Learning Outcome 7 Flashcards
The two main systems of the nervous system are the: ___________and __________nervous systems.
Central and Peripheral
The central nervous system (CNS) consists of the_________ and___________.
Brain and Spinal Cord
The peripheral nervous system consists of all nervous tissue outside of the CNS; this
includes _________and _________. Each nerve follows a defined path and serves a specific region of the body.
Cranial and Spinal Nerves
All body systems need to be kept within certain parameters in order to maintain life; the ______________ provides the regulatory function.
Nervous System
Glial Cell
- One of a variety of cells that provide a framework of tissue that supports the neurons and their activities.
- Non Excitable
- Support/Protect Neurons
Neuron
- Are Cells
- Communicative function of the nervous system
- Excitable, Functional unit of the nervous sytem
Nervous System 3 Main Functions
- Sensation
- Integration
- Response (Motor)
Sensory: perception, or sensing, of changes in both ____________ and ______________ environment. This information is then sent to the _____________ and ___________ through cranial and spinal
nerves. In other words, the perception of internal and external changes (stimuli).
- Internal and External
- Brain and Spinal Cord
Peripheral Nervous System includes 3 Categories
- Enteric
- Somatic
- Autonomic
Enteric
The enteric nervous system (ENS) is responsible for controlling the smooth muscle and glandular tissue in your digestive system. It is a large part of the PNS, and is not dependent on the CNS.
Somatic
- The somatic nervous system (SNS) is responsible for conscious perception and voluntary motor responses.
- Some somatic motor responses are reflexes, and often happen without a conscious decision to perform them. If your friend jumps out from behind a corner and yells “Boo!” you will be startled and you might scream or leap back.
Autonomic:
_______________ neurons that convey
information from autonomic sensory
receptors, located primarily in visceral
organs, to the CNS
Afferent (sensory)
Autonomic:
_______________neurons that conduct
nerve impulses from the CNS to
smooth muscle, cardiac muscle, and
glands. The motor responses are not
normally under conscious control, and
are therefore considered __________
- Efferent (Motor)
Autonomic
- The autonomic nervous system (ANS) is responsible for involuntary control of the body, usually for the sake of homeostasis (regulation of the internal environment).
- Sensory input for autonomic functions can be from sensory structures tuned to external or internal environmental stimuli. The motor output extends to smooth and cardiac muscle as well as glandular tissue. The role of the autonomic system is to regulate the organ systems of the body, which usually means to control homeostasis.
Autonomic Division
- Sympathetic (Fight or flight)
- Parasympathetic (Rest & Digest)
Functional Unit of nervous system
Neurons (Nerve Cells)
What are four properties of neurons?
-Electrical signals/communicating
-produce movements in response to those stimuli
-Inducing thought processes within the brain
-structure, or shape. The three-dimensional shape of these cells makes the immense numbers of connections within the nervous system possible.
_____________________ the part of the neuron that contains the
nucleus and organelles
Cell Body (soma)
the process that propagates nerve impulses
toward another neuron, muscle fiber, or gland cell
Axon?
the highly branched receiving, or input,
portions of a neuron
Dendrites
a multilayered lipid and protein covering for
axons produced by neuroglia . Their presence greatly increase the speed
of nerve impulse conduction
Myelin Sheath
site of communication between two neurons
or between a neuron and an effector cell
Synapse or synaptic cleft?
gaps in the myelin sheath of an axon. These
sections allow for the “jumping” action of nerve conduction – increasing
the speed
Nodes of Ranvier
interstitial fluid-filled space separating two
neurons, or a neuron and muscle cell, or gland
Synapse or synaptic cleft?
chemicals which helps with conducting nerve
impulses between presynaptic and post-synaptic neurons, through the
synaptic clef
Neurotransmitters?
Label a Neuron
3 Types of Neurons (Axon Shape)
- Unipolar - have only one process emerging from the cell. True unipolar cells are only found in invertebrate animals, so the unipolar cells in humans are more appropriately called “pseudo-unipolar” cells. Invertebrate unipolar cells do not have dendrites. Human unipolar cells have an axon that emerges from the cell body, but it splits so that the axon can extend along a very long distance.
- Bipolar- have two processes, which extend from each end of the cell body, opposite to each other. One is the axon and one the dendrite. Bipolar cells are not very common. They are found mainly in the olfactory epithelium (where smell stimuli are sensed), and as part of the retina.
- Multipolar - neurons are all of the neurons that are not unipolar or bipolar. They have one axon and two or more dendrites (usually many more). (MOST COMMON)
3 Functional Classifications of Neurons
- Afferent (Sensory) - Info from receptors to the CNS Ex) if you burn your hand, sensory neurons send signals to your brain to let you know you feel pain.
- Efferent (Motor) - carry information from the CNS to the body’s muscles, organs, and glands. Motor neurons control all of the body’s movements.
- Interneurons (Association) - connect other neurons within the CNS. involved in processing information in simple reflex circuits and more complex brain circuits.
Where are the cell bodies located in both types of neurons?
