Brain Development Flashcards
List the 3 primary vesicles of the brain and the secondary vesicles of the forebrain
- Prosencephalon
- optic vesicles
- telencephalic vesicles
- diencephalon - Mesencephalon
- Rhomboencephalon
What are the two areas in the diencephalon?
Thalamus
Hypothalamus
Describe the formation of the neural tube and neural crests.
Flat disk with layers - endoderm, mesoderm, ectoderm
Ectoderm is the neural plate that forms a groove ROSTRAL to caudal. Folds fuse together to form neural tube
Pinched off areas lying laterally to the neural tube are called the neural crests (PNS)
Describe the differentiation of the telencephalon
- Telencephalic vesicles grow posteriorly so that they lie over and lateral to the diencephalon
- Another pair of vesicles spout off the ventral surfaces of the cerebral hemispheres, giving rise to the olfactory bulbs
- Cells of the walls divide and differentiate into various structures
- White matter system develops
What are ventricles and where are they located?
Fluid filled spaces
Lateral ventricle - cerebral hemispheres
Third ventricle - space centre of diencephalon
What are the three main white matter tracts?
- Cortical white matter: contains all the axons that run to and from the neuron in the cerebral cortex
- Corpus CALLOSUM: continuous with the cortical white matter and forms and an axonal bridge that links cortical neurons of two cerebral hemispheres
- Internal capsule: links the cortex with the brain stem, particularly the thalamus
What are the primitive functions of the hypothalamus?
Controls the visceral nervous system which regulates bodily functions in response to the needs of the organism.
What is the difference between the tectum and tegmentum
Tectum - dorsal surface of the mesencephalic vesicles
Tegmentum - floor of midbrain
Where is the cerebral aqueduct?
Midbrain
CSF filled space
Connects rostrally with the third ventricle of the diencephalon
What are the functions of the midbrain?
Sensory systems
Motor control
Describe the differentiation of structures in the hind brain
The cerebellum (ROSTRAL)
The pons (ROSTRAL)
Medulla oblongata (caudal)
What do the rhombic lips form into?
Cerebellum
What is decussation?
The crossing of axons from one side to another
Define neuralation
The formation of the neural tube from the neural ectoderm during embryonic development
Briefly explain the purpose of the dorsal, lateral and ventral columns in the spinal cord
Dorsal column - sensory information to the brain.
Lateral column - contains axons on the descending corticospinal tract. These axons inner age the neurons in the intermediate zone and ventral horn. Controls voluntary movement
Describe the evolution of the neocortex
The cerebral cortex with six or more layers of neurons.
Only found in mammals
Has expanded over the years
Explain the neuron doctrine
The concept that the neuron is the elementary functional unit of the brain and that neurons communicate with each other by contact, to continuity
What are the differences between the Nissl and Golgi stains
Nissl - a class of basic dyes that stain the sonata of neurons
GOLGI - stains neurons and all their neurites
What is the difference between somatic and visceral PNS?
Somatic - innervates skin, joints, muscles
Visceral - innervates internal organs, blood vessels, glands
Name the three membranes that surround the brain
Dura mater
Subarachnoid membrane
Pia mater
Define choroid plexus
Specialised tissue in ventricles that secrete CSF
Describe the differentiation of the spinal cord
Spinal Canal - CSF filled cavity
Dorsal horn - upper section
Intermediate zone - middle
Ventral horn - lower
Describe the differentiation of midbrain structures
Tectum
1. Superior colliculus - direct input from eye
2. Inferior colliculus - input from ears
Tegmentum
- substantia nigra
- red nucleus
What are the special features of the human brain when compared to rat brains?
Convolutions in brain for more surface area
Smaller olfactory bulb
Well developed temporal lobe
Describe the structural components of a neuron
Soma
Neurites
- dendrites
- axons
Name the three areas of the axon
Axon hillock
Axon proper (middle)
Axon terminal
What are the differences between axon and soma?
Endoplasmic reticulum does not extend into axon
Axons have a unique protein composition
Describe the mechanism of axoplasmic transport
Anterograde - soma to terminal
Retrograde - terminal to soma
Explain the slow axoplasmic transport
Delivery of cytoskeletal and cytoplasmic components to periphery.
Unidirectional
To allow growth or maintenance
Explain fast axoplasmic transport
Transport of membrane associated material
Anterograde and retrograde (recycling)
How are neurons classified?
Number of neurons
Dendritic and somatic morphology
Connections within CNS
Axonal length (Golgi Type 1 or 2)
Neurotransmitter type
Gene expression
What are the major types of glial cells and their functions?
Astrocytes - influence neurite growth, chemical content and contains GFAP
Oligodendrites - myelinated
Microglia - clean
Ependymal cells - production, circulation and monitoring of CSF
What does the peripheral nervous system consist of?
Somatic PNS - collect information from the skin, muscle and joints
Visceral PNS - innervates internal organs, blood vessels and glands
Explain the afferent and efferent axons
Afferent - towards
Efferent - away
What are the twelve cranial nerves?
- Olfactory
- Optic
- Oculomotor
- Trochlear
- Trigeminal
- Abducens
- Facial
- Auditory-vestibular
- Glossopharyngeal
- Vagus
- Spinal accessory
- Hypoglossal
Briefly describe the ventricular system
CSF filled caverns and canals. CSF produced by choroid plexus in ventricles
CSF exits via subarachnoid space or apertures near the cerebellum
