Human Phys - Chapter 10: The Central Nervous System

What are emergent properties?

Abilities that appear when many neurons work together but aren’t found in one neuron alone.

Examples: thinking, language, learning, memory, emotions

Easy:

One neuron = one player.

Neural network = the whole team.

What is neural plasticity?

The ability of neural circuits to change their connections based on experience or sensory input.

Easy: Plasticity = the brain can rewire itself.

10.2 — Evolution of Nervous Systems

How did nervous systems become more complex during evolution?

Nerve net → primitive brain → brain + ganglia → larger, specialized brain

Examples:

• Jellyfish = nerve net

• Flatworm = primitive brain

• Earthworm = brain + ganglia

• Humans = highly developed brain

Easy: spread out → more organized → more specialized

What is a ganglion?

A cluster of neuron cell bodies.

In earthworms, ganglia along the nerve cord can control simple reflexes without needing the brain.

Easy: ganglion = mini control center

What major brain change occurred as vertebrates evolved?

The forebrain/cerebrum became much larger, especially in humans.

• Cerebrum → reasoning and cognition

• Cerebellum → coordination and balance

Easy:

Cerebrum = think
Cerebellum = balance/move

10.3 — Anatomy of the CNS

What do the neural tube and neural crest become?

• Neural tube → CNS

• Neural crest → PNS

• Hollow part of neural tube → brain ventricles + central canal

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Easy:

Tube = central, Crest = peripheral.

What are the main brain divisions during development?

Forebrain → Midbrain → Hindbrain

Later:

• Forebrain → cerebrum + diencephalon

• Midbrain → midbrain

• Hindbrain → cerebellum + pons + medulla

Plus the spinal cord.

Easy: Fore = cerebrum/diencephalon; Hind = cerebellum/pons/medulla.

Gray matter

mostly neuron cell bodies + dendrites

Gray = bodies

White matter

mostly myelinated axons

wires

Nucleus

cluster of cell bodies in CNS

Tract

bundle of axons in CNS

What are the meninges in order from outside → inside?

Dura → Arachnoid → Pia

• Dura = thick outer layer

• Arachnoid = middle

  • subarachnoid space

• Pia = thin layer touching the brain

Easy: D-A-P

And the subarachnoid space is between arachnoid and pia.

What does CSF do?

CSF gives the CNS:

• Physical protection → brain floats + gets cushioned

• Chemical protection → keeps the neuron environment controlled

Easy: CSF = float + cushion + control

Your professor specifically emphasizes the brain’s effective weight dropping about 30× because of buoyancy.

Where is CSF made and where does it go?

Made by the choroid plexus in the ventricles.

Flow:

Ventricles → subarachnoid space → around brain/spinal cord → arachnoid villi → blood

Easy: Make → circulate → reabsorb.

What is the blood-brain barrier (BBB)?

A selective barrier that protects the brain by controlling what can leave the blood and enter brain tissue.

Made mainly by tight junctions between brain capillary cells, helped by astrocyte foot processes.

Easy: BBB = brain security checkpoint

The hypothalamus is an important exception because it needs to sample the blood for endocrine control.

Why does the brain need so much blood flow?

Neurons constantly need:

glucose + O₂ → ATP

The slides note that about 15% of blood pumped by the heart goes to the brain.

Easy: brain = energy hog

10.4 — The Spinal Cord

Dorsal root vs ventral root?

• Dorsal root = sensory/afferent info IN to CNS

• Ventral root = motor/efferent info OUT to muscles and glands

Easy:

Dorsal = sensory in, Ventral = motor out.

Dorsal root

sensory/afferent info IN to CNS

sensory in

Ventral root

motor/efferent info OUT to muscles and glands

motor out

What is the dorsal root ganglion (DRG)?

A cluster containing the cell bodies of sensory neurons.

Easy: DRG = sensory neuron bodies.

Posterior horn vs anterior horn?

• Posterior/dorsal horn = sensory

• Anterior/ventral horn = motor

Easy:

Back = sensory
Front = motor

Posterior/dorsal horn

sensory

Back = sensory

Anterior/ventral horn

Motor

Front = motor

What do the spinal cord tracts do?

White matter is organized into columns of axon tracts.

• Ascending tracts = sensory info UP to brain

• Descending tracts = motor commands DOWN from brain

• Propriospinal tracts = stay within the spinal cord

Easy:

Ascending = up
Descending = down
Propriospinal = stays home

Ascending

sensory info UP to brain

Descending tracts

motor commands DOWN from brain

Propriospinal tracts

stay within the spinal cord

What is a spinal reflex?

A response that is integrated in the spinal cord without waiting for the brain.

The sensory information can still be sent to the brain afterward.

Easy example: touch something hot → hand pulls away before you consciously think about it.

10.5 — The Brain

What are the 3 parts of the brain stem and their main jobs?

