Chapter 3 Flashcards
What is the nervous system thought of as
The major controlling and communicating system of the body
Goal of neuroscience
To understand the nervous system: how it develops and changes and how it’s affected by various drugs and diseases
What are neurons?
Assembly of interconnected cells that form a complex web of connections that pulse with electrical and chemical energy and are used for receiving, processing and communicating information
What 4 characteristics allow the brain and the rest of the nervous system to command behaviour
Complexity, adaptability, integration and electrochemical transmission
Define synapses
Tiny spaces between neurons where the gaps are referred to as synaptic gaps or clefts . Used for neuron to neuron connection
Define the connectome project
A term coined in reference to the genome and aims to create a highly detailed map of all the connections of a nervous system across several species
How are neurons integrated in our daily lives through their structural arrangements and patterns of activity?
The structural arrangements of connections among neurons are your memories whereas the pattern of activity among neurons serve as the basis of your consciousness, emotions, personality and more
Define integration
The brain receives information through multiple sources, analyzes the information and releases a response. Does it by extracting patterns of incoming data and using past experiences, your knowledge and current emotions to integrate
Why is the brain considered the ultimate organ of adaptability?
Due to its ability to change and reorganize itself throughout a person’s life
What is neuroplasticity?
A process that allows the brain to constantly adjust to new experiences and form new neural connections which can lead to improved function
Define hippocampus
The structure in the limbic system that has a special role in the storage of memories
Define acquired savant syndrome
Individuals gaining special skills or talents after suffering brain injury or disease
What is electrochemical transmission?
Information processing system powered by electrical impulses and chemical messengers
An impulse travels down a neuron electrically and communicates with the next neuron using chemicals
Define afferent (sensory) nerves
Carry information from sensory receptors to the brain and spinal cord. Pathways communicate information about the external environment (phone vibrations) and internal conditions (hunger)
Define efferent (motor) nerves
Communicate information from the brain and spinal cord to the other areas of the body such as muscles and glands
What are the 2 primary divisions of the human nervous system?
Central nervous system and peripheral nervous system
What are the components of the central nervous system
Spinal cord
Brain
- Hindbrain: cerebellum, medulla, pons
- Midbrain: reticular formation
- forebrain: limbic system, hypothalamus, cerebral cortex, basal ganglia
What are the components of the peripheral nervous system?
Somatic nervous system
- sensory nerves
- Motor nerves
Autonomic nervous system
- parasympathetic branch: calms the body
- sympathetic branch: arouses the body
What does the somatic nervous system control?
Sensory and motor neurons
What does the autonomic nervous system control?
Monitors organs for processes such as breathing, heart rate and digestion
Define the peripheral nervous system
Network of nerves that connects the brain and spinal cord to other parts of the body and its function is to bring information to and from the brain and spinal cord
Which nervous system is involved in the fight or flight response
The sympathetic nervous system
Which nervous system is associated with the “rest and digest” response
Parasympathetic nervous system
In an emergency, what does the sympathetic nervous system do?
Trigger the body’s release of powerful hormones such as stress hormones that allow you to focus all your attention on what needs to be done at the current moment
The average volume of the human brain is roughly
1300 cubic centimetres
2 major classes of cells in the nervous system
The neuron and the glial cell
How are glial cells critical to brain function
Provide support, nutritional benefits, protection. Help neurons run faster and more efficiently
The “glue” that holds the nervous system together
What brain disorders may glial cells play a critical role in if they don’t function properly?
Alzheimer’s disease, chronic pain, epilepsy
What are the 5 common features of a neuron
Cell body
Dendrites
Axon
Axon terminals
Cell membrane
Function of a cell body in a neuron
Metabolic and genetic hub of the neuron
Contains machinery necessary for maintaining neuron function such as enzymes and structural proteins
Houses the nucleus which contains sequences of DNA that determine structural and functional properties of neurons
What factors can impair the ability to form and store new memories?
Sleep deprivation, stress, alcohol consumption and more
Define dendrites
Branchlike fibres projecting from a neuron which receive information and orient it towards the neuron’s cell body
What do dendrites increase?
Surface area of the neuron which provides multiple sites for synaptic contact
What neuro developmental disorders are associated with alterations in dendrite shape, size and number
Down syndrome, Alzheimer’s disease, schizophrenia, autism spectrum disorder
Define axon
The part of the neuron that carries information away from the cell body toward other cells
Define action potential
The brief wave of positive electrical charge that sweeps down the axon
What does the axon use for transmission of information?
