Midterm 3 Flashcards
1
Q
how many chromosomes does each human cell have?
A
46 chromosomes in 23 pairs, one pair of these chromosomes are sex chromosomes
2
Q
what is a chromosome?
A
a chain of DNA contained within the nucleus of all human cells
3
Q
gametes
A
- ovum (produced by ovaries) and the sperm produced by the male testicles
- contain only 23 chromosomes each
- ensures that when the egg and sperm get fertilized to form a baby, it contains 23 pairs and restores the total chromosomal count to 46
4
Q
chromosomes of gametes
A
- females have XX chromosomes while males have XY chromosomes
- males can generate sperm with either X or Y chromosomes
- ovum contain only an X chromosome
- the presence of the Y chromosome is responsible for trigger male development; in the absence of a Y chromosome, the fetus will undergo female development
5
Q
biological sex
A
- a scientific description of the reproductive anatomies that have evolved to fulfil the function of sexual reproduction
- sex is fundamentally defined by male and female reproduction anatomy called phenotypic sex, independent of humans and society
- for over 99.9% of people, the sex of a person as female or male is clear, determined at conception, and observable whether prior to birth (by chromosomal analysis or sonogram) or at birth
- in any individuals, reproductive anatomy is almost always unambiguously male or female and observed correctly at birth, regardless of ultimate sexual function or dysfunction
- does not meet the defining criteria for a spectrum
6
Q
disorder of sexual development (DSD)
A
- conditions in which chromosomal sex (XX or XY) is inconsistent with phenotypic sex (reproductive organs) or in which the phenotype is not classifiable as either male or female, occurs in 0.018% of population
- sometimes referred to as intersex
- most of these disorder are male or female-specific and do not cause ambiguous biological sex
- some individuals have reproductive anatomies with both male and female features; here, biological sex classification is a complex process with input from medical professionals and parents
7
Q
gender
A
a social construct
8
Q
prenatal development
A
- early development is controlled by genes, either follows normal development or inherited abnormal development
- the embryo or fetus is sensitive to extrinsic factors such as nutrients, viruses, drugs and physical activity
- a healthy fetus has the best chance of reaching its full genetic potential, including its potential for skill performance
- view physical growth and development as a continuous process that begins at conception
- individuals are, in part, products of the factors that affected their prenatal growth and development
9
Q
embryonic development
A
- period from conception to 8 weeks
- differentiations of cells to form specific tissues and organs
- limbs formed and heartbeat begins at 4 weeks
- human form noticeable at 8 weeks, eyes, ears, nose, mouth, fingers and toes are formed
- size of a bean by 8 weeks
10
Q
fetal development
A
- called a fetus
- period from 8 weeks to birth
- continued growth by hyperplasias (increase in cell number), and hypertrophy (cell size)
- cephalocaudal growth (head to toe), head and facial structures grow fastest, followed by the upper body and then by the relatively slow-growing lower body
- proximodistal (near to far), the trunk tends to advance, then the nearest parts of the limbs and finally the distal parts of the limbs
11
Q
fetal nourishment
A
- oxygen and nutrients diffuse between maternal and fetal blood in the placenta
- placenta will filter out some potentially harmful chemicals, viruses, but can’t filter out it all
- poor maternal health status can affect the fetus
12
Q
abnormal prenatal development
A
- congenital anomalies - a wide range of abnormalities of body structure or functions that are present at brith and are of prenatal origin
- the source of abnormal development can be genetic or external
- genetic: trisomy 21, aka down syndrome
- structural: congenital heart defects, often no clear cause, could be genetic, exposures, diet, or maternal disease
- external exposures: a teratogen is an agent or fact that causes abnormal prenatal development upon exposure, eg. Rubella virus, early exposure can lead to miscarriage, harmful is exposed during first 4 weeks
13
Q
external causes of abnormal development
A
- the placenta screens some substances (eg. large viruses) but not all harmful ones
- harmful environmental factors include pressure, temperature, X rays, pollutants
- tissues undergoing rapid development at time of exposure are most vulnerable
14
Q
physical growth
A
a quantitative increase in size
15
Q
development
A
- a continuous process of change in function capacity
