Pyche 425- Caramillo-Hatch (Exam 1 chapters 1&2)

Split Brains

one of the biggest phenomenon that led to learning about the brain

disconnecting parts of the brain that lead to changes in behavior and conscouisness

What area in the brain is "disconnected" in a split brain?

corpus callosum

Split Brain: Corpus Callosum

large bundle of nerves that connects one side of the brain with the other

ex.split brain surgery used to treat severe epilepsy

connects two cerebral hemishperes: the two symmetrical halves of the brain, they constitute the major part of the brain

-receive sensory information from opposite sides of the body

-control movements of the opposite sides

allow the two himespheres to talk to each other

after split brain surgery the two sides work independently

Split Brain: the outcomes

sensory, memory, and motor systems cannot exchange information

Split Brain: Generalization

a general conclusion based on many observations of similar phenomena

Split Brain: Reduction

phenomena is described in terms of the more elementary processes that underlie it

René Descartes

Believed the body was a machine

Introduced the idea of reflexes

First to introduce the idea that there is a link between the mind and the brain

Connection between the mind and the body (they TALK)

Reflexes: an automatic, stereotyped movement produced as a direct result of a stimulus

Reflexes

an automatic, stereotyped movement produced as a direct result of a stimulus

Johannes Müller

Application of experimental techniques to physiology

Not just observation and philosophy!

Doctrine of specific nerve energies

Because all nerve fibres carry the same types of message (electrical), sensory information must be specified by the particular nerve fibres that are active.

Optic nerves carry visual information, auditory nerves carry sound information

The messages occur in different "channels"

Begin in a particular area of the brain, end in a particular area of the brain

Some "parts" are responsible for interpreting certain information

Charles Darwin

An organism's characteristics have functional significance

FUNCTIONALISM

Natural Selection

process by which inherited traits that confer a selected advantage become more prevalent in a population

Evolution

gradual change in the structure and physiology of plant and animal species as a result of natural selection

Mutations

a change in genetic information in the sperm/egg, which can be passed on to an organism's offspring

Create new organisms/species

Most mutants fail to survive

Those who do generally have a selective advantage

Can be caused by environmental changes

Evolution of the brain:

Agile hands, color vision, fire, bipedalism, language, etc.

Must be supported by a larger brain

Larger brain needs a larger skull

Both require longer gestation and longer weaning post birth (neoteny)

More convolusions, moveable skull sections, larger cortex

Cells of the nervous system

neurons

supporting cells

the blood-brain barrier

Central Nervous System (CNS)

The brain and the spinal cord

Peripheral Nervous System (PNS)

The part of the nervous system outside the brain and spinal cord, including the nerves attached to the brain and the spinal cord

The human nervous system comprises two kinds of cells

Neurons

Glia

The human brain contains approximately --- billion individual neurons

100

sensory neuron

A neuron that detects changes in the external or internal environment and sends information about these changes to the central nervous system.

motor neuron

A neuron located within the central nervous system that controls the contraction of a muscle or the secretion of a gland.

interneuron

A neuron located entirely within the central nervous system.

Perceiving, learning, remembering, deciding, and controlling complex behaviors

Components of a neuron

Dendrites

Soma/cell body

Axon

Terminal Button

Axon Hillock

Nodes of Ranvier

Myelin Sheath

Dendrites

Branching fibers with a surface lined with synaptic receptors responsible for bringing information into the neuron

Dendritic spines branch out and increase the surface area of the dendrite

Larger surface area = the more information it can receive

More telephone wires? More calls that can be received.

Cell body/soma

Contains the nucleus, mitochondria, and endoplasmic reticulum (organelles!)

Responsible for the metabolic work of the neuron

Axons

Thin fiber of a neuron responsible for transmitting nerve impulses toward other neurons, organs, or muscles

Might have a myelin sheath, an insulating material that contains interruptions in the sheath known as Nodes of Ranvier

Termianl Buttons

the end points of an axon release chemicals to communicate with other neurons

bipolar neuron

A neuron with one axon and one dendrite attached to its soma (sensory; visual, auditory)

unipolar neuron

A neuron with one axon attached to its soma; the axon divides, with one branch receiving sensory information and the other sending the information into the central nervous system (touch, pain).

multipolar neuron

A neuron with one axon and many dendrites attached to its soma.

neurotransmitter

A chemical that is released by a terminal button; has excitatory or inhibitory effect on another neuron.

membrane

A structure consisting principally of lipid molecules that defines the outer boundaries of a cell and also constitutes many of the cell organelles, such as the Golgi apparatus.

