Chapter 3-Neurons Flashcards
What are the functional units of the nervous system
Cells of a nervous system and its internal structures as well as genes, cells, behavior
Golgi debated…
The nervous system is composed of a “nerve net”
Cajal debated…
- Nervous system is made of discrete cells
- Neuron hypothesis-Neurons are the units of brain function
- Used the Golgi stain to prove his hypothesis
Basic neuron structure
- Cell body
- Branching extensions called dendrites
- Axon main root acts as messenger
Neurons
Most behaviors are produced by neurons whose functional groups attach to the brain and spinal cord.
Dendrites
Gather information from other neurons
Cell body
The core region with the nucleus that integrates info
Axon
Carries info to be passed on to other cells
Dendritic spines
Protrusion from the dendrite that greatly increases the surface area and is the usual point of contact with axons from other cells
Axon hillock
Space between axon and soma, where an action potential begins
Axon collaterals
Branches of an axon
Terminal button
Knob at the tip of the axon that conveys information to other neurons; also called the end foot
Synapse
Gaps between one neuron and another
Sensory neurons
Carry information from the sensory receptors in or on the body to the spinal cord
Interneurons
Associate sensory and motor activity within the CNS
Motor neurons
Send signals from the brain and spinal cord to the muscles
Bipolar neurons
Transmit afferent sensory information from the retina to the neurons that carry info to the brain’s visual centers
Somatosensory dendrite
Connects directly to its axon, so the cell body sits to on side of this long pathway
Stellate cell
Small-Many dendrites extend from the cell body
Pyramidal cell
Has a long axon, a pyramid shaped cell body, and two sets of dendrites
Purkinje cell
A distinctive interneuron with extremely branched neurons making a fan shape
Three features of neuronal networkes
- Input
- Association
- Output
Describe the language of neurons
Neurons receive many excitation and inhibition signals and the sum of these signals are taken and the neuron acts accordingly, becoming active or not
5 types of glial cells
- Ependymal cells
- Astrocyte
- Microglial cells
- Oligodendroglial cells
- Schwann cells
Ependymal cells
Small. ovoid cells found in the walls of the ventricles. Make and secrete cerebrospinal fluid
Hydrocephalus
Buildup of pressure in the brain and swelling of the head caused by the flow of CSF being blocked, leading to intellectual impairment
Astrocytes
Star shaped cells that provide structural support for the neurons, transport substances between the neurons and capillaries, play a role in scar forming, and provide fuel for the brain
Microglia
Originate in the blood as offshoot of immune system, performs phagocytosis, plays the role of the brains immune system by identifying and attacking foreign tissue, provide growth factors to help repair the brain
Oligodendroglial cells
Cells in CNS that myelinate axons
Schwann cells
Glial cells in the peripheral nervous system that myelinate axons
Myelin
Glial cells that cover axons
Multiple Sclerosis
Nervous system disorder caused by loss of myelin
Paralysis
Loss of sensation and movement due to nervous system injury
PNS
Microglia and Schwann cells that help repair neurons
CNS
Repair does not take place, regrowth may be inhibited
The cell membrane
Separates the intercellular and extracellular fluid, regulates movement of substances into and out of the cell, and is made of phospholipids
Element
Naturally occurring substance
Atom
Smallest quantity of an element that retains the properties of that element
Molecules
Formed when atoms bind together
Nucleus
The cells executive office
Chromosome
Double helix structure that holds an organisms DNA together and contains genes
Gene
Segment of DNA that encodes the synthesis of particular proteins, sequence of nucleotides determines what amino acid is made
Ribosomes
Protein structures that act as catalysts for protein synthesis
Translation
Later phase in protein synthesis in which messenger RNA travels from nucleus to ER. mRNA then translated to form amino acids and then a protein
Transcription
Early phase in protein synthesis where DNA strands unwind and form a complimentary strand of RNA
Codon
Sequence of three bases of mRNA that code into a particular amino acid
Golgi bodies
Package proteins in membranes and give them a label indicating where to go
Microtubules
Transport vesicles to their destination
What determines weather a proteins shape can change
The precise amino acid sequence
Three ways things can cross through the cell membrain
Channel, gated channel, or through a pump
Medallion genetics
Studies how genes influence our traits
Chromosome 1-22 vs Chromosome 23
Chromosome 1-22 are autosomes, and attribute our physical appearance and behavior, chromosome 23 is a sex chromosome
Single Nucleotide polymorphism
A change in a single nucleotide
Tay-Sachs disease
Inherited birth defect caused by recessive allele that causes loss of genes necessary to break down certain fatty substances. Leads to death by about age 5
Huntington’s disease
Motor and cognitive disorder caused by an increase in CAG in chromosome 4, which kills brain cells
Genetic disorders result from…
A aberration in a entire chromosome rather than a single defective allele
Down syndrome
Having three copies of chromosome 21 leading to intellectual disability
4 ways to modify a gene
- Selective breeding
- Cloning
- Transgenic techniques
- Knockouts
Selective breeding
Very effective way to alter gene expression with the goal of maintaining spontaneous mutations
Cloning
Producing an offspring that is genetically identical to another animal
Transgenic technique
Introduction or removal of genes from an embryo
Phenotypic plasticity
The extent of which a brains phenotypes can range with the same genotype is very vast
Epigenetics
The influence of the environment on the selection of one or another phenotype
What two codes allow for gene expression
- DNA
- Epigenetics
Histones modification
Methyl groups are added to histones allowing them to either be opened up or locked, leading to gene expressioon
Gene methylation
Methyl groups bind to CG base pairs to block transcription
mRNA modification
ncRNA bind to mRNA, blocking translation
Three types of Epigenetic Mechanisms
Histone modification
Gene methylation
mRNA modification
