Exam 1 Flashcards
What are the types of glia, including their function?
Glia (glial cells) — Support cells (structural, functional support) for neurons. There are 5 types: ependymal-small, ovoid, secretes cerebrospinal fluid, astrocyte-star-shaped, symmetrical, nutritive and support functions, microglial-small, mesodermally derived, defensive function, oligodendroglial-asymmetrical, forms myelin around axons in the brain and spinal cord, and schwann-asymmetrical, wraps around peripheral nerves to form myelin
What are some details about the blood-brain barrier, including the role of astrocytes (astroglia)?
The blood–brain barrier (BBB) is a highly selective permeability barrier that separates the circulating blood from the brain extracellular fluid (BECF) in the central nervous system (CNS). The blood–brain barrier is formed by brain endothelial cells, which are connected by tight junctions with an extremely high electrical resistivity of at least 0.1 Ω⋅m.[1] The blood–brain barrier allows the passage of water, some gases, and lipid-soluble molecules by passive diffusion, as well as the selective transport of molecules such as glucose and amino acids that are crucial to neural function. On the other hand, the blood–brain barrier may prevent the entry of lipophilic, potential neurotoxins by way of an active transport mechanism mediated by P-glycoprotein. Astrocytes are necessary to create the blood–brain barrier. A small number of regions in the brain, including the circumventricular organs (CVOs), do not have a blood–brain barrier.
Astrocytes (Astro from Greek astron = star and cyte from Greek “kyttaron” = cell), also known collectively as astroglia, are characteristic star-shaped glial cells in the brain and spinal cord. The proportion of astrocytes in the brain is not well defined. Depending on the counting technique used, studies have found that the astrocyte proportion varies by region and ranges from 20% to 40% of all glia.[1] They perform many functions, including biochemical support of endothelial cells that form the blood–brain barrier, provision of nutrients to the nervous tissue, maintenance of extracellular ion balance, and a role in the repair and scarring process of the brain and spinal cord following traumatic injuries.
Know the main parts and functions of the brainstem, including dysfunctional effects,
such as decreased level of consciousness/coma, respiratory suppression/arrest,
or abnormal cardiorespiratory control?
The brain stem consists of medulla, pons, midbrain. There are ascending & descending tracts between spinal cord and thalamus, cerebellum, cortex. Especially those tracks & neurons that involve the cortex & the cerebellum are critical for posture, smooth muscle movements, muscle tone. The brainstem includes neurons that regulate: 1)
respiration, cardiovascular activity, consciousness, alertness; 2)
reflexes, simple behaviors mediated by cranial nerves (mainly for head; parasympathetic for thoracic, abdominal organs). The brainstem also includes the reticular activating system (RAS), which has neurons located throughout brainstem and activates the thalamus, hypothalamus, and neocortex for arousal from sleep. It also helps keep one alert during day.
Injury to the RAS leads to problems w/ arousal, alertness, coma. Lastly, the pons, which is a bridge between the cerebellum & the rest of brain, contains neuron cell bodies of the locus coeruleus project to the brain and to the spinal cord and release NE. The pon also contains neuron cell bodies of raphe nuclei, which are located from the medulla through the midbrain and project to many areas of brain and release serotonin.
What are the 2 divisions of the autonomic nervous system (ANS), including the primary
functions and implications for working with clients
The 2 divisions of the autonomic nervous system are the: 1) neural, which uses neurotransmitters, synapses
responses are faster to develop, are shorter-term, and reach limited number of cells; 2) endocrine, which uses hormones via blood stream, responses are slower to develop, are more prolonged, and reach greater number of cells. Both systems are involved in subconscious (“automatic”), homeostatic processes, including: cardiovascular, respiratory, digestive, urinary, and reproductive. Both are controlled by the CNS (primarily hypothalamus) and are affected by emotional factors, and sensory input from both inside & outside body
The ANS is the neural system. It innervates smooth muscle, cardiac muscle, glandular epithelium. It contains the Sympathetic nervous system (SNS), or the “fight or flight” system which is responsible for extreme excitement, and exertion. Stress causes global activation of SNS and increases release of NE in tissues. Symptoms include: heart rate, blood pressure, blood flow to skeletal muscles, blood glucose levels, sweating, and pupil diameter. The SNS concurrently decreases:
gut motility, digestive gland secretion, and blood flow to abdominal viscera (i.e. skin).
