NURS 165 - Module 4/Quiz 4

Hormones and the Brain,

What is the endocrine system made up of?

glands and the hormones they secrete

Who is the primary hormone producers?

the endocrine glands

How many hormones are identified in the human body so far?

~50 hormones

Who produces and releases hormones?

heart, lungs, liver, skin, muscles, fat cells, immune system, gastrointestinal mucosa, and placenta

What does it take to become an endocrinologist?

13 years of schooling

What is endocrine? What is an example?

• umbrella stmt for the whole system

• really should be used for systematic release only

  • ex: insulin

What is paracrine?

adjacent cells or surrounding tissue rather than into bloodstream

ex: testosterone

What is autocrine? What is an example?

within the cell

ex: T-Cells

What is exocrine? What are some examples?

exterior glands that secrete fluids

ex: sweat, saliva, tear ducts, etc.

What are the four parts of the endocrine system?

Endocrine, Paracrine, Autocrine, Exocrine

What is the main function of the endocrine system?

regulate and maintain the body’s functions (homeostasis) by releasing chemical hormones messengers — energy level, reproduction, growth and development, and response to injury, stress, and environmental factors

What does the endocrine system facilitate/coordinate?

1. Digestion

2. Storage of nutrients

3. Electrolyte and water metabolism (K+/Na+/Cl-)

4. Metabolism

5. Growth and development

6. Reproductive function

What are the 10 major glands that produce and secrete hormones?

• hypothalamus

• pituitary

• pineal

• thyroid

• parathyroids

• thymus

• adrenals

• pancreas

• the ovaries

• the testes

What are neurotransmitters?

fast acting with short response term response

What are neuropeptides?

• amino chains

• slow acting with longer response time

• they can affect gene expression, local blood flow, synaptogenesis, glial cell morphology, etc

• energy expenditure

What are hormones?

• chemical messengers

  • amino chains

  • secreted from endocrine cells and travel to distinct tissues, including the central nervous system, to evoke a response

    • travel via blood rather than neurons

    • single purpose

      • deliver messages

      • to different sites

      • direct affects: growth, development, and signals other activities

What are neuro-hormones?

• any hromone produced and released by neuroendocrine cells; neurosecretory cells, into blood

• by definition of being hormones

  • they are secreted into the circulation for systemic effect

  • but they also have a role of neurotransmitter

What is oxytocin do?

• stimulates contraction of uterus and milk ducts in the breast

  • baby bonding/the snuggle chemical

• produced by the pituitary

What are the general features of the endocrine system?

• chemical messengers

  • endocrine system regulates body activities

  • transported in the bloodstream

  • to target cells or organs

• effect

  • longer, more generalized vs. nervous system

• endocrine glands spread through the body

  • one system with critical interrelationships

What are some examples of hormones?

testosterone, estrogen, oxytocin, melatonin

How does synthesis and secretion occur through hormones?

• triggered by neuro receptors and signals

  • hypothalamus — commander in chief

  • pituitary gland — master gland

    • stimulates specific activates and processes — some have cycles

How does the endocrine system regulate physiological functions?

• negative feedback regulates secretion hormones

• cycles of secretion maintain physiological / homeostatic control (balance) — range from minutes to months

What is the difference between steroid hormones and nonsteroid hormones? Name examples of each.

Steroid hormones:

• enters the cell

• made of lipids — is fat soluble

• can diffuse across

• examples: testosterone and estrogen

Nonsteroid hormones:

• do not enter the cell

• made of amino acids — not fat soluble

• cannot diffuse across → binds with receptors

• examples: glucagon and insulin

What is the hypothalamus and what does it do?

• contains neurons — controls releases of hormones from anterior pituitary — linked by blood vessels

• responsible for: emotion, pain, body temperature, drains into anterior pituitary

• senses blood hormone levels and signals pituitary

  • increase or decrease hormone stimulation/production

  • negative feedback system

How many hormones are produced/secreted by the hypothalamus? How do they affect the pituitary?

• 7 hypothalamic hormones

  • released into portal system

  • connects hypothalamus with pituitary

• cause targets in pituitary to release 8 hormones

How many hormones does the pituitary gland secrete?

eight — more than any other gland

What does the pituitary gland do?

• serves as the master gland

• hormone stimulating factors cause secretion of hormone from specific glands (TSH)

• controls functions including

  • growth and development - growth hormone (GH)

  • metabolism - thyroid/insulin

  • ovulation - FSH, LH, TSH

  • lactation - oxytocin, prolactin

What is a negative feedback loop?

