Adolescents and Adulthood Flashcards

Age Group Revisited

• Pre-Adolescence: The period of life before puberty.
• Adolescence: The period between childhood and adulthood, generally between 10-18 years, though the onset and termination are highly variable.
  • Males: 10-22 years
  • Females: 8-19 years
• Adulthood: Age 20 to death
  • Young Adult: 20-40 years
  • Middle Age: 40-65 years
  • Older Adult: 65 years to death

Adolescents and Adulthood

• Adolescence:
  • Characterized by:
    • Body systems reaching maturity (structurally and functionally).
    • Sexual maturity.
    • The timing and tempo of changes are highly variable between individuals and sexes.
• Adulthood:
  • Characterized by:
    • Attainment of full maturity.
    • Peak performance and development.

Proportion Changes

• Head: x 2
• Arms: x 4
• Trunk: x 3
• Legs: x 5

Sitting Height/Stature Ratio

• Relative leg length and trunk length.
• Infants have smaller legs.
• Lower extremities grow faster than the trunk during childhood and adolescence.
• Late adolescence trunk grows after leg growth has ceased.
• Females generally have shorter lower extremities than males.

Shoulder to Hip Ratio

• Biiliocristal Breadth to Biacromial Breadth ratio.
• Breadth of hips compared to shoulders.
• Ratio higher in females, indicating females hips make up a greater % of their shoulders.
• Males ratio declines as shoulder increase in size faster and greater than their hips.

Velocity Curve for Height

• Depicts the rate of growth in height over age for both boys and girls.
• Shows phases:
  • Acceleration
  • Deceleration
  • Initiation of Adolescent spurt.
  • Termination of Growth
• Peak height velocity (PHV): Maximum rate of growth in stature.

Adult Stature Differences

• Primarily due to boys experiencing approximately 2 years more of preadolescent growth than girls.
• Males grow at approximately $5 cm/year$ before the adolescent growth spurt, resulting in approximately $10 cm$ of growth that females do not experience.
• Males have a higher peak.
• Testosterone increases $Ca^{2+}$ deposition, promoting bone growth.
• Mid-growth spurt during childhood (6.5-8.5 years), more common in males but not always apparent.

Attainment of Adult Stature:

• Growth can continue into mid-20s.
• Annual increment of less than $1.0 cm$.
• Four successive months increments of less than $0.5 cm$.

Bone Composition

• Bone Matrix:
  • 35% organic
    • Collagen and Proteoglycans
    • Flexible strength
  • 65% inorganic
    • Minerals = calcium and phosphate
    • Weight-bearing strength
• Bone Cells:
  • Osteoblasts
    • Bone-forming cells
    • Produce organic material
  • Osteocytes
    • Osteoblasts surrounded by bone matrix
  • Osteoclasts
    • Bone-destroying cells
    • Reabsorption or break-down

Growth in Bone Length

• Occurs at the Epiphyseal Plate, which include:
  • Zone of Resting:
    • Chondrocytes do not divide.
  • Zone of Proliferation:
    • Chondrocytes produce new cartilage.
  • Zone of Hypertrophy:
    • Chondrocytes produced in the Zone of Proliferation enlarge and mature.
  • Zone of Calcification:
    • Hypertrophied chondrocytes die, blood vessels from the diaphysis grow, osteoblasts deposit new bone matrix.
• Reach adult size when the Epiphyseal plate ossifies and becomes a line.

Growth in Articular Cartilage

• Articular cartilage at the end of the bone grows similarly to inside the bone.
• No clear cut zones.
• Outer cartilage similar to zone of resting.
• Inner cartilage calcifies and ossifies.
• When it reaches full size bone stops replacing cartilage.
• This cartilage doesn’t become ossified unlike the epiphyseal plate.

Bone Growth

• Bone is deposited by osteoblasts on the outer surface.
• Bone is reabsorbed by osteoclasts on the inner surface.

