Principles of growth Flashcards
1
Q
What non-pathological influences are there on growth?
A
- Familial factors - taller parent -> taller child
- Environmental - passive smoking, stress, altitude
- Seasonal - better growth during summer
- Age, sex, puberty
2
Q
What happens during the first trimester?
A
- Day 1 - Fertilisation
- Day 2 - Cleavage
- Day 3 - Compaction
- Day 4 - Differentiation
- Day 5 - Cavitation (ICM)
- Day 6 - Zona hatching
- Day 7 - Implantation
- Day 9 - ICM differentiation
- Day 12 - Bilaminar disc formation
- Day 12 - mesoderm formation
- Day 18 - mesoderm spreading
- Day 23 - amniotic sac enlargement
3
Q
What happens during weeks 10-12?
A
- Foetus starts developing
- Eyelids close and wont reopen until 28th week
- Tooth buds appear
- Limbs are long and thin
- Foetus can make a fist with its fingers
- genitals appear well differentiated
- RBCs are produced by the liver
- Heartbeat can be detected by US
4
Q
What happens during weeks 13-16?
A
Main development of external genitalia is completed
5
Q
What happens at 22 weeks?
A
- Foetus reaches a length of 28cm and weighs 500g
- Eyebrows and lashes are well formed
- Eye components are developed
- Foetus has startle reflex
- Footprints and fingerprints continue forming
- Alveoli are forming in lungs
6
Q
What happens at 24 weeks?
A
- Foetus = 38cm long and 1.2kg
- Nervous system develops enough to control some body functions
- Eyelids open and close
- Cochlea now developed - myelin sheaths in neural part of auditory system continue to develop
- Resp system is still immature but can carry out gas exchange
7
Q
What happens at 30 weeks?
A
- Foetus = 38-43cm long and weighs about 1.5kg
- Body fat increases
- Rhythmic breathing movements, but lungs arent fully mature
- Thalamic brain connections, with mediate sensory input
- Bones fully developed but still soft
8
Q
What happens at 34 weeks?
A
- Foetus = 40-48cms, weighs 2.5-3kg
- Lanugo begins to disappear
- Body fat increases
9
Q
What happens between 35 and term?
A
- Foetus is considered full-term at end of 39th week
- 48-53cm
- No lanugo except upper arms and shoulders
- small breast buds present on both sexes
10
Q
What growth factors affect foetal life?
A
- IGF1,2
- Foetal insulin (modulates expression of IGF)
- Foetal glucocorticoid - tissue differentiation and prenatal development of organs such as lungs (maturation of surfactant) and liver (control of glycaemia)
- TH
- GH
11
Q
What is Karlberg’s ICP model?
A
- Infancy, Childhood and puberty model
- breaks down growth mathematically
- provides an improved instrument for detecting and understanding growth failure
12
Q
How does the ICP model describe childhood growth?
A
- At infacy you have an explosive growth spurt – do about half of height growth in first 2 years
- Childhood growth is a lot more steady – roughly around same amount each year between 4 and 11/12
- In puberty it jumps up again
- Levels off after puberty because epiphyseal plates stop growing
13
Q
What factors does the ICP model take into account?
A
- At first, in early life, most of the growth is down to nutrition
- At infancy and childhood – Nutrition, GH and IGF-1 come in to factor growth
- Puberty is a mix of GH and Sex hormones – cause a spurt in growth
14
Q
What is the hormonal influence of the HPA on the growth plates?
A
- GH released by the pituitary can act directly on growth plates on GH receptors
- Can also act with other factors such as binding proteins
- GH causes liver production of IGF-1, which regulates GH production, but also acts on the bone
- Somatostatin (GHIH) decreases GH
- Ghrelin increases GH production
15
Q
What is the pattern of GH secretion?
A
- GHRH has a pulsatile release - highest in morning and night