• “Inhibitory loop”

• a type of self-regulating system

• response will reverse a stimulus that is outside of the set parameters

Compare the negative feedback loop to the thyroid gland.

• thyroid gland = heater

• thyroid hormone (TSH) = heat

• hypothalamus & pituitary gland = thermostat

What is a positive feedback loop?

• not too many in the body

• response that reinforces the change detected (it functions to amplify the change)

• continue to amplify the initial change until the stimulus is removed

What are some examples of positive feedback loop?

• childbirth — stretching of uterine walls cause contractions that further stretch the walls (this continues until birthing occurs)

• lactation — the child feeding stimulates mulk production which causes further feeding (continues until the baby stops feeding)

• ovulation — the dominant follicle releases estrogen which stimulates LH and FSH release to promote further follicular growth

What are hormone receptors?

• binding sites on target cell (on surface, cytoplasm or nucleus of target cell)

• activated only when specific hormones bind to them

• if a hormone does not/cannot bind to receptor — no physiological effect

What are target cells?

• cells with specific receptor/binding sites for specific hormone

• hormone binds to receptors on target cell — series of cellular events unfold

• eventually impact gene expression and protein synthesis

What can hormone disruptors do?

• can cause problems at any point along hormone pathways

• cause issues in embryonic development

• altered adult functioning

• hormone mimics — binding to receptor sites send false message not initiated by brain

• block natural hormone — no ability to bind to receptor site therefore no effefct

• alteration of hormonal synthesis and/or degradation

• influence target cell response

How long can endocrine biological cycles last?

range from minutes to years

What are some cycles that occur throughout the animal kingdom?

hibernation, mating behavior, body temperature/other physiological processes

what are circadian rhythms?

rhythms/cycles show changes on daily, even hourly

What is menstrual cycle controlled by?

many hormones secreted in cyclical fashion

When is thyroid secretion usually higher?

in winter vs summer

What is childbirth controlled by? When is it highest?

hormonally controlled; highest between 2 and 7 am

What are internal cycles of hormone production controlled by?

hypothalamus

What is testosterone?

• hormone associated with males, sexual interest, muscle mass, etc

• secreted by both male and female (men > female) by adrenal gland/testicles

How do women compare to men in testosterone?

women are more sensitive to effect of testosterone — minimal amount needed to ‘turn on’ or activate sexual response systems

How does testosterone affect sexual desire?

• increased levels DO NOT increase sexual desire and can be involved in negative physical effects (cardiac)

• low levels of testosterone can reduce sexual interest in males/females

• castrated males can have lowered testosterone levels causing slow, gradual loss of sexual desire (surgical/medical-anti adrenergic meds)

• women note reduction in sexual desire if adrenal glands/ovaries are removed

  • administration of exogenous hormones (estrogen and testosterone) can heighten sexual desire

What does estrogen do?

• provides general sense of wellbeing in women

• males produce estrogen - adrenal glands

• maintains thickness/elasticity of vaginal lining

• contributes - vaginal lubrication

• unclear role of estrogen in sexual behavior

• post-menopausal issues — ovaries or no ovaries

  • estrogen therapy vaginal lubrication, some increase in sexual desire, pleasure and orgasm capacity

• “mood-mellowing” benefits

• feminizing effects of estrogen on breasts, skin, etc

• protect against clotting, schizophrenia, and Alzheimer disease

• memory and learning

What is the purpose of oxytocin? Where is it produced and released into?

• produced in the hypothalamus — released into bloodstream by pituitary gland

• sexual response; sexuality; emotional attraction

• facilitates milk production / ejection of milk from breast

• snuggle chemical — mother / child bonding — 2 hour contact at birth

• similar effect / response with bonding sexual partners — associated with uterine contractions during orgasm

• secreted during physical intimacy

• touch - powerful trigger release of hormone

• elevation of oxytocin / enhanced blood levels contributes to emotional bonding of sexual partners

• synthetic version - Pitocin — used to induce labor

What is melatonin? What is it secreted by?

• secreted by the pineal gland — also produced in the retina of the eye

• some effects on sleep/wake cycle

  • highest at night

  • lower BP, temp, and increase in tiredness

• a free radical scavenger — sleep is important

• can be inhibited by blue wavelength light

• derivative of seratonin

What are some hormones synthesized in glands?

ovaries, testes, adrenal gland, thyroid gland

What are the functions of endocrine?

