Flashcards in neurons,glia, brain tissue Deck (19):
1. For each of the following, know which is gray matter and which is white matter: nucleus, lemniscus, ganglion, peduncle, cortex, funiculus, body, fasciculus, tract.
Gray matter: nucleus, ganglion, cortex, body. White matter: lemniscus, peduncle, funiculus, fasciculus, tract
2. Know the function and distribution of astrocytes
CNS: maintain ionic equilibrium by removing extra potassium released by firing neurons, clearance and recycling of neurotransmitters from extracellular space, end feet envelop CNS blood vessels and aid in transport of nutrients from blood vessels to neurons plus local regulation of blood flow.
2. Know the function and distribution of microglia
Major phagocytic cells of CNS. They arise embryonically from outside the neural tube and take residence in the nervous system. In response to tissue damage, microglia undergo rapid proliferation to clear the debris from the brain.
2. Know the function and distribution of oligodendrocyte
form the myelin in the central nervous system.
A single oligodendrocyte may myelinate several nearby axons.
2. Know the function and distribution of Schwann cell.
form myelin in the peripheral nervous system. A single Schwann cell can form myelin around only one axon.
3. Know the general function of Nissl substance.
Nissl substance: collections of rough endoplasmic reticulum to produce proteins.
Two types of neurotransmitter receptors and functions
Ionotropic receptor: changes conformation to permit passage of ions through a pore in the receptor. The flow of ions either depolarize or hyperpolarize.Metabotropic receptors activate second-messenger systems (e.g. G-proteins) within the neuron.
Which cell play role in chronic pain syndrome
4. Describe the relationship between cerebral blood flow and fMRI and PEt scans.
fMRI relies on the intrinsic properties of
hemoglobin to measure blood flow; PET relies on an injected tracer, usually a radioactive analog of
5. Know why substances in the circulatory system do not freely enter the brain parenchyma.
Capillaries of brain are zipped up by tight junctions, for a substance to cross from the blood into the extracellular space of the brain, it must either diffuse through the endothelial cells (lipid-soluble) or be actively transported across the endothelial barrier.
Circumventricular organs blood brain barrier
At small sites along the ventricular walls in the caudal medulla and hypothalamus, there is no blood-brain barrier. These areas of the CNS are involved in monitoring the composition of the blood or else produce something that is secreted into the blood. Astrocytes effectively wall off these circumventricular organs from the rest of the CNS to maintain the isolation of brain extracellular space from plasm
7. Describe neural regeneration and glial response to damage in the peripheral nervous systems.
Schwann cells clear myelin debris, line along endoneurium and promote outgrowth of axons from damaged nerve. The cntral terminals of nerve cells provoke microglia which express cytokines/trophic factors that then activate astrocytes. Microglia strip synapses, causing reorganization of synpatic systems in affected brain areas.
Long term effects of peripheral nerve damage
neuropathic pain states: hypersensitivity, hyperalgesia (increased sensitivity to pain) or allodynia (conversion of normally innocuous stimuli to pain). Due to changes in the CNS
7. Describe neural regeneration and glial response to damage in the central nervous systems.
Oligodendrocytes express molecules that inhibit axonal outgrowth. Microglia activate astrocytes which form a glial scar (chemical/physical barrier to axonal regeneration).
What is autoregulation
Arterioles in the brain, as elsewhere in the body, respond to increases in blood pressure by increasing vascular tone to maintain a constant vascular bore (inner diameter)
describe autoregulation in brain
BP increases > stretches blood vessels > activation of second messenger culminating in inhibition of Ca activated K channels > cell is depolarized > increased vascular muscle tone > vessel diameter maintained constant
What is functional hyperemia
A local increase in neuronal activity results in a substantial increase in the local blood flow
Name 2 mechanisms by which functional hyperemia occurs
1) neurons generate a gaseous messenger, NO, which diffuses to reach the blood vessels. NO dilates the local vessels. 2) the second mechanism involves astrocytes.