Intro to Nervous System Flashcards
Describe the components of a chemical synapse
The presynaptic ending that contains neurotransmitters. The synaptic cleft between the two nerve cells. The postsynaptic ending that contains receptor sites.
What does axodendritic mean? Axosomatic?
- Axodendritic: axon to dendrite, Most common
- Axosomatic: axon to cell body
What is an electric synapse
gap junctions between neurons
What is tic doulouroux?
Extremely painful chronic condition , A blood vessel compresses the trigeminal nerve causing loss of myelination of sensory nerve fibers, The lack of insulation allows touch and pain nerve fibers to cross-talk, Touch is perceived pain by brain
How does regeneration occur in the PNS? Does it occur in the CNS? Explain.
- In the PNS: If only axon is destroyed (not cell body), Schwann cells help axon sprout through a regeneration tube, There can be partial recovery
- In the CNS: historically no, but possibly in hippocampus and olfactory bulb
Using your own example, indicate the general flow of stimulation through the nervous system
- SENSORY INPUT: fly lands on arm and bends one or more hairs activating neurons wrapped around hair root
- INTEGRATION: activation of neurons processed by brain and/or spinal cord
- MOTOR RESPONSE: muscles of your other arm are activated so you can reach over and brush off fly
Compare the CNS and PNS
- CNS: Integration and interpretation of sensory input, Dictates motor response, Brain and spinal cord
- PNS: Neurons transport sensory input toward CNS & motor output away from CNS, Includes cranial and spinal nerves
Visceral and somatic nervous systems are involved with which parts of the body?
Visceral functions: organs within body cavities
Somatic functions: all other structures, esp. muscles and skin
Compare neurons and neuroglia
- Neurons: Able to respond to a stimulus and carry and electrical impulse, Excitable cells
- Neuroglia: Help neurons function more efficiently, Non-excitable cells
Functions of Astrocytes
- Most abundant glial cell
- Surround capillaries and neurons
- Forms the blood brain barrier
- Regulate neurotransmitter levels
- Increase blood flow to active brain regions
- Produce BDNF (brain-derived trophic factor) which promotes neural growth
Functions of Microglia
- Smallest and least abundant glial cell in CNS
- Macrophages
- Consume microorganisms and dead neurons
- Originate in red bone marrow and migrate to CNS during fetal development
Functions of Ependymal Cells
- Form simple epithelium that lines hollow portions of brain and spinal cord
- Have cilia that help circulate cerebrospinal fluid in CNS
Functions of Oligodendrocytes
- form Myelin sheaths in the CNS
- have many processes that wrap around many different axons
Functions of Satellite Cells
- In PNS
- Surround cell bodies
- Prevent “crossover” when many cell bodies are crowded together
Functions of Schwann Cells
Surround axon, form myelin sheaths in PNS
Which cells produce myelin in the PNS? CNS?
- CNS: Oligodendrocytes
- PNS: Schwann Cells
What do myelin sheaths do?
increase speed of action potential down axon, prevent cross talk of axons
The spaces on the axons that are between myelin sheaths are called:
Node of Ranvier
Briefly describe multiple sclerosis
Autoimmune disease where myelin is attacked in CNS
- Oligodendrocytes are destroyed
- Plaques develop when myelin is destroyed
- Inflammation develops and can damage axons
What shapes do efferent neurons, afferent neurons, and interneurons have? Where are these
different neurons located?
Efferent: Motor neuron, multipolar CNS
Afferent: Sensory, Unipolar CNS
Interneurons: 99% of neurons, CNS, Multipolar
