MIDTERM #1 Flashcards
What are neurons?
Specialized cells found only in the nervous system
What are neuron’s primary purpose?
Communication
What are systems of cells mass communicating to do complex processes called?
Neural networks
Draw a neuron
What are dendrites?
A specialized structure for collecting info
What are synapses?
Where axons meet dendritic spines
The ____ dendrites receive info from the ___ axon (pre/post-synaptic?
post synaptic dendrites
Pre synaptic axon
____ signals from the axon causes the dendrites to change the post-synaptic cell
Chemical
Where does gene expression and protein production occur?
The cell body
Where is the starting location of action potentials?
Axon hillock
Where do action potentials travel from the cell body to the axon terminal?
Axon
When is a lack of myelination not a problem?
When axons are short (electrical charge doesn’t leak as much)
What is myelination
Layers of fatty tissue that wrap around the axons
Natural insulation for long axons that help action potentials, allowing them to travel further and faster
What are nodes of ranvir
Gaps in the myelin sheath that cover the axons of some nerve cells
Speeds up transmission of electrical signal
What is white matter? What is its purpose
Part of the brain that is densely packed with axons wrapped in myelin
Carries info, almost no info processing
What is gray matter? What is its purpose?
Part of the brain with little to no myelin, primarily cell bodies and dendrites
Where processing happens
What is multiple sclerosis?
Disorder resulting in the destruction of myelin in the central nervous system
Causing action potential to not always reach their target
What are the symptoms of multiple sclerosis
Muscle weakness
Vision issues
Loss of sensation
Tremors
What are glial cells
Support neurons so they can focus on communicating
Formally thought to be the “glue” of the nervous system
What do astrocytes do besides filtering content from blood to neurons?
Deliver energy to neutrons
Clears excess NT from synapses
Filters blood before reaching the neuron
Structural support for neurons
Promoting synaptic formation
May be important for flushing out and cleaning brain during sleep
What is the most function of astrocytes?
Filter content from blood to the neurons
Wraps around blood vesicles in the brain
Allows in good, blocks bad
What is myelination glia?
Glia that form and wrap myelin around the axon of neurons
What are the two classes of glia?
Oligodendrocytes
= brain and spine (CNS)
Schwann cells
= everywhere else (PNS)
What is microglia?
the nervous system’s immune cells
Work like white blood cells
What is the function of microglia?
move around the brain to:
- clear out debris
- destroy invaders
- support healing to damage
What is the PNS? What does it do?
Peripheral nervous system (everything outside the CNS)
Processing
Connects the CNS to all the sensory receptors, muscles, and organs,
What is the CNS comprised of?
brain + spinal cord
What can the PNS be divided into?
Afferent (sensory) system = info coming INTO the CNS
Efferent (nervous) system = info coming out to the body
How does the afferent system work?
Sensory info travels along axons into the CNS
When touch receptors are activated, sends action potentials along a nerve to arrive at the spine
How does the efferent system work?
Action potentials from the CNS travel along the axons to stimulate muscles
What can the efferent system be divided into?
somatic
Autonomic
What does the somatic motor system control
all voluntary control
connects to all skeletal muscles
Does not decide movements, just carries info from the CNA
What does the autonomic motor system control
all involuntary control
Connects to all smooth muscles (organs)
What can the autonomic motor system be divided into?
sympathetic + parasympathetic
What is the function of the spinal cord?
where all info passes through between the brain to the PNS
A dense cord of axons carrying info
How is the spinal cord organized
info passes in and out of each vertebra = less info further down
Organized based on
- which direction/where the info is moving
- type of info traveling
Damage to the spinal cord?
impacts become more significant based on how close it is to the brain
A mid-shoulder injury to your spinal may lead to a loss of control to where?
loss of sensation to arms, torso, legs
Possible loss of motor control
What is the brain stem?
first site of processing info and sends out commands
On top of spinal cord
What is the oldest, “most simple” part of the brain? (Also called reptilian brain)
brainstem
What is the brainstem responsible for
control of foundational physiological processes
Ex: HR, breathing, BP, maintaining consciousness
What happens with damage to the brainstem?
strokes in the brainstem can damage areas responsible for breathing and HR
Can also cause locked-in syndrome = conscious but can only move eyes, damage to where all connections pass through to the spinal cord
What is the cerebellum important for?
fine motor movement, fact-checking movements
What happens with damage to the cerebellum?
