Definitions Flashcards
chronic traumatic encephalopathy (CTE)
form of progressive brain damage that has been linked to repeated concussions. associated with an array of cognitive and emotional deficits in affected individuals, including an ability to concentrate, memory loss, irritability, and depression, usually beginning within a decade and worsening with time.
neurons
cells in the nervous system that communicate with one another to perform information-processing tasks. composed of three basic parts: the cell body, dendrites, and the axon.
cell body
also called the soma; coordinates the info-processing tasks and keeps the cell alive. functions such as protein synthesis, energy-production, and metabolism take place here.
nucleus
contained in the cell body; houses chromosomes that contain DNA.
cell membrane
surrounds the cell body and allows some molecules to flow into and out of the cell.
two types of specialized extensions of the cell member that allow neurons to communicate
dendrites and axon.
dendrites
receive info from other neurons and relay it to the cell body. comes from the greek word for “tree”
axon
carries info to other neurons, muscles, or glands, can be very long, even stretching up to a meter from the base of the spinal cord to the big toe.
synapse
junction or region between the axon of one neuron and the dendrites or cell body of another. transmission of info across the synapse is fundamental to communication between neurons, a process that allows us to think, feel, and behave.
myelin sheath
covers the axon; an insulating layer of fatty material.
glial cells
composes the myelin sheath; support cells found in the nervous system. named for the greek word “glue.” some digest parts of dead neurons, others provide physical and nutritional support for neurons, and other form myelin to help the axon carry important info more efficiently.
axons insulated with myelin
can more effectively transmit signals to other neurons, organ, or muscles.
dymyelinating diseases
such as multiple sclerosis, the myelin sheath deteriorates, slowing the transmission of info from one neuron to another. leads to problems including loss of feeling in the limbs, partial blindness, and difficulties in coordinated movement and cognition.
sensory neurons
(somatic side) receive info from the external world thru sensory receptors and conveys info to the brain via from the axons that carry the Aps back to the spinal cord. specialized ending on dendrites that receive signals for light, sound, touch, taste, and smell.
motor neurons
(somatic side) carry signals from the brain to the spinal cord to the muscles to produce movement. long axons that can stretch to muscles in our extremities from spinal cord.
interneurons
(inside cns, skull, vertebrate) connect sensory, motor, or other interneurons. some carry info from the nervous system to motor neurons and others perform a variety of info-processing functions within the nervous system. connects one area of brain w/ another.
conduction
info travels inside a neuron via an electrical signal that travels from the dendrite to the cell body to the axon.
transmission
signal has to be passed from one neuron to another, usually via chemical messengers traveling across the synapse.
ions
small electrically charged molecules. flow across the neuron’s cell membrane creates the conduction of an electrical signal within the neuron.
resting potential
No communication, negative char within the neuron . difference in electrical charge between the inside and the outside of a neuron’s cell membrane. differences arise from the concentrations of ions. a high concentration of a positively charged ion, potassium (K+), as well as negatively charged protein ions (A-), inside the neuron’s cell membrane. a high concentration of positively charged sodium ions (Na+) and negatively charged chloride ions (Cl -) outside the neuron’s cell membrane.
resting state
the channels that allow the flow of K+ molecules across the cell membrane are open, while the channels that allow the flow of Na+ and other ions are generally closed.
charge of neuron at rest
due to the higher concentration of K+ molecules inside the neuron, some K+ molecules move outside through open channels, leaving the inside of the neuron with a charge of -70 millivolts relative to the outside.
Hodgkin and Huxley
could produce a signal by stimulating the axon with a brief electric shock, which resulted in the conduction of an electric impulse down the length of the axon.
action potential
communication; brief positive electrical charge that travels down as axon as charged ions move in and out of the axon’s membrane to the synapse.
threshold
the level at which an electrical shock reaches to cause action potential to occur. all or none firing.
all or none
electric stimulation below the threshold fails to produce an action potential, whereas electric stimulation at or above the threshold always produces the action potential, which always occurs with exactly the same chars and at the same magnitude regardless of whether the stimulus is at or above the threshold. all or none firing.
during an action potential
the K+ channels briefly shut down and the channels that allow for the flow of positively charged sodium ions (Na+) are opened. Na+ flow inside, increasing the positive charge inside the axon relative to the outside. +40 millivolts.
after action potential
after max is reached, the membrane channels return to their original state and K+ flows out until the axon returns to its resting potential. leaves extra Na+ ions inside and extra K+ outside.
refractory period
ions are imbalanced; time following an action potential during which a new action potential cannot be initiated. imbalance is reversed by a chemical “pump” in the cell membrane that moves Na+ outside the axon and moves K+ inside the axon.
