Question | Answer |
Anatomical Classification: CNS | brain and spinal cord |
Anatomical Classification: PNS | spinal nerves, cranial nerves and associated ganglia (collection of neurons) |
Functional Classification: somatic nervous system | controls skeletal muscle |
Functional Classification: ANS | controls smooth muscle, cardiac muscle and glands |
What week does CNS appear? What does it appear as and what is this called? | beginning of 3rd week
as a slipper-shaped plate of thickened ectoderm which is called NEURAL PLATE. |
What is the neural groove? neural folds? | Neural plate invaginates along its central axis.
Neural folds are the raised borders of the neural groove. |
By the end of the 3rd week, neural folds move closer and fuse in midline, which converts the neural groove into what? | Neural tube |
Where does the formation of the neural tube begin and then where does it progress? | Begins in cervical region of embryo and progresses toward cranial and caudal ends. |
Neural tube closes around what week? What does the neural tube give rise to? | around 4th week
brain and spinal cord |
What are neural crest cells? | Neuroectodermal cells lying at tip of neural folds separate from neighboring cells and migrate to sides of neural tube. |
Derivatives of Neural crest cells: Part 1 | sensory and autonomic ganglia
Schwann cells (myelin)
meninges of brain and spinal cord (arachnoid and pia mater)
melanocytes |
Derivatives of Neural crest cells: Part 2 | suprarenal (adrenal) medulla (similar to sympathetic ANS ganglion)
cartilages of pharyngeal arches
endocardial cushions and aorticopulmonary septum (split into R/L parts of heart) |
What condition results as the Rostral neuropore fails to close? What day does it close normally? What are some symptoms? | Polyhydraminos (closes at day 25)
Increased alpha-feto protein
Cannot swallow b/c lack of brain
Lack of circulation causes buildup of fluid |
What condition results as the Caudal neuropore fails to close? What day does it normally close? | Spina Bifida (2 days after Rostral = day 27)
Increased alpha-feto protein |
What are the 3 primary brain vesicles? | prosencephalon or forebrain
mesencephalon or midbrain
rhombencephalon or hindbrain |
During the 5th week, the 3 primary brain vesicles divide into a total of 5 vesicles. What are they? | Prosencephalon - telencephalon and diencephalon
mesencephalon (no division)
rhombencephalon - metencephalon and myelencephalon |
What do each of the 5 secondary brain vesicles correlate to? | Telencephalon - cerebral hemispheres
Diencephalon - thalamus, hypothalamus
Mesencephalon - midbrain
Metencephalon - pons and cerebellum
Myelencephalon - medulla oblongata |
T/F - Cavity of the brain vesicles are continuous with the cavity of the spinal cord? | True. |
What cavity correlates with the 4th ventricle? | Cavity of rhombencephalon (hindbrain) |
What is another name for the cavity of mesencephalon? | cerebral aqueduct (of Sylvius) |
What cavity correlates with the 3rd ventricle? | Cavity of diencephalon. |
The lateral ventricles correlate to what cavity of the brain? | cavity of telencephalon (1 inside each cerebral hemisphere) |
What condition is caused by enlarged lateral and 3rd ventricles as well as atresia of the cerebral aqueduct? | Noncommunicating Hydrocephalus |
Which is the most severe skull defect associated with herniation of cranial contents and explain them? Meningohydroencephalocele, Meningocele, Meningoencephalocele | Meningohydroencephalocele - most severe; meninges, CSF, Brain matter and part of ventricle
Meningocele - meninges and CSF
Meningoencephalocele - meninges, CSF and brain matter |
What condition is characterized by unilateral/bilateral clefts in cerebral hemispheres? These result in large loss of brain tissue and open communication b/w ventricles and subarachnoid space. | Schizencephaly |
Parts of Neuron: cell body, dendrites, axon
What are some characteristics of a cell body? | metabolic center of neuron
contains nucleus and most cellular organelles
rER forms prominent clumps (Nissl bodies) in neuronal cytoplasm - present in dendrites but not axon |
Characteristics of dendrites and axons? | Dendrites - 1 or more per neuron; shorter than axon; transport impulses TOWARD cell body
Axon - 1 per neuron; no Nissl bodies; longer than dendrites; transports impulses AWAY from cell body |
What kind of transport transports molecules and organelles from cell body to distal end of axon? (uses microtubules and Kinesin) | Anterograde axonal transport |