Struggles with fine motor functions and adaptations
Unable to error check movements
What is importance of the thalamus?
major relay station for most info in the brain
Important for filtering/regulating flow of info
What happens with damage to the hypothalamus?
everything can be damaged due to the amount of info that passes through it…
Symptoms of strokes in the thalamus may struggle with:
- arousal and pain regulation
- sensory experiences
- motor langage function
- cognitive function, mood, motivation
What is the importance of the hypothalamus?
internal regulation + homeostasis =
- body temp
- appetite
- circadian rhythms
PROCESSES CONTROLLED BY HORMONES
What important structure is connected to the hypothalamus?
pituitary gland = master gland controlling hormone regulation
What are 2 examples of a disorder caused by damage to the hypothalamus?
hypopituitarism = under stimulation of the pituitary gland causing issues with…
- metabolism
- stress regulation
- puberty
- growth
Hypothalamic obesity - obesity due to inhibited eating
- brain never receives “full” signal due to improper communication
What is the importance of the basal ganglia?
regulating motor control
Highly connected with the frontal cortex
What are 2 examples of a disorder caused by damage to the basal ganglia?
parkinson’s = hypokinesia = reduced movement
Huntington’s = hyperkinesia = uncontrollable increase of movement
Possibly: OCD
What is the importance of the hippocampus?
Memory consolidation (short -> long term)
Spatial navigation
What happens with damage to the hippocampus?
anterograde amnesia = unable to create new memories
What is the cerebral cortex?
outermost region and most recently evolved brain area
What is the structure of the cerebral cortex?
same general structure
- flat sheets of cells (gyri + sulci -> folds)
- constructed of 6 layers, vary in thickness and cell type
What are the lobes within the cerebral cortex?
Occipital
Parietal
Temporal
Frontal
What is the function of the occipital lobe?
visual processing
What is the function of the parietal lobe?
Processing spatial info
Controlling attention
Processing touch perception
Controlling eye movements
What is the function of the temporal lobe?
Auditory processing
Object categorizations
Supports HC for memory
What is the function of the frontal lobe?
Executive function
Working memory
Planning movements
Controlling movement
Part of language processing and production
Why should you wear a helmet when biking?
Neurons are highly suspect able to damage… most severe neurological damage is irreversible
Not wearing a helmet increases chances of going to the ICU after an accident by 13%
What are the stages of neural development?
1) fertilization
2) zygote
3) cleavage
4) morula
5) blastocyst
what is gastrulation?
the formation of three germ layers
bastula folds inwards to form the gastrula
What are the layers formed in gastrulation?
Ectoderm = skin, neurons, nervous system
Mesoderm = muscles, blood, bones
Endoderm = GI tract, lungs, internal organs
What is a noggin? What is its function?
a signaling molecule released from the notochord
Blocks BMP signals (that promote skin development) so that neural tissue can form -> ectoderm becomes the first plate
What is the process of neurulation?
1) neural plate forms, folds into neural crest
2) neural crest closes, forms neural tube
3) neural crest cells gives rise to PNS structures
4) embryo elongates
What is an example of a disorder that occurs when neurulation goes wrong
Spina bifida = neural tube defect where the spinal cord doesn’t fully close, leads to physical and neurological issues
Can be prevented by taking folic acid before/during pregnancy
What does SHH do?
directs dorsal-ventral patterning in neural tube (determines front or back)
Essential for motor neuron differention
What occurs with disruptions to SHH?
Holoprosencephaly = midline defects
Forebrain fails to divide into two hemispheres, leading to seizures and developmental delays
How does SHH concentration work?
high concentration at base = front of nervous system
Low concentration at top = back of nervous system
What occurs during prenatal brain development?
neurogenesis = neurons form
Brain structure formation = forebrain, midbrain, hindbrain
Early synaptogensis = first neural connections emerge
What occurs during infancy and early childhood brain development?
rapid synaptogensis = formation of millions of neural connections daily
Reflexes + early learning
(Rooting, grasping, startle reflexes)
Synaptic pruning begins
Ex: différents in enriched/deprived environments
What occurs during adolescent development?
Increased myelination = faster neural transmission
Prefrontal cortex maturation = still developing, affecting impulse control
Heightened dopamine activity leads to increased risk-taking
Ex: teenage driving insurance
What occurs during adulthood and aging brain changes?
plasticity declines = learning + adaptation slow
Cognitive reserve matters = lifelong learning preserves function
Neurogenerative risks increase
Ex: Alzheimer’s, Parkinson’s
What are the stages of neural development?