• maintain internal homeostasis

• support cell growth

• coordinate development

• coordinate reproduction

• facilitate responses to external stimuli

When did ideas of differences of the male and female brain begin circulating?

during the time of ancient Greek philosophers around 850 BC

Who discovered what in 1854?

Emil Huschke discovered that the “frontal lobe in the male is all of 1% larger than that of the female”

What have scientists discovered about the male and female brain over the past 10 years?

elucidated biological sex differences in brain structure chemistry and function

“These variations occur throughout the brain, in regions involved in language, memory, emotion, vision, hearing and navigation”

What was the initial thought about sex hormones and the brain?

• ONLY differences affected of the BRAIN influencing

  • Hypothalamus — sex drive/erotic preference, mating behaviors, sex hormones

What does the hypothalamus control?

sex drive/erotic preference, mating behaviors, sex hormones

What do we know now about sex hormones and the brain?

• the entire brain is influenced by hormones

• variations occur throughout brain including regions involving:

  • language, memory, emotions, vision

  • hearing and navigation

How do we determine differences in male and female brains?

We measure:

• Neurochemistry

  • hormones and neurotransmitters (serotonin, dopamine, estrogen, testosterone)

• Cognitive Processing

  • problem-solving, memory, decision-making

• Structural differences

  • size and connectivity (hippocampus, amygdala, callosum, etc.)

• Brain Activity

  • blood flow, imaging (fMRI, PET. EEG)

What are the noted behavioral differences among male and females?

some scientists state over 100 areas of the brain differ, involving:

• language — temporal lobe (Wernicke’s area)

• memory — hippocampus

• emotions and aggression — amygdala

• visuospatial skills — parietal lobe

• vision — occipital lobe

• impulse control and decision making — frontal lobe

• sensory relay — thalamus

• connectivity — corpus callosum

• processing vs transmission — gray vs white matter

What is the cerebral cortex?

• the outermost layer of the brain

• associated with our highest mental capabilities

• primarily constructed of gray matter

• between 14 and 16 billion neurons are found here

How do males and females differ in terms of brain matter?

Females have more Gray Matter than Males

Males have more White Matter than Females

What is white matter?

• transporter

• transmits more sensory and motor impulses

• controls involuntary functions: BP, HR, RR, body temp

• myelinated axons connecting different parts of gray matter to each other

• about 60% of the brain

• more in the cortex

What is Gray matter?

• retrieves information from white matter and sends instructions back to the effector organs

• controls the senses of the body — hearing, feeling, speech, and memory

• pinkish-gray color

• cell bodies, dendrites, and axon terminals of neurons… where all synapses are

• about 40% of the brain

• more on the surface

What is the difference between grey matter and white matter?

grey matter has NO myelin sheath, while white matter is myelinated — white color comes from lipid component of myelin

What are the differences between left and right hemisphere processing among males and females?

Males:

• fully developed by the ages of 26-30 years old

• higher white matter/gray matter ratio

  • within days of birth — seen on scans

• more connections within hemispheres

  • may be optimized for motor skills

Females:

• fully developed between 21-22 years old

• higher gray matter/white matter ratio

• more connected between hemispheres

  • may be optimized for combining analytical and intuitive thinking

  • denser network of “local processors”

How many male or female operators are there?

more 911

What is the Corpus Callosum?

• responsible — connecting the TWO hemispheres via a thick bundle of nerve fibers

• seen about 26 weeks’ gestation

• larger in females and difference in shape

  • more densely packed neurons in females bs males

  • better connection between hemispheres?

    • better communication between hemispheres

    • allows communication at a younger age

    • language ability seen > 4 years earlier

• males: thinner relative to brain weight

What is the limbic system?

• Hippocampus (larger in females)/Amygdala (larger in males)

• Responsible — emotions, learning, and memory

What is the hippocampus?

• memory and learning (3 areas and 4 subareas)

  • larger in females relative to brain size

  • more and stronger connections from hippocampus to amygdala

    • affects emotional memories

  • emotional memories are stronger in women

  • slightly different shape and size with more neural density in women

What is the Amygdala?

• emotions (~13 different regions)

• larger in males relative to brain size --

  • fear, happiness, regulating sexual behavior, regulating social behavior

    • rough and tumble play

What was the study of Dr Scoville?

