mental health: PSYCHOBIOLOGY
|organic basis||In recent years, a greater emphasis has been placed on the study of the ____________ for psychiatric illness.|
|The Nervous System: The Brain: The Cerebrum|| Consists of a right and left hemisphere connected by a deep |
groove of neurons (nerve cells) called the corpus callosum.
|The Nervous System: The Brain: The Cerebrum: The cerebral cortex||is identified by numerous folds (called gyri) and deep grooves (called sulci) that extend the surface area of the cortex, thus permitting the presence of millions more neurons than would be possible otherwise.|
|The Nervous System: The Brain: The Cerebrum: Each hemisphere||is divided into four lobes, each named for the overlying bones in the cranium: the frontal lobe, parietal lobe, temporal lobe, and occipital lobe.|
|The Nervous System: The Brain: Frontal lobes.|| The frontal lobes are responsible for voluntary body movement, including movements that |
permit speaking; thinking and judgment formation; and
expression of feelings.
|The Nervous System: The Brain: Parietal lobes.|| The parietal lobes are responsible for perception and interpretation of most sensory information |
(including touch, pain, taste, and body position).
|The Nervous System: The Brain: Temporal lobes.|| Responsible for hearing, short-term memory, and sense of smell; expression of emotions |
through connection with the limbic system.
|The Nervous System: The Brain: Occipital lobes.||Responsible for visual reception and interpretation.|
|diencephalon|| connects the cerebrum with lower brain structures and consists of the thalamus, |
hypothalamus, and limbic system.
|The thalamus||integrates all sensory input (except smell) on the way to the cortex; also has some involvement with emotions and mood.|
|The hypothalamus|| regulates anterior and posterior lobes of |
the pituitary gland and exerts control over actions of the autonomic nervous system. Also regulates appetite and temperature.
|The limbic system||consists of medially placed cortical and |
subcortical structures and the fiber tracts connecting them with one another and with the hypothalamus. It is sometimes called the "emotional brain" and is associated with feelings of fear and anxiety; anger and aggression; love, joy, and hope; and with sexuality and social behavior.
|The Midbrain: Mesencephalon||is responsible for visual, auditory, and balance ("righting") reflexes.|
|The Hindbrain: The pons|| is charged with regulation of respiration and |
skeletal muscle tone; ascending and descending tracts connect brainstem with cerebellum and cortex.
|Medulla.|| is a pathway for all ascending and descending fiber tracts. It contains vital centers that regulate heart rate, blood pressure, and respiration; reflex centers for |
swallowing, sneezing, coughing, and vomiting.
|The cerebellum||regulates muscle tone and coordination and maintains posture and equilibrium.|
|Nerve Tissue: neurons||The nerve cells of CNS tissue are called _____________.|
| neurons are composed of |
|a cell body, an axon, and dendrites.|
|The cell body||contains the nucleus and is essential for the life of the neuron.|
|The axon transmits||impulses away from the cell body.|
|The dendrites||are processes that transmit impulses toward the cell body.|
|Three classes of neurons||exist within the CNS: afferent (sensory), efferent (motor), and interneurons.|
|Afferent neurons|| carry impulses from receptors in the internal and external periphery to the CNS, where they are interpreted into various |
|Efferent neurons||carry impulses from the CNS to muscles (which respond by contracting) and glands (that respond by secreting).|
|Interneurons|| exist entirely within the CNS. They may carry only sensory or motor impulses, or they may serve as integrators in the |
pathways between afferent and efferent neurons.
|Synapses.|| The junction between two neurons is called a synapse and the small space between the two neurons is called a synaptic cleft. Neurons conducting impulses toward the synapse are called presynaptic neurons |
and those conducting impulses away are called postsynaptic neurons.
|A chemical neurotransmitter|| is stored in the axon terminals of the |
resynaptic neuron. An electrical impulse causes its release into the synaptic cleft, where it combines with receptor sites on the postsynaptic neuron and determines whether another electrical impulse will be
|The autonomic nervous system|| (ANS) has two divisions: the sympathetic |
and the parasympathetic.
|The sympathetic division|| is dominant in stressful situations and |
prepares the body for "fight or flight.
|The parasympathetic division|| dominates when an individual is in a |
relaxed, nonstressful condition.
|Neurotransmitters|| play an important role in human emotions and behavior and are the target for the mechanism of action in many psychotropic |
|Neurotransmitters are stored||in terminal vesicles of neuronal axons. When an electrical impulse reaches this point, the neurotransmitter is released |
from the vesicles into the synaptic cleft, where it binds with receptor sites on the postsynaptic neuron to determine whether another electrical impulse will be generated. After the neurotransmitter has accomplished this task, it is either inactivated and dissolved by enzymes or returned to the vesicles to be stored and used again.
|Major categories of neurotransmitters include|| -cholinergics |
|Cholinergics: Acetylcholine||is found in the cerebral cortex, hippocampus, limbic structures, and basal ganglia. It is involved in sleep, arousal, pain perception, movement, and memory.|
|Monoamines: Norepinephrine|| is found in the thalamus, hypothalamus, limbic system, hippocampus, cerebellum, and cerebral cortex. It influences mood, cognition, perception, locomotion, |
cardiovascular functioning, and sleep and arousal.