Velocity Curve for Weight

• Depicts the rate of change in weight during adolescence spurt
• Weight-for-stature is not accurate during the adolescence growth spurt, as generally height increases followed by weight.

Human Physique & Somatotyping

• Somatotyping is a system of classifying body types in terms of three categories:
  • Endomorphy (relative fatness)
  • Mesomorphy (relative musculoskeletal robustness)
  • Ectomorphy (relative linearity or slenderness of a physique)
• Classified on a scale from 1 to 7 (though higher ratings are possible) in each of the three categories.
• The three numbers together give a somatotype number, with the Endomorphy score first, then Mesomorphy and finally Ectomorphy (e.g. 1-5-2).
• The scores may also be plotted in a shield diagram or somatograph, representing the somatotype on a two-dimensional scale.

Ectomorphy

• Ectomorphic characteristics would be:
  • Tall and thin
  • Narrow body
  • Thin arms and legs
  • Little body fat
  • Wiry muscles
• The calculation for the ectomorphy rating is based on the measurements of:
  • height
  • weight and
  • height/weight ratio

Mesomorphy

• Mesomorphic characteristics would be:
  • Strongly built
  • Broad muscular chest and shoulders
  • Very muscular arms and legs
  • Little body fat
• The calculation for the mesomorphy rating is based on the measurements of:
  • height,
  • breadths of the humerus and femur
  • girths of the biceps (flexed and relaxed) and calf
• The girths are corrected for body fat using the skinfold measure.

Endomorphy

• Endomorphic characteristics include;
  • Stocky
  • Large round body
  • Short thick neck
  • Short arms and legs
  • Tendency to store body fat
• The calculation for the endomorphy rating is based only on;
  • the sum of 3 skinfolds (triceps, subscapular, supraspinale), corrected for height.
• Therefore, the higher the skinfolds, the higher your endomorphy score.

Puberty

• Puberty = the period of time in which secondary sex characteristics.
• Characterised by:
  • Accelerated body growth
  • Rapid growth of the gonads
  • Increased production of gonadal hormones
  • External genital development in boys
  • Breast development and menarche in females
  • Pubic hair in both sexes
  • = Attainment of the capacity to procreate
• The hypothalamic-pituitary-gonadal axis secretions throughout Infancy and Childhood are low
  • Possibly due to inhibition of neurons = low GnRH
• During puberty there is a marked increase in production of sex steroids/hormones
  • GnRH = increase in LH and FSH

Puberty in Females: Associated Hormones

• Estrogen (feminizing hormone)
  • Growth of ovaries and secondary sex characteristics
  • Stimulates GH = increase in height and pelvic widening
  • Stimulates fat deposition on the hips, thighs, buttocks and breasts
  • Supresses FSH and LH
• Progesterone
  • Acts on the uterus to prepare for fertilization
  • Supresses FSH and LH
• Inhibin
  • Supresses FSH

Manifestations of Puberty in Females

• Thelarche: Breast Development
  • Formation of lobules and ducts by estrogen, progesterone, and prolactin
  • Completion by glucocorticoids and GH
  • Adipose tissue and fibrous tissue enlarge the breast
• Pubarche: Pubic and axillary hair growth
  • Stimulated by androgens from the ovaries and adrenal cortex
• Menarche: 1st episode of menstrual bleeding
  • Occurs between age 11 and 16
  • Less that 17% body fat can delay this event (consider dancers and gymnasts)

Follicle Development

• Gamete = sex cells (sperm cell or oocyte)
• The number of primary oocytes females are born with is the maximum they will ever have
• Birth to Puberty
  • Primary Oocyte -> Primordial follicle
• Puberty Begins: Growth of Granulosa cells
  • Primordial follicle -> Primary follicle
• Cyclical hormonal changes
  • Primary follicles -> Secondary follicle
• Secondary follicle continues to enlarge -> Mature follicle

Ovulation

• Ovulation = the secondary Oocyte is released
• Fate
  • Pregnancy
    • Remaining granulosa cells -> corpus luteum cells
    • Secretes progesterone and small amounts of estrogen
    • Remains active throughout pregnancy
  • No fertilization
    • Corpus Luteum remains active for 10-12 days then degenerates -> corpus albicans

Menstrual Cycle

• Typically a 28-day cycle.
• Follicular Phase: Development of follicles.
• Proliferation Phase: Of the Uterine mucosa.
• Luteal Phase: Existence of the corpus luteum.
• Secretory Phase: Maturation and secretion by uterine glands.

