child growth and development Flashcards
(33 cards)
patterns of growth and development
most rapid rate in the weeks following birth
rate declines during early childhood
final growth spurt at puberty
males- 12.5 to 15 years old
females- 10.5 to 13 years old
brain, skull, eyes and ears growth and development
develop much earlier than other parts
relative proportion of head to body decreases with age
lymphoid tissue growth and development
growth reaches a max just before puberty
thymus atrophies after puberty
thymus in children is well developed structure- vital in development of immune system
reproductive organ growth and development
these develop markedly during puberty
triggering sexual development
triggered by GnRH from hypothalamus
stimulates LH and FSH in APG
stimulates oestrogen and progesterone in women and testosterone in men
GnRH is essential for normal adult sexual physiology
effects of oestrogen and progesterone
O= causes cellular proliferation and growth
reproductive: increase in size of ovaries, uterus and vagina
development of breast
growth of pubic hair
broadening of pelvis
enlargement of external genitalia
nonreproductive: help keep bone strong (inhibit osteoclasts)
causes closure of epiphyseal plates
increased subcutaneous fat deposition (boob, thigh and ass)
lower cholesterol
P= continues prep of endometrium for possible preg and promotes development of breast (act on alveolar cells)
the menopause
ovulation and menstruation become irregular and finally stop
oestrogen levels drop to 1/10 of what it was before
inhibitory effects of oestrogen on the hypothalamus is restricted = hot flushes/ night sweats and irregular cycles
FSH and LH levels rise
physiological changes:
- hot flushes/ heavy sweating
- atrophy of uterus, vagina, ovaries and breasts
- decline in bone mineral density
- headache/ hair loss etc
effects of testosterone in males
puberty: increase size of dick, scrotum and balls
essential for sperm production
responsible for secondary sexual characteristics:
- deep voice
- male pattern hair growth
- sex drive
- muscle and bone growth
male reproductive aging
more subtle than females
can retain capacity into 80s/90s
decline in test synthesis causes:
- reduced muscle strength
- fewer viable sperm
- reduced sexual desire
what factors regulate bone growth
dietary intake
physical activity
hormones
genetics
bone growth and development
growth in bone length occurs in epiphyseal plate
growth in width of long bones occurs by appositional growth (on external surface)
bone remodelling 3-7% of total bone mass is recycled each week
dietary regulation of bone growth
minerals:
forms and strengthens bone ECM
- Ca and P= make bone ECM hard
- Mg= help form bone ECM
- F= help strengthen bone ECM
- Ma= activates enzymes involved in synthesis bone ECM
vitamins:
A= stimulate osteoblast activity
C= synthesis of collagen
D= absorption of Ca in gut
K and B12= synthesis of bone proteins
synthesis of vitamin D
1,25 dihydroxy vitamin D is the active form
precursors obtained by from the diet
or catalysed by sunlight in the skin
vitamin D deficiency
rickets:
- weight bearing bones bend
- deformities of pelvis and rib cage
physical activity regulation of bone growth
mechanical stress important for bone strength
- causes increased osteoblast activity= increased deposition of bone
- if no mechanical stress- bone reabsorption occurs more rapidly than formation
if bedridden, loss of bone can be 1% per week
athletes have thicker and stronger bones
high impact intermittent strains cause more deposition i.e running, jumping
trabeculae at arranged along lines of stress
can absorb compressive loads
remodelled in response to changes in activity
hormonal changes of bone growth (childhood)
GH:
- secrete by APG
- stimulate bone formation (osteoblasts)
- directly stimulates chondrocytes= increased deposition rate of cell differentiation
- increase bone mass in adult
- increase levels of IGF1+2 (insulin- like growth factors 1 and 2)
= excess GH= acromegaly and gigantism
thyroid hormone:
- produced by thyroid gland
- promote bone growth (stim osteoblasts)
insulin:
- secrete from pancreas
- promote bone growth by increasing synthesis of bone proteins
hormonal changes of bone growth (puberty)
gonadal steroids: important in normal bone growth and dev and well as the dev of peak bone mass
oestrogen:
- shut down growth at epiphyseal plate
- reg bone formation and re-absorption
- principal circ hormone in females but all in males (dev bone strength)
androgens e.g. testosterone:
- responsible for bone strength in males
hormonal control of bone growth (calcium homeostasis)
PTH:
- increases blood calcium levels
- stimulate osteoclasts bone reabsorption in response to low calcium blood plasma
- PTH stimulates renal production of vitamin D (help calcium absorption in gut)
calcitonin:
- produced by cells in thyroid gland
- decreases blood calcium levels if too much
- inhibits osteoclastic activity
hypocalcaemia and hypercalcaemia
HYPO: causes heart to slow down or beat too rapidly
muscle got into spasm
confusion and coma
HYPER: depression of nervous system
muscle weakness
fatigue
cardiac arrhythmias
normal aging
probable upper limit is 110 years
aging is the sum of all the changes that take place in your body over time
- eventually leads to functional impairments/ death
- increased vulnerability to stressors
- gradual inability to respond to physiological challenges
causes of aging
- accumulation of toxic metabolites
- endocrine changes
- free radical damage
- accumulation of errors in general material
rate of aging genetically determined but very dependent on environmental factors
glucose regulation in aging
glucose tolerance is reduced due to reduced tissue sensitivity for insulin
type 2 diabetes is common with diabetic complication
kidney function in aging
glomerular flirtation rate decreases with age
can result in delayed elimination of some drugs
in very elderly:
- tubular damage results in kidney being less back to concentrate urine
- susceptible to dehydration
aging muscles
muscle mass decreases (sarcopenia)
need to exercise to maintain muscle mass