Nucleus

A structure on the central region of a cell containing the chromosomes

chromosome

A strand of DNA, with associated proteins, found in the nucleus; carries genetic information.

deoxyribonucleic acid (DNA)

A long, complex macromolecule consisting of two interconnected helical strands; along with associated proteins, strands of DNA constitute the chromosomes.

gene

The functional unit of the chromosome, which directs synthesis of one or more proteins.

messenger ribonucleic acid (mRNA)

A macromolecule that delivers genetic information concerning the synthesis of protein from a portion of a chromosome to a ribosome.

ribosome

A cytoplasmic structure, made of protein, that serves as the site of production of proteins translated from mRNA.

enzyme

A molecule that controls a chemical reaction, combining two substances or breaking a substance into two parts.

non-coding RNA (ncRNA)

A form of RNA that does not encode for protein, but has functions of its own.

mitochondrion

An organelle that is responsible for extracting energy from nutrients.

adenosine triphosphate (ATP)

A molecule of prime importance to cellular energy metabolism; its breakdown liberates energy.

endoplasmic reticulum

Parallel layers of membrane found within the cytoplasm of a cell.

Rough ER contains ribosomes proteins

Smooth ER lipids

Golgi apparatus

A complex of parallel membranes in the cytoplasm that wraps the products of a secretory cell.

Packages cells into vesicles

lysosome

An organelle surrounded by membrane; contains enzymes that break down waste products.

cytoskeleton

Formed of microtubules and other protein fibers, linked to each other and forming a cohesive mass that gives a cell its shape.

microtubule

A long strand of bundles of protein filaments arranged around a hollow core; part of the cytoskeleton and involved in transporting substances from place to place within that cell.

axoplasmic transport

An active process by which substances are propelled along microtubules that run the length of the axon.

anterograde

In a direction along an axon from the cell body toward the terminal buttons.

retrograde

In a direction along an axon from the terminal buttons toward the cell body.

glia

The supporting cells of the central nervous system.

astrocyte

A glial cell that provides support for neurons of the central nervous system, provides nutrients and other substances, and regulates the chemical composition of the extracellular fluid.

oligodendrocyte

A type of glial cell in the central nervous system that forms myelin sheaths.

Schwann cell

A type of glial cell in the peripheral nervous system that forms myelin sheaths.

microglia

The smallest of glial cells; act as phagocytes and protect the brain from invading microorganisms. Also remove waste material.

phagocytosis

The process by which cells engulf and digest other cells or debris caused by cellular degeneration.

blood-brain barrier

A semipermeable barrier between the blood and the brain produced by the cells in the walls of the brain's capillaries.

The _____________ that is transmitted down the axon of a neuron

Does not travel directly down the axon, but is regenerated at points along the axon so that it is not weakened

Saltatory Conduction

electircal message

The speed of nerve impulses ranges from less than ___ meter/second to ____meters/second

A touch on the shoulder reaches the brain more quickly than a touch on the foot

1meter/sec; 100 meters/sec

Messages in a neuron develop from disturbances of the ____________

resting potential

At rest, the membrane maintains an electrical gradient known as __________

A difference in the electrical charge inside and outside of the cell

The neuron is polarized

polarization

The inside of the membrane is slightly negative with respect to the outside

approximately -70 millivolts

The resting potential of a neuron refers to the state of the neuron prior to the sending of a nerve ________

impulse

The membrane is _________________, allowing some chemicals to pass more freely than others

selectively permeable

Sodium, potassium, calcium, and chloride pass through _________ in the membrane

channels

When the membrane is at rest:

Sodium channels are closed

Potassium channels are partially closed allowing the slow passage of potassium

The _______________ is a protein complex

Continually pumps three sodium ions out of the cells while drawing two potassium ions into the cell

Helps to maintain the electrical gradient

More K in cell, more Na outside of cell

sodium-potassium pump

The resting potential remains stable until the neuron is __________ (IPSPs & EPSPs!)

stimulated

Hyperpolarization

increasing the polarization or the difference between the electrical charge of two places (more negative!)

