Ch1 Flashcards
The nervous system has two main types of cells
neurons and glia
Receive information and send it to other cells
Neurons
Support the neurons in many ways.
Glia
The adult human brain has about
86 billion neurons
In the late 1800s, scientist – used new staining techniques to show that there is a small gap between the end of one neuron’s fiber and the next neuron
Santiago Ramón y Cajal
Two scientists of the late 1800s and early 1900s are widely recognized as the main founders of neuroscience—
Charles Sherrington and the Spanish investigator Santiago Ramón y Cajal (1852–1934).
Golgi’s Staining Technique
Camillo Golgi developed a method using silver salts to stain nerve cells. This technique allows researchers to see the structure of individual neurons
Microscopy and the Nervous System
Before the late 1800s, the structure of the nervous system was poorly understood due to limitations in microscopy. The use of Golgi staining revolutionized research, allowing for the clear visualization of individual nerve cells.
The outer boundary of a cell that controls what enters and exits. It is semi-permeable and regulates the flow of essential substances like water, oxygen, sodium, potassium, calcium, and chloride.
Plasma Membrane
Found in all animal cells (except red blood cells), the nucleus contains the chromosomes, which house the cell’s genetic material.
Nucleus
The “powerhouse” of the cell, responsible for producing energy (ATP). Mitochondria have their own DNA, distinct from the nuclear DNA, and can vary genetically. Abnormal mitochondrial function is linked to conditions like autism and depression.
Mitochondria
Structures that produce proteins, which are essential for the cell’s structure and function. Some are free-floating, while others are attached to the endoplasmic reticulum (ER).
Ribosomes
A network of tubes that transports proteins synthesized by ribosomes to various parts of the cell
Endoplasmic Reticulum (ER)
Contains the nucleus and other essential cell structures
Soma (Cell Body)
Branched extensions that receive signals from other neurons
Dendrites
A long, thin extension that transmits signals away from the soma to other cells
Axon
The endings of the axon where the neuron communicates with other neurons or muscles
Presynaptic Terminals
carry signals from the brain and spinal cord to muscles and glands. It has a soma located in the spinal cord, with dendrites that receive incoming signals and an axon that transmits impulses to muscles.
Motor Neurons
carry information from sensory receptors (like touch or light) to the central nervous system (spinal cord and brain). It have a special structure at one end, adapted to detect specific stimuli (e.g., light, sound, or touch).
Sensory neurons
Golgi vs. Cajal
The debate between Golgi (who believed neurons merged) and Cajal (who showed that neurons remained separate) remains central to understanding how the nervous system functions.
A long, thin fiber that carries electrical impulses away from the cell body. The term comes from the Greek word for “axis.” They are typically of constant diameter but can be over a meter long (e.g., axons from the spinal cord to the feet)
Axon
Many axons are covered by an insulating layer. This speeds up the transmission of signals. In vertebrates, it is interrupted by gaps known as nodes of Ranvier.
Myelin Sheath
These neurons carry information into a structure (e.g., sensory neurons bring information from sensory organs to the nervous system
Afferent Neurons
These neurons carry information away from a structure (e.g., motor neurons transmit signals from the brain to muscles or glands).
Efferent Neurons
These neurons are found within the nervous system and have dendrites and axons confined to the same structure (e.g., neurons in the thalamus that connect sensory information).
Interneuron
These neurons have widely branching dendrites and can receive input from up to 200,000 other neurons.
Purkinje Cells (Cerebellum)
These neurons have short dendritic branches and receive input from only a few neurons.
Bipolar Neurons (Retina)
The supporting cells of the nervous system, outnumbering neurons in some parts of the brain. They perform many crucial functions
Glial cells (or neuroglia)
Astrocytes
-Star-shaped cells that wrap around synapses and blood vessels in the brain.
Shield synapses from chemicals in the surrounding environment.
Synchronize neuron activity by taking up and releasing ions and neurotransmitters, helping to coordinate brain waves (e.g., the rhythm of breathing).
Regulate blood flow: Astrocytes dilate blood vessels to increase nutrient supply to active brain areas.
Tripartite Synapse: Astrocytes may modify neuron communication by releasing their own chemicals in response to neurotransmitters from neighboring axons.
Astrocytes are essential for learning and memory, as they contribute to neuroplasticity.
Found in the brain and spinal cord, these cells build the myelin sheath around axons, providing insulation and improving signal transmission
Oligodendrocytes
Found in the peripheral nervous system, these cells perform a similar function to oligodendrocytes by forming myelin sheaths around peripheral axons.
Schwann Cells
Guide the migration of neurons and their axons/dendrites during embryonic development. After development, most differentiate into neurons or astrocytes
Radial Glia
is a crucial defense mechanism that protects the brain from harmful substances while still allowing necessary nutrients to enter
Blood Brain Barrier
Neurons require a constant supply of nutrients to function properly. The primary fuel for neurons is
glucose, a type of sugar, and they are highly dependent on a steady supply of oxygen.
Thiamine deficiency (often due to chronic alcoholism) can lead to
Neuron death and Korsakoff’s syndrome
the baseline electrical charge difference across the neuron’s membrane when it is not actively transmitting a signal.
The resting potential
A large, brief electrical change in the membrane potential that travels down the axon.
Action Potential
An action potential occurs at full strength once the threshold is reached.
All-or-None Law
The action potential travels down the axon, with myelinated axons conducting signals faster through saltatory conduction.
Propagation
Myelinated axons transmit action potentials faster and more efficiently, saving energy.
Myelin
A disease that destroys myelin, leading to slower action potentials and a range of neurological symptoms
Multiple Sclerosis
Absolute Refractory Period
During this time, the neuron cannot fire another action potential, no matter how strong the stimulus.
This happens because the sodium channels are inactivated after the peak of the action potential.
This period lasts about 1 millisecond
Sodium Channels
When the neuron is depolarized to the threshold, voltage-gated sodium channels open, allowing sodium (Na⁺) ions to rush into the axon
Potassium Channels
After depolarization, voltage-gated potassium channels open, allowing potassium (K⁺) ions to flow out of the axon, repolarizing the membrane
The flow of ions (sodium and potassium) changes the charge across the membrane, generating the action potential
Ion Flow
Relative Refractory Period:
After the absolute refractory period, the neuron can fire again, but only if the stimulus is stronger than usual.
This is because the potassium channels are still open, and the membrane is more negative than usual, making it harder for the neuron to fire.
This period lasts about 2-4 milliseconds
Local neurons don’t have axons and use – which are weaker and decay over time
graded potentials
Chemicals actively transported into Brain
Glucose
Amino Acid
Purines
Choline
Iron
Certain Vitamins
Increased polarization, exaggeration of usual negative charge within cells
Hyperpolarization
Decrease in amount of negative charge in cells
Depolarization
how drugs and other substances affect the brain and behavior, as well as
how they can be used to treat psychological disorders.
Psychopharmacology
nvestigates the relationship between brain function and behavior, focusing on how
brain damage or dysfunction can impact cognitive processes and psychological
functioning especially in human patients
Neuropsychology