Growth Physiology

Question 1

what can growth involve

Answer 1

• increase in cell numbers
• increase in cell size
• some cells can grow or regenerate but others cannot

Question 2

what is hyperplasia

Answer 2

increased cell numbers

Question 3

what is hypertrophy

Answer 3

increased cell size

Question 4

what are some cells that can regenerate

Answer 4

liver
skin
blood cells

Question 5

what are some cells that cannot regenerate

Answer 5

neurons

Question 6

which factors can affect growth

Answer 6

• genes, hereditary
• environment

Question 7

what are environmental factors that impact growth

Answer 7

• nutrition
• disease
• growth factors, such as hormones

Question 8

what are some hormones influencing growth

Answer 8

• thyroid hormones
• growth hormone
• sex hormones
• insulin
• cortisol
• vitamine D, parathyroid hormone

Question 9

are the impacts of thyroid hormone on growth direct or indirect

Answer 9

indirect

Question 10

when does the brain and face stop growing

Answer 10

12

Question 11

when does growth of the head reach a plateau

Answer 11

12

Question 12

why is most orthodontic treatment not carried out until after 12

Answer 12

growth is not stable until after this

Question 13

what is the first growth spurt associated with

Answer 13

growth hormone, plateau happens

Question 14

what is the second growth spurt associated with

Answer 14

presence of reproductive organs and associated homrones

Question 15

what is the second growth spurt associated with

Answer 15

reproductive organs

Question 16

why do vitamin D and parathyroid hormone have an effect on growth

Answer 16

their role in mobilisation of calcium and bone formation

Question 17

what are the functions of thyroid hormone

Answer 17

• normal development and growth
• protein synthesis in the brain of the fetus and infant
• normal development of neurons
• childhood growth
• facilitates the action of growth hormone and the sympathetic nervous system

Question 18

symptoms of fetal hypothyroidism

Answer 18

sparse hair
large tongue
permanent mental impairments

Question 19

explain hypothyroidism

Answer 19

• deficiency of thyroid hormones in childhood can impede both brain development and skeletal growth
• delayed tooth eruption
• growth defects can be rectified by thryoxine supplements
• some improvement in mental functions, recovery incomplete
• extent of recovery varies with onset and duration of the hypothyroid state

Question 20

describe the action of growth hormone

Answer 20

metabolic and growth promoting actions
main growth promoting effects in postnatal period, infancy and adolescence

Question 21

describe the metabolic actions of growth hormone

Answer 21

• increase blood glucose levels
• decrease glucose uptake by cells
• increase lipolysis, make fatty acids available for energy production
• facilitate the uptake of amino acids for protein synthesis, especially in the liver and muscle

Question 22

what are some growth hormone effects exerted by

Answer 22

insulin growth factor 1

Question 23

where is IGF1 produced

Answer 23

liver

Question 24

what are the effects exerted by IGF1

Answer 24

• cartilage, bone, soft tissues, viscera
• cartilage proliferation in long bones until the epihphyses close

Question 25

what are the growth centres of the bone called

Answer 25

epiphyses

Question 26

describe the role of sex hormones in growth

Answer 26

- responsible for the pubertal growth spurt - effects mediated by increased secretion of growth hormone and IGF1 - stimulate bone growth, accelerate the closure of epiphyses - testosterone has anabolic effects on protein synthesis - testosterone is the anabolic steroid

Question 27

how does insulin contribute to growth

Answer 27

- promotes foetal growth - promotes post natal growth by stimulating the secretion of IGF1 - facilitates protein synthesis by making glucose available for energy production

Question 28

describe the effects of cortisol on growth

Answer 28

- inhibits growth when levels are too high - stimulate protein catabolism - suppresses bone growth and promotes bone resorption - raised levels of cortisol in stress and illness account for the growth retarding effects of childhood illnesses

Question 29

how do vitamin d and parathyroid hormone contribute to growth

Answer 29

by ensuring adequate amounts of calcium and phosphate are available for bone formation

Question 30

what is vitamin D responsible for

Answer 30

calcium absorption from the gut

Question 31

how does parathyroid hormone have an impact on plasma calcium levels

Answer 31

increases them

Question 32

what does excess growth hormone in childhood lead to

Answer 32

gigantism

Question 33

what does excess growth hormone in adulthood lead to

Answer 33

longitudinal growth is not possible and the appositional growth occurs in extremities hands feet and jaw will increase in bulk and lead to acromegaly

Question 34

describe acromegaly

Answer 34

this is when there is excess growth hormone being produced after the epiphyses are closed so a person is just bulky

Question 35

what is diastema

Answer 35

gaps between the teeth

Question 36

how does the skull change in acromegaly

Answer 36

increased mandible growth and enlarged sella turcica

Question 37

what is achondroplasia

Answer 37

defective cartilage growth that affects long bones and cartilage growth centres like the spheno occipital synchondrosis in the cranial base

Question 38

what does ageing involve

Answer 38

gradual deterioration of all parts of the body complicated by disease

Question 39

what does an individuals lifespan depend on

Answer 39

genetics environment no evolutionary advantage to it

Question 40

what environmental factors increase longevity

Answer 40

good nutrition lifestyle absence of disease

Question 41

describe the biology of ageing

Answer 41

decline in the ability of cells to divide accumulation of damage, errors in dna sequence, abnormal proteins and damage to organelles like mitochondria shortening of telomeres due to free radicals

Question 42

when does apoptosis occur

Answer 42

in development from a tooth germ replaces worn out cells destroys tumour cells

Question 43

what is ageing accompanied by

Answer 43

reduced performance of body systems and organs