Psychobio Midterm

Parts of the Cell Overview

Cell Membrane

Surrounds cell body and processes, regulates what can enter or exit a cell, composed of a phospholipid bilayer ( hydrophilic heads-towards the outside, and hydrophobic tails-towards the inside)

Extracellular Fluid

Separates cells from each other, composed of water with dissolved salts and other chemicals

Intracellular Fluid

Composed of water with dissolved salts and chemicals but varies in its concentrations of these substances

Nucleus

Cell brain." Surrounded by a nuclear membrane, contains chromosomes.

Endoplasmic Reticulum

Cell factory." Membranous sheets folded to form numerous channels. Functions as a manufacturing and packaging system.

Smooth Endoplasmic Reticulum

Manufactures lipids and hormones. Helps transport proteins to Golgi bodies.

Rough Endoplasmic Reticulum

Studded with ribosomes. Ribosomes responsible for the assembly of proteins (translation).

Golgi Bodies

Package proteins in membranes and label them with a message for their destination

Mitochondria

Supply energy for a cell (ATP)

Microtubules and Microfilaments

Provide structure to a cell, aid in cell movement, and provide a transportation network for proteins

Lysosomes

Vesicles that transport and store cell wastes

Ependymal Cells

Line the walls of the ventricles and produce cerebrospinal fluid

Astrocytes

Star-shaped cells that provide physical and nutritional support for neurons: 1) clean up brain "debris"; 2) transport nutrients to neurons; 3) hold neurons in place; 4) digest parts of dead neurons; 5) regulate content of extracellular space

Microglia

Very small cells. Provide growth factors to aid in neuronal repair. Remove waste as well as viruses, fungi, and other microorganisms. Function like part of immune system

Schwann Cells

Provide the insulation (myelin) to neurons in the peripheral nervous system. Each cell wraps itself repeatedly around an axon

Oligodendrocytes

Provide the insulation (myelin) to neurons in the central nervous system. This acts as an insulating agent like rubber on electrical wires. Sends out large flat branches that enclose and separate adjacent axons

Meninges Overview

Dura Mater

Hard mother. Firm double layer of fibrous tissue enclosing the brain

Arachnoid

Spider's Web. Thin delicate sheet of connective tissue that follows the brain's major contour

Cerebrospinal Fluid (CSF)

Colorless salt solution providing cushion for brain expansion and movement

Pia Mater

Soft mother. Moderately tough membrane of connective tissue fibers that cling to the brain's surface

Nucleotide Bases

Cytosine, Guanine, Adenine, Thymine (DNA), Uracil (RNA)

Base Pairing

DNA
A--T
G--C
RNA
A--U
G--C

Protein Synthesis

The synthesis of proteins takes two steps: transcription and translation. Transcription takes the information encoded in DNA and encodes it into mRNA, which heads out of the cell's nucleus and into the cytoplasm. During translation, the mRNA works with a ribosome and tRNA to synthesize proteins.

Afferent vs. Efferent Overview

Afferent

Data about sensory stimuli coming from the periphery toward the brain is called afferent (to carry toward) information.

Efferent

Motor information moving from the CNS to the periphery is referred to as efferent (to carry away from) information.

Ipsilateral

Same side
Example: signals from one side of the body to a brain structure on the same side of the body

Contralateral

Opposite side
Example: signals from one side of the body to an opposite side structure

Genotype vs. Phenotype Overview

Genotype

Individual's collection of genes.

Phenotype

The external expression of certain genetic influences (physical characteristics)

Central vs. Peripheral Nervous Systems Overview

Central Nervous System (CNS)

Consists of brain and spinal chord. a. Main coordinating and controlling center of the body that processes information to and from the peripheral nervous system. Regulates the PNS

Peripheral Nervous System (PNS)

All the rest of the nervous tissue outside the CNS. Transmits sensorimotor information.12 pairs of cranial nerves and 31 pairs of spinal nerves.

