Nervous Tissue
How is the axon terminal recognized?
- Lots of secretory vesicles (neurotransmitters) and mitochondria
What are 5 different ways that Glial Cells support neurons?
1. Biochemical (speed up impulses) 2. Structural (physical support) 3. Nutritive (growth and maintenance) 4. Immune (scavenge toxins, debris) 5. CSF Production
General functions of the nervous system (4)
1. Detect and analyze sensory output (PNS) 2. Coordinate body activities 3. Store experiences 4. Learning and memory (based on storing experiences)
What are the 3 layers of CT that cover peripheral nerves?
1. Endonerium - Surrounding individual nerve fibers 2. Perineurium - Surrounding a group of fibers (fascicle) 3. Epineurium - Surrounding the whole nerve
Name the 3 layers that separate blood cells from the CSF
1. Simple cuboidal (ependymal) cells 2. Pia mater 3. Endothelial cells of capillaries
What can pass the blood brain barrier?
Alcohol, medication such as for Parkinson's (Matildopie)
The part which passes the CSF into the dural sinuses
Arachnoid Villi/Granulation
- This part of the neuron sends impulses away from the cell body - It is considered an efferent fiber
Axon
The _____ _________ is the end part of the axon that delivers the message (chem/elec) to the next cell (another neuron, muscle fiber, gland cell)
Axon Terminal
Is there a max # of dendrites you can have?
No. You can have multiple.
The nervous system is a _____________ and divided into 2 parts: the ______ and the ________
continuum; PNS (peripheral nervous system); CNS (central nervous system)
How do we remove excess CSF that we have accumulated? How does aging slow down this process?
- Arachnoid Granulation (unidirectional channel) so CSF can get into the blood (not vice versa) into the Sub-Arachnoid Space - @ 70-80 years, Arachnoid granulation becomes calcified -> increased pressure -> hydrocephalis (can compress the brain and destroy the nervous system)
Can you spot the Dura (tough) mater and the arachnoid?
- Dura mater: Protects CNS from MECHANICAL TRAUMA (Dense CT) - Arachnoid: Circulation of CSF (loose CT)
- From the blood to the brain, what is the order of the different layers? - What prevents passage of material between the endothelial cells?
- Endothelial cells of the capillaries, basement membrane, astrocytes - Tight junctions (not as well developed in newborns)
Schwan Cells function
- Lay down myelin sheet, nourishment, act as macrophage - Can only myelinate 1 short segment of the nerve fiber - Usually 1 cell per 1-2mm segment 1 axon. Discontonuous -> "Nodes of Ranvier"
Can you spot the: dura mater, dense irregular CT, arachnoid, pia mater, sub arachnoid space, the central nervous system. - What indicates loose CT? - Where is the subdural space? Can it be seen in a real life cell?
- Lots of cells indicate the loose CT - The subdural space is labeled SDS. It can't be seen in a real life cell, it is a potential space.
- In the image, can you spot the: nucleus (is it euchromatic or heterochromatic?), nucleolus, Nissl substance (composed of ______ and ________), axon - Classify this neuron picture
- Nucleus is EUCHROMATIC (b/c very active) - Rough Endoplasmic Reticulum and ribosomes - Axon stained lighter (because it sits by the Golgi complex) - Neuron is multipolar
Myelination for CNS
- Oligodendrocyte - 1 oligodendrocyte for even up to 60 nerve fibers
Image Notes
- Pia major carries the blood vessels - Chorroid Plexus (capillary networks formed by pia major) - Ependymal cells - Star -> space of venricle - CSF (cerebral spinal fluid) is extracted from blood plasma and filtered by the ependymal and pia major
The neuron is composed of the following parts:
- Soma (cell body or perikaryon) - Dendrites (receptive region) - Axon (conductive region) - Axon terminal (synaptic ending)
What is the pia mater?
- The innermost layer of the CNS. - VASCULAR layer that carries blood vessels into the CNS (LOOSE CT) - Nutrition of the CNS, carries the blood
What is the arachnoid?
- The intermediate layer of the CNS - Layer of LOOSE CT involved in CSF (cerebral spinal fluid) CIRCULATION (nothing else) - Contains the "Arachnoid Villi/Granulation" which passes the CSF into the DURAL SINUSES - Contains the "Sub-Arachnoid Space" which contains the CSF and is the space between the arachnoid and pia mater.
What is the dura mater?
- The outermost layer of the CNS - Layer of DENSE CT - Protects CNS against MECHANICAL TRAUMA - Sometimes split into 2 layers, with a space in between (the DURAL SINUSES -> collects veinous blood of CNS)
Un-myelinated Axon
- Up to 10 axons "swallowed" by a single Schwann cell (for PNS) - Axons continue to communicate with extracellular space (E)
Aggregations of cell bodies outside the CNS are called _________ (________/________)
- White matter most superficial (as opposed to in the cerebrum/cerebellum)
What can destroy the tight junctions that prevent material from moving between the endothelial cells?