how action potentials spread
when an AT is generated at the beginning of the axon, it spreads a short distance, which generates an AT at a nearby location on an axon, thus conducting charge down the length of the axon.
nodes of Ranvier
break points between myelin clumps covering axons. named after Louis-Antoine Ranvier, who discovered them.
saltatory conduction
an electric current that passes down the length of a myelinated axon, the charge jumps from node to node rather than transverse the entire axon. helps speed the flow of info.
terminal buttons
knob-like structures that branch out from an axon. filled with tiny vesicles.
vesicles
found within terminal buttons; contains neurotransmitters.
receptors
parts of the cell membrane that receive neurotransmitters and either initiate or prevent a new electrical signal.
presynaptic neuron
Sending neuron that the action potential travels down the length of its axon to the terminal buttons, where it stimulates the release of neurotransmitters from the vesicles into the synapse.
Postsynaptic neuron
Receiving neuron where neurotransmitters that float across the synapse bind to receptor sites on nearby dendrites of these neurons
Synaptic transmission
New electrical signal initiated in the postsynaptic neuron, which at generate an action potential in that neuron. Allows neurons to communicate with one another.
neurotransmitter binding
Some will only bind to specific receptor sites on dendrites.
Neurotransmitters leave the synapse through three processes
Reuptake, enzyme deactivation, and auto receptors
Reuptake (synaptic communication terminated)
Neurotransmitters can be absorbed by the terminal buttons of the presynaptic neuron’s axon.
Enzyme deactivation (synaptic communication terminated)
Neurotransmitters can be destroyed by enzymes in the synapse.
Autoreceptors
Neurotransmitters can bind to these on the presynaptic neuron. Detect how much of a neurotransmitter has been released into a synapse and signal the presynaptic neuron to stop releasing the neurotransmitter when an excess is present.
Acetylcholine (ACh)
Neurotransmitter involved in a number of functions, including voluntary motor control. Found in neurons of the brain and in the synapses where axons connect to muscles and body organs, such as the heart. Contributes to the regulation of attention, learning, sleeping, dreaming, and memory. Alzheimer’s disease is associated with the deterioration of this.
Dopamine
Neurotransmitter that regulates motor, behavior, motivation, pleasure/reward, and emotional arousal. Plays a role in drug additions. High levels linked to schizophrenia and low levels linked to Parkinson’s disease.
Glutamate
Major excitatory neurotransmitter in the brain, meaning that it enhances the transmission of info between neurons.
GABA (gamma-aminobutyric acid)
Primary inhibitory neurotransmitter in the brain. Tends to stop the firing of neurons. Helps fall asleep, prevents seizures/getting too excited.
Overactive neurons
Caused by too much glutamate or too little GABA. causes seizures.
Norepinephrine
Involved in vigilance, or a heightened awareness of dangers in the environment. Low levels implicate mood disorders.
Serotonin
Involved in the regulation of sleep and wakefulness, eating, and aggressive behavior. Low levels implicate mood disorders.
Endorphins
Chemicals that act within the pain pathways and emotion centers of the brain. Help full the experience of pain and elevate moods.
Agonists
Drugs that increase the action of a neurotransmitter.
Antagonists
Drugs that block the function of a neurotransmitter.
Parkinson’s disease
Movement disorder characterized by tremors and difficulty initiating movement and caused by the loss of neurons that use the neurotransmitter dopamine.
How dopamine is creates
Created in neurons by a modification of a molecule called L-dopa. Ingesting L-dopa will spur the surviving neurons to produce more dopamine.
Amphetamine
Drug that stimulates the release of norepinephrine and dopamine. Both amphetamine and cocaine prevent the reuptake of these releases and this floods the synapse with these neurotransmitters, resulting in increased activation of the receptors. Increase results in euphoria, wakefulness, and a burst of energy. Norepinephrine also increases heart rate dangerously.
Nerves
Bundles of axons and the glial cells that support them.
Nervous system
An interacting network of neurons that conveys electrochemical info throughout the body.
Central nervous system (CNS)
Composed of the brain and the spinal cord. Receives sensory info from the external world, processed, and coordinates this info and sends commands to the skeletal and muscular systems for action.
Peripheral nervous system (PNS)
Connects the CNS to the body’s organs and muscles. Subdivisions include the autonomic and somatic nervous systems.
Somatic nervous system
Set of nerves that conveys info between voluntary muscles and gathers sensory input (pain, heat, cold, pressure); sent back to the CNS. Conscious control and use it to perceive, think, and coordinate behavior.
Autonomic nervous system (ANS)
Set of nerves that carries involuntary and automatic commands that control blood vessels, body organs, and glands. Largely outside conscious control. Divided into sympathetic and parasympathetic nervous systems.