|Monoamines: Dopamine|| is found in the frontal cortex, limbic system, basal ganglia, thalamus, posterior pituitary, and spinal cord. It is involved in movement and coordination, emotions, voluntary |
judgment, and release of prolactin.
|Monoamines: Serotonin|| is found in the hypothalamus, thalamus, limbic system, cerebral cortex, cerebellum, and spinal cord. It influences sleep and |
arousal, libido, appetite, mood, aggression, pain perception, coordination, and judgment.
|Monoamines: Histamine||is found in the hypothalamus. Its exact function is unclear but may have some influence on mood.|
|Amino Acids: Gamma-aminobutyric acid|| (GABA) is found in the hypothalamus, |
hippocampus, cortex, cerebellum, basal ganglia, spinal cord, and retina. It is involved in the slowdown of body activity.
|Amino Acids: Glycine||is found in the spinal cord and brainstem. It causes recurrent inhibition of motor neurons.|
|Amino Acids: Glutamate|| and aspartate are found in pyramidal cells of the cortex, cerebellum, and the primary sensory afferent systems; also the hippocampus, thalamus, hypothalamus, and spinal cord. They are involved in the relay of sensory information and in the regulation of |
various motor and spinal reflexes.
|Neuropeptides: Endorphins and enkephalins|| are found in the hypothalamus, thalamus, limbic structures, midbrain, and brainstem. Enkephalins are also found in the GI tract. They are involved in the modulation |
of pain and the reduction of peristalsis (enkephalins).
|Neuropeptides: Substance P|| is found in the hypothalamus, limbic structures, midbrain, brainstem, thalamus, basal ganglia, and spinal cord. It is |
involved in the regulation of pain.
|Neuropeptides: Somatostatin||is found in the cerebral cortex, hippocampus, thalamus, basal ganglia, brainstem, and spinal cord. In its function |
as a neurotransmitter, it has both inhibitory and stimulatory properties. Depending on the part of the brain, it has stimulatory
effects on dopamine, serotonin, norepinephrine, and acetylcholine, and inhibitory effects on norepinephrine, histamine, and glutamate. It also acts as a neuromodulator for serotonin, and possibly other neurotransmitters.
|"master gland"|| Endocrine functioning in the CNS is under the influence of the hypothalamus, |
which has direct control over the pituitary gland, sometimes called the _______________.
|The pituitary gland has two major lobes|| the posterior lobe (also called the |
neurohypophysis) and the anterior lobe (also called the adenohypophysis).
|The pituitary gland: posterior lobe|| is under neural control of the hypothalamus. |
-vasopressin (or antidiuretic hormone) -oxytocin, are produced in the hypothalamus and stored in the posterior pituitary. Their release is mediated by neural impulses from the hypothalamus.
|The pituitary gland: posterior lobe: Vasopressin||(antidiuretic hormone) conserves body water and maintains normal blood pressure. Its release is stimulated by pain, emotional stress, dehydration, increased plasma concentration, and decreases in blood volume.|
|The pituitary gland: posterior lobe: Oxytocin|| stimulates contraction of the uterus at the end of pregnancy and stimulates release of milk from the mammary glands. Its role in |
behavioral functioning is unclear.
|The pituitary gland: The anterior lobe||produces a number of hormones whose release is under the control of releasing hormones that are produced by the hypothalamus. When these pituitary hormones are required by the body, the releasing hormones from the hypothalamus pass through the capillaries and veins of the hypophyseal portal system to capillaries in the anterior pituitary, where they stimulate secretion of these specialized hormones.|
|The pituitary gland: The anterior lobe: Growth hormone||is responsible for growth in children and for continued protein synthesis throughout life. During prolonged stress, it has a direct effect on protein, carbohydrate, and lipid metabolism, resulting in increased serum glucose and free fatty acids to be used for increased energy.|
|The pituitary gland: The anterior lobe: Thyroid-stimulating hormone||stimulates the thyroid gland to secrete thyroid hormones necessary for metabolism of food and regulation of temperature.|
|The pituitary gland: The anterior lobe: Adrenocorticotropic hormone||(ACTH) stimulates the adrenal cortex to secrete cortisol, which plays a role in the response to stress.|
|The pituitary gland: The anterior lobe: Prolactin||stimulates the breasts to produce milk.|
|The pituitary gland: The anterior lobe: Gonadotropic hormones|| stimulate the ovaries and testes to secrete |
estrogen, progesterone, and testosterone. Estrogen and progesterone also play a role in ovulation, and testosterone, in sperm production.
|The pituitary gland: The anterior lobe: Melanocyte-stimulating hormone||stimulates the pineal gland to secrete melatonin, a hormone that may be implicated in the etiology of seasonal affective disorder (SAD).|
|Circadian rhythms|| follow a near-24-hour cycle in humans and may influence a variety of regulatory functions, including the sleep-wake cycle, body temperature regulation, patterns of activity such as eating and drinking, and |
|The role of circadian rhythms||in psychopathology is being studied.|
|during darkness hours|| Some mood disorders have been linked to increased secretions of melatonin |
|progression||Rhythms associated with the menstrual cycle show monthly cycles of ______________.|
|The sleep-wake cycle||is one of the most common biological rhythms that demonstrates circadian influence. Sleep disturbances are common in many individuals.|
|The sleep-wake cycle is genetically|| determined and demonstrates an |
approximate 24-hour rhythm.
