Chapter 3 - Biological Foundations of Bahaviour Flashcards
Neurons are the basic building blocks of the nervous system, made up of what three parts? describe them
Cell body/Soma
- contains biochemical structure needed to keep neuron alive
- nucleus carries genetic info that determines how cel will develop and function
Dendrites
- branch like emerging from cell body
- collects messages from other neurons, send them to cell body
Axon
- extends from cell body, conducting electrical impulses to other neurons, muscles or glands
- connects with dendrite branches from other neurons
How many neurons does a human have at birth?
100 billion, loosing 10,000 every day
What are Glial cells
They surround neurons and hold them in place
- made up of fatty tissue
- also manufacture nutrients from myelin sheath, absorb toxins and waste
- guide newly divided neuron to place during brain development
what does the blood-brain barrier do
prevents substances from entering brain
Describe the sate inside and outside of a neuron
- neurons are surrounded by a positively charged liquid environment (Na+)
- inside of the neuron is negative (Cl- and negative protein ions)
- the resting potential across the membrane is -70mV
Describe events leading up to action potential
Action potential (nerve impulse) is a sudden reversal in neuron’s membrane voltage
- depolarization occurs; changes from -70mV to +40
- only occurs if the graded potential reaches action potential threshold, about -55mV (obeys all or none law)
- This change occurs due to ion channels, which open allowing a rushing in of Na+, making the neuron less negative (depolarization)
- Ion channels then close, K+ channels open and the positive ions go back to their respective positions outside the cell
- resting potential is restored
what is the refractory period
time period during which the membrane is not excitable and cannot discharge another
action potential
- occurs immediately after impulse passes
- limits rate at which action potential can be triggered (300 impulses/sec in humans)
What is the Myelin sheath and what is its purpose? Also was are the nodes of ranvier?
- a fatty, whitish insulation layer derived from glial cells that covers axons
- thins out at regular intervals, called the nodes of renvier
- allow for higher conduction speeds along axon and faster transmission time
- prevents loss of signals
what is a polarized neuron
a neuron at resting potential
what is a depolarized neuron
a neuron which sodium channels have opened and Na+ has rushed into the cell making it positive
what is hyperpolarization
a change in a cell’s membrane potential that makes it more negative
When neurons are classified by shape there are three kinds. which are…
Bipolar - an axon and one dendrite extending from the cell body toward opposite poles
Multipolar - multiple dendrites and a single axon.
Unipolar - neurons have one axon (usually the cell body on the side of the axon)
what is an excitatory neuron
Will depolarize postsynaptic membrane (EPSP) making it positive
What is an inhibitory neuron
Hyperpolarizes membrane (IPSP) making it negative
EPSP’s and IPSP’s are additive across space and time
what does this mean
if you were to get two epsp’s you could add them together to get the total effect of both of them
same with ipsps
or if you have an ipsp and epsp that are equal, they will cancel each other out
who discovered synaptic transmission
Otto Loewi
What is a synaptic cleft/ synapse
- neurons don’t touch each other
- tiny space between axon terminals to dendrite of the next neuron
Carrying messages through synapse to excite or inhibit the other neurons evolves what five steps
Synthesis - chemical molecules formed inside neuron
Storage - Molecules stored in synaptic vesicles
Release - Action potential causes vesicle to move to surface of terminal, molecules are releases into fluid-filled space
Binding - molecules cross the space and bind to receptor sites (large protein molecules embedded in the membrane)
Deactivation
whos experiment studied the flexor response and helped discover the synapse?
Sherrington
he suggested that the transmission from neuron to neuron was not electrical but rather chemical
what are neurotransmitters
the chemicals found in synaptic vesicles that travel across synapse during synaptic transmission
The binding of neurotransmitters to receptor sites causes two possible effects which are…
Excitation
- depolarizes next neuron
- makes post-synaptic neuron more likely to fire
- causes sodium to enter postsynaptic neuron
Inhibition
- hyperpolarizes (more negative),
- causes action potential to not occur
- changes the potential from -70mV to -72mV
this makes it more difficult to excite the neuron to the threshold and cause action potential, thus inhibiting neuron
the receptor sites on the postsynaptic membrane will only allow for neurotransmitters what are the right _____ to bind/pass
shape
how are inhibiton and seizures linked
seizures are caused by a lack of inhibition
t or f? some neurons can be both expiatory and inhibitory
True! depends on the type of receptor
Different areas of the brain have more or less of certain types of receptor, why?
