Key takeaways U1 Flashcards
Types of cells in the human brain
Neurons, glia.
Cells lining the blood vessels, cells that make up
the meninges, cells that make cerebrospinal fluid,
pituitary cells that secrete hormones into the blood
The human brain contains approx how many neurons
86 billion neurons.
Xenopus brain contains how many neurons
Approx 16 million neurons
Mammals with big forebrains are…
gyrencephalis (have gyro and sulci)
Mammals with small forebrains are…
Lissencephalic (smooth surfaced forebrain)
Xenopus
veterbrate “model organism”
Benefit of vertebrate model organisms (or model organisms more broadly)
allow us to
study features of the nervous system that are evolutionarily conserved (basic features like
the origin of neurons from the neural plate/tube), but easier to study for a variety of
reasons: e.g. external development (instead of inside the mother) like Xenopus, availability of genetic and viral tools like mice, highly developed primate visual system like Rhesus
monkeys.
Abilities of model organisms that we do not have
locating moving prey
using echolocation (bats), not feeling pain (naked mole rats), detecting electric fields (electric fish),regenerating the adult nervous system (newts) or experimental advantages like connectomes (worms and flies)
Organisation of the vertebrate brain
Sensory information enters the brain via the cranial
nerves (olfactory, optic, trigeminal (mixed), facial, auditory vestibular and vagus. The other
cranial nerves are purely motor (oculomotor, trochlear, abducents, hypoglossal, spinal
accessory) or mixed (trigeminal, facial, glossopharyngeal, vagus,)
Sensory cranial nerves
olfactory, optic, vestibulocochlear (auditory)
mixed cranial nerves
Trigeminal, facial, glossopharyngeal, vagus
Motor cranial nerves
oculomotor, trochlear, abducens, spinal accessory, hypoglossal
Neuraxis in Xenopus vs primate brain
In Xenopus, linear. In primate brain, it is curved anterior to the hindbrain so that a cross section through the human forebrain is called coronal (parallel to the face).
List 3 types of neurons in the CNS
Sensory: cell body outside of the CNS, axon enters
the CNS to synapse. Motor: cell body inside of the
CNS. Axon exits the CNS and synapses on muscle (or
autonomic ganglia, collections of cell bodies that
innervate the viscera). 3) Interneuron.
Symmetrical sections
Coronal/transverse or horizontal
Asymmetrical sections
Saggital
Location of ventricles
Lateral ventricles (I and II) are anterior
VI ventricle is posterior
III ventricle is ventral.
Horizontal sections
Taken parallel to the rostral caudal axis of the brain. Parallel to the ground. (if standing upright)
Sagittal sections
Sections taken in the plane diving the two hemispheres.
Coronal/frontal sections
Sections in the plane of the face.
Transverse section
Perpendicular to the long axis of the brainstem and spinal cord. Dorsal ventral and posterior/anterior axis are the same
Longitudinal section
Parallel to the long axis of the brainstem and spinal cord.
Axes of the brain and spinal cord
Anatomical location of parts of the CNS is established when and how
Established during embryonic development. Molecular signals in the embryo convey positional info. TF expression in embryonic cells enables response to these signals.