Biological Basis and Stress Flashcards
what happens to sensory information when it is received by the brain? what does this allow? What does processing often involve?
When the sensory information is received at the brain it is processed. This enables perception—interpretation of the sensory information so meaning can be assigned
Processing often involves integrating incoming information with other information already in the brain
what actions can the brain carry out if required? What does this do?
If required, the brain will also coordinate a response by initiating appropriate action by sending neural messages to the muscles, glands and internal organs
This, in turn, enables muscles to move, causes glands to secrete hormones and initiates the responses of internal organs, thereby enabling the body systems to function effectively
What are the building blocks of the nervous system?
Neurons and glial cells (or glia) are the building blocks of the nervous system
how many neutrons and glial cells are there? what are each? How and why do neurons vary?
The NS contains billions of neurons and glial cells
Neurons are specialised cells that are organised in circuits and pathways and are involved in the reception, processing and transmission of information in the NS
Glial cells support the neurons function
Neurons vary in size, shape and location depending on their function
what is the structure of a dendrite? how many may a neurone have? What does the structure allow neutrons to do?
An extension of the neuron (like a branch)
Most have protrusions called dendritic spines (small)
A neuron can have 1 to 20 dendrites
Dendrites can have one or many branches- the spines may be in the thousands
A neuron may have thousands of connections through branches and spines
What is the function of dendrites? What do spines provide? What is plasticity?
Detect and receive information from other neurons
Spines provide a site with receptors where neurons can connect and receive info from other neurons
Plasticity is the ability for the neutron to grow more dendrites
Each spine may have multiple kinds of receptors which gather different types of chemical information
Consequently, neuron can receive thousands of messaged at once
Dendrites send received info down the soma where it is integrated
what does the soma do?
The soma collects and integrates information from thousands of neurons
Once integrated by the soma, information is sent along the axon
what is the structure of an axon? How many?
A tube-like extension
Most neurons only have one but some have branches that allow messages to be sent to multiple cells
Vary in length (m-mm)
Nerves are cable-like bunches of axons
what is the function of an axon?
Transits neural information to other neurons or cells
what is the structure of myelin? what are the gaps called?
Many axons are myelinated, not all
A white, fatty substance (made of certain glial cells)
Surrounds the axon
Not continuous, occurs in segments that are separated by unmyelinated gaps called nodes of Ranvier
what is the function of myelin?
Insulates the axon and prevents interference from activity of other neurons (plastic on a cable)
Allows rapid movement of messages (no interruption or distortion)
Messages travel faster
Neural messages jump from node to node which is believed to speed up transmission
what is the structure of axon terminals?
Small branches at the end of axons called axon collaterals
At the end of these are axon terminals
Each axon terminal has a small know-like swelling at its tip called a terminal button , synaptic vesicle, synaptic know or synaptic button.
It is small and like a sac
what is the function of axon terminals?
Store and secrete neurotransmitters that are manufactured by the neuron and carries a chemical message to other neurons or cells.
Neural impulses stimulate the release of neurotransmitters
The collaterals and axon terminals allow messages to be sent to many neurons at once
what are sensory neutrons? what do they do? where do they receive info from? what are the also called?
Receive information from external or internal environments
Detect and respond to specific information
Transmit info to CNS
Info from external: received by sense organs, internal: from muscles, organs and glands
Has a sensory receptor to receive sensory information
Also called afferent neurons
what are motor neurones? what do they do? what is an important aspect of their structure? What are the also called?
Transmit messaged from the CNS to muscles, organs and glands
Enable muscles to move, glands to secrete and activate internal organs
The axon is covered in myelin sheath
Also called efferent neurons
what are interneurones? where are they? what do they do?
Transmit messaged from the CNS to muscles, organs and glands
Enable muscles to move, glands to secrete and activate internal organs
The axon is covered in myelin sheath
Also called efferent neurons
what are neurohormones? where are they released? what are two types and what do they do?
Chemical messenger molecules
Released into the bloodstream
Oxytocin: involved in contractions of the womb during childbirth and lactation
Vasopressin: involved in retaining water in the body and contrition of blood vessels
what do neurotransmitters allow for? Where do they occur? Where do they bind?
Communication over synapses
Occurs between terminal button of the pre-synaptic neuron and the dendrites of the post-synaptic neuron
Bind to specific receptor sites in the post synaptic neurone
what is reuptake? what do some medications do with this process?
Neurotransmitters that do not bind are reabsorbed by the pre-synaptic neurone in a process called reuptake
Many medications work by affecting the process of reuptake in order to increase or decrease the availability of neurotransmitters in the brain
what are the two types of neurotransmitters and a description of both?
There are two types of neurotransmitters, excitatory and inhibitory
Excitatory: stimulate or activate post-synaptic neurone to preform their functions
Inhibitory: block of prevent the post-synaptic neurone from firing. Uncontrolled activation of GABA could result in a spread throughout the brain, causing sizers similar to anxiety and epilepsy
what is the function of glutamate?
memory and learning
is glutamate ex or in?
ex
what does too much glutamate cause?
migraines or seizures
what does too little glutamate cause?
lethargy
what is the function of GABA?
arousal
is GABA in or ex?
in
what does too much GABA cause?
lethargy
what does too little GABA cause?
seizures, insomnia, anxiety, tremors
what is the function of Acetylcholine?
muscle movement, learning and memory
is acetylcholine ex or in?
ex
what does too much acetylcholine cause?
depression
what does too little acetylcholine do?
