Growth and Ageing

Question 1

what is hyperplasia?

Answer 1

increase in cell numbers

Question 2

what is hypertrophy?

Answer 2

increase in cell size

Question 3

what cells can regenerate?

Answer 3

liver, skin and blood cells

Question 4

what is growth affected by?

Answer 4

genes, heredity, environment

Question 5

what environmental factors contribute to growth?

Answer 5

nutrition, disease, growth factors such as hormones

Question 6

what part of the body grows the fastes?

Answer 6

brain

Question 7

what part of the body takes the longest to grow?

Answer 7

reproductive organs

Question 8

what hormones influence growth?

Answer 8

thyroid hormones, growth hormones, sex hormones, insulin, cortisol, vitamin D and PTH

Question 9

what is the thyroid hormone essential for in terms of growth?

Answer 9

normal development and growth, protein synthesis in brain of foetus and infant, normal development of neurons, childhood growth

Question 10

what is the indirect action of the thyroid hormone on growth?

Answer 10

it facilitates actions of growth hormones and sympathetic nervous system

Question 11

what are the physical signs or foetal/neonate hypothyroidism?

Answer 11

sparse hair, large tongue, permanent mental impairments

Question 12

how does a deficiency of thyroid hormones effect the brain and skeleton?

Answer 12

it impedes the development of them

Question 13

what oral effect does a thyroid hormone deficiency have?

Answer 13

delayed tooth eruption

Question 14

how are the growth defects of hypothyroidism rectified?

Answer 14

by thyroxine supplements

Question 15

what actions does the growth hormone have?

Answer 15

metabolic and growth promoting actions

Question 16

when does the growth hormone have the most action in promoting growth?

Answer 16

postnatal period, infancy and adolescence

Question 17

what are the metabolic actions of the growth hormone?

Answer 17

increased blood glucose levels, decreaed glucose uptake by cells, increased lipolysis making fatty acids available for energy produced, facilitates uptake of amino acids for protein synthesis

Question 18

what is IGF-1 and what does it do

Answer 18

insulin growth factor which causes cartilage proliferation in long bones until epiphyses close

Question 19

what are the 2 types of dwarfism

Answer 19

hypothyroid (infant proportions) and hypopituitary (normal proportions)

Question 20

what are the sex hormones?

Answer 20

testosterone and oestrogen

Question 21

what are sex hormones responsible for in terms of growth?

Answer 21

pubertal growth spurt, also stimulate bone growth but accelerate closure of epiphyseal growth plates

Question 22

what are the effects of the sex hormones mediated by?

Answer 22

increased secretion of GH and IGF-1

Question 23

what is the effect of testosterone on protein synthesis

Answer 23

it has an anabolic effect on protein synthesis increasing muscle bulk

Question 24

how does insulin contribute to growth?

Answer 24

promotes foetal growth, promotes post-natal growth by stimulating secretion of IGF-1, facilitates protein synthesis (by making glucose available for energy production)

Question 25

what happens when cortisol is present at higher than normal levels?

Answer 25

it inhibits growth, stimulates protein catabolism, suppresses bone growth and promotes bone resorption

Question 26

how do vit D and PTH contribute to growth?

Answer 26

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

Question 27

what is vitamin D responsible for?

Answer 27

calcium absorption from the gut

Question 28

what does PTH do?

Answer 28

raise plasma calcium levels

Question 29

what is gigantism?

Answer 29

accelerated normal growth in children

Question 30

what is acromegaly?

Answer 30

appositional growth in extremities (hands, feet and jaw) in adults

Question 31

what is achondroplasia?

Answer 31

defective cartilage growth affecting long bones and cartilage growth centres e.g. spheno-occipital synchondrosis in cranial base

Question 32

what does ageing involve?

Answer 32

gradual deterioration of all parts of the body

Question 33

what does an individuals lifespan depend on?

Answer 33

genetics and environment (good nutrition, lifestyle and absence of disease)

Question 34

what happens to cells over time?

Answer 34

the ability of the cells to divide declines

Question 35

when cells age what happens when they are dividing?

Answer 35

errors in DNA sequence, abnormal proteins, damage to organelles (e.g. mitochondria)

Question 36

what is apoptosis?

Answer 36

programmed cell death

Question 37

when does apoptosis occur?

Answer 37

in development e.g. tooth germ and nervous system, to replace worn out cells and to destroy tumour cells