Biopsych Exam #1

Neurons

process and transmit information

glial cells

provide structure & support to neurons

astrocytes

glial cells that maintain chemical environment

microglial cells

glial cells that serve as “cleanup crew”

myelin sheath

allows electrical impulses to transmit quickly along nerve cells

Oligodendrocytes

produce myelin

Schwann cells

glial cells in the PNS that create myelin for neurons

Nodes of Ranvier

gap between myelin sheath and Schwann cells

synapses

gaps between neurons where information is transferred

action potential

reversal in neuronal polarization

neurotransmitters are released when action potential reaches terminals

inside of cell (-), outside of cell (+)

comes down axon and causes calcium channels to open

all AP are equal in amplitude and velocity

sodium potassium pump

pumps 3 Na+ out for every 2K+ pumped in

brain has to pump constantly, why brain uses so much energy

resting membrane potential

higher concentration of potassium is inside the cell membrane

voltage-gated ion channels are closed

inside of cell (-70mV)

diffusion

chemical force that causes molecules to move down the concentration gradient

refractory period

at the peak of action potential (AP) when sodium channels close

salutary conduction

the movement of action potential along an axon, from node to node

inotropic receptors

lock-and-key mechanism

direct

metabotropic receptors

releases 6 proteins which lead to events that open ion channel

indirect

more prolonged effect

electrical and chemical

2 methods of neuron communication

excitatory postsynaptic potential (EPSP)

most frequent opening of neurotransmitter-dependent sodium channels

inhibitory postsynaptic potential (IPSP)

either opens potassium (K+) channels or chloride channels (CI-) or both

balance between these 2 will determine if cell will fire

reuptake

clears synapse so signal ends

enzymatic degradation

enzyme breaks down neurotransmitters

autoreceptors

act as a negative feedback mechanism

neurotransmitters

carry chemical signals from 1 neuron to the next target cell

interact with many different receptors across brain

located in axon terminal

ligand

substance that binds to a receptor

ex. neurotransmitters are endogenous ligands

agonists

binds to same receptor site, mimics effects of neurotransmitter

ex. drug triggers release of NT from vesicles

antagonist

binds to receptor but does NOT open ion channel

ex. drug stimulates auto receptors - decreases NT

competitive binding

direct agonists, direct antagonists

noncompetitive binding

indirect agonists, indirect antagonists

acetylcholine

a neurotransmitter that plays a central role in central and peripheral nervous system

serotonin

(monoamine) implicated in control of sleep states, anxiety, mood, pain

dopamine

(monoamine) involved in reward/learning, motor control

ex. eating chocolate, taking drugs, etc. activates nucleus accumbent and releases dopamine

norepinephrine

(monoamine) modulates mood, arousal, vigilance, sexual behavior (sympathetic nervous system)

GABA is an…

amino acid

Glutamate is an…

amino acid

neuropeptides

get released and effect neurons in area

ex. endorphines (outside of brain) reduce pain

hormones

chemicals that travel through the bloodstream to act on targets

hormonal vs neural

hormonal - involuntary, travels through body, slower

neural - voluntary, travels to specific destination, rapid, short distance

anterior

hormones are secreted into blood vessels

releases tropic hormones

do NOT directly regulate processes in the body

posterior

receives neurons from hypothalamus

hormones are not synthesized

stores and releases 2 hormones

1) vasopressin

2) oxytocin

forebrain

processes sensory information

helps with reasoning and problem-solving

regulates autonomic, endocrine, and motor functions

cerebral cortex

(forebrain) primarily composed of gray matter

2 hemispheres connected by corpus callosum

higher-level processing

midbrain

helps to regulate movement and process auditory and visual information

tectum tegmentum

hindbrain

helps to regulate autonomic functions, relay sensory information, coordinate movement, maintain balance/equilibrium

pons

cerebellum

nebula oblongata

gray matter

mostly cell bodies, dendrites

white matter

mostly myelinated axons

frontal lobes

executive functioning

planning

voluntary muscle movements

parietal lobes

somatosensory cortex/association areas

temporal lobes

primary auditory cortex

visual association cortex

Wernicke’s area (language)

amygdala

hippocampus (autonomic nervous system)

occipital lobes

visual cortex

Meninges

brain and spinal cord protected by series of membranes

CSF/ventricles

shock absorber

ipsilateral

structures on the same side of body/brain

contralateral

structures on opposite sides of body

central nervous system (CNS)

brain and spinal cord

spinal cord is channel for information to and from the brain

peripheral nervous system (PNS)

cranial/spinal nerves and peripheral ganglia

efferent

nerves project to target organs and muscles

afferent

nerves carry sensory information to the brain

autonomic nervous system

sympathetic division and parasympathetic division

sympathetic division (“stress”)

fight or flight, release norepinephrine

ex. you’re asked to give a presentation in front of 100 faculty members

parasympathetic division (“peace”)

associated with energy conservation

releases acetylcholine

proliferation/neurogenesis

(1) 1 progenitor cell + 1 brain cell

cell migration

(2) cells move along radial glial cells

differentiation

(3) cells express genes to make proteins become a type of neuron OR glial cell

synaptogenesis

(4) connects to other neurons

ends of axons + dendrites

growth cones: ends of axons and dendrites from which extensions emerge

myelination

(5) glial cells develop from the same immature cells as neurons

sensory cells myelinated before motor

neuronal cell death

(6) “neural Darwinism”

synapse rearrangement

(7) some synapses are lost and new ones form

Darwin’s theory of natural selection

variations affect the probability that an individual will survive and reproduce, increasing the likelihood of offspring

1) reproduction will increase a population until stopped

2) individuals of a species aren’t identical

3) some variation in inherited

4) not all offspring survive to reproduce

selective advantage

some mutations are beneficial, leading to greater survival of individuals who have them

ex. birds who store food have larger hippocampus

Encephalization factor

relationship between brain and body weight

humans have the biggest brain relative to their body weight

implications = longer gestation period, brain continues to grow, extended period of development, 25% of metabolism goes towards brain maintenance

Mendel’s Theory of Genetics

dominant/recessive traits, phenotype (visible), genotype (invisible)

somatic mutations

passed down to other cells through mitosis

germ-line mutations

happens in sex cells, gets passed down

ex. babies can be born w/o phenylalanine

epigenetics

understanding when/which genes are expressed

acetylation (“a”)

turns gene on

opens chromatin

promotes gene Activation

ex. cocaine

methylation

turns gene off

represses transcription

DNA methytransferase (“writer”) attaches a methyl group to spot on gene

ex. depression

intergenerational transmission

epigenetic changes typically aren’t inherited

ex. exception - agouti mice

histones + DNA =

chromatin