- makes these areas more or less sensitive to specific neurotransmitters, and helps prevent “crosstalk” from
other areas - allows neurotransmitters to have specific functions
Tell me about the neurotransmitter glutamate
- excitatory
- related to learning and memory
- too much = seizures
Tell me about the neurotransmitter Acetylcholine
Excitatory
related to muscle movement and memory, behavioral inhibition
too little = Alzheimer’s, paralysis
too much = convulsions, all muscles will starts contracting
Tell me about the neurotransmitter dopamine (DA)
excitatory & inhibitory (mainly inhibitory)
related to reward, pleasure, voluntary movement, control of thoughts
too little = Parkinson’s (problems initiating and controlling movement)
too much = Schizophrenia (hallucinations, hearing voices)
tell me about the neurotransmitter GABA (Gamma-amino-butyric-acid)
inhibitory
found throughout brain - involved in most behavior especially motor control and lowering anxiety
too much = inhibits brain function (alcohol increases GABA release)
too little = tremors, lose motor control, anxiety
tell me about the neurotransmitter serotonin
inhibitory & excitatory
involved in mood, pleasure (eating, sleep, sex)
too little = depression
too much = insensitivity to pain (released in accidents or injury)
tell me about the neurotransmitter endorphins
- inhibitory
- inhibits pain
- too little = hypersensitivity to pain
- too much = insensitivity to pain
what’s an agonist
increases the activity of a neurotransmitter
- If its an inhibitory agonist it will make an inhibitory neurotransmitter more inhibitory
what’s an antagonist
decreases the activity of a neurotransmitter
what’s a neuromodulator
Increase or decrease sensitivity of neurons to whatever neurotransmitter(s) they receive
tell me about the neurotransmitter Norepinephrine (NE)
functions in excitatory and inhibitory systems
related to arousal, eating
drugs function by affecting neurotransmitters. They ____ or ______ amount of transmitter, which ______ or ______ receptor sites, terminates transmitter function
increase, decrease
stimulate, blocks
what does cocaine do
stimulates release of dopamine, prevents reuptake
what does curare to
stimulates the release of DA by releasing a molecule that looks like acetylcholine to bind to it’s receptor site, so ACh cannot bind there anymore
prevents reuptake
can cause paralysis
what does black widow venom do
Stimulates release of Ach and can cause cardiac arrest
What does the Botulism toxin do
blocks release of Ach,
covering presynaptic neuron, prevents release
what does nicotine do
stimulates receptor molecules “duplicating” effects of Ach, increased heart rate
what does caffeine do
blocks adenosine receptor sites
which is a neurotransmitter that makes you sleepy
what are the three different types of neurons that carry out functions
Sensory neurons – carry input messages from the sense organ to the spinal cord and brain (outside to in)
Motor neurons - transmit output impulses from the brain and spinal cord to the muscles and organs (inside to out)
Interneurons - relay stations - take information from one or many neurons, amalgamate it and pass it on
the ______ consists of all the neurons in the brain/spinal cord
Central nervous system
the _______ is composed of all the neurons that connect the CNS with muscles/glands/sensory receptors
Peripheral Nervous system
what are sensory neurons
they carry input messages from the sense organs to the spinal cord
what are motor neurons
transmit output impulses from the brain and spinal cord to the body’s muscles and organs
what are interneurons
relay stations that take information from one or many neurons and put it together and pass it on
explain the somatic nervous system
- consists of sensory neurons that transmit messages from eyes, ears, and other sensory receptors, and motor neurons that send messages from the brain/spinal cord to the muscles
- control our VOLUNTARY MOVEMENTS
explain the autonomic NS
-controls glands, muscles that form the heart, blood vessels, lining of stomach, and intestines.
