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Flashcards in Chapter 3 Deck (94):
1

Golgi

thought the nervous system was composed of interconnected fibers

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Ramon y Cajal

used the brain embryos of chicks and found that the nervous system is made up of discrete cells that become more complex with age

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Cell body (soma):

core region of a cell containing the nucleus and other organelles for making proteins

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Dendrites

branching extension that collect information from other cells

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Axon

“root” or single fiber that carries messages to other neurons

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Neurons

are plastic; most CNS neurons are never replaced throughout life

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Dendritic spines

small protrusions from on a dendrite; point of contact with the axons of other cells

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Axon hillock

where the axon begins; juncture of soma and axon where the action potential begins

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Axon collaterals

branch of an axon

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Teleodendria

small branches that may emerge from the lower tip of an axon

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Terminal button

located at the end of teleodendrion; sits close to the dendritic spine; creates an “almost connection called a synapse

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Synapse

information-transfer site between neurons

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Sensory Neuron

brings information into the brain from sensory receptors; Types: bipolar, somatosensory

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Interneurons (association cells)

associate sensory and motor activity in the CNS; branch extensively; Types: stellate, pyramidal, Purkinje

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Motor Neurons

carry information out the brain and spinal cord to the body’s muscles; have long axons and cell bodies; located in the lower brainstem and spinal cord

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Bipolar Neuron

Type of sensory neuron; found in the retina and contains one short dendrite and one short axon; transmit afferent sensory information from the retina’s light receptors to the neurons that carry information to the visual centers

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Somatosensory Neuron

bring sensory information from the body into the spinal cord

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Stellate Cell

type of interneuron; small with many dendrites extending around the cell body

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Pyramidal Cell

type of interneuron; brings information from the cerebral cortex to the rest of the brain and spinal cord; has two dendrites and is pyramid shaped

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Purkinje Cell

type of interneuron; fan shaped; carries information from the cerebellum to the rest of the brain and spinal cord

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Relationship between sensory, interneurons and motor neurons

Sensory (collect afferent)→interneurons→ motor neurons (efferent creates behavior)

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Action Potential

neurons fire only if its excitatory inputs exceed its inhibitory inputs.

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Glial Cells

support cells; help neurons relay information by binding them together and providing them nutrients, support and protection; can replace themselves

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Ependymal Cells

type of glial cell; located on the walls of ventricles; produce and secrete CSF

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CSF

constantly being made; flows toward the base of the brain where it is absorbed into the blood vessels. Purpose: shock absorber, eliminates waste, assists in maintaining a constant temperature, source of nutrients for brain areas near ventricles

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Hydrocephalus

the fourth ventricle can become fully or partly blocked and can restrict CSF flow causing a buildup of pressure that begins to expand the ventricles and push on the surrounding brain; can cause severe mental retardation

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Brain tumors

grow from glial cells. Types: Gliomas (slow growing, not usually malignant if from astrocytes), Meningiomas (tumors usually encapsulated and can often be easily removed), Metastatic (transfer of tumor cells from one region to another, difficult to treat)

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Astrocytes (astroglia)

type of glial cell; creates the blood-brain barrier; provide structural support within CNS--their extensions attach to blood vessels and the brain’s lining creating scaffolding that hold neurons in place; provide pathways for the movement of nutrients between blood vessels and neurons; secrete chemicals that keep neurons healthy and help them heal if injured; enhance brain activity by receiving signals from neurons when they pass on the blood vessels, which allow the blood vessels to expand to provide more fuel (oxygen and glucose)

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Blood-Brain Barrier

protective partition between blood vessels and the brain; end feed of astrocytes attach to blood vessels and prevent an array of substances from entering the brain through the blood vessel walls; does not allow other (good) substances to enter either → difficult to treat brain infections

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Microglia

type of glial cell; originate in the blood (immune system) and migrate throughout the nervous system; monitor health of brain tissue and play a role in its immune system; identify and attack foreign tissue; provide growth factors that aid in repair; they engulf foreign tissue and dead brain cells (called phagocytosis);

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Phagocytosis

when microglia engulfs foreign tissue and dead brain cells

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Olingodendroglia

Type of glial cell; myelinate axons in the brain and spinal cord; send out large, flat branches that enclose axons; contributes to the neurons’ nutrition and function by absorbing chemicals that the neuron releases and releasing chemicals that the neuron absorbs

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Schwann Cells

Type of glial cell; myelinate axons in the PNS; wraps itself repeatedly around part of an axon; contributes to the neurons’ nutrition and function by absorbing chemicals that the neuron releases and releasing chemicals that the neuron absorbs

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Myelin

insulation for axons; prevents adjacent neurons from short-circuiting

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Multiple Sclerosis (MS)

myelin formed by oligodendroglia is damaged and the neurons’ functions become disrupted; the loss of patches of myelin leads to scaring aka plaque

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Paralysis

cessation of both movement and sensation

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PNS Glial Repair

when a PNS axon is cut it does and returns to the cell body. Microglia remove debris from dying axon, Schwann cells (provide its myelin) shrink and divide forming numerous small glial cells that are along the path the axon used to take. The neuron sends out axon sprouts that search for the path and then follow it. Schwann cells envelop the new axon, forming new myelin and restoring function

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CNS Repair

CANNOT be repaired; oligodendrocytes inhibit neuron regrowth

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Organelles

internal parts of a cell

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Cell membrane

cell’s double layered outer wall that separates the cell from its surroundings; regulates what enters/leaves;

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Extracellular Fluid

separates all neurons and glia; composed mainly of water with dissolved salt and other chemicals

