Set #1 (Lecture 9 and Textbook PGs 41-49 Study Guide)

What is neuroanatomy?

The study of the structure and organization of the nervous system.

About how many neurons and miles of axons do humans have?

About 86 billion neurons and 93,000 miles of axons.

What two approaches can make the complicated brain easier to understand?

Studying its development and evolution.

What is the neural plate?

The earliest beginning of the nervous system, where part of the embryo thickens and separates from surrounding cells.

How does the neural plate become the neural groove?

The plate sinks down while cells on both sides rise around it.

What is the neural groove?

The sunken-down stage that develops from the neural plate.

What does the neural groove eventually become?

The neural tube.

What is the neural tube?

A tube formed when the neural groove closes.

What remains in the center of the neural tube?

A hole.

What is the neural crest as described in lecture?

The stage where the tube gets larger and stands up along the developing body.

What happens to the neural tube as development continues?

It elongates and becomes more complicated.

What is differentiation?

Cells become different from surrounding cells and more specialized.

What are the three early divisions of the developing brain?

Prosencephalon, mesencephalon, and rhombencephalon.

What is the prosencephalon?

The forebrain, located toward the front.

What is the mesencephalon?

The midbrain, located in the middle.

What is the rhombencephalon?

The hindbrain, located toward the back.

What happens to the three early brain divisions as development continues?

They become five divisions.

What does the prosencephalon divide into?

The telencephalon and diencephalon.

What is the telencephalon?

The division at the very top of the brain.

What does "telencephalic" mean?

Originating from telencephalon tissue.

What is the diencephalon, and what example did the professor give?

It is a forebrain division; the hypothalamus is an example.

What happens to the mesencephalon when the three divisions become five?

It stays the mesencephalon and does not divide further.

What does the rhombencephalon divide into?

The metencephalon and myelencephalon.

Which rhombencephalon division is closer to the midbrain?

The metencephalon.

What are the five developmental brain divisions?

Telencephalon, diencephalon, mesencephalon, metencephalon, and myelencephalon.

What is the basic progression of these brain divisions?

Three early brain pouches become five, which later develop into different brain structures.

What does "evo devo" mean?

Studying evolution and development together.

Why can scientists study other animals to understand the human brain?

Evolutionarily related species share basic nervous-system organization and function.

What does continuity between species mean?

Different species can share similarities in brain organization and function.

What example did the professor give for continuity between species?

Fritsch and Hitzig stimulated the cortex of dogs and observed responses.

What ancient animals were discussed when studying early vertebrate brains?

Ancient bony fish.

Why is actual ancient brain tissue difficult to study?

Brain tissue is gelatinous, disappears quickly after death, and does not fossilize well.

What is an endocast?

A cast of the inside of a skull where the brain had been.

What material was traditionally used to make an endocast?

Plaster of Paris.

How can an endocast help scientists study an ancient brain?

The inside of the skull provides information about the brain's shape.

What are serial sections?

Sections used to examine an object piece by piece.

How can serial sections and reconstruction help study ancient brains?

The sections can be put together to estimate the brain's overall shape.

What did ancient vertebrate brains reveal?

The same basic brain regions existed in the same order.

What was the order of the five regions in the ancient vertebrate example?

Myelencephalon, metencephalon, mesencephalon, diencephalon, telencephalon.

How can modern imaging help scientists study extinct brains?

Skull fossils can be used to reconstruct what the brain may have looked like.

What extinct animal did the professor use as an example of brain reconstruction?

Tyrannosaurus rex.

What basic brain plan is shared across vertebrates?

The same basic five-part developmental organization.

Does evolution usually give different vertebrates completely new brain divisions?

No. It elaborates parts of the existing basic plan.

What is an adaptation?

A change that helps an animal function and survive in its particular environment or niche.

What can determine which brain regions become especially developed in a species?

The environment and skills the species needs for survival.

What adaptation did the professor discuss in animals living in murky water?

An electrical organ and an enlarged brain region for processing electrical information.

What animal was used as the electrical-system example?

The elephant nose fish.

Why don't humans have the same electrical-processing specialization?

Humans do not have that type of electrical organ.

