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Neurons
the basic building block of our nervous system, also known as a nerve cell
dendrites
a neuron’s bushy branching extensions that recieve messages/info and conduct impulses toward the cell body
axon
the neuron extension that passes the message recieved from dendrites through its branches to other neurons/muscles/glands
What recieves the message in our nervous system?
Dendrites
What passes the message in our nervous system?
Axons
myelin sheath
a fatty tissue layer which holds axons and speeds up their imuplses
degeneration of the myelin sheath can cause:
multiple scolorisis as communication to muscles slows down and leads to loss of muscle control
nuerons fire impulses which are called:
the action potential
action potential
a nueral impulse, or a brief electrical charge which travels down an axon
when do neurons transmit messages?
when stimulated by signals from our sense or triggered by chemical signals from neighboring neurons
the terminal branches of an axon…
forms junctions with other cells
neural impulse
the electrical signal traveling down the axon otherwise known as the action potential
axons pass messages….
away from the cell body to other neurons/muscles/glands
the fluid outside an axon’s membrane consists of ____ charged ions
postive
the resting axon’s fluid interior consists of ___________ ions.
negative
resting potential
the positive outside and negative inside charge ions
the axons surface is…..
selectivley permeable
refractory period
the period of inactivity after a neuron has fired where the neuron pumps positive charged sdodium ions back outside
increasing the level of stimulation above the threshold will not _________ the neural pulse’s intensity
increase
a neurons reaction is
an all or nothing response
how does a strong stimulus affect a neural impulse?
it doesn’t change the strength or speed but it can trigger MORE neurons to activate
what are the main components of a neuron?
the cell body, dendrites, axons, myelin sheaths, terminal branches
threshold
the level of stimulation required to trigger a neural impulse
all or nothing reponse
a neurons reacitino is either full strength firing or not firing at all
synapse
the meeting point between two neurons
synaptic gap/cleft
the tiny gap between the meeting point of two neurons (synpases)
neurotransmitters
chemical messengers which cross between the synaptic gap between two neurons and bind to the receptor site
reputake
when the sending neurons reabsorbs excess neurotransmitters
how many neurotransmitters can a particular brain pathway use?
one or two
endorphins
(morphine within), natural opiate like neutrotrasmittors linked to pain control and pleasure
what can overflooding the brain with artifical opiates do?
cause the brain to stop producing their own natural endorphins
agonist
molecules that are similar enough to a neurotransmittor to simtulte a response by binding to a receptor site
antagonists
molecuels that blocks a neurotransmitter response by binding to receptors
neurotransmitters are produced
in the body
drugs and chemicals can have what effects on a neurotransmittor?
angonistic or antagonisitc
How do neurons communit with each other?
What happen if received neuron signal exceed a maximum threshold?
the neuron fires and trasmits an electrical impulse down its axon by a chemistry to electricity process
when action potentials reach the end of an axon they…
stimulate the release of neurotransmitters
what happens if incoming signals from one axon to another are strong enough?
the receiving neuron generates its own action potential and relays the message to other cells
agonists ________ by mimikicing neurotransimiter or blocking their reputake
excite
nervous system
the body’s speedy, electrochemical communication enetwork which consists of all of the nerve cells for the peripheral and central nervous system
central nervous system (CNS)
the brain and spinal cord
peripheral nervous system (PNS)
the sensory and motto neurons that connect the central nervous
synapse
the meeting point between two neurons
synaptic gap
the gap between two neurons
reputake
the reabsorbtion of neurotransmitters back into the sending neuron
function of Serotonin
MOOD
affects mood, hunger, sleep, and arousal
contributes to well-being and happiness
undersupply of serotonin can cause:
depression
Function of Dopamine
PLEASURE
influences movement, learning, attention, addiction, motivation and emotion
causes people to repeat behaviors
Oversupply of Dopamine
schiozphrenia
Undersupply of Dopamine
tremors and decreased mobility in Parkinson’s disease and ADHD
Function of Acetylcholine (ACh)
LEARNING
activates muscle action, learning, and memory
What happens when ACh neurons detoriate?