• 1953

• drilled and sucked out parts of his brain

• lost memories from prior decade and unable to form new ones

• found uses different regions by getting sensory data (event), transcribed by neurons on the cortex temporarily, travels to the hippocampus, special proteins strengthen the cortical synaptic connections — if strong enough then the hippocampus transfers the memory back to the cortex for permanent storage

• he could “record'“the memory for a very short time (seconds to minutes) then could not transfer into long term memory — no hippocampus

• while drawing star — found that declarative memory (dates, names, facts) is different than procedural memory (riding bike, signing name — relies on Basal Ganglia and Cerebellum)

• examined by more than 100 neurosurgeons

What is the thalamus?

• limbic system — ~60 regions

• beneath the cortex (mostly gray matter)

  • relay station: sends sensory impulses to the cerebral cortex

  • relays: visual, auditory, somatosensory, taste — NOT smell

  • key roles in: motor activity, emotion, memory, arousal

What are the differences in the Thalamus among males and females?

• Males: thalamus almost 3x larger than in females

  • linked to stronger sensorimotor integration and visuospatial skills

• Females: smaller thalamus, but greater inter-hemispheric efficiency (balance with corpus callosum connectivity

• size and connectivity differences may influence stress response, attention, and sensory processing across genders

What is the Hypothalamus?

• part of the limbic system

• responsible — maintaining homeostasis (4 regions and 6 subzones)

• eating, drinking, temperature regulation, sleep regulation, mating behavior, etc

• preoptic area - sexual/mating behavior

  • if damaged — decreased sexual activity

  • Males

    • hormonal (androgens) sensitive areas:

      • more hormones equals larger size

      • about 2.2 times larger in Males

    • contains 2 times more cell

• Superchiasmatic nucleus —

  • circadian rhythms and reproduction cycles

  • is the brain’s master clock

    • Males: more like a sphere

    • Females: more elongated

What is the Temporal Lobe?

• responsible — language and comprehension

• Lt Hemisphere

  • Wernicke’s Area - language processing center

  • Broca’s area - production of speech

What is the temporal lobe like among females?

• more densely packed neurons and slightly different in size

• language ability developed 4-6 years ahead of males

• more neurons in the language area

• better verbal and language skills

• females developed bilaterally

  • after a stroke, women retrieve language sooner and better

What is the frontal lobe?

• part of the cerebral cortex

• responsible for behavior and emotional control center, our personality/consciouness

• males:

  • not significant larger (1% larger)

• females:

  • matures a full two years before men

  • bulkier/denser

    • better with attention, problem solving, and impulse control

• frontal love development differences influence how males and females approach risk, attention, and self-control

What is the parietal lobe?

• responsible for interpreting somatosensory information about objects in our external environment (5 senses)

• Males

  • more neural connections, denser, and more activity

  • larger surface area

    • greater visuospatial skills

      • better with mentally rotating 2 to 3D objects

        • Mental/Visual rotation

      • track moving objects and aim projectiles with better accuracy

        • hitting a target and throwing a ball overhand with accuracy

      • better “dead reckoning” - estimating direction/distance traveled from a fixed point

  • Females

    • rely more on landmarks with navigation

    • can learn enhancing activities such as mental rotation of objects

What is the occipital lobe?

• visual cortex

• responsible for processing images

  • high concentrations of male sex hormone (androgen) receptors throughout visual cortex

• Males

  • engage the visual cortex more

    • heightened visual and spatial ability

  • males have 25% more neurons

  • excel on tasks requiring activation of visual cortex

  • engaged in math equations

• Females

  • perceptual speed is better

    • have better accuracy of object location - finding waldo

    • better color identification

  • better at rapidly identifying matching items

What are some brain “differences” among males and females?

Males

• “Bigger brain”

• larger ventricles

• thinner cortex

• more white matter

• larger amygdala

• smaller hippocampus

• larger thalamus

• smaller and less dense corpus callosum

Females

• “Smaller brain”

• smaller ventricles

• thicker cortex

• more gray matter

• smaller amygdala

• larger hippocampus

• smaller thalamus

• larger and denser corpus callosum

What are some differences in the location of brain function among males and females?