Action potentials
Define synaptic boutons
Small, bulb shaped structures at the end of an axon where chemicals are stored and released to affect the functioning of neighbouring neurons
Define cell membrane
A thin specialized boundary that maintains the cell’s integrity
Define myelin sheaths
Speed up transmission of nerve impulses by insulating axons
Why is the cell membrane necessary?
Serves as a barrier between the interior and surrounding environment
What are ions?
Particles that come from atoms that have either gained (negatively charged) or lost (positively charged) one or more electrons
Which ions carry positive charges and which carry negative charges?
Sodium and potassium carry positive charged while chloride is negatively charged
Describe the movement of ions?
Since ions and other molecules are distributed unevenly throughout the membrane, they will want to move from areas of high concentration to areas of low concentration. This process is called diffusion
Describe the movement of ions?
Since ions and other molecules are distributed unevenly throughout the membrane, they will want to move from areas of high concentration to areas of low concentration. This process is called diffusion
Define selective permeability
The membrane selectively allows certain molecules and ions to pass while restricting the movement of others
When the neuron is not transmitting information….
It is in resting state
Due to separation of ions across the membrane, the cell is said to be
Electrically polarized
Define resting potential
The stable, negative charge of an inactive neuron
What produces a neuron’s resting potential?
When the fluid outside the neuron is rich in sodium ions but low in potassium whereas the fluid inside the neuron is high in potassium and low in sodium. At rest, the neuron is more selectively permeable to potassium allowing it to flow out and also slightly permeable to sodium allowing it to flow in
How does the sodium potassium pump maintain proper ion concentrations
Pump moves in 2K+ ions while ejecting 3 Na+ ions
Define neurotransmitters
Chemical messengers (molecules) released into the synapses that allow the nervous system to send messages between neurons or from neurons to muscles
What is the voltage of the axon membrane at rest
-70 mV
How is the action potential triggered?
Neurons can either release excitatory or inhibitory inputs, if the sum of excitatory inputs exceeds the sum of inhibitory inputs, the axon might be sufficient to change its resting potential and generate an action potential
Define depolarization
When the axon becomes more positive and is reduced to a less negative value of around -50mV. If resting potential was -70, the axon must be depolarizer by at least 20mV
Define axon hillock
The spot where the action potential is generated and has a higher concentration of Na+ and K+ channels than anywhere else
What causes electrical changes??
The movements of sodium and potassium ions into and out of the axon
Define refractory period
“Time out” - ensures that a neuron is not generating another action potential too quickly
Summarize the electrical activity of neurons
- Resting potential: maintains a small negative change of -70mV
- Action potential: when the neuron is stimulated by the release of neurotransmitters, it fires allowing the channels to open and sodium to rush in resulting in a positive charge
- Refractory period: sodium ions exit until it reaches resting potential
A fatty substance that surrounds some axons and is a poor conductor of electricity preventing electrical currents from leaking out
Myelin sheath
Define nodes
Non myelinated areas along the axon that contain a very high concentration of voltage gated Na+ and K+ channels - membrane needs to be depolarized at these nodes
True or false: action potentials move more rapidly if they leap from node to node
True
Define multiple sclerosis
Degenerative disease of the nervous system in which myelin tissue hardens disrupting neuronal communication
How does information travel between neurons?
Axon of presynaptic meets dendrites of postsynaptic where then synaptic vesicles are released containing neurotransmitters which open the channels on the postsynaptic neuron allowing the neuron to fire
Explain the 5 steps involved in synaptic transmission
- Action potential arrives at the presynaptic terminal
- Neurotransmitters are synthesized and stored into vesicles
- The depolarization from action potentials opens voltage gated ca2+ channels
- Ca2+ causes neurotransmitter release
- Neurotransmitter binds to receptors causing channels to open or close and reuptake transmitters bring neurotransmitter from synapse back into presynaptic terminal for recycling
Excessive neurotransmitter release causes the neuron to stop firing
What do the enzymes in the synaptic cleft do?
Chemically break down the neurotransmitter
How do drugs work on neurotransmitters?