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Intracellular Fluid

found inside cells

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Nuclear Membrane

surrounds the cell’s nucleus

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Nucleus

stores, copies and distributes the genetic blueprints for the cell’s proteins

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Endoplasmic Reticulum (ER)

extension of the nuclear membrane; place where proteins are created with instructions from the blueprints; studded with ribosomes

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Tubules

microfilaments (reinforce cell’s structure), microtubules (form the transportation network that carries the proteins to their destinations), other’s aid in cell’s movements

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Mitochondria

provides energy

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Lysosomes

vesicles that transport incoming supplies and move and store wastes

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Phosopholipids

form cell membranes; contains a head of phosphorus bound with other atoms (positive) and two tails that are lipids (negative); the opposite charges creates the bilayer

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Genes

blueprints for making proteins; segments of DNA that encode the synthesis of particular proteins; contained within chromosomes

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Chromosomes

double-helix structures that hold an organism’s entire DNA; humans have 23 pairs; each is a double-stranded molecule of DNA that is capable of replicating and determining the inherited structure of a cell’s proteins

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Nucleotide Bases

constituent molecules of the genetic code; make up chromosomes; Types: Adenine (A); Thymine (T); Guanine (G), Cytosine (C); the sequence of bases is the code that spells out the particular order in which amino acids should be assembled to construct a certain protein

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Pairing of Nucleotide Bases

Adenine→ Thymine
Guanine → Cytosine

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Transcription (Protein Production)

appropriate segment of DNA strand unwinds to expose the sequence of nucleotide basis, which serve as a template to attract nucleotides. Nucleotides attach to form a complementary strand of RNA

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Nucleotides

free-floating molecules

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Ribonucleic Acid (RNA)

single stranded nucleic acid molecule requires for protein synthesis; similar to DNA but the base uracil (u) takes the place of thymine in pairing with adenine.

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Messenger RNA

transcribed strand of RNA; carries genetic code out of the nucleus to the endoplasmic reticulum

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Ribosomes

stud the reticular formation; protein structures that act as catalysts in the building of proteins; reads genetic code off the mRNA

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Translation

when ribosomes read genetic code of mRNA; a particular sequence of nucleotide bases in the mRNA is transformed into a particular sequence of amino acids

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Transfer RNA (tRNA)

assists in translation

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Codons

a sequence of three bases along on mRNA molecule; encodes a particular amino acid

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Polypeptide chain

humans use 20 different amino acids to synthesize their chains

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Peptide Bond

chemically link together amino acids in polypeptide chain

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Flow of genetic code

A portion of a DNA strand (gene) is transcribed into an mRNA strand and the mRNA strand is translated by ribosomes into a molecular chain of amino acids (a polypeptide chain)

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Protein

a folded-up polypeptide chain; can modify the length and shape of other proteins and thus act as enzymes; can be embedded into a cell’s membrane to form channels and gates or exported to act as messengers

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Golgi Bodies

wrap protein molecules in membranes and load them onto motor molecules that bring them to their destination via microtubules radiating through the cell

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Protein destinations

within cell (unloaded into intracellular fluid), cell membrane (carried to membrane where it inserts itself), exported (leaves the cell using a vesicle)

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Exocytosis

when a protein is exported by a cell

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Vesicle

during exocytosis; is the membrane that wraps the protein and then fuses with the membrane of the cell and then expels the protein into the extracellular fluid

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Receptor

groove in a protein molecule where small molecules, such as glucose or other proteins can bind and cause a protein to change shape. Shape changes allow proteins to serve new functions

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Channels

opening in a protein embedded in the cell membrane that allows the passage of ions

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Pump

protein in the cell membrane that actively transports a substance across the membrane

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Gate

protein embedded in a cell membrane that allows substances to pass through the membrane on some occasions but not on others

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Genotype

genetic makeup; influences phenotype

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Phenotype

physical and behavioral traits

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Mendelian Genetics

effects that genes have in influencing our traits

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Epigenetics

how the environment influences gene expression

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Autosomes

chromosome pairs 1 through 22; contain genes that contribute most to physical appearance and behavior

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Sex chromosomes

23rd pair of chromosomes; contribute to physical and behavioral sexual characteristics

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Alleles

two matching copies of a gene (one from mom other from dad) that are contained on every cell

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Homozygous

nucleotide sequences in a pair of alleles is identical

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Heterozygous

nucleotide sequences in a pair of alleles is different

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Wildtype allele

the nucleotide sequence that is most common in a population

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Mutation

less frequently occurring nucleotide sequence in a population

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Dominant

member of a gene pair that is routinely expressed as a trait

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Recessive

a member of a gene pair that is routinely unexpressed

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Tay-Sachs disease

caused by a dysfunctional protein that acts as an enzyme known as HexA that fails to break down a class of lipids (fats) in the brain; symptoms usually appear at birth or a few months later

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Huntington’s disease

buildup of an abnormal protein that kills brain cells in the basal ganglia and the cortex; symptoms usually start in midlife and include abnormal involuntary movements, memory loss, deterioration of behavior, death

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Down syndrome

affects approximately 1 in 700 children; result of an extra copy of chromosome 21 called a trisomy; have characteristic facial features and may have heart defects, respiratory infections, and mental retardation; are prone to leukemia and Alzheimer’s

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Genetic Engineering

manipulating a genome, removing a gene from a genome, modifying a gene, or adding a gene to the genome; include selective breeding, cloning and transgenics

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Cloning

producing an offspring that is genetically identical to another animal

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Chimeric animals

composites formed when an embryo of one species receives cells from a different species

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Phenotypic plasticity

capacity to develop into more than one phenotype; due in part to the capacity of the genome to express a large number of phenotypes and in part to epigenetics

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Concordance

incidence of similar behavior traits