-Toxins such as bile (in blood circulations) -> jaundice (impaired liver function) -> Fix (put person under UV)
The synapse has _ parts. They are: __________, _________, __________
3; pre-synaptic terminal (delivers NT), synaptic cleft (intercellular space), post-synaptic membrane (receives NT) - Synapses happen between the axon or dendrite and the soma/dendrite/axon (ex. axo-somatic synapse, axo-dendrite synapse)
The blood brain layer is made of _ layers that __________ blood cells from neurons
3; separate
How many cerebral ventricles are there?
4
How many types of fiber types are there? What are the 2 types?
Myelinated, unmylinated
The Central Nervous System is composed of:
Brain, brain stem, and spinal cord
How are neurons classified?
By the # of processes, and its shape
Which part of the nervous system is responsible for processing information?
Central Nervous System
CSF aka _____ _________
Choroid plexus - 3 layers involved in production and secretion of CSF within the cerebral ventricles
Can you spot the: axon terminal, pre synaptic membrane, synaptic cleft, mitochondria, cell membrane, post synaptic membrane, - What is the dark patch?
Dark patch: collection of receptors
- This part of the neuron is the receptive region of the cell that conducts impulses towards the cell body. - It can be classified as an afferent fiber
Dendrite
Nerve fiber is a general term for
Dendrite or Axon
Nervous tissue develops from the _______________
Ectoderm
Name 4 types of Glial Cells
Ependyma, Astrocyte, Microglia, Oligodendrocyte
Peripheral ganglia are basically occupied by ___________ and ___________ cells
Ganglionic; satellite
______ Cells: Non-conducting cells that assist and SUPPORT NEURONS/NERVOUS TISSUE in different ways
Glial
Nervous tissue can be classified as _______ _______ (composed of mostly _______ ______), and ______ ________ (composed of mostly ________ ________)
Grey matter; nerve cells; white matter; nerve fibers
In the cerebrum or the cortex, is which tissue is more superficial, grey or white?
Grey. (Grey matter can be different colors because it is occupied by a different # of neurons)
Where are ganglia mostly found?
In the spinal cord. - Also given names such as spiral ganglia (because part of the spinal cord)
Ganglionic cells
Large round neurons (mostly pseudo-unipolar)
The CNS is covered by 3 layers of ______________. They are (from inside out):
Meninges; pia mater; arachnoid; dura mater
What are some of the contents of an axon?
Mitochondria, SER (not RER), microtubules for axonal support (move vesicles and proteins, recycle structural components)
What are some contents of dendrites?
Mitochondria, smooth ER, microtubules, neurofilaments, LACK a Golgi complex
Can you spot the myelin sheath and the axon and the nodes of ranvier?
Myelin sheath: foamy white substance
These cells are among the most active cells, and actively produce protein
Neurons
What are the 2 types of cells in the nervous tissue?
Neurons, and Glia
Compare and Contrast Neurons and Glia:
Neurons: excitable cells, neuro transmission Glia cells: Non excitable, enhance efficiency of transmission
How many axons can you have on a neuron?
Only 1
Where can you find satellite cells?
Only in the ganglia
_____________ (________ or _________) are bundles of nerve fibers (______/______) that are wrapped by connective tissue that's present in ______ different levels
Peripheral; somatic; visceral; axon/dendrite; 3
Function Ependyma
Produce CSF
Function Oligodendrocyte
Produce and lay down myelin (electrically insulates the nerve fibers) in the CNS ONLY
What are 2 specific types of neurons? (Hint: both start with P)
Pyramidal, and Purkinje (in cerebellum)
Function Astrocyte
Receive nutrients from blood (capillaries), process, scan, and give it to the neurons
Function of satellite cells
SURROUND and SUPPORT the ganglionic cells and form single layer of flat cells -> modified Schwann cells - Derivatives of glial cells - Note: white space is an artifact (not seen in real life)
For the PNS, what wraps around the nerve fiber
Schwann Cells
Function Microglia
Smallest glial cell. Macrophages of the nervous system.
The peripheral nervous system can be divided into the __________ and __________/__________ components.
Somatic; autonomic/visceral
If the sensory output is external, then this is considered the ________ environment. The information is passed to the _________ muscle
Somatic; skeletal
The Peripheral Nervous System is composed of:
Spinal, cranial, and autonomic nerves
The space between the arachnoid and the pia, and contains the CSF.
Sub-arachnoid space
Which part of the nervous system is used to distribute information?
The Peripheral Nervous System
Clusters of cell bodies within the _____ ________ of CNS, are known as __________ (______/motor/_______)
White matter; Nuclei; sensory/motor/autonomic
Are non-myelinated fibers both in the CNS and the PNS?
Yes
If the sensory output is internal, then this is considered the _______________/__________ environment. The information is passed to the ________ muscle and ___________
autonomic/visceral; smooth; glands
The perikaryon is the trophic _______ of the cell and contains:
centre; nucleus, PROMINENT nucleolus, cytoplasm, cytoskleton, organelles, golgi apparatus, mitochondria, Nissl substance (ribosome-rich RER)
- Neurons can be classified as:
multipolar, bipolar, and pseudo unipolar
Myelin is a __________ ________ electrically __________ the nerve fibers
phospholipid layer; insulating