nursing 321: chapter 3 (psychobiology)

what trend is seen in modern psychiatry regarding mental illness?

there is a growing emphasis on the organic (biological) basis of psychiatric illness, with some mental illnesses now considered physical conditions

define psychobiology

the study of the biological foundations of cognitive, emotional, and behavioral processes

what is the startle reflex?

an automatic response, everything else gets processed by the CNS

what are the three major divisions of the brain?

forebrain, midbrain (mesencephalon), hindbrain

what structures make up the forebrain?

the cerebrum and diencephalon

what is the cerebrum? how is it divided?

- the largest part of the brain

- into two hemispheres (right = creative, left = logic) separated by the corpus callosum

what is the cerebral cortex?

the outer surface of the cerebrum

what lobes are found in each cerebral hemisphere? explain each lobe

- frontal: voluntary movement, personality, decision-making

- parietal: sensory perception and spatial awareness, language

- temporal: hearing, memory (short-term memory), language comprehension, smell

- occipital: vision

where are the basal ganglia located?

in the cerebral hemispheres

list and explain three parts of the diencephalon

- thalamus: sensory relay station to the cortex

- hypothalamus: homeostasis (controls hormones and autonomic functions), sleep-wakefulness, anorexia nervosa

- limbic system: emotion (fear, anxiety, anger, joy, hope, sexuality), motivation, and memory (hippocampus: short-term memory, amygdala (OMG center, fires off messages to the hypothalamus)

what is the function of the midbrain (mesencephalon)?

motor movement and visual/auditory reflexes

what structures make up the hindbrain? explain the function of each

- pons: regulates sleep, respiration, facial movements

- medulla: vital functions (HR, breathing, BP, reflexes)

- cerebellum: coordination, balance, fine motor control

what are the main parts of a neuron?

cell body, axon, dendrites

what are the three classes of neurons? explain

- afferent: carry impulses from the periphery to the CNS

- efferent: carry impulses from the CNS to muscles and glands

- interneurons: found only in the CNS, make up about 99% of neurons and connect sensory and motor neurons (ex. frontal lobe talking to parietal lobe)

what is a synapse?

the junction between two neurons

what structures are involved in a synapse?

synaptic cleft, presynaptic neuron, postsynaptic neuron

what happens when a nerve impulse reaches the end of a neuron?

the electrical signal is converted to a chemical signal (neurotransmitter) that crosses the synapse

what do neurotransmitters determine?

whether the message continues or stops

what are the 2 kinds of receptor site responses?

excitatory: continue the message

inhibitory: stop the message

what are inactivator mechanisms?

enzymes and reuptake pumps that inactivate neurotransmitters in the synapse

what are the two divisions of the autonomic nervous system? explain each

- sympathetic: dominant during stress

- parasympathetic: dominant during relaxation

freebie

they are key to the therapeutic action of many psychotropic medications

where are neurotransmitters stored?

in vesicles in the presynaptic neuron

neurotransmitters are removed from the synapse in 2 ways:

• reuptake pumps

• enzymes break them down

explain the possible endocrine correlation to the following conditions:

- depression

- panic

- OCD

- depression: thyroid hormone hyposecretion, increased melatonin

- panic: elevated levels of thyroid hormone

- OCD: increased cortisol levels

FREEBIE define neuroendocrinology

the study of interactions between the nervous and endocrine systems and their effects on cognitive, emotional, and behavioral functioning

what controls hormone release from the pituitary gland?

the hypothalamus

why is the hypothalamus important in psychiatry?

many pituitary hormones influenced by it have implications in psychiatric disorders

what does the anterior pituitary do? what hormones does the anterior pituitary release?

- makes and stores its own hormones and releases them when signaled by the hypothalamus

- TSH, ACTH, prolactin, MSH, gonadotrophic hormone, GH

what does the posterior pituitary do?

releases hormones made by the hypothalamus

explain adenohypophysis and neurohypopophysis

- adenohypophysis: actively makes hormones (growth hormone, thyroid-stimulating hormone (TSH),

aadrenocorticotropic hormone (ACTH), prolactin, gonadotrophic hormones, melanocyte-stimulating hormone)

- neurohypophysis: no new hormones, just stores and releases (antidiuretic hormone (ADH) and oxytocin)

how are circadian rhythms related to mental illness?

abnormal rhythms are associated with many mental illnesses

what conditions are linked to disrupted biological rhythms?

premenstrual symptoms and mood disorders

which neurotransmitters affect sleep?

acetylcholine, histamine, and tryptophan (a serotonin precursor)

what neurochemicals influence the sleep-wake cycle?

SLANG:

• serotonin

• L-tryptophan

• ACh (acetylcholine)

• norepinephrine

• GABA

what is genetic vulnerability?

the interaction of nature and nurture that influences whether a disorder is expressed

what are the two types of immune responses? explain

- nonspecific: neutrophils and macrophages, which destroy invasive organisms and damage tissue

- specific: cytokines regulating immune and inflammatory responses