sensory systems Flashcards
action potential?
rapid increase in positive charge in nerve fibre (axon), that travels down the fibre. action potentials are all or nothing events compared graded potential. also called nerve impulse or spike.
axon?
a long projection of a neuron that typically conducts action potentials away from the neuron’s cell body. also known as a nerve fibre.
cell?
the basic structural, functional and biological unit of all known living organisms.
cell body?
the core region of a cell containing the nucleus and other cell organelles.
dendrite?
branching extensions of the neuron’s plasma membrane that increases the surface area of the neuron and collect neuronal activity from other cells.
equilibrium potential?
the membrane potential at which a particular type of ion has no driving force to diffuse through the plasma membrane in either direction. at the equilibrium potential, chemical and electrical gradients are equal in magnitude.
gila cells?
non-neuronal cells in the nervous system that provide support and protection for neuron’s. among many other functions, gila cells are responsible for the myelination of axons.
graded potential?
a relatively small change in membrane potential, for example by opening ligand gated ion channels. the strength of a graded potential is given relative to the strength of stimulation (compare action potential).
ligand gated channels?
a group of ion channels which open to allow ions such as Na+, K+, Ca2+ or Cl- to pass through the membrane in response to the binding of messenger.
membrane potential?
the difference in electrical potential between the interior and the exterior of a biological cell.
myelin?
a fatty substance that surrounds the axon of many neuron’s. myelin increases the membrane resistance helping to speed the conductance of action potentials.
neuron docterine?
the concept proposing that the neuron is the fundamental unit of the nervous system. compare reticular theory.
neurotransmitter?
chemical messenger released by neuron’s onto a target cell with an excitatory or inhibitory effect.
oligodendrocytes?
a type of gila cell in the central nervous system. oligodendrocytes wrap around axons to form the myelin sheath (equivalent to Schwann cells).
nucleus cell?
a membrane enclosed organelle found in eukaryotic cells that contains most of the cells genetic material.
plasma membrane?
a biological membrane that separates the inferior of all cells from the outside environment. the plasma membrane is selectively permeable to ions and organic molecules and controls the movement of substances in and out of the cell.
postsynaptic?
referring to the neuron or parts thereof after the synapse with respect to the flow of information. compare presynaptic. postsynaptic potential changes in the membrane potential of the postsynaptic neuron of a synapse. postsynaptic potentials are graded potentials that are their excitatory or inhibitory.
potassium?
the ion of potassium atom which is positively charged. one of the main players contributing to the membrane potential of neuron’s.
presynaptic?
referring to the neuron or parts thereof before the synapse with respect to the flow of information. compare postsynaptic.
resting potential?
the membrane potential in the absence of stimulation. the resting potential of neuron’s is typically around -70 mV inside negative. it depends on the equilibrium potentials of contributing ion and the selective membrane permeability for these ions.
reticular theory?
an obsolete scientific theory in neurobiology that states that the nervous system is made up of a single interlinking network. compare neuron doctrine.
Schwann cells?
the principle gila of the peripheral nervous system. Schwann cells wrap around axons to form the myelin sheath.
sodium?
the ion of the sodium atom which is positively charged. one of the main players contributing to the membrane potential of neuron’s.
sodium potassium pump?
an energy consuming enzyme that pumps sodium out of the cells while pumping potassium into cells. it is essential for maintaining the resting potential and therefor normal brain functioning.
synapse?
the junction between a neuron and another cell that forms the information transfer site between two cells.
vesicles?
small membrane compartments that store and release neurotransmitters at synapse.
voltage gated channels?
gated membrane channels that open and close only at specific membrane potentials. voltage gated channels are essential for the generation of action potentials.
ipsilateral?
on the same side of the body such as two parts on the same left. antonym of the contralateral.
lateral?
towards the side, away from the midline. antonym of the medial.
medial?
towards the midline away from the side. antonym of lateral.
anterior?
toward the front end (antonym of posterior).
autonomic nervous system (ANS)?
the part of the PNS that influences the function of internal organs. the ANS acts largely unconsciously and regulates the heart rate, digestion, respiratory rate, pupillary response, urination, and sexual arousal.
brainstem?
the posterior part of the brain, adjoining and structurally continuous with the spinal cord. in humans, it is usually described as including the medulla oblongata, pons, and midbrain.
brodmann area?
a region of the cerebral cortex that is defined by its cytoarchitecture, or histological structure and organisation of cells. central nervous system (CNS). the brain and the spinal cord.
cerebellum?
a large, highly convoluted (in-folded) structure located dorsal to the brainstem at the level of the pons. also known as “little cerebrum”.
cerebral cortex?
the layered sheet of neuron’s that covers the surface of the brain and contains the machinery for creating perception, as well other functions, such as language, memory, and thinking. It is divided in two (lateral) hemispheres, each containing four major lobes.
contralateral?
on the opposite side of the body (antonym of ipsilateral).
coronal plane?
a plane that shows brain structures as seen from the front. also called frontal plane.
distal?
located more distant from the point of origin or attachment (antonym of proximal).
dorsal?
toward the back, away from the ventral (stomach) side. the top of the brain is considered dorsal because it has this position in four-legged animals (antonym of ventral).
frontal lobe?
one of the four major lobes of the cerebral cortex.
grey matter?
a major component of the central nervous system that contains primarily neuronal cell bodies.
inferior?
below another part (antonym of superior).
occipital lobe?
one of the four major lobes of the cerebral cortex, which holds amongst others the primary visual cortex.
parietal lobe?
one of the four major lobes of the cerebral cortex, which holds amongst others the primary somatosensory cortex.
peripheral nervous system (PNS)?
the part of the nervous system apart from the brain and the spinal cord.
posterior?
toward the rear end (antonym of anterior).
proximal?
located close (approximate) to the point of origin or attachment (antonym of distal).
sagittal plane?
a plane that shows brain structures as seen from the side.
