L7: Neurobiology I Flashcards
central nervous system
brain and spinal cord
peripheral nervous system
nerves that connect the brain or spinal cord with the body’s muscles, glands, and sense organs
both nervous systems are composed of two cell types
neurons and glial cells
neurons
cells in the nervous system specialized to initiate, integrate, and conduct electrical signals
glia
non-neuronal cells that maintain homeostasis, form myelin, and provide support and protection for neurons
glial cells make up __% of the cells in the nervous system
90%
four types of glia
astrocytes, microglia, oligodendrocytes, ependymal cells
astrocytes
support cells, control extracellular environment
of neurons
microglia
immune system of the CNS
oligodendrocytes
form the insulating material, myelin
ependymal cells
ciliated cells that create a selectively permeable epithelial layer, that separates the CNS fluid compartments
olygodendrocytes can extend its processes to up to 50 axons (T/F)
true
Schwann cell can wrap multiple neurons (T/F)
false
myelin
composed of multiple concentric layers of phospholipid membrane
tiny gaps between Schwann cells
Nodes of Ranvier
glial cells in PNS
Schwann and satellite cells
ganglion
a collection of nerve cell bodies found outside the CNS and appear as knots or swelling along a nerve
satellite cells
non-myelinating PNS glial cells that form protective capsules around nerve cells
nucleus
a collection of nerve cell bodies inside the CNS
membrane between the bones and tissues of the CNS
meninges
three layers of meninges
dura, arachnoid, pia matter
dura
the thickest, associated with veins
arachnoid
loosely tied to the inner membrane, leaving a subarachnoid space between two layers
pia matter
thin membrane, associated with arteries
a final protective component of the CNS
extracellular fluid that helps cushion the neural tissue
extracellular environment for neurons
cerebrospinal fluid and interstitial fluid
interstitial fluid lies inside
the pia matter
cerebrospinal fluid is found in
the ventricles and the space between the pia matter and the arachnoid membrane
cerebrospinal and interstitial fluid communicate
via the leaky junctions of the pial membrane and the ependymal cell layer lining the ventricles
the brain floats in
CSF
CSF is secreted by
choroid plexus
choroid plexus consists of
capillaries and a transporting epithelium
choroid plexus cells
selectively pump sodium and other solutes from plasma into the ventricles, creating an osmotic gradient that draws water along with the solutes
CSF flows
from the ventricles into the subarachnoid space
the rate of fluid
replenish the entire volume of CSF about three times a day
CSF is reabsorbed into the blood
at fingerlike projections of the arachnoid membrane called arachnoid villi
CSF functions
physical and chemical protection
buoyancy of CSF reduces the weight of the brain
nearly 30-fold
lighter weight translates into
less pressure on blood vessels and nerves attached to the CNS
CSF provides
protective padding
choroid plexus is selective about
which substance it transports into the ventricles
CSF contains compared to blood
very little protein, no blood cells, Na+ concentrations are similar, K+ concentrations are lower
blood brain barrier
acts to maintain selective permeability of substances into the brain
blood brain barrier
necessary to isolate the body’s main control center from potentially harmful substances (toxins, hormones, ions, neurotransmitters, pathogens)
tight junctions
formation of them is stimulated by paracrine signals from adjacent astrocytes whose foot processes surround capillary
what cells form tight junctions
endothelial cells in brain capillaries
typical capillaries
lack tight junctions resulting in relatively leaky capillary walls
transcytosis
the movement of a molecule across an endothelial cell by endocytosis
transcytosis
the movement of a molecule across an endothelial cell by endocytosis
transcytosis
the movement of a molecule across an endothelial cell by endocytosis
hydrophilic molecules can only cross the blood brain barrier
using specific transport proteins
transcytosis ___ across capillary endothelial cells in the CNS
does not occur
what can pass the blood brain barrier?
hydrophobic molecules, glucose, and amino acids
what can’t pass the brain blood barrier?
catecholamines, inorganic ions, certain drugs
