal horns of the spinal cord?
They receive sensory information from the outside world and send it to the sensory cortex of the brain
What is the function of the lateral horns of the spinal cord?
They are mainly involved with the sympathetic division of the autonomic motor system. These help regulate processes like urination, digestion and heart rate.
How is the spinal cord involved in coordinating reflexes?
Some sensory neurons synapse in the spinal cord, and can produce fast involuntary motor responses to sensory stimulus
What is the function of cerebrospinal fluid?
It is a clear watery liquid, which is pumped around the spinal cord, and the brain cushioning them from impact and bathing them in nutrients
What are the two major types of peripheral nerves found in the peripheral nervous system
Cranial nerves and spinal nerves
How many cranial nerve pairs are there in the body and what do they innervate?
There are 12 and they innervate the head and neck
How many spinal nerve pairs are there in the body and how are they classified?
- Spinal nerve pairs.
Eight. Cervical.
12 thoracic
Five lumbar
Five sacral
One coccygeal
What is the general path of sensory nerves in the somatic nervous system division of the peripheral nervous system?
Sensory nerves which have axons that carry sensory information from the peripheral tissues, like the skin back to the cell bodies in the posterior horns of the spinal cord
What is the general path of the motor nerves in the somatic nervous system division of the peripheral nervous system?
Motor nerves contain the axons that carry motor information from the cell bodies in the anterior horns of the spinal cord to the neuromuscular junction, which is where these axons contact the skeletal muscle cells
What are the divisions of the autonomic nervous system and the peripheral nervous system?
Sympathetic and parasympathetic
What are the cell bodies of preganglionic neurons of the autonomic nervous system located
In nuclei in the lateral horns of the spinal cord
What are the cell bodies of postganglionic neurons of the autonomic nervous system located?
In ganglia outside of the spinal cord
What is the general path of motor nerves in the autonomic nervous system division of the peripheral nervous system?
Signals are sent from the hypothalamus to preganglionic neurons, which exit the spinal cord to reach the ganglia and synapse with the postganglionic neurons. Then the axons of postganglionic neurons exit the ganglia to reach the organs and synapse with the target organ cells.
Where do signals for the autonomic nervous system start?
Hypothalamus
What is the general function of the sympathetic division of the autonomic nervous system and the peripheral nervous system?
It controls functions like increasing the heart rate and blood pressure as well as slowing digestion this blood flow to the muscles in brain, and can help you either run away from a threat or fight it the fight or flight response
What is the general function of the parasympathetic division of the autonomic nervous system and the peripheral nervous system?
It’s slow as the heart rate and stimulates digestion. The effects can be summarized as rest and digest.
What is a myotome?
The specific muscles innervated by a specific spinal nerve
What is a dermatome?
The specific area of the skin that sends sensory information through a specific spinal nerve
Are the somatic and autonomic nervous system’s divisions of the central nervous system or peripheral nervous system?
Peripheral nervous system
Does the somatic nervous system primarily control voluntary or involuntary activities?
Voluntary
What part of the nervous system controls, smooth, muscle, cardiac muscle and glands
Autonomic nervous system
What information do somatic sensory fibers convey
They convey sensory information from the skin, skeletal muscles and joints, somatic sensory fibers, allow the transmission of sensory information, such as touch, pain, temperature, and proprioception
What information do visceral sensory fibers convey
They convey sensory information from the viscera back to the CNS. They provide information about things such as the amount of oxygen in your blood, your arterial blood pressure and the level of distention of your stomach after a meal.
What information do special sensory fibers convey
They convey sensory information related to our special senses, such as smell sight taste hearing and balance back to the CNS for interpretation
What is the enteric nervous system?
The intrinsic nervous system of the G.I. tract, sometimes considered a third sub division of the autonomic nervous system
Which sub division of the autonomic nervous system is responsible for the fight or flight response
The sympathetic nervous system
Which sub division of the autonomic nervous system is responsible for the rest and digest response
The parasympathetic nervous system
What response would you expect from the pupils with activation of the sympathetic nervous system?
Pupil, dilation to improve vision
What heart rate response would you expect with activation of the sympathetic nervous system?
Increased heart rate
What blood pressure response would you expect with activation of the sympathetic nervous system?
Increased blood pressure
What organs or tissues would you expect to see blood flow diverted to with activation of the sympathetic nervous system?
Blood flow with increased to skeletal muscles and the brain
What organs or tissues would you expect to see blood flow diverted from with activation of the sympathetic nervous system?
Blood flow with decreased to the G.I. tract and kidneys
What heart rate response would you expect with activation of the parasympathetic nervous system?
Decreased heart rate
What blood pressure response would you expect with activation of the parasympathetic nervous system?
Decrease blood pressure
What response would you expect from the Gastro intestinal tract with activation of the parasympathetic nervous system
Increased motility and digestive secretions in the G.I. tract
Where are cell bodies of the preganglionic neurons of the sympathetic nervous system division located?
In the lateral horns of the thoracolumbar spinal cord segments
Where are cell bodies of the preganglionic neurons of the parasympathetic nervous system division located?
In the gray matter of the brain, stem and sacral region of the spinal cord
Which are longer in the sympathetic nervous system, the preganglionic or postganglionic fibers
Postganglionic fibers are longer since they travel from the synapse in the sympathetic chain along the thoracolumbar spinal cord to target the organs
The preganglionic neurons of the sympathetic nervous system, leave the CNS from the thoracic and lumbar spinal segments and synapse, relatively close to the spine and paravertebral or prevertebral ganglia
Which are longer in the parasympathetic nervous system, preganglionic or postganglionic fibers
Preganglionic fibers are longer the preganglionic neurons of the parasympathetic nervous system leave the CNS from the brainstem and sacral, spinal segments and synapse far away closer to their target organs, and consist of a long preganglionic neurons and a short postganglionic neuron
Can the enteric nervous system act independently, or only through sympathetic and parasympathetic nervous system activity?
