Lifespan Exam 2

Neurons

Cells that transmit electrical signals in the brain and nervous system

Myelin Sheath

Protective fatty layer around axons that speeds up neural impulse transmission

Four lobes of the Brain

frontal, parietal, temporal, occipital

cerebral cortex

Outer layer of the brain responsible for higher level function

Prenatal Brain development:

25 days- Brain resembles that of a worm

40-50 days- resembles vertebrate brain

100 days- develops features of a mammal’s brain

5 months- looks like a primate brain

last 3 months- takes on human brain structure

Steps to brain formation:

1. ectoderm- outer cell layer that forms nervous system

2. neural plate- thickened region of ectoderm

3. neural tube- becomes brain and spinal cord

Proliferation

rapid production of neurons (250,000/minute)

Anencephaly

Condition where major parts of the brain fail to develop; often fatal

Microcephaly

Brain and head are abnormally small due to disrupted growth

Migration

Movement of neurons to specific brain locations guided by glial cells 

Synaptogenesis

formation of new connections (synapses) between neurons

Synaptic pruning

removal of weak or unused synapses to make neural communication more efficient 

Synaptic Density

total number of connections between neurons; peaks in early childhood and decreases into adulthood

Differentiation

neurons develop specialized functions depending on their location and purpose

Myelination

formation of myelin sheath around axons to improve communication; begins around 4 months after conception and continues through adolescence

Brain growth spurt

starts at 3 months before birth and last through first 2 years;

brain weight 25% at birth, 75% at 2 years, 90% at 4 years

Why brain grows

due to new synapses, dendrites, and increased neurotransmitter activity 

Lateralization

The specialization of the left and right hemispheres for different tasks (left= language, right= spatial processing)

Becomes more consistent with age

Functional specialization

different brain regions develop to handle specific functions

Prefrontal cortex

The CEO of the brain- controls executive functions such as decision-making, impulse control, planning, organization, and self monitoring

Undergoes heavy pruning during adolescence

Experienced-Expectant Plasticity

Brain expects normal sensory input during critical periods. Missing these experiences can cause permanent deficits.

Experiences-dependent plasticity

Brain changes and grows based on unique individual experiences

Binocular disparity

Combining slightly different images from each eye to perceive depth and distance; develops around 6-7 months

Normal structural changes

Neurons shrink but are not typically lost. Myelin and neurotransmitters decline, slowing processing speed

Alzheimer’s Disease

characterized by neuron loss, memory failure, and cognitive decline 

Neurogenesis in Older adults

new neurons continue forming in the hippocampus and olfactory bulb

Brain Compensation

Older brains may recruit additional regions to maintain performance

Newborn reflexes

survival reflexes- blinking , rooting, sucking

primitive reflexes- grasping, stepping (disappears after few months) 

REM sleep in Newborns

newborns- 50% REM

adults- 20% REM

REM sleep stimulates brain development 

Newborn sensory abilities (most to least)

Most developed senses: taste, smell, touch

Least develop senses: vision and hearing at birth

Visual Acuity Development

Newborn: 20/800-20/200

4 months: 20/60

6-12 months: 20/20

Color vision develops…

develops by 3-4 months

Depth Perception

Mature by 6-7 months

Hearing…

Infants prefer high-pitched sounds and human voices; locate sounds by turning their heads

Cephalocaudal Principle

Growth occurs from head to tail- head develops first

Proximodistal principle

growth proceeds from center of body outward

Growth pattern

Rapid growth in infancy to slower in childhood to rapid again in puberty

Pituitary gland

Master gland that releases hormones controlling growth and other glands

Hypothalamus

Regulates pituitary activity; helps coordinate hormonal balance

Hormonal function over time

Hormones can perform different functions at different life stages (ex. growth hormone shifts from bone growth to tissue repair in adulthood)

secular trend

generations in developed countries experience earlier puberty and greater height due to improved nutrition and health

Factors influencing puberty

Biological- genetics, body fat, hormones

environmental- nutrition, stress, family conflict, socioeconomic conditions 

Tither and Ellis study

Younger sisters in high-conflict homes reached menarche months earlier- stress can accelerate reproductive development 

Adverse Childhood Experiences include

Abuse, neglect, household dysfunction

Effects of ACE

higher risk of chronic illness, mental health problems, and risky behaviors in adulthood

Intergenerational transmission

Patterns of behavior and stress can pass across generations; positive interventions and coping strategies can break the cycle

Dynamic systems theory

motor development results from interactions between the child’s body, environment, and goals- learning through trial and error and feedback

what’s an example of the dynamic system theory

a baby learns to crawl by reaching for a toy; each attempt improves coordination

Visual cliff experiment:

tests depth perception and fear of heights in infants using an apparent drop off

Bone density peaks

peaks around 30-35, declines after 50

Estrogen loss..

after menopause accelerates bone breakdown which could cause osteoporosis risk

Osteoporosis

bones become porous and fragile, common after menopause

Osteoarthritis

degeneration of joint cartilage causing pain and stiffness

Aging of body systems affects…

vision, hearing, immune system, cardiovascular system, respiratory system, and reproductive system

Hows vision affected

lens become stiff, yellow, and cloudy, pupils shrink. trouble with glare and night vision, and reduced color sensitivity

Hows hearing affected?