Thus, the SNS generally acts in a global manner. The Parasympathetic Nervous System (PNS) is involved in “Rest and digest” and increases the release of ACh in tissues. The PNS effects are more localized than the SNS. For most organ systems, the SNS and PNS have opposite effects.
The specific effect in each system depends on which specific type of receptor is activated. An overall balance is critical.
Each must become temporarily dominant for a specific situation. Emotional dysfunction may cause/worsen disease if extreme or chronic. Psychologists, may
help decrease morbidity/mortality by helping pts obtain proper balance and obtain valuable information about pts’ emotions, effects of drugs by observing physical manifestations of ANS
What are the primary functions of the hypothalamus?
(a) homeostasis and
regulation of physiologic parameters, (b) control over the ANS and endocrine
systems, (c) “translation” of limbic output to physiologic responses, and (d)
aspects of sexual behavior.
What is the difference between depolarization (excitation) and hyperpolarization
(inhibition) and the relationship between each of these and graded potentials
Graded potentials — Gradual changes in potential
If Na+ or Ca2+ channels open, Na+ or Ca2+ can enter.
Charge on membrane becomes less negative, or depolarized (excited).
Now closer to its firing threshold of -50 mV
Is an excitatory post-synaptic potential (EPSP)
If Cl- or K+ channels open, Cl- or K+ can exit.
Charge on membrane becomes more negative, or hyperpolarized (inhibited).
Now further from its firing threshold of -50 mV
Is an inhibitory post-synaptic potential (IPSP)
Which aspect of action potentials (frequency or amplitude) indicates the
intensity of sensory information to the brain?
Amplitude of action potential is constant and cannot provide information about intensity.
Intensity is provided by frequency of action potentials because more intense stimulus increases probability that firing thresholds will be reached and that action potentials will be generated.
True or False: Only some action potentials (firing of the neuron) are the same throughout the nervous
system and occur in an “all-or-none” fashion and as such do not reveal their
source or destination, which is determined by the anatomy of the involved
neurons.
False, All action potentials (firing of the neuron) are the same throughout the nervous
system and occur in an “all-or-none” fashion and as such do not reveal their
source or destination, which is determined by the anatomy of the involved
neurons.
Know the neurobiology of multiple sclerosis (MS), including the major hypothesis that
it is an autoimmune reaction (possibly due to an earlier infection) in which the
body attacks its own myelin sheath surrounding neurons
Pathology may cause neurological diseases.
Multiple sclerosis (MS)
Episodic, inflammatory, multifocal disease
Autoimmune response against myelin antigens (possibly due to earlier infection)
Less myelin slows speed of propagation and causes “cross-talk” (“short-circuiting”) in motor, sensory axons.
Affects optic nerves, cerebral hemispheres, brainstem, cerebellum, spinal cord
Two most common types:
Relapsing-remitting (RRMS)
Accounts for 80-85% of new cases of MS
After 15 yrs, most evolve into secondary progressive MS (SPMS)
Most will require assistance w/ ambulation; some will become totally dependent for ADL’s
Primary progressive MS — 15-20% of new cases
What are the psychiatric sxs that commonly occur in MS? (These are
primary sxs due to the neuropathology of MS, not just psychological reactions
to suffering from a chronic illness)
Early sxs
Weakness in a limb
Sensory changes (parasthesias, heat sensitivity)
Optic neuritis w/ eye pain, change of vision
Difficulties w/ gait or coordination
Urinary urgency or frequency
Sexual dysfunction
Fatigue
Often get worse w/ stress, fatigue, exercise, heat
May present initially w/ mild alterations in mood, behavior, cognition, personality
Are mostly primary — Due directly to neuropathology, not a secondary psychological reaction to having a chronic illness
May also be a superimposed psychological reaction
Early complaints of intermittent & variable sxs are often incorrectly attributed to depression, anxiety, somatization, even malingering or factitious disorders.
