Brain Anatomy & Function
The nervous system is divided into two groups the Central Nervous System and the Peripheral Nervous System. The human brain and spinal cord are part of the Central Nervous System (CNS). The Peripheral Nervous System (PNS) is other that contains the spinal and cranial nerves.. It works with the CNS to move the body and send messages to your organs. The CNS takes the information and sends commands back to the PNS like a communication pathway.
The brain plays an enormous role in the human body’s nervous system. It’s primary function is to process and transmit information throughout the body. The brain is the command center of the nervous system. It is responsible for the control of such functions as: thoughts, emotions, memory, movement, and sensory perception. The brain is divided into three major regions:
The Cerebrum- Developed from our forebrain and is responsible for higher cognitive functions is the largest part of a human brain. Contains the basal ganglia
The Cerebellum- Responsible for the bodily balance and coordination. It communicates with other parts in the CNS one of three nerve tracts.
The Brainstem- Responsible for the body’s regulation of its life sustaining functions (breathing, heart rate)
Thanks to Robina Weermeijer : @averey
Nervous Cellular Tissue Called Neurons
Neurons are composed of a cell body, dendrites, and one axon.
Neurons have 3 Specialized Shapes and are classified by structural differences that allow them to function. Each neuron conducts an impulse in one direction.
Multipolar
Bipolar
Unipolar
Neurons are also grouped into functional categories that depend on if they carry information into, within, or out of the CNS.
Sensory neurons conduct impulses from the PNS into the brain or spinal cord
Interneurons are inside
A neuron’s cell body is supported by a network of fine threads called neurofilaments. Neurotransmitters are synthesized here by enzymes.
Dendrites are highly branched or thorny and have a receptive surface that allows neurons to communicate. Neurons receive input through the dendrites and cell body, and send an impulse down the axon. An axon conducts impulses and convey biochemicals and organelles into action or inaction.
The Synapse is where the neurons communicate. The presynaptic neuron sends information while the postsynaptic neuron receives the input at the synapse. Synaptic transmission is the one way mechanism that stimulates or inhibits the postsynaptic cell receiving the input from neurotransmitters. When the neurotransmitter binds to a postsynaptic neuron something is being turned on or off.
Neurotransmitters, Biogenic Amines, Amino Acids, Neuropeptides, & Gases
Acetylcholine is a neurotransmitter controls the skeletal muscle’s actions in the CNS and stimulates the skeletal muscle contraction at neuromuscular junctions that turn on or off at autonomic nervous system synapses.
Norepinephrine and Dopamine will excite or inhibit actions in the automatic nervous system. In the central nervous system these biogenic amine create a sense of well being and low blood concentrations in our bodies have been found to play a role in depression.
Serotonin is an inhibitory biogenic amine in the CNS that plays a role in our need to sleep while Histamine released from the hypothalamus keeps us awake.
The amino acid, Glutamate is an excitatory neurotransmitter most abundantly found in the CNS. Another amino acid called GABA plays an inhibitory role in CNS communication. Glycine has also been found to signal inhibition.
Neuropeptides are created in the CNS and act as neurotransmitters or modulators. Enkephalins are neuropeptides that are created when the person is in pain and bind to the same opioid receptor cite. Endorphin are produced by the body which resemble poppy derived opiated which are also inhibitory but are classified as neuropeptides that inhibit the release of substance P. Substance P, on the other hand is a neuropeptide that plays an excitatory role in the perception of pain in our peripheral nervous system.
Nitric Oxide is a gas that plays a role in memory in the CNS and causes vasodilation in the peripheral nervous system.
Imbalances with neurotransmitter levels are associated with multiple disorders.
Clinical Depression- low serotonin &/or norepinephrine
Mania- Excess norepinephrine level
Inappropriate Emotional Responses- Found in subjects who were deficient in GABA and had an excess in dopamine
Insomnia- Lack of serotonin
The biology of neurotransmission helps explain drug addiction. When a drug alters the activity of a neurotransmitter on a postsynaptic neuron it either halts or enhances the transmission. An antagonist blocks neurotransmitters from binding to a receptor; while an, agonist triggers an action or helps another neurotransmitter bind at the synapse. The effect of the drug depends on which one it is, Many addictive substances bind to receptors in the nucleus accumbens for dopamine.
With repeated use of something addictive the number of receptor targets decline and the user has to use more of the same drug to feel the same effect.
Neural pathways that transmit norepinephrine control arousal, dreaming, and mood.
