Nervous System Part 1 Flashcards
what is the resting potential that is found on the cell membranes of nerve and muscle cells?
an electrical charge that must be present at all times to allow action potentials to be present in the muscle and nerve cells.
why is the RP called a transmembrane potential?
it is the difference in charge found across the cell membrane. the RP is a slight negative charge on the inside of the cell membrane compared to a slight positive charge found on the outside of the cell membrane.
what is the voltage of the RP in millivolts?
-70 millivolts
what is the main cause of the resting potential?
the constant leaking of potassium through the nongated potassium channels creates most of the voltage for the RP.
why are action potentials so important to the body? what three main body functions do AP’S control?
AP’S are the electrical currents that control brain activity, help control organ activities, and cause muscle contraction.
why is the action potential called a reversal of the resting potential?
in the AP the positive charges are on the inside of the cell membrane. in RP the positive charges are on the outside of the cell membrane.
what is another way to describe the action potential?
it is a strong depolarization because it is a positive electrical charge. the value of AP is +20 Mv.
in what two other ways is the AP different from the RP?
the RP is present when the muscle cells are resting. the AP causes action.
what are the three phases of the AP and what causes each phase?
first phase: depolarization. caused when gated sodium channels open causing sodium to enter. causes the voltage to change from -70 to +20.
second phase: repolarization. caused when gated potassium channels open causing K to exit.
third phase: hyperpolarization. caused by too much K leaving the cell. the gated K channels remain open. this causes the voltage to drop slightly below -70.
why do sodium and potassium move in opposite directions when their gated channels are opened? how is their movement connected to their contractions inside versus outside the cells?
NA moves into cells when its gated channels are opened because there is a large concentration of NA outside of cells. K moves outside of the cells through its channels because there is a large concentration of K inside the cells. NA/K pumps move three NA out of the cells while moving two K into the cells.
when an excitatory neurotransmitter is released form a nerve cell at a synapse does it automatically cause an action potential?
no.
what does an excitatory neurotransmitter is released form a nerve cell at a synapse cause?
it causes a depolarization to occur. a depolarization is when the RP becomes more positive. it is a small positive charge.
what specific ion channel is opened by an excitatory neurotransmitter?
an excitatory NT causes a depolarization by opening gated sodium channels letting sodium in. this means an excitatory NT’s receptor is actually a gated NA channel.
how can an action potential be caused by an excitatory neurotransmitter?
two depolarizations must occur together and add together to produce an action potential, when added. the two depolarizations bust reach -55 mV in order to created the AP. -55 is the threshold.
(use picture on page 4)
in the left graph image, the two arrows (with E) represent two seperate releases of excitatory neurotransmitter. the three picture images on the right show A, B, and C of that graph. what is happening?
temporal summation of depolarizations or two depolarizations overlapping in time to create an action potential.
what is the purpose of an inhibitory neurotransmitter?
it tries to stop an AP from occurring in a musclce or nerve. it cancels out AP.
what does an inhibitory neurotransmitter do when it is released at a synapse?
it causes a hyperpolarization to occur. a hyper polarization is when the resting potential becomes more negative. it can cancel out a depolarization if it is present.
what specific ion channel is opened by an inhibitory neurotransmitter?
an inhibitory NT opens gated K channels. this lets K exit the cell, creating a hyperpolarization.
what is an inhibitory NT that is used in skeletal muscle?
dopamine
how does Parkinsons disease show the importance of inhibitory NTs in our bodies?
whith parkinsons disease, the brain produces less and less dopamine over time. this means that dopamine no longer cancels out APs in skeletal muscle. the result is that the body has uncontrolled muscle contractions.
what is an inhibitory NT used solely within the CNS? how is it useful medicinally?
GABA. it stops APs from being made in the brain. anticonvulsants for epilepsy stop seizures because they increase GABA release. seizures are caused by random APs that fire off in the brain.
many NTs have both excitatory or inhibitory effects, depending on the recepor type they bind to in an organ. what is an example of a NT like this that is used in both the sympathetic and parasymphathetic nervous systems? page 5nicotinic rec
ACH, acetylcholine
many NTs have both excitatory or inhibitory effects, depending on the recepor type they bind to in an organ. what is the general name for this NTs receptors? page 5
cholinergic receptors
many NTs have both excitatory or inhibitory effects, depending on the recepor type they bind to in an organ. at what location is this NT used in both the sympathetic and the parasympathetic nervous systems? page 5
in the ganglia
many NTs have both excitatory or inhibitory effects, depending on the recepor type they bind to in an organ. what is the specific name for this NTs receptors in this location? page 5
nicotinic receptors
in what other location are nicotinic receptors found?
in skeletal muscle. they are part of the somatic nervous system, the nerves that cause skeletal muscle contraction.
when ACH is released onto organs is it released from sympathetic or parasympathetic nerves?
parasympathetic nerves release ACH onto organs,
what is the specific name for ACH receptors in organs?
cholinergic receptors foundin all organs are called muscarinic receptors.
give an example of how ACH causes excitatory effects in some organs while causing inhibitory effects in others?
ACH causes excitatory effects in digestive organs because it increases digestive activities, such as increasing the stomach’s production of gastric juice. however ACH causes inhibitory effects in the heart because it slows down the heart rate.
In a synapse formed between two neurons what part of the second neuron do the terminal knobs of the first neuron synapse with?
The dendrites.
What important happens at the synapse between the synaptic knob and the dendrite?
Depolarizations or hyperpolarizations are produced depending on the type of neurotransmitter is released onto the dendrites.