- the ability to move, live and excel in the real world
- humans are always developing, but change may be more or less noticeable at certain points
16
Q
maturation
A
- the developmental process leading to a state of full function
- an adult like state
- maturation implies progress toward physical maturity, the state of optimal functional integration of an individual’s body systems and the ability to reproduce
17
Q
concepts of maturation
A
- two children of the same age can be dramatically different in maturation status, with one being an early maturer and the other being a late maturer
- two children of the same size can be different ages
- it is difficult to infer maturity from age alone, from size alone or even size and age considered together
- an individual child can appear small and slight of build but may be relatively mature for their chronological age
18
Q
postnatal development
A
- anthropometry is the science of the measurement of the human physical form
- growth is predictable and consistent but not linear
- overall growth follows a sigmoid (S-shaped) patterns: rapid growth after birth, followed by gradual but steady growth during childhood, then by rapid growth during early adolescence, and finally by levelling off
- anthropometric sex differences are minimal in early childhood, with boys begin very slightly taller and heavier
19
Q
height
A
- height follows a sigmoid pattern
- girls: peak height velocity occurs at 11.5 to 12 years, growth in height tapers off around 14, end around 16
- early maturing girls tend to be initially taller, but girls who mature later have a longer growth period and tend to consequently be taller in adulthood, similar tend occurs in boys
- average height girls: 5’3”, boys: 5’9”
- boys: peak height velocity occurs at 13.5 to 14 years, growth in height tapers off around 17, ends around 18
- long period of growth of males contributes to absolute height differences, they have an additional 2 years of growth
20
Q
weight
A
- weight follows a sigmoid pattern
- it is susceptible to extrinsic factors, especially diet and exercise
- people grow up and then fill out
- peak weight velocity follows peak height velocity ( by 2.5-5 months in boys, 3.5-10.5 months in girls)
21
Q
relative growth
A
- head-heavy, short-legged form at birth, some body parts need to grow faster
- in girls, shoulder and hip breadth increase at about the same rate
- in adolescence, boys increase in shoulder breadth
22
Q
menarche
A
- the first menstruation
- girls as a group mature at a faster rate than boys; they enter their adolescent growth spurt sooner and their secondary sex characteristics appear sooner
- in the past several decades, the average age of menarche has decreased to between 12 and 12.5 years, it was 16-17 years in the mid-1800s
- diet, sedentary behaviour, and low physical activity are thought to contribute by causing elevated estrogen levels
- higher income is associated with lower early menarche rates, but higher rates for late menarche
- factors that contribute to early menarche include risky sexual behaviour, obesity, diabetes, cardiovascular disease and breast cancer
23
Q
male puberty
A
- boys have no landmark comparable with girls’ menarche for puberty; the production of viable sperm is a gradual process
- age at voice break and age of first conscious ejaculation, which are late markers of puberty, occurring between ages 13.3 and 14.5
- age at peak height velocity (PHV), are alternative markers of puberty
- measurement of reproductive hormones in serum, urine or saliva
- existing data regarding the impact on obesity of puberty in boys are conflicting, some research shows delayed puberty seen in very lean as well as very obese boys
24
Q
Tanner and Marshall Scale
A
- scale assessing stage of male development
- stage 1: before any physical signs of puberty appear (age 9-10 average)
- stage 2: 11 years
- stage 4: 14 years, puberty obvious
- stage 5: 15 years
25
Q
extrinsic influences on postnatal growth
catch-up growth
A
- during periods of rapid growth, such as just after birth and in early adolescence, growth is particularly sensitive to alteration by environmental factors such as breastfeeding and nutrition
- catch-up growth: rapid physical growth of the body to recover some or all potential growth lost during a period of negative extrinsic influence, occurs once the negative influence is removed
- whether the child recovers some or all of the growth depends on the timing, duration, and severity of the negative environmental condition
26
Q
play
A
- important to healthy brain development
- allows children to create a world they can master, address fear, and practice adult roles