Prevents the reuptake of certain transmitters which increases levels of that transmitter in the synaptic cleft
Define neurotransmitters
Any substance that is released at a synapse by a neuron and can affect another neuron or cell (muscle, gland)
Define acetylcholine
Involved in muscle contractions, learning, memory and attention. Individuals with Alzheimer’s disease have an acetylcholine deficiency
Define GABA
Amino acid found in the CNS and plays a key function by inhibiting many neurons from firing
Define glutamate
Found in excitatory synapses and plays a key role in stimulating neurons to fire - invoked in learning and memory. Overstimulation of too many neurons can release in migraine and seizures
Define norepinephrine
Is stimulated by stress, can inhibit the firing of some neurons but simultaneously excite the heart muscle and intestines
Controls alertness and triggers agitation and little quantity has been associated with depression
Define dopamine
Helps control voluntary movement and affects sleep, mood, attention, learning.
Low levels are associated with Parkinson’s disease
Define serotonin
Involved in the regulation of sleep and waking activity, mood, attention and learning
Define neuropeptides
Sequences of amino acids that are enveloped by vesicles and transported to axon terminals. Produce much longer effects on their target cells
Define endorphins
Natural opiates - Substances that depress nervous system activity and eliminate pain by inhibiting the firing of neurons. Should the body from pain and elevate feelings of pleasure
Define oxytocin
Neuropeptide that plays an important role in the experience of love and social bonding - powerful surge released in mothers that have given birth and is used for lactation (milk production) for breast feeding
If the average duration of a neuron’s refractory period is 100 milliseconds or 0.1 seconds. How many action potentials are triggered in one second
10 action potentials
1000ms/ 100ms = 10
Where is the hind brain located
Skull’s rear, lowest portion of brain
Main parts of the hindbrain
Medulla, cerebellum and pons
Define cerebral cortex
Wrinkled outer layer of forebrain, governs higher brain functions such as thinking and learning
Define Amygdala
Involved in fear and discrimination of objects necessary for organism’s survival
Define pons
Governs sleep and arousal
Define reticular formation
Diffuse collection of neurons involved in arousal and stereotyped patterns such as walking
Define cerebellum
Rounded structure involved in motor coordination
Define medulla
Governs breathing and reflexes
Define thalamus
Relates information between lower and higher brain centres
Master gland of limbic system
Pituitary gland - is triggered by the hypothalamus
Define pituitary gland
Regulates the hypothalamus and other glands through the release of hormones - plays a role in controlling growth and physical maturing
Define paraplegia
Inability to voluntarily move the lower parts of the body
Major Life support system of brain
The medulla since it controls and coordinates vital functions such as breathing and digestion
Brain stem consists of
Medulla, pons and midbrain
Damage to the cerebellum can lead to
Poor performance of coordinated movements
The midbrain located between the hindbrain and forebrain relays information where?
Between the brain, eyes and ears
Define substantia nigra
One of the main structures responsible for the production of dopamine, damage can lead to Parkinson’s disease
Definition of limbic system
Group of structures in the brain that regulate emotion, behaviour and memory
What is the function of the thalamus?
Process, sort and relay information to the appropriate places in the forebrain involved in sensation, motor actions and emotions
Define the basal ganglia
Large neuron clusters located above the thalamus and under the cerebral cortex that work with the cerebellum and the cerebral cortex to control and coordinate voluntary movements
Define limbic system
Loosely connected network of structures that is the border between the cortex and the thalamus - important for memory and emotion with 2 important principal structures being amygdala and hippocampus
Where is amygdala located
Temporal lobe
What is the neocortex
The outermost part of the cerebral cortex
What do the left and right hemispheres of the brain do?
The left hemisphere is involved in complex language processing and production and also problem solving and critical thinking whereas the right hemisphere is often linked to spatial awareness, creativity, humour and more
What does brain lateralization mean?