Most have mood & affective instability, alterations in behavior or personality, which usually occur throughout illness.
Major depression, bipolar disorder, anxiety, irritability
Some experience euphoria (incongruent w/ condition or premorbid personality).
10% have pathological laughing, crying.
May not clear with remission of physical sxs
Correlate poorly w/ MRI findings, severity of physical findings, length of illness
May exhibit apathy, disinhibition, hallucinations, delusions
Tx w/ interferon β-1b may induce depression.
Mild-moderate cognitive deficits (e.g., attention, speed of information processing, memory recall, executive functioning) in > 50%
Severe cognitive decline in 20-30%
What is the differences between the 2 main types of receptors, including their main
functions and characteristics?
1st family is comprised of ligand-gated ion channels (ionotropic receptors, ion-channel-linked receptors).
Allow movement of ions across membrane through a gate that opens when NT binds
Rapid change in membrane potential (msecs)
Mediate fast behavior
May be excitatory or inhibitory
2nd family is comprised of metabotropic receptors
Alter internal chemistry
Often result in alteration of protein synthesis via effects on gene transcription
Change ion channels indirectly
Receptor & effector functions performed by separate molecules
What is the relationships among the ANS, the hypothalamus, and the limbic system
(especially the amygdala); that is, what controls what?
ANS:
Viscera are influenced by 2 interdependent systems.
Neural — Uses neurotransmitters, synapses
Responses are faster to develop, are shorter-term, reach limited number of cells.
Endocrine — Uses hormones via blood stream
Responses are slower to develop, are more prolonged, reach greater number of cells.
Both systems are involved in subconscious (“automatic”), homeostatic processes, including:
Cardiovascular, respiratory, digestive, urinary, reproductive
Both controlled by CNS (primarily hypothalamus)
Both affected by emotional factors, sensory input from inside & outside body
The ANS is the neural system.
Innervates smooth muscle, cardiac muscle, glandular epithelium
Sympathetic nervous system (SNS)
“Fight or flight” — Extreme excitement, exertion, stress cause global activation of SNS
Increases release of NE in tissues
Heart rate
Blood pressure
Blood flow to skeletal muscles
Blood glucose level
Sweating
Pupil diameter
Concurrently decreases:
Gut motility
Digestive gland secretion
Blood flow to abdominal viscera, skin
Thus, SNS generally acts in a global manner.
Parasympathetic Nervous System (PNS)
“Rest and digest”
Increases release of ACh in tissues
PNS effects are more localized than SNS.
For most organ systems, the SNS and PNS have opposite effects.
Specific effect in each system depends on which specific type of receptor is activated.
Overall balance is critical.
Each must become temporarily dominant for a specific situation.
Emotional dysfunction may cause/worsen disease if extreme or chronic.
Psychologists, MFT’s may:
Help decrease morbidity/mortality by helping pts obtain proper balance
Obtain valuable information about pts’ emotions, effects of drugs by observing physical manifestations of ANS
Hypothalamus:
Hypothalamus — Survival of animal or species by maintaining homeostasis & regulating physiologic parameters, sexual behavior
Subserves 3 systems
Autonomic (through effects on brainstem, spinal cord centers)
Endocrine (hormones, releasing factors affecting anterior pituitary)
Limbic (is primary output of limbic brain)
Electrolyte/water balance (ratio) Food intake (hunger, satiety) Temperature (sweating, shivering) Autonomic activity (blood pressure, rate/force of heart beat, respiratory rate/depth, digestive tract motility, etc.) Sleep-wake cycle/circadian rhythmicity General body metabolism
Lesions/dysregulation may cause:
Abnormal appetite/eating (obesity, anorexia, bulimia)
Vasomotor sxs of menopause (hot flushes, night sweats, insomnia, depression)
Fatigue, diminished drive
Memory deficit (mammillary bodies)
Diabetes insipidus (excessive urinary output & water intake)
Limbic System: Comprised of: Amygdala Hippocampal formation Mammillary bodies (of hypothalamus) Anterior thalamus Cingulate cortex Fornix (connects hippocampus & mammillary bodies)
Comprised of subcortical & cortical structures that encircle brainstem, thalamus, basal ganglia
Subcortical portion involved with subconscious, fast responses to stimuli w/positive or negative values
Cortical portion mediates conscious feelings
Important for survival of species, including motivation, emotion, memory
Amygdala:
Learning new fears (conditioning), responding to innate fears
The most important structure in brain for fear
Anxiety disorders associated w/ hyperactive amygdala
Coordinates emotional responses
Autonomic & endocrine responses via output to hypothalamus, brainstem
Defensive behavior via output to brainstem
Conscious awareness via output to prefrontal cortex, cingulate cortex
How does estrogen (especially fluctuating levels) affects the body, brain, and monoamines of females?