What does the worm example show about nervous systems?

Nervous systems existed even in relatively simple animals.

How is a worm's nervous system organized compared with a vertebrate's?

It is more distributed instead of being strongly centralized.

What does a worm's brain consist of?

Two clusters of neurons called ganglia.

What is the difference between ganglion and ganglia?

Ganglion is singular; ganglia is plural.

Is a worm's brain necessary for movement?

No. Its nerve cord and interspersed ganglia can function independently.

Why does the textbook compare a worm's ganglia to "city-states"?

The ganglia can function with considerable independence instead of having clear leadership from the brain.

How did nervous-system organization change during vertebrate evolution?

Neural tissue became increasingly centralized in the brain and spinal cord.

What became the clear leader of the vertebrate nervous system?

The brain.

What did centralization allow the vertebrate nervous system to do?

Communicate more sophisticatedly with organs, muscles, and the environment.

What cost came with making the brain the central controller?

Brain failure became extremely dangerous because survival depends heavily on it.

Why does the vertebrate brain need strong protection?

The animal's survival depends on the brain functioning.

What brain-protection system does the textbook mention?

The blood-brain barrier.

Is the vertebrate nervous-system design perfect according to the textbook?

No.

How does the textbook describe evolution's effect on the vertebrate nervous system?

Evolution continually modifies the system, allowing more sophisticated environmental interactions than in an invertebrate worm.

What are the two major divisions of the nervous system?

Central nervous system and peripheral nervous system.

What does CNS stand for?

Central nervous system.

What structures make up the CNS?

The brain and spinal cord.

What does PNS stand for?

Peripheral nervous system.

What is the PNS?

Everything in the nervous system outside the brain and spinal cord.

What is the general role of the PNS?

It acts as a go-between for the body/environment and the CNS.

What are the two main divisions of the PNS?

Somatic nervous system and autonomic nervous system.

How are axons with similar destinations organized?

They are bundled together like a cable.

What do bundles of axons help connect?

They help connect the nervous system to different organs and muscles throughout the body.

What is a tract?

A bundle of axons within the CNS.

What is a nerve or peripheral nerve?

A bundle of axons in the PNS that carries information between the CNS and the rest of the body.

What is the easiest difference between a tract and a nerve?

A tract is in the CNS; a nerve is in the PNS.

What is the main function of nerves and tracts?

Communication.

What does "soma" mean?

Body.

What is the somatic nervous system?

The PNS division that deals with the body and external environment and generally controls voluntary movements.

What two types of information are part of the somatic nervous system?

Sensory information and motor information.

What is sensory information?

Information the nervous system receives regarding what is happening inside or outside the body.

What is motor information?

Information used to produce a response or movement.

What is afferent information?

Sensory information traveling toward the CNS.

What are afferent nerves also called?

Sensory nerves.

What is efferent information?

Motor information traveling out from the CNS.

What are efferent nerves also called?

Motor nerves.

What is the easiest way to distinguish afferent and efferent?

Afferent information comes in; efferent information goes out.

What happens first in the textbook's mosquito example?

Sensory neurons detect the mosquito.

What do afferent nerves do in the mosquito example?

Carry sensory information toward the CNS.

What are interneurons?

Neurons that transmit impulses between other neurons.

What do interneurons do in the mosquito example?

Help direct information toward the appropriate motor neurons.

What do efferent nerves do in the mosquito example?

Carry motor information to the muscles needed to respond.

What responses does the textbook give in the mosquito example?

Shaking the mosquito away and later scratching the itchy bite.

Why is speed important in sensory-to-motor communication?

The body may need to respond quickly to something happening in the environment.

What helps nervous-system information travel quickly in this example?

Myelin.

What two categories of nerves communicate between the CNS and body?

Cranial nerves and spinal nerves.

How many cranial nerves are there?

12.

Where do cranial nerves exit and what areas can they target?

They exit different brain areas and can target the head, face, and shoulders.

What types of functions can cranial nerves have?

Sensory, motor, or both.

What is cranial nerve X?

The vagus nerve.

What makes the vagus nerve notable in the textbook?

It extends to internal organs.

How many pairs of spinal nerves are there?

31 pairs.