Nervous Histology (REYNOLDS) Flashcards
What does the nervous system do and how does it do it?
- Thinking
- reasoning
- emotions
- sensation
- respiration
- digestion
- cardiovascular
- movement
- temperature control
How does the nervous system do it?
- An electrochemical signala called an action potential sends messages to the body
What are the 6 components of the nervous system?
Brain, spinal cord, nerves, supporting cells, CNS and PNS
The nervous system can be divided into sensation –> integration —> reaction. Which of the following is responsible for sensation?
A. CNS
B. PNS
B. PNS
The nervous system can be divided into sensation –> integration —> reaction. Which of the following is responsible for integration?
A. CNS
B. PNS
A. CNS
Discuss Neurons in regards to the nervous system:
- Sensory neurons
- Motor neurons
- Interneurons
Sensory (afferent) neurons: signals from receptors to CNS
Motor (efferent) neurons: signals from the CNS to effector tissue
Interneurons: signal between neurons (most numerous of the above)
note: neuroglial cells outnumber all other neurons by 10:1
Discuss Neuroglial cells:
- What are they and what do they do?
- Are there a lot of them?
- What scientist identifies neuroglial cells?
- Alzheimers?
Neuroglial cells:
Cells that:
- provide neuronal support and nutrition
- maintain homeostasis
- forms myelin
- participates in transmission
Outnumber neurons 10:1
Thomas Harvey and Marian Diamond discovered neuroglial cells
Alzheimer’s:
- Caused by a glial cell deficiency
- Glial cells breakdown beta-amalide which is what forms plaques and tangaloids around nervous cells
What are the 4 neuron characteristics?
- Conducting potential
- Longevity (last 100’s of years)
- Amitotic (no new neurons)
- High metabolic rate (use a lot of energy)
Discuss Soma in regards to the nervous system:
Soma
-
Cell body (perikaryon)
- nucleus and most organelles
- Neuronal RER = Nissl body (where somas are found)
- described as “gray matter”
- Bundles of intermediate filaments (neurofibrrils) maintain integrity
- Form clusters:
- In CNS called Nuclei
- In PNS call Ganglia
Discuss Dendrites in regards to the nervous system:
Dendrites
- Most neurons have several
- Receive impulses and carry them toward the soma
- Significantly increases surface area, further increased by dendritic spines
Discuss Axons in regards to the nervous system:
Axons
- Most neurons have ONE
- Long w/ uniform diameter
- Carry action potentials away from soma, originates at axon hillock
- Ends may branch into collaterals
- Terminate at axon terminals (or bulb) ful of synaptic vesicles
Which of the following do most neurons have only ONE of?
A. Dendrites
B. Axons
B. Axons
Most neurons have ONE axon
Most neurons have several dendrites
Which of the following receive impulses and carry them toward the soma?
A. Dendrites
B. Axons
A. Dendrites
Which of the following carry action potentials away from soma?
A. Dendrites
B. Axons
B. Axons
Dendrites = carry impulses to soma
Axons = carry action potentials away from soma
A ______ is a junction where the axon bulb of one neuron interacts with another neuron or an effector organ like a muscle or gland.
Synapse
Which of the following arrows refer to the synaptic cleft?
A. arrow #1
B. arrow #2
C. arrow #3
D. arrow #4
C. arrow #3
Which of the following arrows refer to the postsynaptic neuron?
A. arrow #1
B. arrow #2
C. arrow #3
D. arrow #4
D. arrow #4
Which of the following arrows refer to the presynaptic neuron?
A. arrow #1
B. arrow #2
C. arrow #3
D. arrow #4
A. arrow #1
Discuss Resting Potential in regards to the nervous system:
Resting Potential
- Neurons are highly polarized (-70mV) due to:
- differential permeability to K+ and Na+ and Na+/K+ pump
- the presence of intracellular impermeable anions (like negatively charged proteins)
- Changes in VM allow for AP generation
note: intracellular is (-) and extracellular is (+)
Discuss Graded Potentials in regards to the nervous system:
Graded Potentials:
Consider a stimulus at the dendrite of a neuron:
- Leaky Na+ channels open allowing Na+ into the cell
- As Na+ comes in, the resting potential becomes more and more positive.
- Some of the Na+ leaks out of the membrane and decrease the degree of polarization
- As you move away (distance) from the point of impact, the amplitude of the stimulus will decrease (similar to throwin a stone into a pond causing ripples)
- Voltage-gated channels are only found in abundance on the axon hillock and axolemma (plasma membrane associated with the axon)
- All or none action potential
- GP amplitude maybe of almost any size - it simply depends on how much Na+ originally entered
- If the initial GP is sufficient, it will spread to the axon hillock where voltage-gated channels allow for AP.
