Neurotransmitters and Blood-Brain Barrier

Neurotransmitters and the Nervous System

• GABA (gamma-aminobutyric acid) is a neurotransmitter that plays an inhibitory role in the nervous system, regulating anxiety.
• One-third of all neurons use GABA for synaptic communication.
• Dopamine is a neurotransmitter that affects thoughts, emotions, motivation, and behavior.

The Blood-Brain Barrier

• The blood-brain barrier is a membrane that controls the passage of substances from the blood into the central nervous system.
• It prevents foreign substances in the blood from disrupting neural functioning in the brain.

Neurons

• Neurons are the basic units of the nervous system, carrying information from cell to cell within the nervous system as well as to and from muscles and organs.
• Neurons receive information from adjacent cells and pass it down the axon.
• The axon is a long extension from the cell body, responsible for transmitting information between neurons.
• Dendrites are branch-like extensions that receive messages from other neurons and pass it down the axon.

Communication between Neurons

• Communication between neurons occurs at synapses, where the axon terminal of one neuron releases neurotransmitters into the synaptic cleft.
• Neurotransmitters depolarize the postsynaptic membrane, making an action potential more likely.
• Inhibitory neurotransmitters hyperpolarize the postsynaptic neuron, reducing the likelihood of an action potential.

The Myelin Sheath

• The myelin sheath insulates the axon, increasing the speed of transmission of messages.
• The nodes of Ranvier are small spaces in the myelin sheath, where the axon is not insulated.

The Nervous System

• The grey matter of the brain gets its color from cell bodies, dendrites, and unmyelinated axons.
• The fundamental unit of the nervous system is the neuron.
• On average, an individual neuron communicates with about 1000 other neurons.

The Peripheral Nervous System

• The peripheral nervous system (PNS) carries information to and from the central nervous system.
• The PNS has two subdivisions: the somatic nervous system and the autonomic nervous system.
• Sensory neurons (afferent neurons) transmit information from sensory cells to the brain.
• Motor neurons (efferent neurons) transmit information from the brain to muscles and glands.

The Brain and Endocrine System

• The pituitary gland is often described as the "master gland" because it stimulates and regulates other glands.
• The endocrine system is a collection of glands that secrete hormones directly into the bloodstream.
• Gonads are endocrine glands that release hormones responsible for sex drive and the development of secondary sexual characteristics.

The CNS and its Functions

• The reticular activating system (RAS) is responsible for maintaining consciousness, regulating arousal levels, and modulating the activity of neurons throughout the CNS.
• The medulla oblongata is an area of the brain that controls heartbeat, circulation, and respiration.
• The cerebral cortex is responsible for symbolic thinking, making it possible for humans to engage in conversations about abstract concepts.

Brain Structure and Function

• The corpus callosum is a band of neural fibers that connect the left and right hemispheres of the brain.
• The septal area is involved in some forms of emotionally significant learning.
• The temporal lobe is involved in the foundation of human thought and language.

Behavior Genetics

• The field of behavior genetics studies the role of genetics in shaping mental processes and behavior.
• Research has shown that heritability estimates of IQ are approximately 0.50, and genetic influences on personality traits, such as neuroticism and aggressiveness, range from 0.15 to 0.5.### Nervous System
• The somatic nervous system is primarily involved in intentional (voluntary) behaviors.
• It transmits sensory information to the central nervous system and carries out motor commands.
• Sensory nerves receive information through receptors in the eyes, ears, tongue, skin, muscles, and other parts of the body.
• Motor neurons direct the action of skeletal muscles.

Thalamus

• The thalamus relays sensory information to the cerebral cortex.
• It acts as a switchboard for routing information from neurons connected to visual, auditory, taste, and touch receptors to the appropriate brain regions.
• It also filters these messages, emphasizing some and de-emphasizing others.

Chromosomes

• Genes are arranged along chromosomes.
• Chromosomes are strands of paired DNA that spiral around each other.
• Human cells have 46 chromosomes, except for sperm cells in males and egg cells in females, which have 23.

Heritability

• A heritability coefficient quantifies the extent to which variation in a trait across individuals can be accounted for by genetic variation.
• Heritability refers to genetic influences on the variability of traits among different individuals.
• A heritability coefficient of 0 indicates no heritability (i.e., no genetic influence), while a coefficient of 1 indicates that a trait is completely heritable (i.e., entirely the result of genetic influence).

Neurons

• Interneurons are responsible for connecting other neurons to each other.
• Dendrites receive information from other neurons and pass it down the axon.
• The cell body includes a nucleus that contains the chromosomes or genetic material of the cell.
• Axons are responsible for transmitting information to other neurons.
• Terminal buttons receive information from the axon and pass it on to adjacent cells via the release of neurotransmitters.
• Neurons send signals by releasing a chemical that alters the electrical charge of the next neuron.
• The resting potential of a neuron refers to the condition in which the neuron is not firing.

Multiple Sclerosis

• Multiple sclerosis is a disorder that involves problems with the myelin sheath.
• Degeneration of the myelin sheath occurs on large clusters of axons and can produce jerky, uncoordinated movement.

Learn about the functions of neurotransmitters like GABA and the role of the blood-brain barrier in the nervous system.