Week 15 Flashcards
Germinal period
The first two weeks after the sperm and egg unite
Gamete
A mature male or female cell used for reproduction
Haploid cell
A cell that contains only one set of a chromosome (egg and sperm)
Zygote
The product when a male and female gamete merge
Diploid
A cell that contains both sets of chromosomes, they are produced when the egg and sperm come together
Cleavage
The process that occurs during the germinal period where the zygote cell clones itself multiple times and is held together in a spherical shape
Morula
The product after a zygote undergoes cleavage multiple times
Epigenetic modification
Changes in cell inheritance that are not due to alterations in the sequence of DNA nucleotides. It allows some genes to be turned on and off, which leads to different proteins being expressed, thus causing different cellular properties and functions
Stem Cells
cells that have the same DNA as every other cell but has not undergone epigenetic modification
Androgens
In the absence of androgens, the fetus becomes female
Blastocyst
The process that a fertilized egg reaches after five to six days of fertilization
Inner cell mass
The cell mass inside the morula that eventually becomes the embryo
Trophoblast
The cells in the outerlayer that protects the inner cell mass and transmits nutrients
Embryo
An organism at its early stage of development
Embryonic period
begins after the implanation in the uterine wall and lasts about eight weeks
Amniotic Sac
Sac filled with liquid where the embryo resides
Placenta
Attached to the inside of the amniotic sac and transfers nutrients and acts as a filter and protective barrier for the organism
What are the three layers the embryo is separated in the Embryonic stage?
Endoderm, mesoderm, ectoderm,
Endoderm
The innermost layer that eventually becomes the digestive system, urinary tract and lungs
Mesoderm
The middle layer that becomes the muscles, bones, and circulatory system
Ectoderm
The outermost layer that becomes the skin, teeth, hair and CNS
Neurelation
occurs when the three cell layers differentiate and the newly formed tube (neural tube) starts to develop into the brain and spinal cord
Neurogenesis
the growth of new neurons (occurs 6-7 weeks after conception)
Neural migration
the process where neurons move, grow, and connect as the basic neural tube develops into a more mature brain
What is the function of genetic instructions?
It tells neurons how to connect as they develop
What influences migration?
timing, location of neurogenesis, interaction with glial cells, etc.
What are the two patterns embryonic development stage can follow?
Cephalocaudal and Proximodistal
Cephalocaudal
development that occurs most intensely at the head and proceeds downward toward the body
Proximodistal
proceeding from the center of the organism outward
Apoptosis
A process of death that is genetically programmed and is required for normal development
The foetal period
- Continues from the ninth week until birth
- After one month, the majority of the organs are developed
- The foetus makes breathing motions as early as ten weeks
- At the end of the fourth month, sleep and wake patterns begin to emerge
- Spontaneous movements are essential to the development of typical nerve and limb growth
- During the fifth month, the vestibular system (required for balance) starts to develop
o The foetus becomes responsive to sound - From six-eight months of ion development, the spontaneous movement decreases which is necessary for the growth of inhibitory neural pathways throughout the body
- The foetus experiences taste and it’s heartbeat changes in response to light stimulation through the mother’s abdomen
What are some factors that affect development?
Stress, nutrition, malnutrition
How does stress affect development?
High levels of stress increases the risk of miscarriage, premature birth and higher rate of illness. High stress can also lead to high levels of aggression, anxiety and depression after birth
How does nutrition affect development?
The food the mother eats is the only food the growing embryo gets. Health foods that contain vitamins, minerals, etc. help brain development and prevent some birth defects
How does malnutrition affect development?
Those affected by famine and poverty have babies that are underweight, deformed, and have a high risk of developing disease for the rest of their life
Teratogens
external compounds that can cause extreme deviations from normal development if introduced to a developing organism
What will the effects of teratogens depend on?
timing, amount, the mother and foetus, and length of exposure
What are some common teratogens
alcohol, cigarettes, prescription drugs, and serious diseases
Alcohol
prenatal exposure to alcohol can cause Foetal Alcohol Spectrum Discorder which is the highest cause of mental retardation. The effects can be minor such as slight behavioural disturbances or major such as facial deforms
Cigarettes
Nicotine causes abnormal development of the placenta
Babies of mothers who smoke have a higher risk of sudden infant death syndrome, lower IQ and behavioural problems
Prescription drugs
certain drugs can affect infants during their development
Serious disease
If the foetus is affected by diseases during development, it can have a devastation effect.
