Chapter 9 - Nerve Tissue Flashcards
1
Q
What is the function of nervous tissue?
A
- reception, processing and transmission of electrical and chemical signaling
2
Q
How many neurons do humans have?
A
> 100 bullion
3
Q
What are the functional divisions of the nervous system?
A
- autonomic - automatic responses, generally outside of your control
- voluntary - things we control
4
Q
What are the anatomical divisions of the nervous system?
A
- CNS - brain and spinal cord
- PNS - nerves and ganglia
5
Q
What is the PNS mainly responsible for?
A
- afferent(sensory) nerves receive info from the environment
- touch, vision, audition
6
Q
Neurons in the sensory ganglia have a slightly diff histological appearance than those in the CNS. True or false?
A
True
7
Q
What is the basic circuitry of an impulse?
A
- PNS axons have synapses in the sensory ganglia or CNS, info is then processed, then a response is then sent back into the PNS from the efferent neurons
8
Q
White matter
A
- axons/dendrites, neuroglia
- white due to myelin sheaths on some axons
- appear clear on a slide bc myelin is destroyed during fixing/staining
9
Q
Gray matter
A
neurons cell bodies and neuroglia
10
Q
Basic properties of neurons
A
- irritability, propagation of impulses
- very large cell body w/ prominent nucleus and nucleolus
- much larger than glial cells
- ribosomes are present
- nonmitotic
11
Q
What are the cell processes of neurons?
A
- axons - conduct signals (can be very long, and are (un)myelinated)
- dendrites - increase surface area, receive signals from other neurons
12
Q
What organelles are abundant in neurons? What type are well developed?
A
- RER, golgi
- possess ribosomes, which are useful for making NTs
13
Q
What becomes visible in aged neurons? What is it?
A
- lipofuscin
- brownish pigment consisting of secondary lysosomes that have digestive material that have not been released from the cell
14
Q
Where do neurons communicate with each other?
A
- synapses
- place of chemical signaling through NTs
15
Q
What special stains are used for neurons?
A
- Nissl stains - rough ER
- osmium stain - myelin sheath
- silver stain
16
Q
What are the types of neurons?
A
- bipolar - 1 axon, 1 dendrite - located in retina, olfactory cells, cochlear and vestibular ganglia
- multipolar - 1 axon, many dendrites that branch from soma - most numerous
- unipolar - soma w/ single process that branches immediately - dorsal root ganglia and cranial ganglia
17
Q
Where are neuroglia more numerous than neurons?
A
- CNS
18
Q
Basic traits of neuroglia
A
- structural and nutritional support for neurons
- role in defense system of CNS
- most will die w/o glia
- do not transmit APs
- do not form synapses
- capable of mitosis
- all express glial fibrillary acidic protein (GFAP) - unique to glial cells (markers for immunohistochemcial staining)
19
Q
Oligodendrocytes
A
- glial cell in CNS
- makes myelin sheath
- allows for saltatory conduction of APs
20
Q
Astrocytes
A
- glial cell in CNS
- generally star shaped, most numerous of the glial cells
- necessary for controlling extracellular movement
- ## have end feet that envelop capillaries in the CNS - help to form BBB - protects brain
21
Q
BBB
A
- blood brain barrier
- composed of endothelial cells (tight junctions) and astrocyte processes
- restricts passage of molecules and pathogens into brain tissue
22
Q
Ependymal cells
A
- glial cells in CNS
- form and assist in circulation of CSF
- line ventricles of brain and central canal of spinal cord
- usually cuboidal
23
Q
Microglia
A
- glial cells in CNS
- phagocytic cells that are derived from monocytes
- short, branched processes
24
Q
Schwann cells
A
- glial cells in PNS
- form myelin sheaths in PNS, wrap numerous times around axons
- provides support to unmyelinated axons
- space btwn adjacent schwann cells are nodes of ranvier
25
Q
CT in PNS
A
- peripheral nerves are large bundles of nerve fibers (axons)
- appear white due to myelin
26
Q
Epineurium
A
- external layer of dense CT in PNS
27
Q
Perineurium
A
- surrounds the smaller bundles of fibers (fascicles) in PNS
28
Q
Endoneurium
A
- surrounds each nerve fiber (very thin); reticular fibers, made by schwann cells in PNS
29
Q
What is the CNS protected/cushioned by?
A
- skull, vertebral column, meninges
30
Q
Meninges
A
- dura mater - dense regular CT
- arachnoid - spider like with space beneath is filled by CSF
- pia mater - innermost layer, processes of glial cells contact it
31
Q
CSF
A
- cushions bran and spinal cord
- produced by ependymal cells in the 3rd and 4th ventricles
- high in glucose, low in protein, has no cells other than occasional lymphocytes
- reabsorbed by arachnoid into venous system
32
Q
Where are soma in the CNS and PNS?
A
- CNS - gray matter
- PNS - ganglia and in specialized sensory regions (olfactory mucosa, vestibular ganglia)
33
Q
Synapses
A
- points of contact btwn neurons
- NTs released here and bind to receptors in the post-synaptic membrane
34
Q
Neuronal regeneration
A
- do not divide in CNS
- peripheral nerves can regenerate if the soma is not destroyed
- upon injury, distal portion degenerates
- Schwann cells proliferate and the proximal portion of an axon can regenerate
- function can return is it reconnects with the correct schwann cells
35
Q
Polio
A
- poliomyelitis
- virus enters motor neurons in ventral horns of SC
- paralysis occurs if virus kills neurons
- symptoms: weakness in arms and legs, tremor, trouble speaking and swallowing, post polio syndrome
36
Q
Glioma
A
- tumor arising from glial cells
- resistant to many chemotherapeutic agents
- Avg survival time ~ 12 months, rarely survive more than 3 yrs
37
Q
Alzheimers
A
- ## neurodegenerative disease that affects memory, coordination and eventually the individuals ability to function
38
Q
What is AZ characterized by?
A
- amyloid plaques - extracellular deposits of beta amyloid, derived from abnormal proteolysis of amyloid precursor protein
- Neurofibrillary tangles - tau, a microtubule stabilizing protein, forms abnormal clumps that interfere w/ the cytoskeleton’s microtubules