When one cerebral hemisphere tends to be more dominant over the other on a specific ability
Define corpus callosum
The large bundle of axons that connects the brain’s two hemispheres - responsible for relating information between the two sides
What are the 4 neocortical lobes
Occipital
Parietal
Temporal
Frontal
Define occipital lobes
Structures located at the back of the head that respond to visual stimuli
Define parietal lobes
Structures are the top and toward the rear of the head that are involved in registering spatial location, attention and motor control
Define parietal lobes
Structures are the top and toward the rear of the head that are involved in registering spatial location, attention and motor control
Define somatosensory cortex
A region in the cerebral cortex that processes information about body sensations, located at the front of the parietal lobes
Define somatosensory cortex
A region in the cerebral cortex that processes information about body sensations, located at the front of the parietal lobes
Define spatial neglect
An inability to orient, respond to or report stimuli presented to the opposite side of the body from a lesion; most common after right parietal or cortical injury in which the person will ignore the objects presented to the left side of the body
Define spatial neglect
An inability to orient, respond to or report stimuli presented to the opposite side of the body from a lesion; most common after right parietal or cortical injury in which the person will ignore the objects presented to the left side of the body
What are the temporal lobes?
Located above the ears and are involved in hearing, language processing and memory - multiple connections to limbic system so damage can lead to difficulty in the transfer of experiences into long term memory
What are the frontal lobes?
The portions of the cerebral cortex behind the forehead that are involved in personality, intelligence and the control of voluntary muscles
Define motor cortex
A region in the cerebral cortex that processes information about voluntary movement - located behind the front lobes
What is the prefrontal cortex
Inhibit irrelevant or inappropriate responses
What is the insula
The region of the brain that represents the internal organs such as the stomach, heart and intestines. It is important for taste, sensations and emotions
Define brain lesioning
Involves experimentally damaging brain tissue in non human animals through either surgically removing parts of the brain
Valuable tools for examining brain structure
MRI and CT scans
What is used to record brain activity
Electroencephalogram (EEG)
What is the endocrine system?
The body system consisting of a set of glands that regulates the activities of certain organs by releasing their chemical products into the blood stream
Define glands
Organs or tissues in the body that create chemicals that control many body functions
Examples of endocrine glands
Pancreas, ovaries, testes, pituitary
Define hormones
Chemical messengers that are produced by the endocrine glands and carried by the bloodstream to all parts of the body
Define pineal gland
The gland near the centre of the brain that secretes melatonin to regulate sleep and some reproductive organs
True or false: melatonin is a light sensitive compound
True
Define thyroid gland
A butterfly shaped gland in the neck that is involved in metabolism
Creator note: (My gland must be small because my metabolism is so bad)
Define parathyroid
Behind the thyroid, 4 small glands in the neck that control the body’s calcium levels
Define thymus
A gland located between the lungs that is critical to the immune system of infants and children
Define adrenal glands
Glands at the top of each kidney that are responsible for regulating mood, energy level and the ability to cope with stress
Define pancreas
A dual purpose gland under the stomach that performs both digestive and endocrine functions
What does insulin control
Blood glucose levels
Define ovaries and testes
Ovaries: Sex related endocrine glands that produce hormones involved in female sexual development and reproduction
Testes: sex related endocrine glands that produce hormones involved in male sexual development
Which chemical precursor is important for the production of melatonin
Serotonin
Three processes that allow the damaged brain to be repaired
Collateral sprouting: the process by which axons of some healthy neurons adjacent to damaged cells grow new branches
Substitution of function: the process by which the damaged regions function is taken over by another area of areas of the brain
Neurogenesis: the process involving the generation and integration of new neurons in the neural circuits of the adult brain
What are brain grafts
Brain tissue implants
Define chromosomes
Threadlike structures that come in 23 pairs, one member of each pair originating from each parent that contain DNA
What are genes
Unit of hereditary information
What is the dominant recessive genes principle
If one gene of a pair is dominant and the other is recessive, the dominate gene overrides the recessive gene. A recessive gene exerts its influence only if both genes of a pair are recessive
The field of molecular genetics involves the….
Manipulation of genes using technology to determine their effect on behaviourb
Define selective breeding
Genetic method in which organisms are chosen for reproduction based on how much of a particular trait they display
What is behaviour genetics??
Study of nature and degree of heredity’s influence on behaviour
Define genotype and phenotype
Genotype: an individual’s genetic heritage
Phenotype: individual’s observable characteristics
What is the CRISPR system used for
Gene editing tool
Define stress
The responses of individuals to environmental stressors
Define stressors
Circumstances and events that threaten individuals and their coping abilities and cause physiological changes to ready the body to handle stress
Define acute stress
Occurs in response to an immediate temporary perceived threat
Define chronic stress
Stress that goes on continuously. Hormones adrenaline and norepinephrine are produced which eventually causes a breakdown of the immune system