Sympathetic vs. Parasympathetic Nervous Systems Overview

Sympathetic Nervous System

Prepares the body for action
- Activation occurs in the thoracic and lumbar spinal cord regions
- Sympathetic system ganglia- autonomic control centers located near the spinal cord

Parasympathetic Nervous System

Slows down the body for rest
-Activation mostly occurs from three cranial nerves
-Vagus nerve- controls most internal organs
-Facial nerve--> salivation
-Oculomotor nerve--> pupil dilation
- Connected to the spinal cord at the sacral region
- Parasympathetic system ganglia- located near the target organs

Gray Matter vs. White Matter Overview

Gray matter

Dense neuronal area

White Matter

Myelin ensheathed axons (covered in myelin to protect-- think electrical wiring that is covered in plastic)

Gyri vs. Sulci Overview

Gyri

The ridges (mountains) on brains

Sulci

The grooves on brains

Oxygen and Glucose Use in the Brain

Resources, neuron is heavy consumer of resources (70%),
The brain uses 25% of the body's oxygen supply.
The brain uses 70% of the body's glucose supply.

Forebrain Overview

Prosencephalon (Forebrain)

#NAME?

Mesencephalon (Midbrain)

#NAME?

Rhombencephalon (Hindbrain)

#NAME?

How can you best view the structure of a synapse?

Can't be viewed through light microscope, best viewed by electron microscope.

Hyperpolarization

An increase in the electrical charge across a membrane, usually due to the inward flow of chloride ions or the outward flow of potassium ions

Depolarization

A decrease in the electrical charge across a membrane, usually due to the inward flow of sodium ions.

Excitatory Postsynaptic Potential (EPSP)

A brief depolarization of a neuron membrane in response to stimulation from a terminal of another neuron, making the neuron more likely to produce an action potential.

Inhibitory Postsynaptic Potential (IPSP)

A brief hyperpolarization of a neuron membrane in response to stimulation from a terminal of another neuron, making the neuron less likely to produce an action potential.

Refractory Periods Overview

Absolutely Refractory

The period during the depolarizing or repolarizing phases of the action potential in which stimulation of the axon membrane will not induce another action potential

Relatively Refractory

The period during the hyperpolarization phase of an action potential in which stimulation of the axon membrane can induce another action potential, but the intensity of stimulation must be higher than that which initiated the first action potential.

Negative Pole

The body with the higher electrical charge

Positive

The body with the lower electrical charge

Insulator

Two poles separated by this. A substance though which electrons cannot flow.

Ionotropic Receptors

- allow the movement of ions across a membrane
- two parts: (1) a binding site for a neurotransmitter and (2) a pore or channel

Metabotropic Receptors

- lacks its own pore through which ions can flow, although it does have a binding site for a neurotransmitter. Through a series of steps, metabotropic receptors produce changes in nearby ion channels or they bring about changes in the cell's metabolic activity
- the receptor is associated with one of a family of proteins called guanyl nucleotide-binding proteins, or G proteins for short

How does a synaptic vesicle release neurotransmitters?

1. The presynaptic membrane is rich in voltage-sensitive calcium channels, and the surrounding extracellular fluid is rich in Ca2+.
2. The arrival of the action potential opens these voltage-sensitive calcium channels, allowing an influx of calcium ions into the axon terminal.
3. The incoming Ca2+ binds to a chemical called calmodulin, and the resulting complex takes part in two chemical actions:
-(a) one reaction releases vesicles bound to the presynaptic membrane
-(b) the other reaction releases vesicles bound to filaments in the axon terminal.

How is a neurotransmitter removed from the synaptic cleft?

