Flashcards in Neural Tissue Deck (29):
3 special characteristics of NEURAL TISSUE
1 ) long lived
3) high metabolic rate
Structure of NEURAL TISSUE (3 parts)
2) Cell body (soma)
Things to know about DENDRITES
-DENDRITES are highly branched processes that retrieve info.
-Their DENDRITIC SPINES increase the surface area to receive more info.
Things to know about the CELL BODY aka SOMA
-They are large in order to produce NEUROTRANSMITTERS (NT)
-Clusters of CELL BODIES in CNS are called NUCLEUS (pl)
- Clusters of CELL BODIES in PNS are called GANGLION (pl) or GANGLIA (s)
Things to know about AXONS
- length varies
-may be myelinated to increase speed of impulse transition
-may have collateral branches = side branches
- has 1000s of terminal branches
- SYNAPTIC KNOBS at end hold vesicles filled w/ NT
- bundles of AXONS in CNS are called tract
-bundles of AXONS in PNS are called nerves
AXONS are wrapped in these 3 connective tissues...
...EDONEURIUM which cover single AXONS and capillaries, PERINEURIUM which covers nerve fascicles (has arteries and veins), and EPINEURIUM which covers multiple nerve fascicles and the blood vessel surrounding.
Types of NEURONS classified by structure (4)
Thangs to know about MULTIPOLAR NEURONS
-they have many DENDRITES, 1 long AXON
-most common in CNS, all MOTOR NEURONS
Thangs to know about BIPOLAR NEURONS
- they have 1 DENDRITE and 1 AXON
- rare, special sense organs
Thangs to know about UNIPOLAR NEURONS
- DENDRITES continuous w/ AXON
- SENSORY NEURONS in PNS
- CELL BODY in dorsal root ganglia
Thangs to know about ANAXONIC NEURONS
- can't distinguish DENDRITES, AXONS
Types of NEURONS classified by function (3)
1) SENSORY (afferent) NEURONS
3) MOTOR (efferent) NEURONS
Things to know about SENSORY (afferent) NEURONS
- Mostly UNIPOLAR, some BIPOLAR
- Carry info from sensory organs/receptor to CNS
-e.g. EXTEROCEPTORS - outside info (touch/sight/temp)
-e.g. INTEROCEPTORS - monitor internal organs
-e.g. PROPRIOCEPTORS - monitor muscle and joint position
Things to know aboot (canadian eh?) INTERNEURONS
- Mostly MULTI
- Between SENSORY and MOTOR NEURONS
- Integrate info
Things to know about MOTOR (efferent) NEURONS
- All MULTI with CELL BODIES in CNS
- Carry info to muscles and glands
Can NEURONS be SENSORY and EXTEROCEPTORS?
Can NEURONS be SENSORY and UNIPOLAR?
Can NEURONS be INTERNEURONS and PROPRIOCEPTORS?
No way Jose
Can NEURONS be INTERNEURONS and MULTIPOLAR?
Can NEURONS be MOTOR and MULTIPOLAR?
What are NEUROGLIA?
They are smaller than NEURONS but outnumber them 10:1. CNS tumours arise from uncontrolled division of NEUROGLIA
4 types of NEUROGLIA in CNS
4) EPENDYMAL CELLS
Things to know about ASTROCYTES
- most common
- create a supportive network for NEURONS
- recycle NT
- guide neuronal migration in embryo
- surround capillary to maintain blood-brain barrier
-control transport of material into interstitial fluid
Things to know 'bout MICROGLIA
They are small cells w/ "thorny" processes. They also defend and remove debris (no WBC in CNS)
Things to know about OLIGODENDROCYTES
Their processes wrap around portions of multiple CNS AXONS. They myelinate/insulate AXONS to increase speed of ACTION POTENTIAL (AP).
Also their name is stupidly long.
Things to know about EPENDYMAL CELLS
-Ciliated cells joined by tight junctions
- Line ventricle of the brain and central canal of the spinal chord
- Produce, monitor, and circulate cerebrospinal fluid (CSF)
2 types of NEUROGLIA in PNS
1) SCHWANN CELLS
2) SATELLITE CELLS
Things to know about SCHWANN CELLS
- Whole cell wraps around part of 1 AXON = myelinate AP (speeds up by 150x)
- Many SCHWANN CELLS needed to myelinate 1 AXON
- Adjacent SCHWANN CELLS don't touch = gap = node of Ranvier
- AP propagated at nodes of Ranvier
- Demyelination results in loss of sensation, motor control, e.g. MS
- SCHWANN CELLS also guide AXON growth during NEURON repair