Download Concepts of Neurobiology

Concepts of Neurobiology
Introduction
 The 101st legislature of the U.S. designated 1990 as the “decade of the Brain” with the
challenge of studying the biological basis of behavior
 In keeping with the “neuroscientific revolution,” greater emphasis is placed on the
organic basis of mental illness
THREE PARTS OF THE BRAIN
1. Forebrain
A. Cerebrum
 Consists of right and left hemisphere connected by a large group of nerves
called the corpus callosum.
 Each hemisphere is divided into four lobes:
 Frontal lobes
 Parietal lobes
 Temporal lobes
 Occipital lobes
B. Diencephalon
 The diencephalon connects the cerebrum with the lower brain structures
 Limbic System: “the bagel” or the “emotional brain”
 Basal Ganglia: decreased dopamine causes E.P.S.
 Hypothalmus: “the regulator;” pituitary gland
 Thalmus: integrates all sensory input except smell
2. Midbrain
 The midbrain, or mesencephalon, is responsible for visual, auditory, and balance
(righting) reflexes
3. Hindbrain or Brain stem
 Pons: regulates respiration and muscle tone
 Medulla: reg. heart rate, blood pressure
 Cerebellum: muscle tone and coordination
Nerve Tissue
 CNS: neurons, composed of:
 Cell body, contains nucleus
 Axon, transmits message to next cell
 Dendrites, receives messages from cells
 Three classes of neurons in CNS
 Afferent (sensory)
 Efferent (motor)
 Interneurons in CNS
1  RNSG 2213
Synapses
 The synapse is the junction between two neurons
 Synaptic Cleft: space between neurons
 Presynaptic neuron: area of axon where neurotransmitters are stored
 Postsynaptic neuron: area of dendrite where receptor sites are located
 Electrical impulses begins the process
Autonomic Nervous System
 Sympathetic: Dominates in stressful situations, prepares body for fight or flight
 Parasympathic: Dominates when person is relaxed
Neurotransmitters
 Play an important role in human emotions and behavior
 Are the target for the mechanism of action for psychotropic medications
 Summary: Neurotransmitters are released into the synaptic cleft from the axon to the
dendrite. The substance is either inactivated or returned to the axon.
CATEGORIES OF NEUROTRANSMITTERS
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1. Cholinergics
Acetylcholine: involved in sleep, arousal, movement, MEMORY
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2. Monoamines
Norepinephrine: effects mood, cognition, perception, locomotion, CV functioning, sleep and arousal
Dopamine: affects movement, coordination, emotions, voluntary judgment, and release of prolactin
Serotonin: affects sleep, arousal, libido, appetite, mood, aggression, pain perception, coordination, and
judgment
Histamine: Not sure of influence on mood
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3. Amino Acids
Gamma aminobutyric acid (GABA) functions as an inhibitor neurotransmitter. Has calming effect.
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4. Neuropeptides
Endorphins and enkephlins, modulates pain and reduces peristalsis. Also called “natural opiates.”
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Neuroendocrinology
 Hypothalamus - has direct control over the pituitary gland, the “master gland”
 All these effect health. Our main concerns are TSH, ACTH, Melatonin
 Circadian Rhythms - implications in many mental illness as it effects the ability to sleep.
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