- undirected play allows children to learn how to work in groups, to share, to negotiate, to resolve conflicts, and to learn self-advocacy skills
- encouraging unstructured play will increase physical activity levels in children
27
Q
sex differences throughout childhood and maturation
brain development
A
- the prefrontal cortex matures 2 years later in boys, responsible for impulse control planning, self-regulation, decision-making and judgement
- cerebellum reaches full size for girls at 11 and boys at 15, modulates emotional, cognitive, and regulation capacity, in addition to balance/coordination
- chronological age is not the same as developmental age
- certain traits are more associated with one sex or the other
- distributions overlap look at the average expression of a trait in one gender, the biggest difference are at the tails of these distributions
- environment and culture matter greatly
- these difference have a relatively small impact on day-to-day life in the 21st century, we motivate people and development differently these days
28
Q
maturation and movement
A
- maturation status is a structural constraint influencing movement
- individuals who are more mature are likely to be stronger and more coordinated than those who are less mature, even at the same chronological age
- it is tempting to infer movement performance potential from size or age alone, but maturation status is a powerful predictor of performance potential
- periods of motor incoordination or “adolescent awkwardness,” may occur during the adolescent growth spurt, last approx. 6 months
29
Q
assessment of physiological maturation
A
- compare measurements with group norms
- the appearance of secondary sex characteristics or menarche
- skeletal changes and status
30
Q
skeletal maturation
A
- ossification is the hardening of the bones
- by comparing an x ray of skeletal maturations with a set of standards, developmentalists can assign individuals a skeletal age
- in early maturers, skeletal age is older than chronological age, and in late maturers skeletal age is younger than chronological
31
Q
adulthood and aging
A
- some measures of body size can change in adulthood
- these changes reflect the aging of tissue, and probably to a greater extent, the influence of extrinsic factors
- height is stable in adulthood but may decrease in older adulthood due to compression of cartilage pads and osteoporosis
- the average adult starts gaining weight in the 20s
- older adults sometimes lose weight due to inactivity and a consequent loss of muscle tissue, and loss of apetite
32
Q
jump height and maturation of developmental system
A
- specific systems of the body can create unique structural constraints
- height is a factor and a product of the body’s skeletal system
- strength is a factor and product of the muscular system
- the amount of adipose tissue influences body weight and thus how easily one can jump up
- the nervous system must coordinate the muscles to produce the jumping movement
33
Q
skeletal system
A
- defines an individual’ structure
- not hard and static; it is living tissue, there are 206 bones
- it undergoes considerable change over the lifespan and reflects the influence of both genetic and external factors
34
Q
muscular system
A
- allow skeletal movement
- more than 200 muscles permit a vast number of movements and positions
- changes over the lifespan under the influence of genetic and external factors
35
Q
adipose system
A
- adipose tissue plays a vital role in energy storage, insulation and protection
36
Q
endocrine system
A
- control over specific cellular functions through hormones such as metabolism, energy levels, reproduction, growth, and response to injury, stress and mood
37
Q
nervous system
A
- no single system is as much the essence of an individual
- the nervous system controls movement and speech, it is the site of thinking, analysis and memory
- its development is important for social, cognitive and motor development
38
Q
rate-limiting constraints
A
- a system that lags in development can be a developmental rate limiter
- muscular: ability to hold ourselves up
- skeletal: bone strength to support ourselves
- adipose: provide energy for activity
- endocrine: manage metabolism
- nervous: coordination of movement
39
Q
prenatal development: skeletal system
A
- prenatally, the embryo has a cartilage model of the skeleton
- ossification begins at primary centres in the mid portions of long bones, at around week 6 or 7 in the womb
40
Q
prenatal development: muscular system
A
- prenatal growth involves hyperplasia and hypertrophy
- muscles increase in diameter (hypertrophy) and length by the addition of sarcomeres
41
Q
muscle fibre type
A
- adult muscle is composed of type I (slow-twitch) and type IIA, IIX, and IIB (fast-twitch) fibres.