|brain wave activity|| b. Sleep is measured by the type of _____________________ during various stages |
|stages of sleep: Stage 0—Alpha rhythm:||Relaxed, waking state with eyes closed.|
|stages of sleep: Stage 1—Beta rhythm:||Transition into sleep; dozing; drift in and out of sleep.|
|stages of sleep: Stage 2—Theta rhythm:|| About half of sleep is spent in this stage. |
Minimal eye movement and muscular activity occur.
|stages of sleep: Stage 3—Delta rhythm:||Deep, restful sleep. Decreased vital signs; no eye movement.|
|stages of sleep: Stage 4—Delta rhythm:|| The stage of deepest sleep. Minimal eye |
movement and muscular activity.
|stages of sleep: (6)REM sleep—Beta rhythm:|| The dream cycle. Period of rapid eye |
movement. Vital signs increase.
|Neurochemical influences.||A number of neurochemicals have been shown to influence the sleep-wake cycle. |
a. Serotonin and its precursor, L-tryptophan, have been shown to induce
b. Norepinephrine and serotonin appear to be most active during non-REM
c. GABA probably plays a role in sleep and arousal.
d. Acetylcholine may induce and prolong REM sleep, whereas histamine
may inhibit the effect.
|neurochemicals shown to influence the sleep-wake cycle: Serotonin||and its precursor, L-tryptophan, have been shown to induce sleep.|
|neurochemicals shown to influence the sleep-wake cycle: Norepinephrine||and serotonin appear to be most active during non-REM sleep.|
|neurochemicals shown to influence the sleep-wake cycle: GABA||probably plays a role in sleep and arousal.|
|neurochemicals shown to influence the sleep-wake cycle: Acetylcholine||may induce and prolong REM sleep, whereas histamine may inhibit the effect.|
|The goal of behavioral genetics||is to clarify the role that genetic factors play in the determination of behavior.|
|The term genotype||refers to the total set of genes present in an individual at the time of conception, coded in the DNA.|
|The term phenotype||refers to the physical manifestations of a particular genotype, such as eye color, height, blood type, language, and hair type. Phenotypes are a combination of genetic and environmental characteristics.|
|Various types of studies are conducted to determine etiological factors associated with psychiatric illness.||-Familial|
A. Normal Immune Response
1. In the cellular immune response, the T4 lymphocytes become sensitized to
and specific for the foreign antigen.
2. The humoral response is activated when antigen-specific T4 cells
communicate with the B cells in the spleen and lymph nodes. The B cells in
turn produce the antibodies specific to the foreign antigen.
|etiological factors associated with psychiatric illness: Familial||Compare the percentages of family members with the illness to those in the general population or a specific control group. An example of a familial illness is schizophrenia.|
|etiological factors associated with psychiatric illness: Genetic:||Search for a specific gene that is responsible for the individual having the illness. An example of a genetic illness is Down's syndrome.|
|etiological factors associated with psychiatric illness: Twin studies:|| Examine the frequency of a disorder in monozygotic and |
|etiological factors associated with psychiatric illness: Adoption studies:||Allow comparisons to be made of the influences of genetics versus environment on the development of a psychiatric disorder. Studies |
have been conducted with adopted children whose biological parent(s) or relatives had the illness, those whose adoptive parent(s) or relatives had the
illness, and with monozygotic twins reared apart by different adoptive parents.
|Psychoimmunology: Normal Immune Response||In the cellular immune response, the T4 lymphocytes become sensitized to and specific for the foreign antigen.|
|Psychoimmunology: Normal Immune Response: The humoral response|| is activated when antigen-specific T4 cells communicate with the B cells in the spleen and lymph nodes. The B cells in turn produce the antibodies specific to the foreign antigen.|
The antibodies prevent the foreign antigen from invading body cells.
|immune system is suppressed||Studies have shown that during times of stress, the ______________________________, resulting in the suppression of lymphocyte proliferation and function.|
|Certain neurochemicals||may influence the immune system.|
|Growth hormone|| may enhance immunity, whereas testosterone and increased production of norepinephrine and epinephrine may decrease immunity. Serotonin has |
demonstrated both enhancing and inhibiting effects.
|Decreased immunity has been associated with|| -grief|
|Immunological abnormalities|| have also been associated with |
alcoholism, autism, and dementia.
|The role of neuroimmunology||remains unclear in the relationship to onset and course of schizophrenia.|
|neuroimmunology: Implications for Nursing||Emphasis in psychiatric nursing is on a smooth transition from a psychosocial approach to one of biopsychosocial focus.|
|Psychiatric nurses must have a specialized knowledge about|| - Neuroanatomy and neurophysiology |
- Neuronal processes
- Circadian rhythms