Medulla → involuntary functions like breathing and blood pressure
Pons → relay between cerebrum and cerebellum; helps control breathing
Midbrain → controls eye movement and visual/auditory reflexes

Easy: Medulla = automatic, Pons = bridge, Midbrain = eyes

Medulla

involuntary functions like breathing and blood pressure

Pons

relay between cerebrum and cerebellum; helps control breathing

Midbrain

controls eye movement and visual/auditory reflexes

What does the cerebellum do?

It coordinates movement.

It helps with:

• voluntary movement

• posture

• balance

• eye movement

Easy: Cerebellum = coordination

What does the thalamus do?

The thalamus is a relay and integration center for sensory and motor information going to the cerebrum.

Easy: Thalamus = traffic station

What does the hypothalamus do?

The hypothalamus controls homeostasis.

It helps control:

• hunger

• thirst

• body temperature

• autonomic functions

• endocrine functions

Easy: Hypothalamus = body balance boss

What are the 3 major gray-matter regions of the cerebrum?

• Cerebral cortex → higher brain functions

• Basal ganglia → movement

• Limbic system → emotion and memory

Easy: Cortex = think, Basal = move, Limbic = feel

Cerebral cortex

higher brain functions

think

Basal ganglia

movement

Limbic System

Emotion and Memory

feel

What are the main parts of the limbic system?

• Amygdala → emotion + memory

• Hippocampus → learning + memory

• Cingulate gyrus → emotion

Easy: Amygdala = emotion, Hippocampus = memory

Amygdala

emotion + memory

Hippocampus

learning + memory

Cingulate gyrus

emotion

What does the corpus callosum do?

It connects the left and right cerebral hemispheres so they can communicate.

Corpus callosum = bridge between brain halves

What are the 4 lobes of each cerebral hemisphere?

Frontal, parietal, temporal, occipital

What are the major functions of the 4 cerebral lobes?

Frontal → voluntary motor control/behavior

Parietal → body sensation

Temporal → hearing + smell

Occipital → vision

Easy:

Front = move

Parietal = feel

Temporal = hear

Occipital = see

Frontal Lobe

voluntary motor control/behavior

parietal lobe

body sensation/feel

temporal lobe

hearing + smell

occipital lobe

vision

10.6 — Brain Function Flashcards

What are the 3 systems that influence brain output?

• Sensory system → monitors internal/external environment

• Cognitive system → voluntary responses

• Behavioral state system → sleep-wake state, emotions/arousal

Easy: Sense → Think → State

Sensory system

monitors internal/external environment

Sense

Cognitive system

voluntary responses

Think

Behavioral state system

sleep-wake state, emotions/arousal

What are the 3 functional areas of the cerebral cortex?

Sensory areas → perception

Motor areas → movement

Association areas → integrate information

Easy: Feel → Move → Connect

What is cerebral lateralization?

The two hemispheres specialize in different functions.

• Left → language/math tends to dominate

• Right → spatial processing tends to dominate

But there is lots of plasticity.

Easy: Left = language, Right = spatial

Sensation

sensory information enters the brain.

input

Perception

the brain interprets what that information means.

means

What are the 4 diffuse modulatory systems?

Norepinephrine

Serotonin

Dopamine

Acetylcholine

They influence things like arousal, sleep, mood, learning, memory, and motivation.

Easy: NE, 5-HT, DA, ACh = brain-state chemicals

What does the reticular formation help control?

Arousal and sleep, plus things like muscle tone and pain modulation.

Easy: Reticular formation = wake-up system

What are the major sleep stages?

N1 → N2 → N3 → REM

N3 = deepest/slow-wave sleep; delta waves

REM = dreaming; EEG looks more awake-like

Deepest sleep happens mostly early in the night.

Easy: N3 = deep, REM = dreams

How does memory move from short-term to long-term?

Short-term memory → consolidation → long-term memory

The hippocampus is especially important for forming explicit memories.

Easy: Consolidation = save button

What does neural plasticity mean for learning and memory?

Learning changes the strength or structure of synaptic connections.

Easy: “Neurons that fire together wire together.”

Implicit vs explicit memory?

Implicit/reflexive = automatic skills/procedures
Explicit/declarative = conscious facts and information

Easy:
Implicit = how
Explicit = what

Implicit/reflexive

automatic skills/procedures

How

Explicit/declarative

conscious facts and information

What

Wernicke’s area vs Broca’s area?

Wernicke’s → understands language
Broca’s → produces language

Pathway:
visual/auditory cortex → Wernicke → Broca → motor cortex

Easy:
Wernicke = understand

Broca = speak

What does the limbic system do in emotion?

The limbic system creates/processes emotion, then the hypothalamus and brain stem can trigger physical responses.

The amygdala is especially important for emotion/fear.

Easy: Limbic = feel

How can emotions affect the body?

Emotion can trigger:

• somatic motor responses

• autonomic responses

• endocrine responses

• immune responses

Easy: Brain emotion → whole-body response