What kind of transport transports used or worn out material from distal end of axon to cell body for restoration? microtubules and Dynein) (endocytosed materials like toxins, viruses and markers for neuroscience research) | Retrograde axonal transport |
T/F - Axons are only myelinated? | False |
T/F - Myelin is a multilayerd sheath formed by supporting cells, begins close to cell body and ends before axon terminates and increases conduction velocity of nerve impulses along axon? | True |
1.What kind of neuron cell body gives rise to a single process? 2.rise to 2 processes? 3.rise to 3 or more processes? | pseudounipolar(unipolar)
bipolar
multipolar |
Which classification of neurons is located in sensory ganglia of spinal nerves and some cranial nerves? | pseudounipolar(unipolar) |
Which classification of neurons is located in retina, olfactory epithelium, and ganglia of CN 8 (vestibulocochlear nerve)? | bipolar |
For functional classification of neurons, what are sensory neurons? | carry information from peripheral receptors to the CNS |
For functional classification of neurons, what are motor neurons? | carry impulses from the CNS to peripheral effectors (muscles, glands) |
For functional classification of neurons, what are interneurons? | resides entirely within CNS
establish neuronal circuits b/w sensory neurons, motor neurons, and other interneurons |
What normally refers to conduction of an electrical impulse TOWARD a structure? | afferent |
What normally refers to conduction of an electrical impulse AWAY from a structure? | efferent |
What does gray matter contain? Is it mainly myelinated or unmyelinated? | cell bodies, dendrites, and axons
mainly unmyelinated |
Neuronal cell bodies are arranged in layers on the surface of cerebral hemispheres and cerebellum called what respectively? | cerebral cortex - cerebral hemishpere
cerebellar cortex - cerebellum |
What does white matter contain? Is it mainly myelinated or unmyelinated? How are they arranged? | contains only axons
mainly myelinated
arranged in tracts (fasciculi, lemnisci) |
What is a group of axons that have similar origin, termination and course and transmit similar formation? | tract |
What is a series of neurons designed to carry a specific type of information from one site to another? (e.g. from peripheral receptors to cerebral cortex, etc) | pathway |
What is decussation? | each cerebral hemisphere perceives sensations from, and controls the movements of the contralateral side of the body
major ascending (sensory) and descending (motor) pathways cross to opposite side within CNS |
What are some supporting cells of the CNS (neuroglia or glial cells)? | ependyma
microglia
astrocytes
oligodendrocytes |
What is a simple cuboidal-to-columnar epithelium that lines ventricles of the brain and central canal of the spinal cord? | ependyma |
What are the 3 types of ependymal? explain | ependymocytes constitute majority
tanycytes most in floor of 3rd ventricl; may be involved in control of ant. pituitary by responding to change in hormone levels in CSF
choroidal epithelial cells cover surface of choroid plexuses; CSF production |
What are microglia cells? | immune effector cells of CNS
develop from hematopoietic cells of monocyte macrophage lineage which migrate to CNS during development
able to become phagocytic scavengers which migrate to sites of damage, proliferate and phagocytose cell debris |
What are astrocytes? | star-shaped body and numerous cytoplasmic processes
protoplasmic astrocytes (gray matter)
fibrous astrocytes (white matter)
reach surface of brain and spinal cord to form a protective covering (external/glial limiting membrane) |
What are some characteristics of astrocytes?
(besides secrete growth factors vital to normal function of neurons; form scars after CNS injuries) | astrocytic processes (perivascular feet) surround capillaries and form part of the blood-brain barrier(regulate passage of materials from blood to CNS)
involved in control of electrolyte and pH balance of CNS ECF
remove NT from synaptic cleft |
What are oligodendrocytes? | involved in formation/maintenance of myelin
myelin is formed by oligodendrocyte processes that wrap around axons
one oligodendrocyte forms myelin around a variable number of axons (up to 40 or 50) |
What are some supporting cells of PNS? Explain. | Schwann cells - involved in formation/maintenance of myelin in PNS; each Schwann cell envelops only part of one axon
satellite cells - surround neuronal cell bodies in sensory and autonomic ganglia |