Two types of neurotically cells wrap around the neuron cell axons to form myelin sheaths. Which of these neuron liar cells does this within the CNS?
Oligodendrocytes.
Two types of neurotically cells wrap around the neuron cell axons to form myelin sheaths. In what two ways is this neuro glial cell different from the second neuro glial cell in the way it makes myelin sheaths?
The other cell that forms myelin sheaths is the Schwann cell. Each oligodendrocyte forms myelin sheaths in up to 15 different neurons while each Schwann cell only forms 1.
Neurons that have a myelin sheath around their axons are known as white matter. Those that don’t are known as grey matter. What is the purpose of white matter?
White matter can induct APs at much faster speeds than grey matter.
What are the nodes of ranvier that are found in the myelin sheath?
The areas of the neurons axon that are not covered by the myelin sheath. They are the gaps in the myelin sheath.
How are the nodes of ranvier related to saltatory conduction of the AP?
The AP hops from node to node as it moves down the axon. This is known as saltatory conduction.
What causes saltatory conduction?
The AP is forced to hop from node to node because it can’t flow through the areas where the myelin sheath covers the axon. This is because the myelin sheath is an insulating device against electrical currents.
Within the CNS, where are myelinated nerves found?
In the brain, white matter is found in the medulla. In the spinal chord, white matter is found in the cortex.
What is another name for the motor division of the peripheral nervous system?
The efferent division.
Through what root do the PNS nerves attach to the spinal chord?
Central root.
In what direction do APs move through motor nerves?
APs start at the brain and move through the body.
What is the afferent division of the PNS?
Afferent nerves are sensory nerves. APs start in the body and move to the brain.
What are two divisions of the motor division of the PNS?
Somatic and autonomic.
What body organs/structures do somatic and autonomic divisions control?
Somatic controls skeletal muscle contractions ONLY. autonomic controls all unconsciously controlled body functions. Cardiac and smooth muscle.
How dodo a the nerve composition differ in somatic/autonomic divisions?
Somatic: one neuron that starts at the brain and reaches organ.
Autonomic: two neurons that synapse at a ganglia. The second reaches organ.
How does the type of control differ in somatic/autonomic divisions?
Skeletal muscle control is consciously controlled while smooth and cardiac muscle is involuntary.
Released onto organs by the sympathetic nerves
Norepinephrine
LSD and other hallucinogens produce their effect by messing with the NT
Serotonin
Sedatives like alcohol increase it’s effects
GABA
Low levels can cause clinical depression
Noradrenalin serotonin dopamine
Has excitototic effects on neurons
Glutamate
Causes the high seen with drugs that are stimulants
Noradrenaline
Low levels cause the uncontrolled muscle tremors of Parkinson’s disease
Dopamine
Pain killers like oxycodone and morphine block it’s release
Substance P
Septic halls important in learning and memory formation
Glutamate
Controls the sleep/wake cycle by responding to light
Seratonin
Natural painkillers which inhibit pain sensations
Endorphins
Main inhibitory NT used in the brain
GABA
Major NT which reinforces behaviors by linking them to a pleasure sensation
Dopamine
Dissociative anestetics block it’s receptors in the brain causing the mind to feel disconnected from the body.
Glutamate
Opioid painkillers act like this NT by using its receptors making them much more effective and addictive than aspirin as painkillers
Endorphins
Notepinephrine or noradrenaline is another example of a NT that can cause excitatory or inhibitory effects. Give an example of how NA caused excitatory effects in some blood vessels but inhibitory effects in other blood vessels.
The basic job of NA is to increase physical activity. NA is responsible for fight or flight. Therefore, it has excitatory effects in skeletal muscle BV because it increases blood flow. Inhibitory effects in skin and organ BV because it reduces the fm look flow to those areas.
What is the general name for NA receptors?
Adrenergic receptors.
How it it possible for NA to have excitatory effects in one location but inhibitory effects in another?
There are two specific types of adrenergic receptors. Alpha and beta. The effect of NA is dependent on which receptor it binds to.
What does NA cause to happen in the liver that goes along with increased physical activity?
NA causes the liver to release sugar so that it can be used to make energy for skeletal muscle contraction.
How are the sympathetic and parasympathetic nervous systems different in the locations that their nerves exit the spinal chord?
Sympathetic- nerves exit at the thoracic and lumbar regions of the spinal chord.
Parasympathetic- nerves exit at the brainstem and sacral regions of the spinal chord.
What are ganglia?
Ganglia are synapses between neurons that occur outside of the brain or spinal chord. They occur in both SNS and the PNS.
How are the SNS and the PSN different in the locations of their ganglia?
Sympathetic: ganglia near spinal chord
PNS: ganglia near organs
How does the location of ganglia affect the length of the preganglionic and postganglionic neurons of the SNS and the PNS?
SNS: preganglionic neurons are short because they’re close to the spinal chord postganglionic are long so they can reach organs
PSN: preganglionic neurons are long since they’re near organs and post ganglionic neurons are short.
Increased peristalsis
Parasympathetic
Passive focusing of eye for far/distant vision
Sympathetic
Orgasm or ejaculation
Sympathetic
Penile erection
Parasympathetic
Almost exclusive control of sweat production
Sympathetic
Vasodilation to skeletal muscle
Sympathetic
Ciliary muscle of eye contracts to focus lens
Parasympathetic
Release of sugar by liver
Sympathetic
Release of adrenalin by adrenal glands
Sympathetic
Constriction of bronchi to lungs
Parasympathetic
Retention of urine by the bladder
Sympathetic
Release of insulin by pancreas
Parasympathetic
Vasoconstriction to organs and skin
Sympathetic