- Concerned with INVOLUNTARY FUNCTIONS
the autonomic NS is split into two part which are
sympathetic NS and Parasympathetic NS
Sympathetic nervous system- a branch of the autonomic system that has an arousal function on the body’s internal organs, speeding up bodily processes and mobilizing the body
Parasympathetic nervous system- a branch of the autonomic system that slows down bodily processes to conserve energy and reduce arousal
whats homeostasis
a balance or constant internal state
explain a reflex arc/ spinal reflexes
a stimulus that doesn’t need to go to the brain but bounces right off the spinal cord
a sensory neuron, connected to an interneuron, connected to a motor neuron
the hindbrain has 2 parts. name them
Brian stem (medulla and pons)
Cerebellum
the brain stem is
the connection between spine and brain, regulates basic survival functions of the body such as heart rate and breathing
the medulla controls____, is located _____, and allows for _________________
(more an 1 word/blank)
controls vital functions including heartbeat and respiration located in the brain stem, and allows for functions to occur automatically
the pons serve as
serves as a bridge carrying impulses between the higher and lower level of the nervous system
explain the midbrain
involved in sensory and motor functions and inattention/states of consciousness
comprised of clusters of
sensory and motor neurons, as well as tracts that connect higher and lower
portions of nervous system
what is reticular formation
Acts as a sentry, alerting higher centres of brain that messages are coming, and either blocking or
allowing them through
Without ret
icular stimulation of higher brain regions, sensory messages do not process despite the
impulse reaching the destination
Affects sleep, wakefulness, and attention
explain the forebrain
comprised of two large cerebral hemispheres that wrap around the brain stem
involved in higher-order sensory, motor, and cognitive functions
Outer portion is covered by the cortex
name (4) important regions of the forebrain we learnt about
thalamus
Basal Glanglia
Hypothalamus
Limbic system
the brain weighs ___, and consumes ____% of our oxygen
3lbs, 20%
explain the thalamus
Important sensory relay station
Organizes inputs from sense organs and routes them to appropriate brain area
explain the Basal Ganglia
Critical for voluntary motor control
Plays important role in the deliberate and voluntary
control of movement
explain the hypothalamus
Plays a major role in controlling many different basic biological drives (sexual behaviour,
temperature regulation, eating, drinking, aggression, etc.)
explain the limbic system
Helps coordinate behaviours needed to satisfy motivational and emotional urges that arise in the
hypothalamus
Inside the limbic system are the ______ and the _______
hippocampus and the amygdala
explain the hippocampus
involved in forming and retrieving memories
explain the amygdala
organizes emotional response patterns ( like fear )
Can produce emotional response without higher regions of brain realizing
what is the cerebral cortex? how is it devided?
thick sheet of grey cells that form the outermost layer of the brain
divided into 4 lobes : frontal, parietal, occipital, temporal
each lobe is associated with particular sensory and motor functions
what are the functions of the lobes
Frontal:
speech and skeletal motor functions
Parietal: body sensations
Occipital: visual area
Temporal: messages from the auditory system
explain the motor cortex
Controls muscles involved in voluntary body movements
Amount of cortex devoted to each body part depends on complexity of movements of that part
explain the sensory cortex
receives sensory input that allows for sensations (heat, touch, cold) as well as senses of balance and body movement
Amount of cortex devoted is dependent on sensitivity of part
what two parts are dedicated to speech comprehension and production
Wernicke’s area - language comprehension
Boca’s area - necessary for normal speech production
explain the association cortex
Found within all lobes of cerebral cortex
each association area is near its projection area (motor association areas next to motor projection areas
Involved in highest level of mental functions (perception, language and thought)
how many neurons are there in the brain
about 100 billion
where is the prefrontal cortex? what does it do?