- The AP will travel down the axon to the synaptic knob and cause neurotransmitter release (exocytosis)
- If the potential change is subthreshold, then no AP will ensue and nothing will happen
Which of the following types of neurons is associated w/ sensory neurons (e.g. taste)?
A. Unipolar neurons
B. Bipolar neurons
C. Multipolar neurons
D. All of the above
E. None of the above
A. Unipolar neurons
Unipolar neurons = sensory neurons (taste)
Bipolar neurons = special senses (sight)
Multipolar = most common; motor neurons and interneurons
Which of the following types of neurons is associated w/ special senses?
A. Unipolar neurons
B. Bipolar neurons
C. Multipolar neurons
D. All of the above
E. None of the above
B. Bipolar neurons
Unipolar neurons = sensory neurons (taste)
Bipolar neurons = special senses (sight)
Multipolar = most common; motor neurons and interneurons
Which of the following types of neurons is associated w/ motor neurons and interneurons?
A. Unipolar neurons
B. Bipolar neurons
C. Multipolar neurons
D. All of the above
E. None of the above
C. Multipolar neurons
Unipolar neurons = sensory neurons (taste)
Bipolar neurons = special senses (sight)
Multipolar = most common; motor neurons and interneurons
Which of the following is the most common type of neuron?
A. Unipolar neurons
B. Bipolar neurons
C. Multipolar neurons
D. All of the above
E. None of the above
C. Multipolar neurons
List the 6 types of glial cells?
- Identify where each of the 6 glial cells are located?
- CNS/PNS
Astrocytes = CNS
Oligodendrocytes = CNS
Microglia = CNS
Ependymal cells = CNS
Schwann cells = PNS
Satellite cells = PNS
Which of the following is the largest and most numerous?
A. Astrocytes
B. Oligodendrocytes
C. Microglia
D. Ependymal cells
E. Satellite cells
F. Schwann cells
A. Astrocytes
Astrocytes:
- largest and most numerous
- controls ionic environment
- assists in the migration of developing neurons
- maintains blood-brain barrier
All of the following are true regarding astrocytes EXCEPT:
A. Larges and most numerous
B. Specialized immune cells derived from WBCs that act as macrophages of CNS
C. Controls ionic environment
D. Assists in the migration of developing neurons
E. Maintains blood-brain barrier
B. Specialized immune cells derived from WBCs that act as macrophages of CNS
Microglia:
- specialized immune cells derived from WBCs that act as macrophages of CNS
- clear unwanted cellular debris caused by CNS
All of the following are associated with the CNS EXCEPT:
A. Astrocytes
B. Oligodendrocytes
C. Schwann cells
D. Microglia
E. Ependymal cells
C. Schwann cells
PNS = Schwann cells and Satellite cells
All of the following are associated with the CNS EXCEPT:
A. Astrocytes
B. Oligodendrocytes
C. Ependymal cells
D. Microglia
E. Satellite cells
E. Satellite cells
PNS = Schwann cells and Satellite cells
Which of the following produce and maintain the insulating myelin sheaths that surround many local neurons?
A. Astrocytes
B. Oligodendrocytes
C. Microglial cells
D. Ependymal cells
E. Satellite cells
F. Schwann cells
B. Oligodendrocytes
Oligodendrocytes: myelinate many local neurons in CNS
Schwann cells = can myelinate a single neuron in the PNS
Which of the following myelinate a portion of a single axon?
A. Astrocytes
B. Oligodendrocytes
C. Microglial cells
D. Ependymal cells
E. Satellite cells
F. Schwann cells
F. Schwann cells
Oligodendrocytes: myelinate many local neurons in CNS
Schwann cells = can myelinate a single neuron in the PNS
Which of the following are specialized immune cells derived from WBC that act as the macrophages of the CNS?
A. Astrocytes
B. Oligodendrocytes
C. Microglial cells
D. Ependymal cells
E. Satellite cells
F. Schwann cells
C. Microglial cells
Which of the following form the lining of fluid-filled ventricles of the CNS?
A. Astrocytes
B. Oligodendrocytes
C. Microglial cells
D. Ependymal cells
E. Satellite cells
F. Schwann cells
D. Ependymal cells
note: ependymal cells are kind of like epithelial cells… they line the fluid-filled ventricles of the brain
Ependymal cells:
- Cuboidal/Columnar cells. Source of cerebrospinal fluid within ventricles of brain
- Circulates CSF, often by ciliary movement
- no basement membrane
Which of the following is the source of CSF within the ventricles of the brain?
A. Astrocytes
B. Oligodendrocytes
C. Microglial cells
D. Ependymal cells
E. Satellite cells
F. Schwann cells
D. Ependymal cells
Which of the following is associated to cerebrospinal fluid (CSF)?
A. Astrocytes
B. Oligodendrocytes
C. Microglial cells
D. Ependymal cells
E. Satellite cells
F. Schwann cells
D. Ependymal cells
Ependymal cells = CSF
Which of the following are small cells that surround neuronal cells in the ganglia outside of the CNS?