It can act on its own, and it is heavily influenced by the CNS, with the parasympathetic and sympathetic nervous system’s modulating its activity
Which type of nervous system cell carries electrical signals, and responds to electrical and chemical signals
Neurons are the functional unit of the nervous system and carry electrical signals and responds to both electrical and chemical signals
What is a group of neuron cell bodies in the central nervous system called
Nucleus
What is a group of neuron cell bodies in the peripheral nervous system called?
Ganglion
Which part of the neuron receives signals from other neurons
Dendrites
Which part of the neuron sends signals along to other neurons
Axons
What part of the cell houses the nucleus, and extends out into axons and dendrites
The cell body
What is a synapse?
It is where two neurons come together, and neurotransmitters, are released to send a signal from one neuron to the next
What are Neuro transmitters?
Chemical signals released by the axon of one neuron to relay a signal to the dendrites or cell body of another neuron through a synapse
How does Nero transmitter binding to receptors on the neuron convert the chemical signal into an electrical one?
The binding of Nero transmitters on dendritic receptors allows charged ions to flow in and out of the cell, converting the chemical signal into an electrical signal
How is it an action potential triggered?
If the combined affect of multiple dendrites receiving input changes, the overall charge of the cell enough then it triggers an action potential
How does the action potential propagate a signal?
The action potential is an electrical signal that races down the neurons axon triggering the release of Neuro transmitters on the other end, and further relaying the signal
Do neurotransmitters primarily communicate a signal from the cell to cell or within a cell
From cell to cell neurons use Neuro transmitters as a signal to communicate with each other, but they use the action potential to propagate that signal within the cell
Which ions are found in greater amounts outside of the cell
There are more sodium chloride and calcium ions on the outside
Which ions are found in greater amounts inside the cell
There are more potassium ions, which we just use for negatively, charged and ions on the inside of the cell
What is the resting membrane potential for a neuron?
Approximately -65 to -70 mV
What is a ligand gated ion channel?
An ion channel that opens when a ligand binds to a receptor to allow certain ions flow in depending on the channel
A ligand can be a neurotransmitter
Why does the flow of sodium into the cell cause depolarization?
When a ligand gated sodium ion channel opens sodium flows into the cell the extra positive charge that flows in makes the cell less negative or less polar so that’s why gaining positive charge is called depolarization
What is an excitatory postsynaptic potential?
A net influx of positive charge from the various ions, moving in and out of the cell, making depolarization to the action, potential threshold, value, more likely
The influx of which ion is critical to depolarization to cause an action potential
Sodium
What is an inhibitory postsynaptic potential IPSP
A net influx of negative charge from the various ions, moving in and out of the cell, causing repolarization of the sailmaking depolarization to the action, potential threshold, value less likely
The influx of which ion would make depolarization less likely, and an action potential threshold, value, less likely to be reached
Chloride
What happens when enough EPSP collectively, pushing the membrane potential down to the threshold value
When the membrane potential hits this threshold value, it triggers an action potential
Specifically the opening of voltage gated sodium channels at the axon, hillock and sodium rushes into the cell, the influx of sodium ions, and the resulting change in membrane potential causes nearby voltage gated sodium channels to open up as well, setting off this chain reaction that continues down the entire length of the axon which is called the action potential
What happens once a lot of sodium has rushed across the neuronal membrane, following the firing of an action potential how does depolarization end?
The cell becomes positively charged relative to the external environment, depolarization ends when the sodium channel stops, allowing sodium to flow into the cells
What is the function of the inactivation gate on the voltage gated sodium channels?
The inactivation gate blocks sodium influx after depolarization until the cell re-polarizes, and the channel enters the close state again, which still does not allow sodium into the cell
How are potassium voltage gated channels involved in the action potential?
Potassium voltage gated channels are slow to respond and don’t open until the sodium channels have already opened and become in activated. The result of this is that after the initial sodium rush into the cell potassium flows out of the cell down, its own electrochemical gradient, removing some positive charge and decreasing the effect of sodium depolarization.
What causes the membrane potential to repolarize?
The open potassium channels that stay open after the sodium channels are in activated there is a net movement of positive ions out of the cell, which causes the membrane potential to become more negative and re-polarize
What happens during the repolarization phase?
The cell relies on the sodium potassium pump, which is an active transporter that moves three sodiums out of the cell and to potassium into the cell during the repolarization phase. The cell is in its absolute refractory period since the sodium channels are in activated and won’t respond to stimuli.
What does the absolute refractory period represent
The absolute refractory period occurs during the repolarization phase of the action potential and keeps the action potential’s from happening to close together in time and keeps the action potential moving in one direction
Why is there a period of hyper polarization following an action potential?
Due to the activity of the sodium potassium pump, and the extended opening of the potassium channels, there is a period of overcorrection, where the neuron becomes hyper polarized relative to the resting membrane potential
What does the relative refractory period represent
Following in activation of sodium channels, they go back to their initial close state and for a short period the potassium channels stay open this time point represents the relative refractory period since the sodium channels are closed, but they can be activated since the potassium channels are still open, and the neuron is in the hyper polarize state. It takes a strong stimulus to do so.
When does the neuron return to its resting membrane potential?
Once the potassium channels close, the neuron can return to its resting membrane potential
What allows the action potential to move down the axon more quickly?
Myelination of the axon
What structures form Myelin in the CNS and PNS respectively
Oligodendrocytes in the CNS and Schwann cells in the PNS
What are the nodes of Ranvier?
Non-myelinated areas of the myelinated axon with voltage gated ion channels that allow the charge to move down the axon through saltatory conduction