Males:

• Language Mechanics: Lt Hemi Front and Back

• Vocabulary: Lt Hemisphere Front and Back

• Visual-Spatial Perception: Rt. Hemisphere-densely packed, highly localized concentrations of neurons

• Emotion: Rt. Hemispgere

Females:

• Language Mechanics: Lt Hemisphere front-densely packed, highly localized concentrations of neurons

• Vocabulary: Lt and Rt Hemispheres front and back

• Visual/Spatial Perceptions: Rt and Lt Hemispheres

• Emotion: Rt and Lt Hemispheres

What are some of the “more noticeable or more prevalent” differences among males and females?

Male:

• hitting a target and throwing a ball overhand with accuracy

• mental/visual rotation

• considered to have heightened visual and spatial ability

• the parietal lobe is more densely packed with neurons (larger)

• brain is considered to be fully developed by the ages of 26-30

Female:

• verbal and language skills

• accuracy of object location

• slightly better at recognition of emotions

• acquires language and verbal ability sooner

• temporal lobe, corpus callosum, and hippocampus are more densely packed with neurons

• the brain is considered to be fully developed between 21-22 years old

What is the step-by-step order of memory/response?

1. Sensory receptors (skin, hand)

2. Peripheral Nerves → Spinal Cord

3. Spinal Reflex (immediate withdrawal)

4. Ascending Pathways → Thalamus

5. Somatosensory Cortex (Parietal Lobe)

6. Limbic System (Amygdala and Hippocampus)

7. Frontal Lobe (Prefrontal Cortex)

What occurs through sensory receptors?

nociceptors and thermoreceptors detect heat, pain, and inflammation (interpreted differently in males vs females)

What occurs through peripheral nerves → spinal cord?

Sensory neurons transmit the signal via the dorsal root to the spinal cord

What occurs through spinal reflex?

before the brain even gets involved, the spinal cord sends a motor reflex → pull the hand away

What occurs through ascending pathways → thalamus?

• the sensory information travels up the spinal cord (spinothalamic tract)

• thalamus acts as a relay station directing the signal

What occurs through somatosensory cortex (parietal lobe)?

interprets where and what the sensation is (“burning pain in my hand”)

What occurs through limbic system?

• Amygdala attached emotional meaning (“dangerous, avoid that”)

• Hippocampus encodes the memory (“remember not to touch a hot stove”)

What occurs through the frontal lobe (prefrontal cortex)?

• integrates sensory + memory + emotion

• guides conscious decision making: “I should use an oven mitt next time”

E

Explain the mosaic brain.

• brain growth and development involve environmental, life experience, and activity

  • with that underpinning, newer research is examining sex differences in the brain as a whole

    • not a sexually dimorphic (occurring in or representing two distinct forms) view of the human brain

• Supports the notion that our brains are a mix of both male and female

• they are checkered with features of both the make and the female brain and not separated into two distinct categories

What is sex?

biological category based on appearance of external genitalia and hormonal influence (male/female)

What is gender?

societal constructed status to which one becomes assigned (male/female: girl/boy)

What are gender roles?

totality of social and cultural expectations for boys/girls: men/women in a particular society at a particular time in history

vary from one society to another

What is gender role ideology?

particular society’s general beliefs and norms regarding how girls and boys or women and men should be (behaviors, traits, etc)

What is core gender identity?

our innermost sense of ourselves as a girl boy, woman or man. A central component of our sense of “self”

What is gender-role socialization?

life-long process of acquiring norms of gender-appropriate behavior in a particular society — learning to be appropriately feminine or masculine

What is the main difference between male and female neuroanatomy and subsequent behavior?

sex hormones (estrogen/testosterone) — SRY TDF

What is growth and change throughout life like with hormonal exposure and experiences?

• birth

• puberty: (Clearly noticeable)

  • explosive growth

  • hypothalamus

    • gonadotrophin-releasing hormone (GRH)

  • children become sexually mature adults

  • testosterone/estrogen sparks reproductive system development

What is SRY?

• found in the male brain

• turned on differently in male/female brains in embryo

  • set in motion organs developed

• receptors in brain respond to hromones

• if gene or receptors in brain not functioning

• if no receptors — brain will not respond to male hormone

What are basic assumptions about male and female brains?

• more alike than different

• differ more within each sex than between sexes

• differences between anatomy (structure) & behavior are a result of hormonal influence

• the degree to which one’s brain is different also involves environmental, social, and cultural influences

What is an attachment?

• a lasting psychological connectedness between human beings

• an adaptive behavior - enhances survival