Afferent (sensory) - Ganglia
Efferent (Motor) - Brain stem/Spinal Cord
What are the two types of sensory neurons? **
peripheral or visceral
What are the two types of motor neurons? Where are the cell bodies for the somatic motor neurons? *******
Upper and lower
What type of cells are non-excitable and support and protect neurons? What are the four different types in CNS? What are each of their functions?
- Neuroglia (Glial Cells)
1. Astrocyte - Support
2. Oligodendrocyte - Insulation/Myelination
3. Microglia- Immune surveillance and phagocytosis
4. Ependymal cell - Creating CSF
What are the two types of glial cells found in the peripheral nervous system? Which type of glial cell produces myelin in the PNS?
- Satellite cell - Support
- Schwann cell - Insulation, myelination
What is myelin
-Lisoprotein (Looks white)
-Insulates axons
-Allows for rapid signalling
Explain how myelination differs in the CNS and PNS
PNS - Myelin sheath formed by schwann cells, wrapping around an axon one segment at a time. Covers each segment with many layers of plasma membrane.
CNS - Oligodendrocytes produce myelin by covering several segments of several axons at the same time. (NO NEUROLEMMA/NO regeneration of axon nerve fibers. Injury is permanent)
Nodes of Ranvier
-Gaps between schwann cells
-Increase speed of nerve implulses
Neurolemma
- Final/outer layer of Schwann Cell
- Contains cytoplasm and nucleus (allows for growth and regeneration of axon nerve fibers)
What is the difference between white matter and grey matter? Where are they both located in the CNS and in the PNS?
White Matter - Myelinated Axons, Tracts in CNS, Nerves in PNS
Grey Matter - Unmyelinated Axons, Cerebral cortex and nuclei in CNS, Ganglia in PNS
ligand-gated channel
opens because a signaling molecule, a ligand, binds to the extracellular region of the channel. This type of channel is also known as an ionotropic receptor because when the ligand, known as a neurotransmitter in the nervous system, binds to the protein, ions cross the membrane changing its charge
mechanically gated channel
opens because of a physical distortion of the cell membrane. Many channels associated with the sense of touch (somatosensation) are mechanically gated. For example, as pressure is applied to the skin, these channels open and allow ions to enter the cell. Similar to this type of channel would be the channel that opens on the basis of temperature changes, as in testing the water in the shower
voltage-gated channel
is a channel that responds to changes in the electrical properties of the membrane in which it is embedded. Normally, the inner portion of the membrane is at a negative voltage. When that voltage becomes less negative, the channel begins to allow ions to cross the membrane
leakage channel
is randomly gated, meaning that it opens and closes at random, hence the reference to leaking. There is no actual event that opens the channel; instead, it has an intrinsic rate of switching between the open and closed states. Leakage channels contribute to the resting transmembrane voltage of the excitable membrane (
resting membrane potential
measured at -70 mV
-Voltage difference across the cell membrane at rest
Membrane Potential
The standard is to compare the inside of the cell relative to the outside, so the membrane potential is a value representing the charge on the intracellular side of the membrane based on the outside being zero,
A localized collection of neuron cell bodies is referred to as a nucleus in the CNS and as a ganglion in the PNS
A bundle of axons is referred to as a tract in the CNS and as a nerve in the PNS
Gray matter is where nuclei are found and white matter is where tracts are found. In the PNS, ganglia are basically gray matter and nerves are white matter.
The somatic nervous system (SNS) is responsible for functions that result in moving skeletal muscles. Any sensory or integrative functions that result in the movement of skeletal muscle would be considered somatic
Voluntary
The autonomic nervous system (ANS) is responsible for functions that affect cardiac or smooth muscle tissue, or that cause glands to produce their secretions. Autonomic functions are distributed between central and peripheral regions of the nervous system
Involuntary
enteric nervous system
responsible for controlling the digestive organs, The enteric nervous system is exclusively found in the periphery because it is the nervous tissue in the organs of the digestive system.
Neurons are the cells responsible for communication through electrical signals. Glial cells are supporting cells, maintaining the environment around the neurons.
Neurons are polarized cells, based on the flow of electrical signals along their membrane. Signals are received at the dendrites, are passed along the cell body, and propagate along the axon towards the target, which may be another neuron, muscle tissue, or a gland. Many axons are insulated by a lipid-rich substance called myelin. Specific types of glial cells provide this insulation.
Several types of glial cells are found in the nervous system, and they can be categorized by the anatomical division in which they are found. In the CNS, astrocytes, oligodendrocytes, microglia, and ependymal cells are found
Astrocytes
important for maintaining the chemical environment around the neuron and are crucial for regulating the blood-brain barrier
Oligodendrocytes
the myelinating glia in the CNS
Microglia
act as phagocytes and play a role in immune surveillance
Ependymal cells
Responsible for filtering the blood to produce cerebrospinal fluid, which is a circulatory fluid that performs some of the functions of blood in the brain and spinal cord because of the BBB. I
.In the PNS, satellite cells are supporting cells for the neurons, and Schwann cells insulate peripheral axons.
Resting Membrane Potential
Action Potential
