Lecture 9 - Nervous System and Neural Tissue Flashcards
3 anatomical components of the nervous system
- Central Nervous System
- Peripheral Nervous System
- Enteric Nervous System
What does the CNS consist of and what is its function?
Brain and spinal cord (connections with the PNS)
It integrates and processes sensory data and motor commands
What does the PNS consist of and what is its function?
Nerves (long neuronal processes interacting with non-neuronal cells/organs) and ganglia (groups of cell bodies outside the CNS)
It is directly connected to the CNS
What does the ENS consist of and what is its function?
Digestive system
Indirectly connected to the CNS via PNS
3 functional classes of the nervous system
- Sensory neurons (receptors) - pass info from outside into the NS
- Interneurons (Integrators) - pass info between other neurons
- Motor neurons (Effectors) - pass info to non neuronal cells
Chemical signals
Release of neurotransmitter into synapses (gaps) between neurons
Electrical signal
Brief changes in the transmembrane potential of the plasma membrane
2 classes of cells in nervous tissue
- Neurons - transmit information
- Neuroglia - play supporting roles
Glial cells
Located in nervous tissue and protect and maintain neurons
4 distinct compartments of a neuron
- Dendrite - receive inputs from other cells
- Cell body/soma - receive inputs & produces proteins
- Axon - transmits action potentials to next cell
- Axon terminals - converts APs to chemical signal
True or False. Information flow within a neuron is unidirectional.
True XD
sensory neuron -> interneuron -> motor neuron
4 ways to classify neuron types
- Multipolar - many dendrites, 1 axon
- Bipolar - 1 dendrite, 1 axon
- Pseudo-unipolar - 1 axon connected to soma, dendrite connect to axon
- Anaxonic - many neurites that act as both dendrite and axon terminal VERY RARE
Somatic Nervous System
Motor neurons innervating skeletal muscle
-> sensory neurons innervating integument and skeletomuscular system
Responsible for voluntary (or involuntary, like reflexes) movement
Visceral/Autonomic Nervous System
Motor (effector) neurons innervating tissues other than skeletal muscle
-> sensory neurons innervating visceral organs
Ependymal cells
Found in the CNS
Line ventricles and secrete cerebrospinal fluid which bathes and cushions the CNS
Microglia
Found in the CNS
white blood cells which perform immune functions for the CNS and also help modify connections between neurons
Myelinating Glia and what are the 2 types?
Provide electrical insulation in both CNS and PNS
-> wrap cellular processes containing myelin (fats and protein) around the axons of neurons to allow electrical signals to travel rapidly and efficiently
-> 2 distinct types: Schwann cells (PNS) and Oligodendrocytes (CNS)
Astrocytes/satellite cells
Astrocyte regulate the extra cellular environment around neurons and also maintain and modify synaptic connections
-> buffer ion concentrations in ECF
-> recycle/buffer neurotransmitters
-> regulate local blood flow (oxygen and nutrient supply)
-> regulate CSF flow
If an axon in the PNS is damaged, can it be repaired?
Yes! It can repair and regrow with the help of the local glia.
- Axon and myelin degenerate and fragment
- Schwann cells proliferate along axon
- Axon grows into injury site along Schwann cell path
- Schwann cells wrap around elongating axon
If an axon in the CNS is damaged, can it be repaired?
No :(. Without active axon terminals, the neuron dies through apoptosis
True or False: New neurons cannot be born into adulthood
True - it a neuron dies, it will not be replaced
What does grey matter consist of?
(Astro/micro)glia
Neuronal somata
Dendrites
Axon terminals
What does white matter consist of?
Myelinated axons (connecting one region to another)
Withdrawal reflex
It is the result of circuits in the spinal cord grey matter to provide spinal reflexes