1) neurogenesis
2) cell migration
3) cell differentiation
4) synaptogenesis
5) pruning + apoptosis
What is neurogenesis? When does it begin? What is it needed for?
birth of neurons
Begins during embryonic development, continues in regions like HC into adulthood
Essential for building nervous system and lifelong plasticity
How does cell migration occur?
Guided by chemical signals and glial cells
Cell migration is related to GnRH and what syndrome?
GnRH neuron migration essential for reproductive function
Kallmann’s syndrome = failure of GnRH neuron migration, leading to delayed puberty + anosmie (loss of smell)
How does cell differentiation occur?
1) genetic instructions
2) environmental signals (extrinsic)
What role does location play in cell differentiation?
ex: motor cortex vs visual cortex
What role does timing play in cell differentiation?
early-born = deeper
Later-born = upper
What role does neighboring cells play in cell differentiation?
surrounded by excitatory neurons = more likely to be excitatory
What is synaptogensis? When does it begin? What is it needed for?
Formation of synapses between neurons, allowing communication
Begins prenatally, continues throughout life
Needed for learning, memory, brain plasticity
What is apoptosis?
programmed cell death removing excess neurons
What disorder is an example of the importance of cell death?
Syndactyly = joined fingers/toes
What is necrosis?
Unplanned cell death, resulting from injury/disease
What is an electrical signal through which neurons/synapses communicate
Action potentials
What is a chemical signal through which neurons/synapses communicate
neurotransmitters, synaptic transmission
What is Hebbian learning
“cells that fire together, wire together”
= frequent activation strengthens neural connections
What is an example of plasticity in the visual cortex?
blind ppl rely on touch + hearing, leading to enhanced sensory maps
what is a critical period
a window of time when the brain is particularly sensitive to specific experiences
Ex: language acquisition
What are 3 examples of environmental influences on brain development?
Nutrition
Toxic exposures
Stress + adversity
What are the symptoms of aging in respect to neural decline
Cognitive engagement shows decline (ex: music, bilingualism, cognitive engagement)
Neurodegenerative disorders involve synaptic loss (ex: Alzheimer’s, Parkinson’s)
What are 2 examples of a disruption in neural development that leads to a neurodevelopmental disorder?
Fragile X Syndrome
- Caused by mutation in FMR1 gene, causing excess synapses due to lack of pruning
- Symptoms: intellectual disability + social deficits
Autism Spectrum Disorder (ASD)
- early brain overgrowth -> excess local, weak long-range connectons
- altered synaptic pruning affects learning + behavior
How can we slow neural aging?
exercise, diet, cognitive engagement
Adult neurogenesis in HC, olfactory bulb
Therapies for neurodegeneration
What does DNA stand for
deoxyribonucleic acid
What is DNA
a molecule carrying genetic instructions for growth, development, and functioning
Found in the nucleus of almost every cell
What is the structure of DNA?
DNA shape = double helix
sugar-phosphate backbone
Base pairs form rungs (A-T, C-G)
What is chromatin
loosely packed DNA
- found in non-dividing cells
- accessible for gene expression
What are chromosomes
Tightly packed DNA
- found during cell division
- makes it easier to move DNA accurately
What is a gene? Where are they located?
a segment of DNA containing instructions to build proteins
Located on a chromosome
What are genes made of?
Promotor = “start” signal, tells cell where to begin transcription
Coding region = contains info to build a protein
Terminator = “stop” signal, ends transcription
Also (most) have:
Exons = protein-coding sequences
Introns = non-coding regions removed before transcription
What are examples of non-coding DNA
regulatory sequences (ex: promotorers, enhancers)
Introns (removed before translation)
Telomeres, centromeres, repetitive elements
What do non-coding regions help with?
turning genes on/off
Protecting DNA during replication
Stabilizing chromosomes
What is the central dogma
DNA (transcription)-> RNA -(translation) > protein
What is transcription?
DNA is copied into mRNA
What is translation?
mRNA is read to build a proteins
(Occurs in the ribosome)
What is a protein
Chains of amino acids
What is the role of proteins
function determined by shape but in general they
- build structures
-act as enzymes - help send/recieve signals
What does hemoglobin (a protein) do
carries oxygen in blood
What kind of replication occurs for DNA
Semi-conservative = each new DNA molecule keeps one old strand and builds one new one
What has to occur before a cell divides
DNA replication
What are the three enzymes in DNA replication
1) helicase = unwinds DNA
“breaker”
2) DNA polymerase = builds new strands by adding nucleotides
“Builder”
3) ligase = joins DNA fragments on the lagging strand
“Gluer”
Why are there multiple origins of replication in DNA replication
replication in one spot would take too long
What happens during transcription?