Depolarization

decreasing the polarization towards zero (less negative!)

The threshold of excitation

a level above which any stimulation produces a massive depolarization

A rapid depolarization of the neuron

Stimulation of the neuron past the threshold of excitation triggers a nerve impulse or __________

action potential

After an action potential occurs, sodium channels are quickly _______

closed

The neuron is returned to its resting state by the ____ potassium channels

open

Potassium ions flow out due to the _________ and take with them their positive charge

concentration gradient

The sodium-potassium pump later ________ the original distribution of ions

restores

The all-or-none law

States that the amplitude and velocity of an action potential are independent of the intensity of the stimulus that initiated it

Action potentials are equal in intensity and speed within a given neuron

After an action potential, a neuron has a ________during which time the neuron resists the production of another action potential

refractory period

The absolute refractory period

the first part of the period in which the membrane cannot produce an action potential

The relative refractory period

the second part, in which it takes a stronger than usual stimulus to trigger an action potential

The myelin sheath of axons are interrupted by short unmyelinated sections called __________

Myelin is an insulating material composed of fats and proteins

At each ____________, the action potential is regenerated by a chain of positively charged ions pushed along by the previous segment

nodes of ranvier

Neurons communicate by transmitting chemicals at junctions, called "________"

The term was coined by Charles Scott Sherrington in 1906 to describe the specialized gap that existed between neurons

synapses

Presynaptic neuron

neuron that delivers the synaptic transmission

Postsynaptic neuron

neuron that receives the message

binding site

The location on a receptor protein to which a ligand binds.

ligand

A chemical that binds with the binding site of a receptor.

synaptic cleft

The space between the presynaptic membrane and the postsynaptic membrane.

synaptic vesicle

A small, hollow, beadlike structure found in terminal buttons, contains molecules of a transmitter.

The major sequence of events allowing communication between neurons across the synapse:

1.The neuron synthesizes chemicals that serve as neurotransmitters

2.Action potentials travel down the axon

3.Released molecules diffuse across the cleft, attach to receptors, and alter the activity of the postsynaptic neuron

The effect of a neurotransmitter depends on its receptor on the__________

postsynpatic cell

Transmitter-gated or ligand-gated channels are controlled by a _________

neurotransmitter

Ionotropic effects

Occurs when a neurotransmitter attaches to receptors and immediately opens ion channels (direct)

__1_ binds and an associated ion channel opens or closes, causing a _2_

If Na+ channels are opened, for example, an EPSP occurs

If K+ channels are opened, for example, an IPSP occurs

1.NT, 2.psp

METABOTROPIC EFFECTS AND SECOND MESSENGER SYSTEMS

Occur when neurotransmitters attach to a receptor and initiate a sequence of slower and longer lasting metabolic reactions, including G proteins

(1) NT 1st messenger binds to receptor

(2) G protein subunit breaks away triggers enzyme

(3) Ion channel opened/closed OR a 2nd messenger is synthesized.

(4) 2nd messengers may have a wide variety of effects open ion channels

reuptake

The reentry of a neurotransmitter just liberated by a terminal button back through its membrane, this terminating the postsynaptic potential.

enzymatic deactivation

The destruction of a neurotransmitter by an enzyme after its release - for example, the destruction of acetylcholine by acetylcholinesterase.

Diffusion

The neurotransmitter diffuses out into the extracellular space to be degraded or reused

gap junction

A special junction between cells that permits direct communication by means of electrical coupling.

neuromodulator

A naturally secreted substance that acts like a neurotransmitter except that it is not restricted to the synaptic cleft but diffuses through the extracellular fluid.

peptide

A chain of amino acids joined together by peptide bonds. Most neuromodulators, and some hormones, consist of peptide molecules.