Ovarian Cycle

• Events in the ovaries
• Events prior to ovulation
  • GnRH secretion = éFHS – stimulates the granulosa cells
  • é LH – stimulates the theca interna cells
  • = follicle growth and maturation
• During follicle maturation, there is an increase in estrogen levels prior to ovulation
• Maturing follicles will secrete Inhibin = ê in FSH
• Increased estrogen = +ve feedback on LH and FSH
• LH surge initiates ovulation + generation of corpus luteum

Post-Ovulation

• After ovulation = ê estrogen
• Corpus luteum secretes progesterone = é in levels
• Progesterone and estrogen provide – ve feedback on GnRH = ê in LH and FSH
• No fertilization = degeneration of the corpus luteum
• = ê in estrogen and progesterone = menses

Uterine Cycle

• Changes in the endometrium of the uterus.
• Primary purpose to prepare to lining of the uterus to create a suitable environment for a fertilized egg.
• After menses, the remaining Endometrium epithelial cells of the uterus begins to proliferate (divide and replace old cells)
• Caused by estrogen
• Also increases progesterone receptors
• Cells become columnar and create folds = tubular spiral glands
• Spiral arteries project and supply nutrients

Uterine Cycle Continued

• 7 days after ovulation the uterus is prepared
• Progesterone from the corpus luteum causes endometrium cells to become secretory
• No fertilization = degeneration of corpus luteum = low levels of estrogen and progesterone = degeneration of lining
• Spiral arteries constrict due to low progesterone = arteries become ischemic and necrotic = base of spiral glands die

Puberty in Males

• 12-14 years of age
• Before puberty small amounts of testosterone inhibits GnRH
• Puberty = Increase in GnRH
• Increase in FSH and LH
• Testosterone still provides negative feed-back to hypothalamus but doesn’t completely inhibit
• Inhibin inhibits FSH

Testosterone

• Responsible for:
  • Maturity of the male genitals
  • Sperm cell production
  • Hair growth
  • Skin to become rougher and darker
  • Increases Sebaceous gland secretion
  • Hypertrophy of the Larynx and change in voice
  • Simulates metabolism
    • Higher rate compared with females
  • Increases erythropoietin production = increase in RBC
  • Greater % of body weight is muscle mass compared with females
  • Rapid bone growth = increased height
  • Stimulates the ossification of epiphyseal plate = reach maximum height quicker

Hormonal Sex Differences

• Males = high levels of testosterone and lower levels of estrogen, opposite for females
• Male hormones are secreted continuously and simultaneously whereas females have a more cyclical and sequential secretion

Cardiovascular Alterations

• Stroke Volume (SV) increases as we grow
  • Pre-adolescent growth spurt = $40 ml$
  • Growth spurt = $60 ml$ at rest
  • Untrained adult male = 70-80 ml
  • Trained aerobically = 100-110 ml
  • During exercise
    • Untrained = 110-120 ml
    • Trained = 200 ml (ave = 150-170ml)
• Heart Rate decreases as we age
  • Decline by 50% from birth to maturity
  • Late adolescents
    • Males = 57-60 bpm
    • Females = 62-63 bpm
  • Young adulthood
    • 20 yrs = 75-79bpm
• Max HR
  • Decline in maximal HR ~$0.8 beats/min/year$ independent of gender
  • $Max HR = 220 - age$
• Cardiac output
  • Adults at rest = 5 L