Occurs in the nucleus
enzyme RNA polymerase reads DNA to build mRNA
mRNA carries info to ribosome in the cytoplasm
What happens during mRNA processing after transcription?
mRNA is edited before leaving nucleus
- introns removed
- exons (coding) spliced together
- a 5’ cap added to front
- poly-A tail added to the end
What happens during translation?
occurs in the ribosome
mRNA is read in codons, turning it into a chain of amino acids (a protein)
Each codon (3-base sequences) = 1 amino acid
What are the four types of mutations
Silent
Missense
Nonsense
Frameshift
What is a silent mutation
No change to the protein
What is a missense mutation
one amino acid is changed
What is a nonsense mutation
introduces a stop codon
What is a frameshift mutation
insertion or deletion that shifts the reading frame
What is an example of a disorder caused by a missense mutation
Sickle cell anemia
Caused by a missense mutation in the hemoglobin gene
Red blood cells become rigid, sickle-shaped
What is an example of a disorder caused by a frameshift mutation
Cystic fibrosis Caused by a deletion (frame shift) in the CFTR gene
Thick mucus in lungs + organs
What is Fragile X syndrome?
Caused by a mutation in the FMR1 gene on the X chromosome
Mutation type: repeat expansion
Leads to gene silencing: no FMRP protein made
What is a gene knockout
when a gene is intentionally disabled
what are examples of model organisms
mice, flies, zebrafish
What is CRISPR
a tool for editing DNA
What is used in CRISPR
guide RNA = leads cas9 to a specific DNA sequence
Cas9 = cuts DNA (scissors)
What is CRISPR used for
Fix genetic disorders
Target cancer genes in tumors
Make immune cells better at fighting disease
Has potential for treating inherited diseases at the DNA level
What is a real example of de-extinction
Dire wolves brought back using DNA from gray wolves
How is DNA compacted?
Wrapping around histone proteins
What is tIghtly packed chromatin? What does it do?
Heterochromatin
Reduced transcription: turns “off”
What is loosely packed chromatin?
Euchromatin
Increase transcription:
Turns “on”
How does epigenetics affect transcription?
changes DNA accessibility
What is epigenetics
heritable changes in gene function without changes in DNA sequence
What are the marks of epigenetics
Methyl groups (DNA methylation)
Histone modifications
What is the role of DNA methylation in epigenetics
usually represses gene expression
What is the role of histone acetylation in epigenetics
Usually activates gene expression
What is the role of histone deacetylation in epigenetics
Usually represses gene expression
What causes genes to be expressed from only the maternal
methylation
What is an example of methylated genes
IGF2 (paternal)
UBE3A (maternal)
What are examples of syndromes due to methylation?
Prader-Willi Syndrone
(Paternal deletion, maternal silenced)
Angelman syndrome
(Maternal deletion, paternal sickened)
What is cell differentiation?
silencing some genes, activating others
what are environmental influences on epigenetics
Nutrition
Parental care
Toxins
Stress levels
What are some nutrients that help the body add methyl groups to DNA
Folate
Vitamin B12
Choline
What is the relationship between parental care and epigenetics
Lack of consistent care can change DNA methylation
Comfort, touch, and attention help regulate stress réponse genes
Where does methylation/acetylation happen?
the HC and cortex
What does temporary methylation effect
short term memory
What does stable epigenetics marks effect
long term memory
How did rat research demonstrate the importance of environment in methylation?
high licking/grooming = lower stress responses in adulthood
Low licking = higher methylation of gene
Cross-fostering showed that the effect was due to experience, not genetics
What genes can be affected by chronic stress, trauma, and adversity due to DNA methylation?
BDNF
NR3C1
FKBP5
How did rat research demonstrate the importance of diet in methylation?
methyl-donor diet (ex: folate) given to pregnant mice with unmethylated gene = healthy offspring
AKA diet can reverse “bad” genes
How can famine effect epigenetics/methylation
Pregnant women who experienced this famine gave birth to children with:
- Higher risk of obesity, diabetes, and heart diseases in adulthood
- lower DNA methylation of the IGF2 gene (growth factor)
Effects decades later…
How does transgenerational epigenetic inheritance work
Methylation patterns may persist in sperm/eggs and bypass reprogramming
Ex: male mice fed a high-fat diet led to offspring had insulin resistance
Methylation ___, acetylation ____ in epigenetics
methylation silences
Acetylation activates
