1 Intro + 2 Anatomy

What was wrong with Trey?

brain filled with fluid - edema

• 5 yr old ran into a car. He started crying and ran to his mother, who took him to the hospital. He was alert at first, but then became lethargic. Neuroimaging was done (see picture), and he died 8 hours later.

What did Aristotle think about brain function?

The heart was the seat of mental capacities; the brain’s job was to cool the blood

What did Hippocrates think about brain function?

Brain is the seat of thought and emotion

What did Galen discover about the brain?

reported behavioral changes in brain-injured gladiators

Phrenology

study of how the bumps on your skull correspond to attributes of personality - assigned seperate functions to cortical areas

What is Pick’s disease?

frontotemporal dementia - degeneration of front of brain, causing memory loss

degeneration in the front of the brain

Dementia/Pick’s disease

What were the pins used for in the picture of brain surgery we saw in class?

Epilepsy treatment

What was wrong with the 14 yo Vietnamese girl?

Stroke in her right brain first, then her left - caused paralysis of arms and difficulty seeing/hearing

• 14 yo Vietnamese girl at school had a seizure, and on arrival in ER could not move her right arm or see to her left. On exam, she was quite short and thin, and hard of hearing. A month later she was back in ER, this time unable to move her left arm, and her hearing was worse.

Reticular Theory vs Neuron Doctrine

Reticular Theory (Golgi)

• everything in the nervous system is one continuous unit

• was proven to be false after the discovery of the neuron doctrine

Neuron Doctrine

• the brain is composed of independent cells - neurons are not connected

• signals are transmitted from cell to cell across synapses (cell gaps)

Who were the scientists who discovered the Neuron Doctrine?

Camillo Golgi - stained brain cells

Santiago Ramon y Cajal - used Golgi’s cell stains to see individual neurons - credited with the Neuron Doctrine

(they shared 1906 Nobel prize because they had to)

Which way does a nerve impulse travel?

Down the axon (soma to axon terminal)

Parts of a neuron

Dendrites - accept signals

Cell body - houses nucleus and organelles

Axon hillock - place where axon meets cell body

Axon - delivers signals

Myelin Sheath - coverings of myelin around the neuron, insulates and helps signals pass through faster

Nodes of Ranvier - gaps in myelin sheath, signals jump from node to node

Axon Terminals - place where signals are transferred from one neuron to another, contains neurotransmitters

Synapse - gaps between neurons

What are the three types of neurons (classification is by # axons/dendrites)?

Unipolar, Bipolar, Multipolar

Unipolar neuron

a single extension branching in two directions, forming a receptive pole and an output zone

What is the place on a unipolar neuron that recieves signals called?

receptive pole

What is the place on a unipolar neuron that sends signals called?

output zone

What is the advantage of unipolar neurons?

Can send signals the fastest (ex: pain information)

What is the disadvantage of unipolar neurons?

Can only take one input

How many axons and dendrites do bipolar neurons have?

one axon, one dendrite

What kind of information do bipolar neurons facilitate?

sensory information, often visual

How many axons and dendrites do multipolar neurons have?

one axon, many dendrites

What is the most common type of neuron (unipolar, bipolar, or multipolar)?

multipolar

What is the advantage of multipolar neurons?

Can accept and comprehend multiple inputs

What is the disadvantage of multipolar neurons?

slowest

What are the 4 functional zones of a neuron?

Input zone, Integration zone, Conduction zone, Output zone

Input zone

neurons collect and integrate info

Integration zone

the decision to produce a neural signal is made, also decides which signal gets through

Conduction zone

where information can be transmitted over great distances

Output zone

where the neuron transfers information to other cells

What are the two kinds of brain cells?

Neurons and Glia/Glial cells

What are the three kinds of neurons? (classified by basic functions)

Sensory/Afferent, Motor/Efferent, and Interneurons

What is the function of sensory/afferent neurons?

Respond to environment (light, odor, touch), carries information to the brain, mostly bipolar neurons

• remember: afferent = towards the brain

What is the function of motor/efferent neurons?

communicate with/signal muscles and glands, carries information away from the brain

• remember: efferent = away from the brain

What is the function of interneurons?

integration - processes sensory impulses, then sends them to motor neurons

What kind of neuron are the most common (sensory/afferent, motor/efferent, interneurons)?

Interneurons

What is the basic function of glial cells, and what are the four kinds?

basic function: support the brain

four kinds: astrocytes, oligodendrocytes, ependymal cells, microglia

What is the function of the astrocyte?

• structural support for neurons

• provides blood-brain barrier

• regulates composition of the extracellular space

• provides nutrients to neuron

What common condition do astrocytes help cure?

headaches - astrocytes clears out any unwanted substances in the head

What is the most common type of glial cell?

astrocytes

A 36-year-old engineer at TI developed incoordination of left arm and tendency to fall to his left, along with headaches. What’s wrong with him?

Astrocytoma (cancer of the astrocytes, most common form of brain cancer)

Rolf is a 15-month-old boy whose astrocytes filled with GFAP. What is his diagnosis?

