Quiz 4 Flashcards
Hormones
Chemicals produced by endocrine glands that travel to target cells via bloodstream
Hierarchical control:
Sensory stimuli–>Hypothalamus–>Pituitary gland–>Endocrine glands–> Target cells affected by hormones
3 controls over hypothalamic-hormone activity
- Feedback- detects level of hormone to see if it needs to be shut down if making too much
- Regulation by limbic system, frontal lobes- Ex. Sight, sound, thought of baby can trigger oxytocin release & milk ejection, but anxiety and stress can inhibit release.
- Experience- example: neurons that release oxytocin increase in size in mother
Pituitary Gland (Master Gland)
- Controls other glands (Adrenal (on top of kidneys), thyroid, gonads, mammary)
- Has systemic affects through release of hormones: (e.g. Adrenal Cortex- secretes cortisol and adrenal medulla secretes adrenaline during sympathetic NS activation)
Adrenocorticotropic hormone (ACTH)
Critical to understand stress
Reproductive hormones
Affect mood, cognition, behavior in both sexes
Testosterone
Increases libido in males and females.
Oxytocin
- Promotes bonding
- Released during labor (uterine contractions), during breast feeding (milk letdown), during coitus in females and males
Prolactin
- Released during breast feeding (milk production)
- Inhibits testosterone
- Males are more aggressive, females more nurturing (?)
Estrogen
Levels shift significantly during female’s life
Rise and cycle from puberty until menopause
Rise dramatically during pregnancy
Plummet postpartum
Erratic during perimenopause (37-55)- due to exposure to estrogenic molecules
Minimal during menopause
Estrogen and depression
Depression mirrors these changes in estrogen.
Increase in female depression doesn’t begin until adolescence and after menopause the level of depression between females and males becomes equal- due to cycle of estrogen not increase or decrease
Estrogen and the brain
Has profound effects on body & brain
Activates genes to synthesize gene products, (trophic factors & enzymes) that synthesize & metabolize neurotransmitters & receptors in females.
Estrogen, emotions and trophic factors
- Change breasts, uterus
- Preserve bone mineralization
- Reduce cholesterol
- Facilitate growth of new synapses
- Prevent apoptosis (planned cell death) and neurodegeneration – trophic factors keep it from being excessive
- Nerve growth factor (NGF)
- Brain-derived neurotrophic factor (BDNF)
Estrogen and emotions
Affects the 3 main neurotransmitters involved in depression (5-HT, NE, DA (and ACh) systems
Estrogen fluctuations
Dysregulation during estrogen fluctuations may cause somatic and brain abnormalities.
Hormones and cognitive function
Cognition is determined by complex interaction of hormones and experience
Stressor
event that has an arousing effect
- Context and degree of control matter
- Physical stressors exist- surgery and excessive exercise
- Chronicity of stress today is a problem
Stress response
Behavioral and physiological responses to cope with stressor
2 biochemical pathways
- “Fast response” by norepinephrine/epinephrine- Prepares body for sudden burst of activity; sympathetic NS
- “Slow response” by cortisol. Prepares body for longer-lasting adaptations (more info in next card)
Slow response by cortisol
- Activated in minutes to hours
- Helps body resist stressors
- Prepares body for longer-lasting adaptations (e.g., restoring energy that has been expended and making more available)
- Essential to life
Chronic cortisol output
Turns off insulin, which causes liver to begin releasing glucose
- But chronic output may increase risk of insulin-resistant diabetes (Type II- insulin is secreted in normal amounts but receptors become resistant because of too much glucose)
Promotes lypolysis (breaking down of fat) for increased energy - But increases abdominal fat that is particularly dangerous for cardiovascular system and that predisposes body to insulin-resistant diabetes
Cortisol and protein
Promotes protein breakdown (catabolism), but excessive output can lead to muscle weakness/wasting.
Cortisol and immune system
Cortisol shuts down systems not immediately needed to deal with stressor
Inhibits immune system
- Can lead to infections
- Glucocorticoids are used to treat autoimmune diseases and decrease tissue rejection.
Inhibits inflammatory response
Inhibits reproductive system
Cortisol and sleep
Inhibits slow-wave sleep (deep sleep)
- Decreased synthesis of 5-HT, DA, NE
- Predisposition to depression/mania
- Decreased synthesis of growth hormone
- Can lead to osteoporosis
- Stunted growth and failure to thrive
Cortisol from stressed mother passes placental barrier and into infant’s blood and brain
High cortisol causes…
- Increased appetite
- Weight gain
- Increased abdominal fat releases chemicals that increase risk of cardiovascular disease and insulin-resistant diabetes
- Glucose intolerance
- Increased risk of insulin-resistant diabetes (NIDDM)
- Marker for depression
Corticotropin-releasing hormone (CRF or CRH)
- Released by hypothalamus (and other structures) in response to stress
- Leads to increased ACTH, which increases cortisol
Hypothalamo-pituitary adrenal axis
central place for stress
Cortisol and the hippocampus
Chronic stress results in continued high level of cortisol, which destroys hippocampal cells.