A. Astrocytes
B. Oligodendrocytes
C. Microglial cells
D. Ependymal cells
E. Satellite cells
F. Schwann cells
E. Satellite cells
Which of the following provide structural and metabolic support for neurons outside of the CNS?
A. Astrocytes
B. Oligodendrocytes
C. Microglial cells
D. Ependymal cells
E. Satellite cells
F. Schwann cells
E. Satellite cells
Which of the following myelinate a portion of a single axon in the PNS?
A. Astrocytes
B. Oligodendrocytes
C. Microglial cells
D. Ependymal cells
E. Satellite cells
F. Schwann cells
F. Schwann cells
Which of the following has the fastest rate of AP conduction?
A. an unmyelinated axon with a large diameter
B. a myelinated axon with a small diameter
C. an unmyelinated axon with a small diameter
D. a myelinated axon with a large diameter
E. all of the above would exhibit the same rate of AP conduction
D. a myelinated axon with a large diameter
Soma or celly bodies located in the CNS are called ______.
A. Nuclei
B. Ganglia
A. Nuclei
Soma or celly bodies located in the PNS are called ______.
A. Nuclei
B. Ganglia
B. Ganglia
Nuclei = CNS
Ganglia = PNS
Discuss Meninges: three layers of supporting tissue (DCCTRA):
- Dura Mater
- Arachnoid
- Pia Mater
Dura Mater:
- Dense CT continuous w/ periosteum
- Simple squamous epithelium along internal surface
Arachnoid:
- Trabeculae attach to pia mater and create subarachnoid space
- Hydraulic cushioning
- CT with no blood v.
Pia Mater:
- Loose/Dense CT (collagen, elastic fibers, fibroblasts) w/ many blood vessels
- Neuroglial process separate pia mater from neural components, which glial cell does this?
- astrocytes
Which of the following is dense CT continuous w/ periosteum?
A. Dura Mater
B. Arachnoid
C. Pia Mater
D. All of the above
A. Dura Mater
Dura Mater:
- Dense Ct continuous w/ periosteum
- simple squamous epithelium along internal surface
Which of the following is Loose/Dense CT (collagen, elastic fibers, fibroblasts) w/ many blood vessels?
A. Dura Mater
B. Arachnoid
C. Pia Mater
D. All of the above
C. Pia Mater
________ separate pia mater from neural components.
Neuroglial processes
Neuroglial processes separate pia mater from neural components. Which glial cell does this?
Astrocytes
Which of the following is CT with no blood v. that acts as a Hydraulic cushioning?
A. Dura Mater
B. Arachnoid
C. Pia Mater
D. All of the above
B. Arachnoid
(T/F)
The brain and spinal cord have a lot of CT and are gel-like.
False
The brain and spinal cord have very little CT and are gel-like
Discuss each of the following:
- Gray Mater
- White Mater
Gray Mater = nerve cell bodies
White Mater = myelinated axons associated neuroglial cells (oligodendrocytes)
Discuss the Cerebellum:
- Cortex
- Medulla
Cerebellum:
Cortex that contains outer molecular layer and inner granular layer interposed with Purkinje cells
Medulla of white matter and glial cells
Discuss the Spinal Cord:
- Extends from ______ into ______
- Terminates between _____ and _____
- Functions:
- What is Peripheral White Matter composed of?
- What is Central Gray Matter composed of?
Spinal Cord
- Extends from base of skull into vertebral canal
- Terminates between 1st and 2nd lumbar vertebrae (L1/L2)
-
Functions:
- Center for thousands of reflex arcs
- Provides for communication between brain and periphery of body
- What is Peripheral White Matter composed of?
- Large multipolar myelinated axons
- What is Central Gray Matter composed of?
- Non-myelinated cell bodies, dendrites and non-myelinated axons (soma primarily)
Which of the following contain myelination?
A. White matter
B. Gray matter
A. White matter
The Peripheral Nervous System (PNS) is composed of all of the following EXCEPT:
A. Nuclei
B. Nerve fibers
C. Nerves
D. Ganglia
A. Nuclei
Nuclei = CNS
PNS:
- Nerve fibers: individual nerve cells (axons)
- Nerves: bundles of nerve fibers (axons)
- Ganglia: swellings associated w/ nerves; location of neuron cell bodies
Discuss each of the following in regards to the PNS:
- Nerve fibers
- Nerves
- Ganglia
PNS
Nerve fibers: individual nerve cells (axons)
Nerves: bundles of nerve fibers (axons)
Ganglia: swelling associated w/ nerves; location of neuron cell bodies
(T/F)
The nervous system is composed of 31 pairs of cranial nerves oand 12 pairs of spinal nerves.
False
The nervous system is composed of 12 cranial nerves and 31 spinal nerves.