Reflexes
Important to infant for survival as well as indicating typical neural development, such remain until death while others disappear
Babinski reflex
the automatic response an infant gives when they have their foot stroke, where they fan and curl their toes
Tonic neck reflex
When an infant turns their head to one side, extend the arm on the same side as their gaze, and flex the arm and knee on the opposite side of the body
Moro reflex
Infants will automatically try and grab something when they feel themselves dropping unexpectedly
Grasping reflex
infants will automatically close their hands when anything presses against their palms
Pre-reaching reflex
When an infant makes an awkward and poorly guided arm movement toward interesting stimuli, around three months they will learn intentional grasping
Motor milestones
- Infants are able to sit up unsupported at around 6 to 7.5 months
- By 9 months they are able to pull themselves up and stand with support
- By 10 months, most infants can use furniture to move around
- By 12-13 months they can walk unsupported
- By 16 months, they are able to pick things up while walking or walk up the stairs without help
- By the age of 2, they are able to run and kick, eat with utensils, drink from cups and open doors for themselves
Synaptogenesis
The process where new synapses are formed
it allows the brain to grow and form new connections
Synaptic pruning
The selective elimination of neuronal synapses, by removing certain ones, it increases efficiency in our brain
Experience-dependent pasticity
The ability of the nervous system to wire and rewire itself in response to lasting changes in experience
Experience-expectant plasticity
development that will not happen unless a particular experience occurs during its critical period
Amblyopia
The loss or lack of development of central vision in one eye that is unrelated to any eye health problems and can’t be corrected by lenses
Mylelination
The development of the myelin sheath around neurons
Myelin
insulates the electrical activity of neurons from each other and makes them more efficient
Why do teenagers do stupid things?
one of the final areas to finish myelination is the dorsolateral prefrontal cortex which is responsible for controlling impulses, planning complex actions, forseeing consequences and working memories
Executive functioning
Functions that control and regulate our behaviour
Puberty
the time at which the human body begins to enter sexual maturity, marking the beginning of adolescence
What is the first sign of puberty?
Growth spurts
When does puberty begin?
When the hypothalamus starts secreting hormones that stimulate the gonads to mature further and secrete sex hormones, thus causing rapid development of our sex organs
What does estrogen do in females?
causes breasts and hips to grow along with the maturation of the uterus and vagina
What does testosterone cause in females?
The development of public hair and physical growth
What does testosterone do in males?
The growth of pubic hair and muscle mass, hearts and lungs
What is menarche?
a female’s first menstruation that occurs after the first growth spurt
What does estrogen do in males?
cause natural sexual maturation
What is early menarche associated with?
depression, substance abuse, and risky sexual behaviour
What is semenarche
the first time males ejaculate
What is late maturation associated with in boys?
lower academic performance
When does muscle strength peak?
During our late twenties and early thirties, after that, they start to decline as they deteriorate
What happens during our early forties or fifties?
A decline in sensory experience
When does peak fertility happen
between twenty and twenty five, after that they decrease
Menopause
The permanent end of menstruation and a women’s fertility
Dementia
refers to disease that cause a decline in mental function, including memory
Parkinson’s disease
Causes tremors, loss of spontaneous movement, rigidity, and disrupted posture
Chronological age
How long we’ve been on this earth
Biological age
genetic makeup and lifestyle factors
How does telomeres affect aging?
Those with shorter telomeres are prone to aging quicker
What are some factors in aging?
telomere shortening, chronological age, oxidative stress, and Glycation
Oxidative Stress
oxidants damage DNA, proteins and lipids
Glycation
Glucose sugar binds to and inhibits DNA, proteins and lipids
What are the diagnostic criteria for dementia?
multiple cognitive deficits, including memory impairments, and one or more of the following: Apraxia, agnosia, and disturbance in executive functioning
What are the two general states for children
Dissociative state and fear state
Dissociative state
oppositional defiance disorder and depression
Fear State
persistent hyper arousal symptoms, combative and aggressive
