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 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
