Pre-Quiz 1 Flashcards
within human organism, the two homeostasis-controlling systems are the following:
the CNS and PNS
The central nervous system consists of
the brain and spinal cord
what are the two major classes of nervous system cells
- neurons: carry/transmit information by the conduction of electrical impulses/action potentials
- glia (neuroglia): provide support and maintenance functions for neural tissue. *unable to transmit potentials
neurons communicate across specialized intercellular spaces or “pipe”-like structures called
synapses
what are the two types of synapses
- electrical: no interruptions between neurons; action potentials conduct directly between adjacent cells through gap junctions
- chemical: the plasma membranes of a presynaptic and postsynaptic neuron in a chemical synapse do not touch one another directly. The space bewteen the neurons is called a synaptic cleft which is filled with interstitial fluid. A neurotransmitter must diffuse through the interstitial fluid in the cleft and bind to receptors on the postsynaptic neuron.
what type of synapses are most abundant in the human body?
Chemical synapses
name the structure of a neuron that is most effective in starting the conduction of electricity
neck, or axon hillock
name the structure of a neuron that is most efficient in receiving information
dendrites
the major control space of a neuron which is around the nucleus and is also called a perikaryon is
the soma
where are nissal bodies found & what are they
they are found in the soma and are the rough ER in the plasmic reticulum
chemical synapses can be found on which structure of a neuron
the synaptic bulbs
what are the three types of neurons
- motor/efferent (descending [from brain to organs]): they are coming out from the CNS and PNS to the effector organs and tissues. ex: contraction of skeletal muscles. They make things happen
- sensory/afferent (ascending): they bring information from the effector organs and tissues to the PNS—> CNS for interpretation
- associative/interneurons: complie a “balance sheet.” you can consider the a middle man. they are the majority of neurons. They connect neurons together.
within the CNS, what type of glia cells (neuroglia )can be found?
- oligodendrocytes: insulating and resist regeneration within CNS.
- astrocytes: within CNS; form the blood-brain barrier
- microglia: within the CNS; considered to be the sanitation department
- ependymal cells: within the CNS; secrete CSF within brain ventricles; provide brain-CSF barrier
within the PNS, what type of glia cells (neuroglia) can be found?
- satellite cells: within the PNS; provide support within ganglia (clusters of functionally united neurons)
- schwann cells: insulating (organized into myelin), and assist regeneration/repair of axons within PNS
the principal difference between the functions of neurons versus glia is what?
neurons transmit information by the conduction of electrical impulses/action potentials. Glia provide support and maintenance functions for neural tissue and are unable to transmit potentials.
why is the structure of neurons’ nodes of ranvier important?
because schwann cells tightly insulate axons and allow the conduction of electricity to jump from node to node. It improves the speed of electricity.
the major common function of oligodendrocytes and schwann cells is
they both produce myelin, which acts as insulation for axons
the major functional difference between oligodendrocytes and schwann cells is
schwann cells are found in the PNS and assist regeneration of axons; oligodendrocytes are found in the CNS and resist regeneration of axons
axons with nodes of ranvier are _____; axons without nodes of ranvier are _____. Which combination is most efficient in terms of conduction speed?
myelinated, unmyelinated; axons with nodes of ranvier
which division of the nervous system includes the brain and spinal cord?
the central nervous system, CNS
within the CNS, clusters of functionally similar/related neurons are called _____.
nuclei
in the CNS, bundles of axons from the neurons of the nuclei are called _____
tracts
what are the three subdivisions of the PNS
- somatic nervous system
- autonomic nervous system
- enteric nervous system
in the peripheral nervous system, clusters of related neurons (cell bodies or soma) are called _____
ganglia/ganglion
in the peripheral nervous system, bundles of related axons are called _____
nerves
somatic nervous system:
includes the external lining and internal lining (peritoneum) of the body wall (sensory & motor)
includes the extremities
includes the special senses (smell, taste, vision, hearing, equillibrium)
autonomic nervous system:
Includes: smooth muscle, cardiac muscle, all secretory glands
Controls “primitive functions of internal milleu
subdivisions of ANS are sympathethic and parasympathetic
enteric nervous system:
Chains of ganglia (plexi/plexus) along several layers of gastro-intestinal tube/alimentary canal
Responsible for peristalsis and secretion of GI juices
Is influenced/commanded by CNS and ANS
what are the two exceptions to the somatic nervous system
- goose bumps, because they are controlled by arrector pilli ssmooth muscles
- sweat glands
*both are controled by the ANS
The intrinsic nervous system of the gastro-intestinal tract, which is called the ENS, is represented by the clusters of functionally related and interconnected neurons. These clustrs are subsequently called:
- enteric plexus of meissner (in sub-mucosa of intestines)
- myenteric plexus of auerbach (peristalsis in intestines)
what are the two types of electrical signals neurons use to communicate with one another when they are electrically excitable?
- action potentials
- graded potentials
what is a resting membrane potential
The resting membrane potential occurs due to a buildup of negative ions in the cytosol along the inside of the membrane and positive ions in the extracellular fluid along the outside of the membrane.
In neurons, the resting membrane potential ranges from -40 to -90 with an avg of -70
leakage channels
channels that randomly alternate between open and closed positions for potassium ions. Like a revolving door
voltage channels
open in response to change in membrane potential (voltage); electrical channel & therefore opens by electricity
Ligand channels
open and close in resopnse to a specific chemical stimulus; usually open before electrical channels
present in interneurons and motor neurons
mechanical channels
open or close in response to mechanical stimulation
present in sensory neurons
light channels
open when affected by entering light (ex: eye retina)
what is the major ion responsible for depolarization and action potentials
sodium
what is the major ion responsible for the guardng/balance of the resting membrane potential
potassium
what ion channels are open during the depolarization phase of action potential
sodium
what ion channels are opening during re-polarization phase of action potential
potassium
the main paths for flow of current across the membrane are called
ion channels
ions more from _____ areas of concentration to _____ areas of concentration
greater; lower
Positively charged cations move towards _____ charged areas and negatively charged anions move towards _____ charged areas
negatively; positively
when the resting membrane potential is considered polarized, this means_
that it has potential to produce work as an electrical current, once movement of ions is allowed.
if there is potential, it is considered polarized
what kind of channels have to open or close in order for graded potentials to occur
ligand-gated or mechanically gated channels have to open or close
what happens during the depolarization phase
the resting membrane potential decreases towards 0 (sodium comes in)
what happens during the repolarizing phase
the resting membrane potential is restored (sodium goes out, potassium comes in)
what is a threshold
when depolarization reaches a ceratin level (about -55mV), and voltage gated channels open
what is a refractory period
the period of time after an action potential begins during which an excitable cell cannot generate another action potential
absolute refractory period
a second action potential cannot be initiated, even with a very strong stimulus
relative refractory period
an action potential can be initiated, but only with a larger than normal stimulus
what is the difference between the presynaptic neuron and the postsynaptic neuron
the presynaptic neuron is the neuron sending the signal
the postsynaptic neuron is the neuron recieving the message
what are the clusters of neuronal cell bodies located in PNS and CNS?
what re the bundles of axons in PNS and CNS?
clusters of neuronal cell bodies
PNS: ganglion CNS: nucleus
bundles of axon
PNS: nerves CNS: tract
