PSYC 301 MIDTERM 1: Jay Hosking

What is Neuroscience?

The scientific study of the nervous system.

Psychology is the scientific study of behavior and the mind.

Human brain facts

• consumes 20% of energy

• Neurons are not replaced

• Convoluted (wrinkled)

Name and describe 2 general types of cells within the nervous system

1. Neurons: dendrite → soma → axon → terminals. Neurons are not replaced.

• Signals are extremely fast because of action potentials

2. Glia: found in CNS and PNS; makes up over half the volume of neural tissue and same numbers as neurons

• Stem cells create new glia

Name 4 types of glial cells and describe some functional roles for each

CNS

• Astrocytes - star; wraps itself around blood vessels and makes up one half of our blood brain barrier. Only way to get things into our brain and regulates synapse of the environment. Connects to one another through gap junctions and uses chemical signals (neurotransmitters gaba or glutamate) - can coordinate multiple synaptic inputs from distinct neurons

• Oligodendrocytes - produces myelin, which speeds up electrical signals to the brain and spinal cord

• Microglia - immune cells of brain and spinal cord; phagocytosis: destroys pathogens and clears waste by engulfing it. Important for shaping synapses

PNS

• Schwann cells - myelinated around a single axon, which speeds up signal transmission and repairs nerves (perisynaptic)

Explain what is meant by a “tripartite synapse”

Conversation of 3: axon, dendrite, astrocyte

1. Presynaptic(axon): vesicles release neurotransmitters into synapse (gap bw cells)

2. Postsynaptic (dendrite): receptors receive neurotransmitter signals

3. Astrocytes release chemical signals (gliotransmitters) and receives signals; glia shape conditions at synapse

Describe the central dogma of molecular biology

Genetic info flows in one direction in a biological system

DNA → RNA → Proteins

1. Replication: DNA makes exact copies of itself

2. Transcription: cells copy specific segment of DNA into a messenger molecule RNA

3. Translation: ribosomes read RNA sequence to assemble a chain of amino acids = functional protein

The things transcribing and translating are all PROTEINS! = the basis of neuronal function

How do cellular structures relate to brain dysfunction?

Damage to gray matter - permanent loss of neurons

Damage to white matter - slows or blocks communication between brain regions

Dendrites - connections lost → synapse loss

Synapse - damage to vesicles/receptors disrupts sending + receiving signals

• astrocytes + glia bring in O2 and shape synaptic conditions

The wonderful cell!!!!

1. mitochondria

• have their own DNA

• Protected from the environment

• Our cells constantly feed them, and it produces byproducts that feeds cells in exchange = symbiotic

  • Mitochondria wants oxygen and sugar, producing CO2 and ATP in exchange, which can be broken later to release energy

• Our brain needs a constant supply of energy and glucose = needs ATP because it doesn’t have an energy storage

2. The cell membrane has a phospholipid bilayer which keeps things in and out of the cell. Proteins allow tings to cross through the membrane

3. Cytoskeleton provides structure and is a highway for things to be carried from one place to another (proteins from soma to axon terminal), but also how bad stuff sneaks in

Describe the relationship between dendrites and some common brain dysfunctions

• Dendrites receive signals at spines—we’re born with many neurons, but not necessarily spines

• Spine count peaks in early school age, but it’s overwired so PRUNING removes least important connections and strengthens new ones.

DYSFUNCTION: too few/lost spines/synapses = lost connections

• synapse loss = memory loss → Alzheimer’s

• Excessive pruning (reduced spine density) - schizophrenia

• Too little pruning - excess spines; too much excitement - autism

2 basic neurons

Projection Neurons: have long axons that project to different brain areas; usually cool shapes. If damaged, regions lose communication

Interneurons: have short axons and only project locally in the same brain area; usually star shaped.

• Used to change the signal along the way (which is why projection neurons don’t go from point A to D)

• Many are inhibitory - dampens activity and keeps circuits balanced and timed by synchronizing

• If damaged, circuits lose balance and fine-tuning; losing inhibition can cause over excitation - seizures, epilepsy,

In gray matter, you can see part of the projection neurons, but the entirety of interneurons

“You are your synapses”

A synapse is a small space between 2 neurons; cells send chemical and electrical signals across these gaps

• when you learn something/form memories, the strength and structure of synapses changes — you today is a record of these connections

• Con - your personality depends on these connections = damage to the brain can change behavior, memory, or sense of self

• Pro - the brain is flexible → synapses can form new pathways whenever you learn or experience smt new

Matter

Gray matter: where information is processed - in CNS; cell bodies of large neurons and the entirety of small neurons. dense = why it appears gray

• damage: depends on region; loss of cells and dendrites = impaired thinking, movement, memory

White matter: wires of connecting signals

• axons coming off neurons are wrapped in myelin, a fatty white substance

• Damage to myelin sheath can slow thinking and affect motor skills; recovery relies on neuroplasticity

Major divisions of the nervous system and their symptoms of damage

Central Nervous System - info processing and commands

• brain (divided into forebrain, midbrain, hindbrain)

• spinal cord, which connects the brain to the rest of the body

Peripheral Nervous System - connects CNS to limbs, organs, skin. Damage = numbness, tingling, pain

1. Somatic Nervous System - controls voluntary movement

• Afferent (sensory - body to brain) and Efferent (motor - brain to body)

2. Autonomic Nervous System - controls involuntary functions (heart rate, digestion, breathing)

   1. Afferent

   2. Efferent

      1. Sympathetic Nervous System - mobilization energy; “fight-or-flight”

         1. Damage - weak response, low BP, dizziness, reduced sweating

      2. Parasympathetic - conserves energy; calms body and restores normal, everyday function (rest and digest)

         1. Constipation, persistent fast heart rate, dry mouth

Neuroanatomical directional terms

List the descending sections of the spinal cord in order. Where would damage cause a greater loss of function and why?

List and discuss the divisions of the human brain in 3 and 5 divisions

brain structures within the myelencephalon and what dysfunctions would result from damage to this area

brain structures within the metencephalon and what dysfunctions would result from damage to this area

brain structures within the mesencephalon and what dysfunctions would result from damage to this area

brain structures within the diencephalon and what dysfunctions would result from damage to this area

brain structures within the telencephalon and what dysfunctions would result from damage to this area

Describe the location and function of the corpus callosum

Major fissures

Major components of the limbic system and basal ganglia

Lobes of the cerebral cortex

What anatomical features protect the brain?