Estrogens
Estradiol is the most potent, plentiful estrogen during childbearing yrs.
“Estrogen” usually refers to estradiol or loosely to estrogens as a group.
Cause female body changes at puberty
Control menstrual cycles; regulate many aspects of pregnancy, birth; stimulate lactation Oxytocin
Released during labor (uterine contractions), during breast feeding (milk letdown), during coitus in females, males
Promotes bonding
Prolactin released during breast feeding (milk production)
Inhibits testosterone. Estrogen levels shift significantly during female’s life.
Rise and cycle from puberty until menopause
Rise dramatically during pregnancy
Plummet postpartum
Erratic during perimenopause (ages 37-55)
Minimal during menopause. Depression mirrors these changes in estrogen.
Depression increases significantly during puberty.
May worsen during luteal phase of cycle
Major risk during postpartum after abrupt fall in estrogen
Risk for depression, psychosis, mania
Risk during perimenopauseFrequency of depression 2-3X higher in females vs males during childbearing years
But is same before puberty and after menopause
Estrogen profoundly affects body, brain.
Activates genes to synthesize trophic factors, enzymes that synthesize, metabolize neurotransmitters, receptors in females. Affects activity of 5-HT, NE, DA (and ACh) systems
Affects the 3 main neurotransmitters involved in depression
Estrogen is sometimes used to augment antidepressants for depression.Dysregulation during estrogen fluctuations may cause somatic & brain abnormalities.
During perimenopause
Vasomotor sxs (hot flashes, sweating) caused by dysregulation of hypothalamic thermoregulatory centers modulated by 5-HT, NE
Sxs of depression
Which techniques measure activity vs structure (neuroanatomy)?
Activity: PET, SPECT, fMRI, rs-fMRI, fNRIS
Structure: CT, MRI, MRS
What are the advantages of CT vs MRI and fMRI vs PET?
CT Advantages:
Good resolution (1 mm in diameter)
Used mainly in ER (done quickly)
Good for imaging bone, TBI, stroke
CT Disadvantages:
X-ray exposure (moderate-high)
Less contrast between gray & white matter than MRI
MRI Advantages:
Better contrast than CT
Good spatial resolution (1 mm in diameter)
No exposure to x-rays or radioisotopes
MRI Disadvantages:
Pts w/ ferromagnetic materials in body cannot be imaged.
Hard for pts w/ claustrophobia (unless open scanner)
Noisy
Subject must be very still.
PET Advantages:
Good spatial resolution (2 mm3)
But fMRI is better (1 mm3).
Used extensively in research to study specialization of brain areas
Useful for diagnosing early neurodegenerative diseases, changes after lesions or treatments
PET Disadvantages: Must be near a cyclotron since radioactive isotope decays rapidly (2-110 mins)
Expensive (about 2 million dollars), requires special preparation/handling of radioactive material
Repeated imaging over short periods is not practical.
Does not measure neuronal activity directly
fMRI Advantages:
No radioactive isotopes, cyclotron required
Excellent spatial resolution (1 mm3)
Same individual can be repeatedly scanned since no radioactive isotope is injected.
fMRI Disadvantages:
Both PET & fMRI require relatively simple tasks compared to complexity of everyday tasks.
But subjects must still be able to pay attention and not move during procedure.
Neuropsychological tests & knowledge are critical for good experiments using these techniques.
