Spinal cord Flashcards
(34 cards)
3 major properties of neurons
- Excitability
- Conductivity
- Secretion
Functional classes of neurons and their locations
Sensory (afferent) –> PNS
Interneurons –> CNS
Motor (efferent) –> PNS
Structural classes of neurons
Multipolar –> one axon lots of dendrites
Bipolar –> it has two extensions
Unipolar –> only one outgrowth
Anaxonic –> function is performed by the body, seen in embryos
Reflex arc
- definition
- characteristics
- Reaction to a stimulus which is controlled by the nervous system
- includes the sensory and motor part, unconscious
Reflex arc
-pathway (7)
- skin receptors
- dendrites of sensory neurons
- body of sensory neurons
- axon send it to the spinal cord
- interneuron
- motor neuron
- reaction is caused
Myelin sheath formation
- in the PNS
- in the CNS
- by Schwann cells (explain), myelin spirals outwards as it is laid down
- by Oligodendrocytes (explain), myelin spirals inwards towards the axon.
Types and synapses and characteristics
- Chemical (inhibitory and excitatory): slower, more sophisticated, uses chemical messengers, inhibition is possible.
- Electrical (gap junctions): no neurotransmitters, it is faster, only electrical signals, ion flow.
Neural circuits
-names
- diverging
- converging
- reverberating
- parallel- after discharge
Diverging and Converging neural circuits
-characteristics
Diverging: one cells receives the info and transmits it to 3,6… Signal becomes stronger. Ex: eyes
Converging: lots of cells get the info and sends it to only one cell. Ex: pain
Reverberating and Parallel after discharge neural circuits
-characteristics
Reverberating: once the cell gets the info, it is transmitted to another circuit and it keeps repeating. Ex: breathing.
Parallel after- discharge: stimulus has different ways to reach the cell, one is faster and the other is slower. Ex: short- term memory
Composition of gray and white matter
Gray –> contains neuronal cell bodies, dendrites and unmyelinated axons.
White –> aggregation of myelinated and unmyelinated axons
Meaning of
- nerve cell bodies in the CNS and PNS
- Nerve fibers in the CNS and PNS
CNS: nucleus
PNS: ganglion
CNS: tract
PNS: nerves
Stages of formation of the Nervous System (4)
- Ectoderm thickens and forms neural plate
- Plate folds inwards and forms neural crest
- Neural fold
- Neural tube
Stages of formation of the brain
- Neural tube closes
- Bulges forms
- 1 vesicle
- 3 vesicles
- 5 vesicles
Name of the 3 vesicles formed during brain development
- their name
- what they will form later on
- Prosencephalon: telencephalon and diencephalon
- Mesencephalon: mid- brain
- Rhombencephalon: metencephalon and myencephalon
Name of the 5 vesicles formed during brain development
- their name
- what they will form later on
- Telencephalon: cerebral hemisphere
- Diencephalon: thalamus, hypothalamus
- Mesencephalon
- Myencephalon: medulla oblongata
- Metencephalon: pons and cerebellum
Spinal cord goes until level of vertebra…
- in adults
- in new borns
- L1
- L3
Location where the spinal cord meets the brain
Foramen magnum
Vertebral levels at which lateral horn are present
C8-L1
S2-S4
Name and location where the spinal cord is thicker
Intumescentia cervicalis –> thicker part at the cervical area.
Intumescentia lumbosacralis –> thicker part in the end (T11- S2)
Two types of fibers in the muscles
- Contractive fibers
- Intra- fusial fibers –> smaller, for maintenance of the muscle tone. Gamma neurons maintain it
Appearance of spinal cord in different levels
- Cervical: biggest, lots of white matter
- Thoracic: lateral horns are present, not big
- Lumbar: lots of gray matter
- Sacral: smallest, lots of gray matter
Consequences if:
- there is damaged to the cervical segment
- there is damaged to the thoracic segment
- there is damaged to the lumbar segment
- full paralysis (worst place)
- arms move, trunk moves partially, loss of sensation in the legs
- legs will be damaged, depending on the level
What happens if there is a loss of connection between the brain and the spinal cord?
Voluntary movement is impossible, reflexes still present