Alzhiemers disease
function of norepinephrine
CONCENTRATION
helps control alertness and arousal by contracting blood vessels
undersupply of norepinephrine
depressed moods and ADHD-like attention problems
function of Gamma-Aminobutyric Acid (GABA)
CALMING
a major INHIBATORY neurotrasmitter, calms firing nerves in CNS
undersupply of GABA
linked to sezuires, tremors, and insomnia
is GABA inhibatory or excitatory?
inhibatory
Function of Glutamate
MEMORY
A major EXCITORY neurotrasmitter, very common and involved in memory and learning
oversupply of Glutamate
overstimulates the brain producing migranes and seizures
why do some people avoid MSG
becausde it can overstimulate the brain
function of Substance P
involved in pain perception and immune response
oversupply of Substance p
chronic pain
endorphins
natural opiate like neurotransmitters linked to pain control and pleasure
why can injecting artifical endorphins be bad?
the brain can stop producing neurotransmitters naturally
drugs and chemicals affect brain synpases by
inhibiting or exciting a neurons firing
agonist molecules
stimulates and activates a response by binding to receptors and micking the effects of the neurotransmitter
what types of molecules excite?
agonist molecules
peripheral nervous system
the sensory and motor neurons that connect our CNS to the rest of our body
purpose of PNS
gathers info and transmits CNS decisions to other body parts
central nervous system
the brain and spinal cord
what is our body’s decision maker
CNS
the PNS consists of
the somatic and autonomic nervous system
somatic nervous system
volunatry control of our skeletal muscles
skeletal nervous system
somatic nervous system
autonomic nervous system
controls the autoregulated action of our gland and internal organs
what category consists of sympathetic and parasympathetic
autonomic nervous system
sympathetic nervous system
arouses the body and expends energy in stressful situations
parasympatheic
calms the body down and conserves energy
sensory neurons
afferent neurons, carry incoming info from tissues and sensory receptors to the CNS
motor neurons
efferent neurons, carry outgoing info from CNS to the muscles and glands
what neurons are efferent
motor
which neurons are afferent?
sensory neurons
which neurons receive signals?
sensory or afferent neurons
endocrine system
a set of glands that secretes hormones into the bloodstream
pituitary gland
located in the core of the brain, controlled by the hypothalamus
influences the release of many hormones, regulates growth, is considered a master gland, and controls all other glands
hypothalamus
region of brain which controls the pituitary gland
parathyroid
helps regulate calcium levels
thyroid
affects metabolism
adrenal glands
sit above the kidneys, triggers flight or fight response, secretes epinephrine and norepinephrine (adrenaline and noadrenaline)
pancreas
regulates sugar levels in blood
testis
secretes male sex hormones
ovary
secretes female sex hormones
adrenaline
secreted by the adrenal glands, responsible for arousal and the fight/flight response, plays a role in emotinoal memory foundation
Cortisol
Secreted by the adrenal glands; helps control blood sugar levels, regulate metabolism, reduce inflammation and assist with memory formation
Melatonin
Secreted by the pineal gland; signals the relaxation and lower body temperature that help with a restful sleep
Neuropeptide Y
Produced by the hypothalamus and acts as a neurotransmitter in the brain
Stimulates food intake, reduces anxiety and stress, reduces pain perception, affects the circadian rhythm.
Higher levels of NPY linked with higher levels of resilience.
Oxytocin
Produced by the hypothalamus and secreted by the pituitary gland. When it affects the brain, it acts as a neurotransmitter. Plays a role in mother-child attachment; believed to play a role in social bonding and trust between people.
Testosterone
Produced by the testes; plays a facilitative role in aggressive behaviour -doesn't cause aggression, but higher levels of testosterone result in higher levels of aggression.
lesion
destruction of tissue
Note
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