Alexander disease - astrocytes fill with GFAP (cytoskeleton fluid in glial cells)

What is the function of oligodendrocytes?

Make myelin, wrap axons with myelin sheaths inside brain and spinal cord

What are Nodes of Ranvier and how are they formed?

Nodes of Ranvier - gaps in the myelin where the axon membrane is exposed

Formed at the place where two oligodendrocytes meet

What is Multiple Sclerosis (MS)?

Oligodendrocyte injury from autoimmune attacks

multiple attacks over several years/decades, over time the brain loses the ability to recover

What is this condition:

Oligodendrocyte injury from autoimmune attacks that occur over a long period of time

Multiple Sclerosis (MS)

How is Multiple Sclerosis treated?

immunosuppressants

What is the function of microglia?

Cells move around, clean up debri from dying neurons and glia

What is the function of ependymal cells?

Line ventricles, secrete and absorb cerebral spinal fluid

What is AIDS Encephalitis?

neurons are accidentally killed while microglia try to get rid of neurotoxins

• brain damage in pateint from the neurotoxins glutamate and nitric oxide from viral-activated microglia

• (HIV/AIDS encephalitis virus activates viral-activated microglia → microglia produce neurotoxins → damages the brain)

What is this condition:

neurons are accidentally killed while microglia try to get rid of neurotoxins

AIDS Encephalitis

Why do more dendrites grow?

When you learn things, you get more dendrites

More dendrites = More surface area

What are the different shapes of neurons?

Double bouquet cell

Chandelier cell

Spiny stellate cell

Pyramidal cell

Large basket cell

Do dendritic spines change?

Yes - they have neural plasticity, and their number/structure are rapidly altered by experience

What is a Synapse?

Gap between two neurons

What is the function of the mitochondria in a neuron?

axonal and dendritic development/regeneration, growth

How does a signal travel across the synapse?

Axon contains vesicles with neurotransmitters

Neurotransmitters travel from the axon to the dendrite

Neurotransmitters bind to receptors on the post-synaptic membrane, triggering an action potential in the recieving dendrite

What are the parts of a synapse?

Presynaptic terminal (bouton)

Mitochondrion

Synaptic vesicles

Synaptic cleft

Neurotransmitter molecules

Presynaptic membrane

Postsynaptic membrane

Dendritic spine

What is the Central Nervous System (CNS) comprised of? What is the Peripheral Nervous System (PNS) comprised of?

• CNS - brain and spinal cord

• PNS - cranial nerves and spinal nerves

What is the function of the autonomic nervous system?

Controls autonomous functions, involuntary

What are the divisions of the autonomic nervous system?

Sympathetic and Parasympathetic nervous system

both systems oppose each other

What does the Sympathetic Nervous System do?

Prepares the body for action (fight-or-flight)

What does the paraysmpathetic nervous system do?

rests and digests, calms the body down

What parts of the CNS activates the parasympathetic nervous system?

Brainstem - Preganglionic neurons in nuclei of III, IV, IX, and X cranial nerves

Spinal cord - Preganglionic neurons in S2-S4

What parts of the CNS activates the sympathetic nervous system?

ONLY SPINAL CORD

Preganglionic neurons in T1-T12, and L1-L2

What are the three planes?

Horizontal, Sagittal, Coronal

How does the coronal plane separate a brain?

Front to back - resembles a butterfly

How does the sagittal plane separate a brain?

side to side - midsagittal slices down the midline

How does the horizontal plane separate a brain?

separates brain from top to bottom

What plane is this?

coronal

What plane is this?

sagittal

What plane is this?

horizontal

Medial

Towards the middle/midline

Ipsilateral

Same side

Anterior

Head end

Proximal

Near center

Dorsal

toward the back

Lateral

toward the side

Contralateral

opposite side

Posterior

tail end

Distal

toward periphery

Ventral

toward the belly

Afferent

carries impulses into a region of interest (sensory)

Efferent

carries impulses away from a region of interest (motor)

What is white matter composed of?

Axon bundles

Why is white matter white?

White matter is made of axon bundles, and the myelin sheaths that cover the axons are white.

What is gray matter made of?

clusters of neuron cell bodies

Why is gray matter gray?

It’s composed of clusters of neuron cell bodies, which are dark gray in appearance.

True or false: Our brain was built in layers due to evolution.

True

What is the function of the basal ganglia?

movement control

Identify the parts of the basal ganglia. (won’t be tested, but good to know)

What is the function of the limbic system?

Emotional memory/regulation

parts of the limbic system diagram (won’t be tested, but good to know

Function of the cerebellum

Motor coordination and learning

Identify the parts of the cerebellum. (won’t be tested, but good to know)

Function of the reticular formation

sleep and arousal, body temperature

damage/abnormalities can cause coma

Diencephalon

• Intermediate between brainstem and

  cortex

• “First brain” involved in the

  nervous system

Structures involved in the diencephalon

• Thalamus

• Hypothalamus

• Mammilary bodies

Identify the parts of the midbrain (will not be tested, but good to know)

What are meninges?

brain wrappings