Intro To CNS Flashcards
What structures are contained in the CNS?
The brain and spinal cord
What structures are included in the PNS?
Nerves (spinal and cranial) and ganglia located outside the CNS
Note: the CNS and PNS form a single unit functionally
What is a neuroglia?
A connective tissue cell in the CNS
What is a neuron?
An excitable/conducting cell
It is composed of a cell body with short projections called dendrites that receive information. The portion that transmit information is called an axon.
What happens when a neuron dies?
It’s function is lost
What is a nerve?
A conduit containing axons that convert information to and from the CNS
What is a nucleus,ganglion, lamina?
A collection of neuronal cell bodies usually associated with a common function
Nucleus is within the CNS
Ganglion is in PNS
Lamina is within spinal cord
What is an afferent cell?
A cell traveling toward the CNS. This is commonly associated with sensory but not all information is perceived by the brain.
E.G. Spinal reflex
What is an efferent cell?
A cell transmitting away from the CNS.
Equivalent to motor neurons
What is modality?
A type of sensory information
E.g. Pain, touch, vibration, itch, etc.
What is sensation?
An impression conveyed by a sense organ through an afferent nerve to a sensory nerve center or a seat of sensation where sensation is received and interpreted (Sensorium) in the brain, as visual image, tase, pressure, itch or pain
E.g. This is the signal that makes it to the brain
What is a sensory modality?
What is perceived/sensed (the type), after a stimulus is applied.
What are the types of sensory modalities?
Chemoreception (chemicals)
Photoreception (light such as eyes)
Mechanoreception (e.g. Touch, itch, pressure, vibration, nociception (pain) or physiological pain such as cutaneous, somatic/bone/joint and visceral)
Thermoreception
Propioception
What is propioception?
The kinesthetic sense that provides the sensory corte with information about the relative position of body parts in space
What is perception?
The interpretation of the sense brought to the brain. Through perception the brain gives meaning to senses by attaching emotions, memories, etc.
At week 3 what layers does the embryo have?
Intra-embryonic ectoderm
Mesoderm
Endoderm
Describe the process of neurolation that occurs between the 3rd and fourth week in utero.
Day 15: a neural plate is formed which folds into a neural tube (day 21-22).
Day 28: the neural tube is finished
What is formed from the neural plate?
A neural tube with a centra canal
What are the 3 primary vesicles seen in an embryo at the end of week 4 (day 28)?
- Procenphalon or forebrain
- Mesencephalon or mid brain
- Rhombencephalon or Hindbrain
When do the primary brain vesicles divide into the secondary brain vesicles?
Day 32
What does the prosencephalon divide into? (Forebrain)
Telencephalon and diencephalon
What does the mesencephalon or mid brain divide into?
It remains unchanged
What does the rhombencephalon or hindbrain subdivide into?
The metencephalon and myelencephalon
During the 5th week what does the Telencephalon differentiate into?
Two cerebral hemispheres and lamina terminalis/terminales
By week 5, what does the Diencephalon differentiate into?
Epithalamus
Thalamus
Hypothalamus
Subthalamus
Pituitary gland/stalk
By week five, what does the mesencephalon become?
The mid brain
By week 5, what does the metencephalon differentiate into? (Part of hindbrain)
Pons and cerebellum
By week 5, what does the myelencephalon divide into?
The medulla oblongata
When is the brain smooth?
Within the first 3 to 4 months of embryonic life
What sulcus forms between the fourth and sixth month to delineate lobes in utero?
Lateral cerebral sulcus
What are glial cells?
Supporting cells of the brain
Includes: Astrocyte Ependymal Oligodendrocytes/Schwann Microfilaments
If neurons are the structural unit of the brain, what are synapses?
They are the functional unit for learning and memory
What are synapses?
Sites of communication between cells
What are some examples of neurotransmitters?
Acetylcholine Norepinephrine Monoamines Amino acids Nitric oxide Neuropeptides
What is myelin?
A lipid rich substance of cell membrane of Schwann cells/neurolemocytes(PNS) and oligodendrocytes (in CNS).
What benefits does myelin give to a cell?
Rapid nerve conduction through a process called saltatory conduction ( nodes are ion rich)
What is a node of ranvier?
An ion rich node (constrictions) where cells producing myelin meet which facilitates rapid nerve conduction by enabling impulses from node to node
What kind of appearance does myelin give cells?
A pale appearance
“White matter”/white rami
What does the forebrain consist of in adults?
Cerebrum and diencephalon
What does the hindbrain consist of in adults?
Pons, cerebellum and medulla oblongata
What is the deepest and longest horizontal grove on the lateral surface of the brain?
Lateral sulcus of sylvius
What does the central sulcus divide?
The frontal lobe from the parietal lobe
What lobes are found on the inferior surface of the brain?
Frontal, temporal and occipital lobes
Where are broca’s motor speech area and Wernicke’s sensory speech area located in most people?
On the left cerebral hemisphere in 95% of right handed people and 70% of left handed people
Name two unsymmetrical features of the brain
The left lateral sulcus is longer
The left cerebral hemisphere may be heavier than the right