- at birth, 15-20% of fibres are undifferentiated.
- by age 1, distribution of muscle fibre type is similar to adult distributions: 50% ST and 50% FT
- exact proportions vary among individuals due to genetics and activities they engage in
42
Q
prenatal development; adipose system
A
- adipose tissue first appears in the fetus at about 3.5 months
- adipose tissue increases rapidly the last two prenatal months
- adipose tissue accounts for only about 0.5kg of body weight at birth
43
Q
prenatal development: endocrine system
A
- the interaction of hormones, genes, nutrients and environmental factors begins in utero
- the placenta produces its own hormones and serves as a barrier to prevent the mother’s hormones from flooding the fetus’ system
44
Q
prenatal development: nervous system
A
- the central nervous system includes the brain and spinal cord, contains neurons which act as messengers
- the peripheral nervous system is made up of nerves that branch off from the spinal cord and extend to all parts of the body
- neurons use electrical impulses and chemical signals to transmit information between different areas of the brain, and between the brain and the rest of the nervous system
- genes direct the development of structures, but the extrinsic factors fine-tune the system
- neurons proliferates in the early prenatal period at an astonishing rate of 250,000 per minute
- immature neurons are formed, made into a general types, and migrate to their final location, they proliferate at a rapid pace and most are formed by the 4th prenatal month
- recent research shows that mass migration occurs up to 3 months after birth, happening at the same time as the infant begins to interact with the environment
45
Q
childhood and adolescence: skeletal system
A
- intramembranous ossification occure to create the flat bones of the face, most of the cranial bones, and the clavicles
- compact and spongy bone develops directly from sheets of connective tissues, the area where the flat bone is to come
- on a baby, those spots are known as fontanelles, they are soft and spongy, helps to protect and cushion brain from impacts
- growth in bone length occurs at secondary ossification centres at the ends of bones called epiphyseal plates, growth plates or pressure epiphyses
- thin layers of cartilage disc entrapped at the distal ends of long bones
- endochondral ossification - when these areas of cartilage are replaced with bone, closing the plate
- increase in bone girth is called appositional growth
46
Q
cessation of bone growth
A
- bone growth stops at different times for different bones
- all typically close by age 18 or 19
- closure occurs at a younger age in girls, for example on average, the epiphysis at the head of the humerus closes in girls between 12 and 16 years but in boys 14 and 19 years
47
Q
childhood and adolescence: muscular system
A
- postnatal growth mainly involves hypertrophy
- muscle growth follows a sigmoid pattern
- differences between the sexes become marked in adolescence, especially in upper body musculature
48
Q
sex differences in muscular system
A
- muscle mass increases rapidly in boys up to about age 17 and ultimately accounts for 54% of men’s body weight
- girls add muscle mass only until age 13, average and muscle mass make up 45% of women’s weight
- the large sex differences in muscle mass involve upper body musculature more than leg musculature
- the rate of growth in arm musculature is nearly twice as high for males as for females, but the difference in calf muscle growth is relatively small
49
Q
childhood and adolescence: adipose system
A
- some fat is needed for energy storage, insulation and protection
- fat increases rapidly until age 6 months, then gradually until age 8
- in adolescence, girls increase fat more dramatically than boys do
- growth is by hyperplasia and hypertrophy, the latter more dramatic in adolescence
- individual variability is great
- individual fatness varies widely during infancy and early childhood
- a baby with a large amount of adipose tissue will not necessarily become a fat child
- after 7 to 8, it is more likely that individuals maintain their relative fatness
- an overweight 8 year old has a high risk of becoming an overweight adult