(autonomic ->) sympathetic nervous system
(fight or flight) revs up organs you need, less energy to things you don’t need. Set of nerves they prepares the body for action in challenging or threatening situations.
(autonomic ->) parasympathetic nervous system
(resting and digesting) interested in conserving energy and only using what you need. Helps the body return to normal resting state.
Brain
Supports the most complex perceptual, motor, emotional, and cognitive functions of the nervous system.
Spinal cord
Branches down from the brain to relay commands to the body.
Spinal reflexes
Simple pathways in the nervous system that rapidly generate muscle contractions.
Injuries on spinal cord
The higher up, the more damaging the effects are.
Hindbrain =
Area of the brain that coordinates info coming into and out of the spinal cord. Controls the most basic functions of life: respiration, alertness, and motor skills. Structure include the medulla, the reticular formation, the cerebellum, and the pons.
Medulla (hindbrain: Myelencephalon)
Extension of the spinal cord into the skull that coordinates heart rate, circulation, and respiration.
Reticular formation (midbrain: Mesencephalon)
extends from hind brain to part of forebrian. nonrepreprhine comes from here. Small cluster of neurons; regulates sleep, wakefulness, and levels of arousal. Cat experiment: stimulation kept the cat alert, severing the connection created a permanent coma.
Cerebellum (hindbrain: Metencephalon)
Large structure of the hindbrain they controls fine motor skills. Contributed to the fine-tuning of behavior: smoothing our actions to allow their graceful execution rather than initiating the actions.
Pons (hindbrain: Metencephalon)
Structure that relays info from the cerebellum to the rest of the brain. Essentially acts as a relay station/bridge between the cerebellum and other structures in the brain.
Midbrain
Relatively small and contains the tectum and tegmentum, which help orient an organism in the environment and guide movement towards/away from stimuli.
Forebrain
Highest level of the brain and controls complex cognitive, emotional, sensory, and motor functions. Divided into the subcortial structures and the cerebral cortex.
Subcortial structures
Areas of the forebrain housed under the cerebral cortex near the center of the brain they include the thalamus, hypothalamus, pituitary gland, hippocampus, amygdala, and basal ganglia, and these structures play an important role in relaying info throughout the brain as well as performing specific tasks that allow us to think, feel, and behave as humans.
Thalamus (Forebrain: Diencephalon)
Delays and filters info from the senses and transmits the info to the cerebral cortex. Receives input from all major senses except smell, and acts as a computer server in a networked system, tasking in multiple inputs and relaying them to a variety of locations. Filters sensory info, giving more weight to some inputs and less to others. Closes the pathways of incoming sensations during sleep, proving a valuable function in not allowing info to pass the rest of the brain.
Hypothalamus (Forebrain: Diencephalon)
Located below the thalamus; regulates the body temp, hunger, thirst, and sexual behavior. controls endocrine system; sends horomones.
Pituitary gland
The master gland of the body’s hormone producing system, which releases hormones that direct the functions of many other glands in the body. Hypothalamus sends hormone signals to the pituitary gland, which in turns sends the signals to other glands that control stress, digestive activities, and reproductive processes.
Hippocampus (limbic system)
Critical for crating new memories and integrating them into a network of knowledge so that they can be stored indefinitely in other parts of the cerebral cortex. Damage is limited to the disruption of everyday memory for facts and events that we can bring into consciousness; memory of learned habitual routines or emotional reactions remain intact.
Amygdala (limbic system)
Located at the tip of each horn of the hippocampus, plays a critical role in many emotional processes, particularly the formation of emotional memories. In emotionally arousing situations, the amygdala stimulates the hippocampus to remember many details surrounding the situation.
Basal ganglia
Set of subcortial structures that direct intentional movements. Receives input from the cerebral cortex and sends outputs to the motor centers in the brain stem.
Striatum
Part of the basal ganglia; involved in the control of posture and movement.
Parkinson’s disease
Uncontrollable shaking and sudden jerks, unable to initiate a sequence of movements to achieve a specific goal. Dopamine producing neurons in the tegmentum have become damaged and the undersupply affects the striatum.
Cerebral cortex (forebrain: telencephalon)
The outermost area of the brain, visible to the naked eye, and divided into two hemispheres. Highest level of the brain and responsible for the most complex aspects of perception, emotion, movement, and thought.
1) organization across the hemispheres
Divides the cortex into left and right hemispheres. Each hemisphere controls the functions of the opposite of the body. Connected by bundles of axons that make communication between parallel areas of the cortex in each half possible.