in the frontal lobes (right behind forehead)
region responsible for mental abilities allowing people to direct behavior in an adaptive fashion
last thing to develop in brain
explain contralateral control
control in the cortex is on the opposite side of the body
what are some neural disorders due to the damage of the association cortex (hint; the highest level) (2)
Apraxia - inability to perform smooth actions
Agnosia - inability to interpret sensory information
the neural bridge that acts as a major communication link between the two hemispheres is _______
the corpus callosum
What is lateralization
refers to the localization of a function in one hemisphere or the other
For most people, left hemisphere involved in verbal abilities, speech, mathematical, and logical abilities
Right hemisphere involved in mental imagery, musical/artistic abilities, and ability to perceive and understand spatial relationships
Left: positive emotions, Right: negative emotions
what is neural plasticity
refers to the ability of neurons to change in structure and function
The brain is capable of greater plasticity _______ __ ____
earlier in life
what is the endocrine system
The endocrine system is a complex network of glands and organs. It uses hormones to control and coordinate your body’s metabolism, energy level, reproduction, growth and development, and response to injury, stress, and mood.
what are hormones
are chemical messengers that are secreted from its glands into the bloodstream.
Cells in the body have receptor molecules that respond to specific hormones from the endocrine glands
function and location of the medulla
- the bottom-most part of your brain.
Its location means it’s where your brain and spinal cord connect, making it a key conduit for nerve signals to and from your body. - It also helps control vital processes like your heartbeat, breathing and blood pressure
location and function of pons
lies just above medulla
a bridge carrying nerve impulses between higher and lower parts of the NS
location and function of cerebellum
- looks like a little brain growing out the back of your brain right above pons
- primarily concerned with muscular movement and coordination but also plays role in certain types of learning and memory
- motor movements initiated in higher brain regions but timing and coordination of them depend on cerebellum
what does the reticular formation do? (in midbrain)
alerts higher centers of the brain that messages are coming either allowing them in or not
function and location of the basal ganglia
- in forebrain, enveloping the thalamus
- motor control, as well as other roles such as motor learning, executive functions and behaviors, and emotions.
function and location of the nucleus accumbens
neural interface between motivation and action, playing a key role on feeding, sexual, reward, stress-related, drug self-administration behaviors, etc.
location and function of the corpus callosum
a neural bridge between the two hemispheres that acts as a major communication link and allows them to function as one unit
explain the frontal lobe
speech productive, motor cortex, and involved in planning and problem solving
includes
- motor cortex
- broca’s area
- prefrontal cortex
explain the parietal lobe
Somatosensory cortex- receives sensory input from various regions of the body
contains somatic sensory and Wernicke’s speech comprehension area
explain occipital lobe
dorsal side?
ventral side?
contains primary visual sensory area
Dorsal side- sends info about orientation and movement of objects to the parietal lobe
Ventral side- sends info about recognition to the temporal lobe
explain the temporal lobe
major site of auditory input to the brain
includes Wernicke’s area- involved in speech comprehension
explain the association cortex
involve in highest levels of mental functions including perception language and thought
what is apraxia
inability to perform smooth motor movements
explain agnosia
inability to interpret sensory information
explain aphasia and the two types
partial or total loss of the ability to communicate using language
Broca’s aphasia- difficulty in creating lauguage
Wernicke’s aphasia- difficulty in understanding launguage
________ _________ is caused by stroke to the right hemisphere, parietal and temporal lobes affected, ignore contralateral (opposite side)
Hemispatial neglect
explain what a split brain operation is
person suffering from severe epilepsy, corpus callosum severed in half to prevent seizures from spreading across hemispheres
when a neuron fires, how does one code for intensity?
