L12: Growth and development

Question 1

4 phases of growth

Answer 1

intrauterine
infancy
childhood
pubertal

Question 2

3 ways cell grow

Answer 2

hypertrophy
hyperplasia
volume of intracellular material

Question 3

when does apoptosis happen in fetal development

Answer 3

webs of fingers

formation of hollow organs

Question 4

when is foetal growth greatest

Answer 4

16-20 weeks

Question 5

when does fat deposition primarily occur in gestation

Answer 5

last weeks

Question 6

when is peak velocity of foetal weight gain greatest

Answer 6

34 weeks

Question 7

what happens to growth after 34 weeks

Answer 7

rate of growth gradually declines

Question 8

senescence=

Answer 8

ageing

Question 9

when is ossification of cartilage completed by

Answer 9

3rd decade

Question 10

what growth is responsible for increasse in height during childhood and adolescence

Answer 10

long bone growth

Question 11

how do long bones grow

Answer 11

proliferation and hypertrophy of chondroblasts lying beneath growth plates

Question 12

what cells then extend into the diaphysis of bone

Answer 12

chondrocytes

Question 13

what happens after puberty to growth plates

Answer 13

the growth plate thins and is replaced by bone

epiphysis and diaphysis fuse

Question 14

where is GH produced

Answer 14

anterior pituitary gland

Question 15

what are the indirect actions of GH mediated by

Answer 15

insulin-like growth factors (IGFs) or somatomedins

Question 16

2 principal IGFs

Answer 16

IGF-1

IGF-2

Question 17

where are IGFs made

Answer 17

liver 
kidneys 
muscle 
cartilage 
bone

Question 18

before birth how is IGF-1 secreted

Answer 18

independant of GH

Question 19

after birth how is IGF-1 secreted

Answer 19

stimulated by GH

Question 20

how is IGF-2 secreted

Answer 20

largely independant of GH

Question 21

what happens with overexpression of IGF-2 in foetuses

Answer 21

disproportionate growth of tongue, muscles, kidney, heart and liver

Question 22

highest conc of IGF-1 in

Answer 22

puberty

Question 23

name 5 other growth factors

Answer 23

T3, T4
prolactin 
placental lactogen 
PTH 
oestrogen/ testosterone

Question 24

when does T3 and T4 secretion begin

Answer 24

15-20 weeks gestation

Question 25

what can inadequate levels of thyroid hormone during late foetal development and early prenatal periods lead to

Answer 25

severe mental retardation (cretinism)

Question 26

excess cortisol leads to

Answer 26

inhibitory growth actions

Question 27

do GH or IGF-1 levels drop in corticosteriods use

Answer 27

no

Question 28

would GH correct retardation in corticosteriod treated children

Answer 28

no

Question 29

what can corticosteriod treatment lead to

Answer 29

osteoporosis

Question 30

what is your growth spurt due to

Answer 30

interactions between sex steriods GH and IGF-1

Question 31

in girls GH secretions causes

Answer 31

oestradiol-17 beta from ovaries

Question 32

in boys GH secretion causes

Answer 32

testosterone from leydig cells

Question 33

what limits bone growth at end of puberty

Answer 33

epiphyseal fusion

Question 34

what triggers GH release

Answer 34

GHRH

Question 35

what inhibits GH release

Answer 35

somatostatin

Question 36

pattern of GH secretion

Answer 36

in pulsatile bursts in slow wave (deep sleep)

Question 37

how does IGF-1 effect GH release

Answer 37

inhibits GH release by suppressing somatotrophs

Question 38

achondroplasia=

Answer 38

a common form of dwarfism in humans

Question 39

mutation in achondroplasia

Answer 39

chromosome 4 that codes for fibroblast growth factor receptor 3

Question 40

mutation in achondroplasia leads to

Answer 40

decreased endochondral ossification chondrocyte proliferation inhibition decreased cellular hypertrophy

Question 41

what develops normally in achondroplasia

Answer 41

other organs -normal intelligence

Question 42

acromegaly =

Answer 42

hyper-secretion of GH

Question 43

what most commonly causes acromegaly

Answer 43

adenoma of pituitary somatotroph cells

Question 44

What does GH deficiency in childhood suggest

Answer 44

pituitary dwarfism

Question 45

what can GH deficiency be accompanied by

Answer 45

under secretion of other pituitary hormones

Question 46

hypopituitary dwarfism can be caused by

Answer 46

``` pituitary or hypothalamic tumours infection infarction vascular malformations head trauma ```

Question 47

normal proportions in which dwarfism

Answer 47

hypopituitary dwarfism

Question 48

what dwarfism mimics GH deficiency but has high GH levels

Answer 48

laron dwarfism

Question 49

what causes laron dwarfism

Answer 49

IGF-1 lack of response

Question 50

classic features of hypothyroidism

Answer 50

``` sluggish dry-haired thick-skinned deep voiced wt gain cold intolerance bradycardia ```

Question 51

children with hypothyroidism=

Answer 51

puffy face low hair line jaundice choke frequently

Question 52

treatment of hypothyroidism

Answer 52

T4

Question 53

if T4 commenced at birth outcome=

Answer 53

good prognosis for normal growth and development