Week 4 Flashcards
Dendrites
Processes that extend outward from the soma, or cell body, or a neuron and typically branch several times. Receive information within the soma, contains genetic information, directs protein synthesis, and supplies the energy and the resources the neuron needs to function
Nucleus
located within the soma, contains genetic information, directs protein synthesis, and supplies the energy and the resources the neuron needs to function
Axon
process that extends far away from the soma and carries an important signal called a action potential to another neuron
Synapse
The place at which the axon of one neuron comes in close contact to the dendrite of another neuron
myelin sheath
The insulating substance that covers the axon of a neuron. Allows the signal and communication of one neuron to travel rapidly to another neuron. Speeds up the process of the action potential. Does not allow any fluid to exist between the myelin and cell membrane
Terminal button
At the end of the axon, forms synapses with spines, or protrusions, on the dendrites of neurons. There are synaptic vesicles that package together groups of chemicals called neurotransmitters
Synaptic gap/ cleft
A very small space, approximately 5 nanometers that exists between presynaptic terminal button and the postsynaptic dendritic spine
Sensory neurons
neurons that help us receive information about the world around us
Motor neurons
allow us to initiate movement and behaviour, ultimately allowing us to interact with the world around us
Interneurons
process the sensory input from our environment into meaningful representations, plan the appropriate behavioural response, and connect to the motor neurons to execute these behavioural plans
Unipolar neurons
Structured in such a way that is ideal for relaying information forward, so they have one neurite (axon) and no dendrites. Involved in transmission of physiological information from the body’s periphery such as communicating body temperature through the spinal cord up to the brain
Bipolar neurons
involved in sensory perception such as perception of light in the retina of the eye. They have on axon and on dendrite which help acquire and pass sensory information to various centres in the brain
Multipolar neurons
The most common, and they communicate sensory and motor information in the brain. One axon and many dendrites, which allows them to communicate with other neurons
Glia cells
play a vital role in neuronal support, but do not participate in the communication between cells in the same fashion as neurons do
Oligodendroglia
Wrap their dendritic processes around the axons of neurons many times to form the myelin sheath. One cell will form the myelin sheath on several axons
microglia and astrocytes, digest debris of dead neurons
carry nutritional support from blood vessels to the neurons, and help to regulate the ionic composition of the extracellular fluid
Two stages of electrochemical action in neurons
First stage is the electrical conduction of dendritic input to the initiation of an action potential within a neuron. Second stage is a chemical transmission across the synaptic gap between the presynaptic neuron and postsynaptic neuron of the synapse
Ion channels
Proteins that span the cell membrane, forming channels that specific ions can flow through between the intracellular and extracellular space
Diffusion
the force on molecules to move from areas of high concentration to areas of low concentration
Electrostatic pressure
the force on two ions with similar charge to repel each other and the force of two ions with opposite charge to attract to one another
Equilibrium potential
the voltage at which no ions flow
Anions
highly concentrated inside the cell and contribute to the negative charge of the resting membrane potential. Diffusion and electrostatic pressure are not forces that determine anion concentration because A- is impermeable to the cell membrane. No ion channels that allow for A- to move between the intracellular and extracellular fluid
Potassium
The cell membrane is very permeable to potassium at rest, but potassium remains in high concentrations inside the cell. Diffusion pushes K+ outside the cell because it is high concentration inside the cell. Electrostatic pressure pushes K+ inside the cell because the positive charge of K+ is attracted to the negative charge inside the cell. In combination, these forces oppose one another with respect to K+
Chloride
The cell membrane is also very permeable to chloride at rest, but chloride remains in high concentration outside the cell. Diffusion pushes Cl- inside the cell because it is high concentration outside the cell. However, electrostatic pressure pushes Cl- outside the cell because the negative charge of Cl- is attracted to the positive charge outside the cell. Similar to K+, these forces oppose one another with respect to Cl-
Sodium
the cell membrane is not very permeable to sodium at rest. Diffusion pushes Na+ inside the cell because it is in high concentration outside the cell. Electrostatic pressure also pushes Na+ inside the cell because the positive charge of Na+ is attracted to the negative charge inside the cell. Both of these forces push Na+ inside the cell; however, Na+ cannot permeate the cell membrane and remains in high concentration outside the cell. The small amounts of Na+ inside the cell are removed by a sodium-potassium pump, which uses the neuron’s energy to pump 3 Na+ ions out of the cell in exchange for bringing 2K+ ions inside the cell
Action potential
an all-or-nothing response that occurs when there is a change in the charge or potential of the cell from its resting membrane potential in a more positive direction, which is a depolarization
Excitatory postsynaptic potentials
a depolarizing current that causes the membrane potential to become more positive and closer to the threshold of excitation
Inhibitory postsynaptic potentials
a hyperpolarizing current that causes the membrane potential to become more negative and further away from the threshold of excitation
ionotripic receptors
ion channel that opens to allow ions to permeate the cell membrane under specific conditions, such as the presence of a neurotransmitter of a specific membrane potential
Nodes of ranvier
Gaps in the myelin sheaths
Endocrine system
Consists of a series of glands that produce chemical substances known as hormones
hormones
