Lecture 12- CNS development and protection Flashcards
what does the brain look like at the 3rd week of development?
human brain starts as a hollow tube
what does the brain develop at the 4th week of development?
specializes in the anterior end
what does the forebrain develop into in late development?
cerebrum
diencephalon
what does the cerebrum develop into in adult brain?
what does the diencephalon develop into in adult brain?
cerebrum: cerebral hemispheres, basal ganglia, lateral and 3rd ventricles
diencephalon: thalamus, hypothalamus
what does the midbrain develop in to in late development?
midbrain
what does the midbrain develop into in adult brain?
superior colliculi
inferior colliculi
substantia nigra
what does the hindbrain turn into in late development?
pons/ cerebellum
medulla
what does the pons/ cerebellum and medulla turn into in adult brain?
pons/ cerebellum: pons and cerebellum
medulla: medulla
what are ventricles? what are they lined with? how many do we have?
fluid filled cavities within the brain lined with ependymal cells we have 4
what is a central canal? what re they lined with?
hollow tube in the spinal cord that is continuous with the ventricles lined by ependymal
what does grey matter consist of?
unmyelinated cell bodies/ neuronal cell bodies
axon terminals
dendrites
what does white matter consist of?
myelinated axons
where is the grey matter normally?
outer surface of the brain
clustered together in groups in the middle of brain
why does the brain and spinal cord (CNS) need protection?
because they are delicate
what are different types of protection used to protect the CNS? (4)
bony skull and vertebral column
wrapped by meninges
cerebrospinal fluid
blood brain barrier
what are meninges?
3 layers of protective membranes
what are the 3 meningeal layers?
dura matter
pia matter
arachnoid membrane
what is the dura matter?
thick most obvious meningeal layer
outer layer, closest to your skull
dura= mother (mothers protect you the most)
what is the pia matter?
delicate meningeal layer that rests against the surface of the brain
inner layer closest to your brain tissue
pia= soft
what is the arachnoid membrane?
meningeal layer attached to pia layer by webs
arachnoid= spider
what happens if you get a deep cut in the scalp?
can be dangerous because some veins pass through the skull, if you get an infection in the cut, your brain will be infected
what is meningitis?
contagious bacterial, viral or fungal infection of the meninges that causes swelling and pressure on the brain. neurons don’t like this pressure so they won’t function together/ properly
what are the 3 types of bleeding that traumatic head injury can cause?
epidural bleeding
subdural bleeding
subarachnoid bleeding
where do epidural bleeds occur?
where do subdural bleeds occur?
where do subarachnoid bleeds occur?
skull and dura
dura and arachnoid membrane
arachnoid membrane and pia matter
what produces cerebrospinal fluid?
choroid plexus in the 3rd and 4th ventricles
where is the cerebrospinal fluid found?
in ventricles
where does cerebrospinal fluid circulate?
throughout the subarachnoid space because it keeps the cerebrospinal fluid moving. some circulates around the spinal cord
where does cerebrospinal fluid exit the brain?
through the foramen of Lushka laterally, or the foramen of Magendie medially to the subarachnoid space
what makes CSF so important?
helps maintain proper solute concentrations in the interstitial fluid surrounding neurons
helps remove waste
provides a cushion for the brain
what is the blood- brain- barrier? where is it located?
barrier between the interstitial fluid of the brain and the plasma
what is the function of the blood brain barrier?
keeps unwanted materials out
keeps wanted materials in
what is the difference between blood circulation in the body and blood circulation in the CNS (blood brain barrier)?
body: endothelial cells are not connected and have pores (very leaky)
CNS: endothelial cells joined by tight junctions, surrounded by astrocyte endfeet (very tight)
what molecules can diffuse across the blood brain barrier?
lipophilic (fat soluble) molecules
ex. steroids, ethanol, nicotine, benadryl
how do polar, hydrophilic molecules cross the blood brain barrier?
transporters
ex. insulin, glucose, Na+