Impairs ability to provide negative feedback
May impair memory
Cortisol and ptsd
- May decrease glucocorticoid-receptor density in hippocampus
- Impairs ability of hippocampus to control cortisol.
- Even short term stress can result in memory problems
Primary insomnia
- Difficulty initiating or maintaining sleep or having non-restorative sleep for at least one month
- Causes clinically significant distress or impairment in functioning
- No clear underlying cause and not due to another sleep disorder, psychiatric disorder, medical condition, medications, or other substances
Chronic primary insomnia is the most common sleep disorder; over 30% of primary care patients
Secondary insomnia
Underlying medical or psychiatric condition causing or significantly contributing to insomnia (e.g., psychiatric disorder, pain, medications, obstructive sleep apnea)
Factors affecting chronic insomnia
Most important are behavioral and psychological factors, not addressed by over the counter drugs
Insomnia and psychiatric conditions
35% of patients seen in sleep disorder centers have an identifiable psychiatric or psychological cause.
- Major depression, dysthymia
- Bipolar disorder, mania
- Anxiety disorders
- Schizophrenia: Voices are often more prominent at night when it is quieter.
Insomnia and medical conditions
- Chronic pain (rheumatoid arthritis, peptic ulcer disease, GERD, fibromyalgia, neuropathies, lower-back pain)
- Hypertension
- Congestive heart failure (CHF)
- Chronic obstructive pulmonary disease (COPD)
- Benign prostatic hypertrophy (BPH)
- Incontinence
- Urinary tract infection (UTI)
- Hyperthyroidism
- Diabetes
Sleep-wake switch
Hypothalamus has switch:
- Throughout day, various chemicals gradually increase, making a person feel increasingly tired.
- At bedtime, chemicals combine w/ the “sleep” component of the “sleep-wake switch,” which releases GABA (inhibitory)
- Brain is inhibited and put to sleep.
- In AM, the “wake” component of the “sleep-wake switch” releases histamine (excitatory), which “wakes up” the brain.
Factors that interfere with slow wave sleep
- Apnea
- Periodic leg movement disorder
- Chronic pain
- Corticotropic-releasing hormone (CRH), cortisol (stress) prevent slow-wave sleep.
- Lack of exercise
Drugs that interfere with slow wave sleep
Most sedatives/hypnotics:
- All benzodiazepines (BZDs), including ones used for sleep
- Alcohol
- Many antihistamines (Benadryl, Nytol, Simply Sleep, Sominex)
Caffeine:
- Even if don’t drink after noon, enough stays in system to interfere.
- At risk, if 250 mg/day (2 cups)
- Very likely to have problem if > 550 mg/day
- Certain drugs may cause caffeine to stay in system for up to 31 hrs (by interfering w/ metabolism).
Drug exceptions to sleep interference
“Z” drugs.
zolpidem (Ambien), zaleplon (Sonata), eszopliclone (Lunesta)
ramelteon (Rozerem)
melatonin supplement
Neurons
Basic signaling units, information processors, computational devices, CPU’s
Glial cells
the support cells (structural and functional support)
Resting membrane potential
At rest, neuron has electrical potential (charge across its membrane) of -70 mV (inside negative relative to outside) due to unequal distribution of charged particles (ions, proteins)
Resting potential
Semipermeability of membrane
- Hard for Na+ to pass into neuron, and proteins (mostly negative charge) are kept inside due to size & charge
Synapse
Site of functional contact
- Presynaptic membrane w/ active zone (where vesicles are located waiting to release NT’s)
- Synaptic cleft – Space between neurons (not truly empty; scaffolding proteins connect two neurons)
- Postsynaptic membrane w/ receptors
excitatory post-synaptic potential (EPSP)
If Na+ or Ca++ channels open, Na+ or Ca++ can enter.
- If that happens, charge on membrane becomes less negative, or depolarized (excited).
- It is now closer to its firing threshold of -50 mV.
inhibitory post-synaptic potential (IPSP)
If Cl- or K+ channels open, Cl- or K+ can exit.
- Charge on membrane becomes more negative, or hyperpolarized (inhibited).
- It is now further from its firing threshold of -50 mV.