chemical messengers that must bind to a receptor in order to send their signal. Secreted into the bloodstream and travel throughout the body, affecting any cells that contain receptors for them. Effects of hormones are widespread. Slower to take effect, and tend to be longer lasting. involved in regulating all sorts of bodily functions, and they are ultimately controlled through interactions between the hypothalamus and the pituitary gland
Pituitary gland
descends from the hypothalamus at the base of the brain, and acts in close association with it. Often referred to as the “master gland” because its messenger hormones control all the other glands in the endocrine system, although it mostly carries out instructions from the hypothalamus. The pituitary gland also secretes growth hormone, endorphins for pain relief, and a number of key hormones that regulate fluid levels in the body
Thyroid gland
releases hormones that regulate growth, metabolism, and appetite
Hyperthyroidism
the thyroid secretes too much of the hormone thyroxine causing agitation, bulging eyes, and weight loss
Hypothyroidism
reduced hormone levels cause suffers to experience tiredness, and they often complain of feeling cold
Adrenal gland
sit atop our kidneys and secrete hormones involved in the stress response, such as epinephrine (adrenaline) and norepinephrine (noradrenaline)
The pancreas
an internal organ that secretes hormones that regulate blood sugar levels: insulin and glucagon. These pancreatic hormones are essential for maintaining stable levels of blood sugar throughout the day by lowering blood glucose levels or raising them
Gonads
secrete hormones related to sexuality, sex, reproduction, and other phenomena, including physical/bodily aspects and behaviour. Located either in the ovaries (usually tied to femaleness) and testes (usually tied to maleness). All gonads secrete estrogens (estradiol, progesterone, and androgens)
Pineal gland
Regulate some biological rhythsm such as sleep cycles
Psychopharmacology
the study of how drugs affect the brain and behaviour is a relatively new science, although people have probably been taking drugs to change how they feel from early in human history
how do psychoactive drugs affect activity
can either increase activity at the synapse (these are called agonists) or reduce activity at the synapse (antagonists). Different drugs do this by different mechanisms
How do neurons communicate with each other
by releasing a chemical (neurotransmitter) across a tiny space between two neurons (the synapse). When the neurotransmitter crosses the synapse, it binds to a post synaptic receptor (protein) on the receiving neuron and the message may then be transmitted onward
Pharmokinetics
The action of a drug through the body, including absorption, distribution, metabolism, and excretion
most common route of drug administration
oral administration, which is relatively slow and perhaps surprisingly-often the most variable and complex route of administration
Oral administration
Drugs enter the stomach and then get absorbed by the blood supply and capillaries that line the small intestine. The rate of absorption can be affected by a variety of factors including the quantity and the types of food in the stomach
Two of the most rapid routes of drug administration
inhalation and intravenous (IV) in which the drug is injected directly into the vein and hence the blood supply
What happens if a drug activates the reward circuits in the brain, and it reaches the brain quickly
the drug has a high risk for abuse and addiction. Psychostimulants like amphetamine or cocaine are examples of drugs that have high risk for abuse because they are agonists at DA neurons involved in reward and because these drugs exist in forms that can be either smoked or injected intravenously. For drugs that reach the brain very quickly, not only is the drug very addictive, but so are the cues associated with that drug
Iv administration
has the distinction of being the most dangerous because if there is an adverse drug reaction, there is very little time to administer any antidote, as in the case of an IV heroin overdose
Drug metabolism
involves the breakdown of psychoactive drugs, and this occurs primarily in the liver. The liver produces enzymes (proteins that speed up a chemical reaction), and these enzymes help catalyze a chemical reaction that breaks down psychoactive drugs
Metabolic tolerance
one kind of tolerance and it takes place in the liver. Some drugs (like alcohol) cause enzyme induction-an increase in the enzymes produced by the liver
Grapefruit juice and metabolism
grapefruit juice suppresses cytochrome P450 enzymes in the liver, and these liver enzymes normally break down a large variety of drugs (including some of the psychotropic drugs). If the enzyme is suppressed, drug levels can build up to potentially toxic levels. In this case, the effects can persist for extended periods of time after the consumption of grapefruit juice
Why might individualized drug doses based on genetic screening be helpful for treating conditions like depression
Many people do not respond to the first antidepressant prescribed and may have to try different drugs before finding something that works for them. There are genetic differences in some of the cytochrome P450 enzymes and their ability to break down drugs. The general population falls into the following 4 categories; Ultra extensive metabolizers, Extensive metabolizers, Intermediate metabolizers,
Poor metabolizers
Ultra extensive metabolizers
break down certain drugs very, very quickly
Extensive metabolizers
are also able to break down drugs fairly quickly
Intermediate metabolizers
break down drugs more slowly than either of the two above groups
Poor metabolizers
break down drugs much more slowly than all of the other groups
children and adolescents and psychotropic drugs
Many psychotropic drugs used for treating psychiatric disorders have been tested in adults, but few have been tested for safety or efficacy with children or adolescents. Most well established psychotropics prescribed for children and adolescents are the psychostimulant drugs used for treating attention deficit hyperactivity disorder, and there are clinical data on how effective these drugs are
the elderly and psychopharmacology
Not typically been included in clinical trials to determine the safety or effectiveness of psychotropic drugs. There is very little high-quality evidence to guide prescribing for older people-clinical trials often exclude people with multiple comorbidities (other diseases and conditions). This is a serious issue because the elderly consume a disproportionate number of the prescription meds prescribed