Alzheimer’s disease
what does dopamine do?
muscle movement, attention, emotions, learning, memory
is dopamine ex or in?
ex or in
what does too much dopamine cause?
schizophrenia
what does too little dopamine cause?
Parkinson’s disease
what does serotonin do?
mood, hunger, sleep, arousal
is serotonin ex or in?
ex
what does too much serotonin do?
euphoria, mania
what does too little serotonin do?
depression
what does norepinephrine do?
alertness, sleep
is norepinephrine ex or in?
ex and in
what does too much norepinephrine do?
anxious, stressed, high arousal, headaches
what does too little norepinephrine cause?
depression
what is the lock and key process?
Each type of NT has a chemically distinct shape
After being released, they search for the correctly shaped receptor site in order to bind to the post-synaptic neurone’s receptors
In order to bind to the receptor, the NT must be precisely matched
The binding unlocks the postsynaptic neurone’s responses so that the neurotransmitter can cause changes in the neurone (excitatory or inhibitory effects)
The Nt is the key and the receptor site is the lock
what can interference with NTS cause?
Too much or too little of neurotransmitters can impact how we think, feel or behave because of its impact on the NS
Abnormal levels can be linked with problems with metal processes such as dopamine in Parkinson’s Disease
What is Parkinson’s Disease? what is it characterised by?
A CNS neurodegenerative disorder characterised by both motor and non-motor symptoms
What are the motor symptoms of PD caused by? what NT is affected?
Motor symptoms come from the degeneration and loss of neurones in the substantia nigra
This is located in the midbrain and has a role in the control of voluntary muscle movements so that they can be executed in a smooth and coordinated manner such as sequences of movement needed for walking, writing, balancing and talking
Neurones here produce the NT dopamine so when this area is damaged, the amount of dopamine available for motor activity reduces as neurones die
The level of dopamine continues to fall over the years
when is PD diagnosed? How many people have it? what is diagnosis based on?
Usually diagnosed between 55 and 65, though it can happen at any time
1 in 350 people in Australia have it
Diagnosis is based on symptoms, a neurological examination and a review of past medical history
There are no really adequate or specific biological or radiological tests available for a diagnosis that would confirm the presence of the disorder
what causes PD? when is risk increased? what is the only factor?
The cause is idiopathic (no known cause)
It is not known what causes dopamine producing neurones in the substantia nigra to die
There is a slightly increased risk in families
Age is the only know factor
What is GABA? What happens to it in PD? What could this cause? What might it do to dopamine?
GABA is an amino acid
It reduces the sensitivity of muscle cells to nerve stimulation, decreasing muscle movement
The amount of GABA in the brain decreases with PD, particulaly in the subthalamic nucleus, which could cause tremors, restless leg syndrome, dyskinesia (impairment of voluntary movement) and dystonia (muscles contract uncontrollably)
There is also some evidence that GABA functions as a dopamine antagonist, blocking the effect of it, which is already depleted in PD
The result is worsened symptoms such as bradykinesia (slowness of movement)
what drug is used to help with GABA?
The drug baclofen (branded Lioresal), a GABA agonist taken to relieve symptoms binds with GABA receptors and mimics its actions
what are symptoms of PD?
Develop slowly and gradually worsens over years
Symptoms vary greatly
Motor and non-motor symptoms vary from day to day
what are the four key motor symptoms used for diagnosis of PD?
Tremor involving continuous, involuntary shaking. 30% of people with PD don’t have tremors. Most often they are resting tremors and occur when the limb is not in use.
Muscle rigidity or stiff muscles whereby the muscles seem unable to relax and are tight even at rest. People have difficulty performing automatic movements.
Slowness of voluntary movement especially when executing repetitive movements, decrease in fine coordination (postural instability), balance problems and gait disturbances tend to occur later in the course of the disorder. Inability to remain steady, upright or corrective action to prevent a fall often results in falling.
Non-motor symptoms: decrease or loss of sense of smell (anosmia), decrease in sweating, increased sensitivity to temperature, fatigue, confusion, panic attacks, anxiety disorders, depression, slowness of thinking, impaired planning and decision making, memory loss.
Is there a cure for PD? What are some treatments and why mightn’t they be working very well?
Cure is unkown
Tremors, rigidity and slowness of movement can be relieved by medications that restore the deficiency of dopamine by increasing dopamine levels in the brain.
Medications: those that are converted into dopamine and those that mimic dopamine and are able to stimulate reception of dopamine by neurones.
Evidence that midbrain dopamine neurones release dopamine and GABA.
It is believed that overlooking this and only treating for dopamine loss might be why the treatments haven’t been very successful.
what is the CNS?
Consists of all nerves in the brain and spinal cord
what does the brain do? how is it organised?
Brain: master of information and decision making organ. It plays a crucial role in everything we do.
Receives and interprets information from the sensory systems and sends motor messages out to all parts of the body so that a coordinated and appropriate response can be made.
Brain cells are organised into identifiable areas and structures that have specialised functions.
what is the spinal cord and what does it do?
Spinal cord: a complex cable or tract of nerve fibres from the base of the brain to the lower back.
Connects the brain to other parts of the body via its connection to the PNS- it is like an information highway.
Receives sensory information from the PNS and transmits it to the brain.
Transmits motor messages from the brain to the PNS, including muscles, organs and glands.