Most common way - intensity is directly proportional to frequency of firing - the more intense the stimulus the more often a neuron will fire
but also:
- neurons have different thresholds, therefore if a neuron has a higher threshold per say and the neuron fires, we know the stimulus must be more intense
- a stronger stimulus affects more neurons, you could keep track of how many fire to tell you how strong the stimulus is
what could limit the frequency of firing of a neuron
the absolute refractory period
the membrane is not excitable and cannot generate another action potential
Sherrington’s experiment was important in explaining the synapse.
explain it
he was trying to measure the speed of a flexion response
he found that the neural impulse travels at about 200 feet/sec
figured if the reflex arc is 2ft long, the latency should be 10 milliseconds
its not - its 100 milliseconds, so its not an electrical circuit where everything touches
he thus suggested that the communication was not electrical, rather chemical which helped discover the synapse
explain the process of reuptake in the synapse
when not all neurotransmitters are transferred to the postsynaptic neuron, the rest are reabsorbed into the presynaptic axon terminal in the process of reuptake
any left over in the synapse are then neutralized (by something like monoamine oxidase)
a neurotransmitter locks into a receptor site on a postsynaptic membrane - sodium channels then open
what is happening
EPSP
An excitatory postsynaptic potential (EPSP) occurs when sodium channels open in response to a stimulus. The electrochemical gradient drives sodium to rush into the cell. When sodium brings its positive charge into the cell, the cell’s membrane potential becomes more positive, or depolarizes.
a potassium channel opens at the postsynaptic membrane, which hyperpolarizes the cell, makes it more negative
what is this called
inhibitory postsynaptic potential (IPSP).
what does constant inhibition do to a neuron
raises the threshold of firing
t or f
a single neuron can synapse with many others
TRUE
it can get up to tens of thousands
neuron A fires, depolarizing neuron A. But it is not strong enough to create an action potential (bet -70 and -50)
it fires multiple times, is it able to create action potential?
yes! because graded potentials are additive across time and space
neuron A id excitatory, neuron B is inhibitory
they both fire at the same time on neuron C
what is likely to happen to C
the epsp from neuron A cancels out the IPSP from neuron B
nothing happens
Neuron A is inhibitory, it fires on neuron B repeatedly
what will likely happen to neuron B
hyperpolarization will occur, the voltage will drop below -70
thus raising the threshold through constant inhibition
the thalamus, midbrain, pons and medulla are all a part of the _____ ______
old brain
what are the three characteristics of the projection areas in the brain
topographical representation - map of each body part, generally moving from the bottom of the body to the top
contralateral control - left hemisphere controls right side, vice versa
function assignment of space - more cortical space given to important features
what is an angiogram
basically an x-ray of the brain, but the area of interest is dyed to see it better
what is a CAT scan
taking an x-ray of brain from a 360 degree rotation, then patching each scan together
What is a PET scan
allows for us to see brain activity
done by injecting radioactive glucose into the brain, and the areas that are functioning will draw more sugar than others will light up (in red, yellow and white)
what is an mri?
expose the brain to a strong electromagnetic field
what is best, most accurate brain scan which gives you imagery of the functions of the brain
fmri
what does the association area ?
integrates and interprets information
takes sensory information and makes sense of it
eastyn jumps off the roof of aceb, she then suffers brain damage and has trouble being able to perfrom smooth actions,
she can perform each action individually but cannot sting her movements together smoothly
what condition does she have
apraxia
what will an individual with agnosia struggle to do
they struggle to interpret sensory information
eastyn suffers a stroke, she then has trouble being able to produce speech.
what condition does she have
brocas aphasia
eastyn gets hit by a bus, she then has trouble being able to understand Mireille when she speaks
what condition does she have
Wernicke’s aphasia
a horse steps on eastyns head and gives her brain damage, she then tries to describe the accident, can speak coherently but the sentences make so sense
what condition does she have
wernickes aphasia
the ______ hemisphere is often referred to as the verbal hemisphere, the _____ hemisphere is often referred to a the nonverbal hemisphere (for right handed individuals)
left - verbal
right - nonverbal
eastyn goes through brain surgery, she has her corpus callosum cut and now has a split brain.
why tf would she do that
she has a neural disorder (such as epilepsy) and is trying to avoid it from spreading to the other hemisphere
is eastyn is a right handed split brain patient and something is projected into her left visual field, will she see it?
yes! but will be unable to see anything in her right visual field