Removal of a neurotransmitter is done in at least four ways:
1. The neurotransmitter simply diffuses away from the synaptic cleft and is no longer available to bind to receptors.
2. The transmitter is inactivated or degraded by enzymes that are present in the synaptic cleft.
3. The transmitter may be taken back into the presynaptic axon terminal for subsequent reuse, or the by-products of degradation by enzymes may be taken back into the terminal to be used again in the cell.
The protein molecule that accomplishes this reuptake is a membrane pump called a transporter.
4. Neurotransmitters are taken up by neighboring glial cells, which may contain enzymes that further degrade those transmitters.

When are voltage-sensitive sodium channels active?

In a membrane, a protein channel that opens or closes only at certain membrane voltages.
The voltage-sensitive sodium channels are more sensitive than the potassium ones, and so the voltage change due to sodium ion influx occurs slightly before the voltage change due to potassium ion efflux.

Parkinson's is related to low levels of which neurotransmitter?

Dopamine / L- DOPA is used in the treatment of Parkinson's Disease

What process does the sodium/potassium pump facilitate?

A complex protein molecule embedded in the cell membrane that continually exchanges three intracellular Na+ ions for two K+ ions. The K+ ions are free to leave the cell through open potassium channels, but closed sodium channels prevent reentry of the Na+ ions.

Saltatory conduction

Propagation of an action potential at successive nodes of Ranvier; saltatory means "jumping" or "dancing.

Tight Junctions

The closely associated areas of two cells whose membranes join together forming a virtually impermeable barrier to fluid

Classification types of neurotransmitters

GABA main inhibitory, glutamate main excitatory. Three groups of transmitters based on their composition:
1. Small-molecule transmitters
2. Peptide transmitters (also called neuropeptides)
3. Transmitter gases

What is found at the axon terminals?

-Presynaptic membrane: Contains protein molecules that transmit chemical messages.
-Synaptic vesicle: Round granule that contains NT's.
-Storage granule: Large compartment that holds synaptic vesicles.
-Synaptic cleft: Small space separating presynaptic terminal and postsynaptic dendritic spine.
-Postsynaptic receptor: Site to which a NT molecule binds.
-Postsynaptic membrane: Contains protein molecules that receive chemical messages.

Serotonin is associated with which disorders?

Depression

Which part of the cell is most affected by psychoanalytic drugs?

Synapse

What other drug can mimic the effects of cocaine?

Amphetamine

Tetraethylammonium

Blocks potassium channels, and therefore blocks hyperpolarization.

Tetrodotoxin

Blocks sodium channels, and therefore blocks depolarization.

What effect does nicotine have on neurotransmitters?

Acts as an agonist to stimulate cholinergic receptors by fitting into the acetylcholine binding site on the receptor and activating it

Know which methods of drug administration are most and least effective.

Further from the target, more dilution. (If you take something orally, but it's for the brain, it'll take longer or won't reach its target and instead diffuse throughout the body.) Injecting directly into bloodstream more concentration and success rate than orally.

Stages of Brain Development

Overlapping stages.
Stage 1: Induction- portion of the ectoderm becomes the nervous system, other cells become hair, skin, and fingernails
Stage 2: Proliferation- neurogenesis (lots of cellular division)
Stage 3: Migration- new cells move to various places in the brain
Stage 4: Aggregation- similar neurons associate to become specific neuronal populations
Stage 5: Differentiation- cells even more delineated into specific neurotransmitter types
Stage 6: Synaptogenesis- circuit formation, including axonal and synaptic growth and regeneration (groups of neurons are segregated into discrete pathways and connections)
Stage 7: Apoptosis- programmed cell death, prunes synapses
Stage 8: Synapse Rearrangement- neuronal connections reestablish synaptic arrangements with neurons that did not die in the previous stage

Blood-brain Barrier

A filtering mechanism of the capillaries that carry blood to the brain and spinal cord tissue, blocking the passage of certain substances.

Axon Hillock

Specialized part of the cell body (or soma) of a neuron that connects to the axon. It is the last site in the soma where membrane potentials propagated from synaptic inputs are summated before being transmitted to the axon.

Type I vs. Type II Synapses

#NAME?