Contralateral control
Right cerebral hemisphere perceives stimuli from and controls movements on the left side of the body. Vice versa.
Corpus callosum
Connects large areas of the cerebral cortex on each side of the brain and supports communication of info across the hemispheres. Largest of the bundles of axons that make communication possible.
2) organization within hemispheres
Second level of organization; distinguishes the functions of the different regions within each hemisphere of the brain. Each hemisphere of the cerebral cortex is divided into four lobes: the occipital lobe, the parietal lobe, the temporal lobe, and the frontal lobe.
Occipital lobe
Located at the back of the cerebral cortex; processes visual info. Sensory receptors in the eyes send info to the thalamus, which in turn sends info to the primary areas of the lobe, where simple features of the stimulus are extracted, such as location and orientation of the object’s edges. Processes further, leading to comprehension. Damage = blindness. Contains visual cortex (oragnizes and processes visual stimuli such as color, movement, depth)
Parietal lobe
Located in the front of the occipital lobe; processes info about touch. Contains somatosensory cortex (organizes and perceives the touch signals)
Somatosensory cortex
Within the parietal lobe; a strip of brain tissue running from the top of the brain down to the sides. Represents the skin areas on the contra lateral surface of the body. Each part of the cortex maps onto a particular area of the body. More sensitive = larger part of the somatosensory cortex is devoted to it. Homunculus illustration.
Motor cortex
In front of the somatosensory cortex, in the frontal lobe. Different parts correspond to different body parts. Initiates voluntary movements and sends messages to the basal ganglia, cerebellum, and spinal cord.
Temporal lobe
Located on the lower side of each hemisphere; responsible for hearing and language. Contains auditory cortex (receives incoming auditory signals from thalamus, sorts into recognizable pattern)
Primary auditory cortex
In the temporal, analogous to the somatosensory cortex in the parietal lobe and the primary visual areas of the occipital lobe. It receives sensory info from the ears based on frequencies of sounds. Secondary areas of the temporal then process the info into meaningful units such as speech and words. Houses the visual association areas that interpret the meaning of visual stimuli and help us recognize common objects in the environment.
Frontal lobe
(cerebral cortex) Specialized areas for movement, abstract thinking, planning, memory, and judgement. Contains the motor cortex (comes up w/ plan to do something) and prefront cortex (stores social norms/rules). Other areas coordinate thought processes that help us manipulate info and retrieve memories.
3) organization within specific lobes
Hierarchy of processing stages from primary areas that handle fine details of info all the way up to association areas.
Association areas
Composed of neurons that help provide sense and meaning to info registered in the cortex.
Mirror neurons
Active when an animal performs a behavior, such as reaching for or manipulating an object, and they are also activated when another animal observed the first animal as it performs the same behavior. Found in the frontal lobe near the motor cortex and in the parietal lobe.
Neurons in association areas
Usually less specialized and more flexible than neurons in the primary areas. Can be shaped by learning and experience to do their job more effectively. Allows for brain plasticity.
Sensory cortices
Not fixed and can adapt to changes in sensory inputs.
Functions in the brain
Functions assigned to certain areas of the brain may be capable of being reassigned to other areas of the brain to accommodate changing input from the environment.
Exercise
Studies in rats and other animals indicate that exercise can increase the number of synapses and even promote the development of new neurons in the hippocampus.
Cilia
Help the Protozoa toward the food source.
First neurons
Appeared in simple invertebrates such as jellyfish.
First CNS
Appeared in flatworms. Collections of neurons in the head including sensory neurons for vision and tease and motor neurons that control feeding behavior.
In all vertebrates
The CNS is organized into a hierarchy: the lower levels of the brain and spinal cord execute simpler functions, while the higher levels the nervous system performs more complex functions.
In lower vertebrate species
The forebrain consists only of small clusters of neurons at the end of the neural tube.
In higher vertebrates
The forebrain is much larger and it evolves in two different patterns. Reptiles and birds have almost no cerebral cortex. Mammals have a highly developed cerebral cortex, which develops multiple areas that serve a broad range of higher mental functions uniquely human abilities include self awareness, sophisticated language, abstract reasoning, and imaging.
Gene
Major unit of hereditary transmission. Sections on a strand of DNA that are organized into large threads called chromosomes.
Chromosomes
Strands of DNA wound around each other in a double helix. Comes in pairs, one from mother and father. Humans have 23 pairs.
Degree of relatedness
Probability of sharing genes.
Monozygotic twins (identical twins)
Most genetically related people; develop from splitting a single fertilized egg and therefore share 100% of their DNA.
Dizygotic twins (fraternal twins)
Develop from two separate fertilized eggs and share 50% of their genes. The same as any two siblings born separately.