Loss of high frequency sounds; caused by aging or loud noise exposure (loss of cochlear hair cells)

How’s the immune system affected

T-cells (virus defense) weaken with age, B cells depend on T cells so immunity declines overall

Hows cardiovascular affected

Heart and blood vessels stiffen, risk of hypertension, heart disease and stroke increases.

How Respiratory system affected?

Lungs lose elasticity, vital capacity decreases by 30% from age 30-80

Hows Reproductive system affected

Female- menopause around age 50, estrogen drop causes hot flashes, mood changes, and bone loss

Male- gradual decline in testosterone and sperm quality, prostate enlarges affecting urination 

Who was Jean piaget?

A psychologist who studied how children think and learn. He published scientific papers as a child and earned a PhD in biology before focused on cognitive development

How did Piaget become interested in child development?

He noticed children gave different reasoning than adults during lab interviews. which made him study how intelligence develops

What is paiget’s main idea about intelligence?

Intelligence is a form of adaption to the environment , just like physical adaptation. Humans adjust their thinking based on their experiences. 

What is the constructivist approach?

the idea that children actively build (construct) their understanding of the world through interactions with their surroundings

What assumptions did Piaget make about children’s nature?

1. children are actively mentally and physically from birth

2. they learn many important lessons on their own

3. they are naturally motivated to learn without external rewards

What is schema (or schemata)

A mental framework or structure that organizes and interprets experiences. Schemas develop from simple actions to abstract ideas

What is assimilation?

When new experiences are understood using existing schemas (ex. calling a zebra a horse)

What is accommodation?

When existing schemas are changed or new ones are created to fit new information (ex. learning that a zebra and horse are different animals)

What is equilibration?

the process of balancing assimilation and accommodation to reach stable understanding

What is equilibrium?

A state mental balance where your understanding fits you experiences

What kind of change is cognitive development?

it’s qualitative (changes in the type of thinking) not just quantitative. Development happens in stages 

Piaget’s four stages of cognitive development

sensorimotor stage, preoperational stage, concrete operational stage, and formal operational stage.

How infants learn during the sensorimotor stage?

Through sensory experiences and motor actions- touching, seeing, hearing, tasting, and moving. This happens from birth-2 years

What are key features of the sensorimotor stage?

learning through reflexes and actions

intentional behavior develops

understanding cause-and-effect

developing object permanence

What is object permanence?

the understanding that objects still exist even when they can’t be seen or heard

What is the difference between a reflex smile and a social smile?

newborns smile reflexively; around 6 months they smile socially in response to people or events 

What is fetal programming?

The process by which the prenatal environment can shape the structure and function of the fetus’s body and brain, influencing health outcomes later in life

What can cause fetal programming?

factors like maternal stress, nutrition, exposure to toxins, or infections can alter gene expression in the developing fetus

How can fetal programming affect health?

It can predispose individuals to diseases such as obesity, heart disease, and diabetes later in life.

What is prenatal diagnosis?

medical procedures used to detect developmental problems in the fetus before birth 

What are common prenatal diagnostic methods?

Ultrasound-uses sound waves to create images of the fetus

Amniocentesis- samples amniotic fluid to test for chromosomal or genetic conditions

chorionic villus sampling- tests placental tissue for abnormalities

What is noninvasive prenatal testing 

a blood test that examines fragments of fetal DNA in the mother’s bloodstream to detect chromosomal disorders like down syndrome 

What is CRISPR

a gene-editing technology that allows scientists to add, remove, or alter DNA sequences precisely 

Why gene editing controversial in prenatal testing?

Ethical concerns include unintended genetic changes, designer babies and long-term effects on future generations

What are the 3 stages of childbirth?

1. labor and dilation of the cervix

2. delivery of the baby

3. delivery of the placenta

What is the Apgar scale

a quick assessment of a newborns health at 1 and 5 minutes after birth, measures appearance, pulse, grimace, activity, and respiration 

Average newborn weight and length ?

about 7.5 pounds and 20 inches

When is baby considered premature?

when born before 37 weeks of gestation

What are some risks associated with prematurity

breathing difficulties, underdeveloped organs, feeding problems, and increased risk of long-term cognitive or behavioral challenges 

What are teratogens?

any environmental agent (drug, virus, radiation) that can harm a developing fetus

What factors determine the severity of teratogen effects?

dose, genetic susceptibility, timing of exposure, and type of agent

what is the critical period?

a specific time in prenatal development when an organ or structure is most sensitive to environmental influences

How does maternal stress impact fetal development?

chronic stress increases cortisol, which can lead to low birth weight, prematurity, and altered brain development. 

Why is prenatal care important?

it monitors fetal growth, reduces risk factors, ensures maternal health, and identifies complication early

what are newborn reflexes?

automatic, built in responses to specific stimuli that help infants survive and develop before voluntary control of movement emerges

What is the rooting reflex

when the baby’s cheek is touched, it turns it’s head and opens its mouth- helps find the nipple

What is sucking reflex

when something touches the baby’s lips they begin sucking- helps with feeding 

What is moro reflex

the startle reflex- when startled the baby flings arms out and then pulls them in as if grabbing for support

What is the grasping reflex

when the baby’s palm is touched, fingers close tightly around the object

What is the babinski reflex

stroking the sole of the baby’s foot causes toes to fan out and curl- disappears as the nervous system matures