Growth And Ageing

Question 1

What is an increase in cell numbers called?

Answer 1

Hyperplasia

Question 2

What is an increase in cell size called?

Answer 2

Hypertrophy

Question 3

Give an example of a cell type which cannot grow/regenerate

Answer 3

Neuron

Question 4

What are some factors which can affect growth?

Answer 4

• genes (heredity)
• environment (nutrition, disease, growth factors eg hromones)

Question 5

What is the order in growth between the brain, height and reproductive organ?

Answer 5

• brain first
• then height/ reproductive organs

Question 6

Do all cells regenerate and grow at the same rate?

Answer 6

No
Eg RBC take 120 days, but skin/mucosa cells are faster and some eg neurones can’t regenerate at all

Question 7

What are hormones which influence growth?

Answer 7

• thyroid hormones
• growth hormones
• sex hormones
• insulin
• cortisol
• vitamin D
• parathyroid hormone

Question 8

Describe the role of the thyroid hormone in growth

Answer 8

• essential for protein synthesis in brain of fetus/infant
• required for normal development of neurons
• needed for childhood growth
• indirect effect on growth
• facilitates actions of growth hormone and sympathetic NS

Question 9

Which hormone is essential for protein synthesis in the brain of fetus/infant?

Answer 9

Thyroid hormones

Question 10

Which hormone facilitates the actions of growth hormone and sympathetic NS?

Answer 10

Thyroid hormones

Question 11

Which hormone has an indirect effect on growth?

Answer 11

Thyroid hormones

Question 12

What is hypothyroidism?

Answer 12

Deficiency of thymidine hormones

Question 13

What are consequences of hypothyroidism in a fetus?

Answer 13

• sparse hair
• large tongue
• permanent mental impairments (impedes brain/skeletal development and growth)
• delays tooth eruption

Question 14

What can be used to treat hypothyroidism?

Answer 14

• growth defects can be rectified by thyroxine supplements
• may not be a complete recovery
• extent of recovery varies with onset and duration of the hypothyroid state

Question 15

Describe the role of growth hormone in growth

Answer 15

• metabolic and growth-promoting actions
• main growth-promoting effects in postnatal period, infancy and adolescence
• mainly indirect metabolic actions (increase in blood glucose, decrease in glucose uptake in cells, lipolysis, facilitates uptake of amino acids for protein synthesis)

Question 16

What is lipolysis?

Answer 16

Making fatty acids available for energy production

Question 17

Which hormone has its greatest growth-promoting effects in postnatal period, infancy and adolescence?

Answer 17

Growth hormone

Question 18

What are the metabolic actions of growth hormone?

Answer 18

• increases blood glucose
• decreases glucose uptake by cells
• increases lipolysis
• facilitates amino acid uptake for protein synthesis

Question 19

Dwarfism types

Question 20

Describe the role of sex hormones in growth

Answer 20

• testosterone and oestrogens
• responsible for pubertal growth spurt
• effects are mediated by increased secretion of growth hormone and IGF-1
• stimulate bone growth but accelerate closure of epiphyseal growth plates
• testosterone has anabolic effects on protein synthesis, increasing muscle bulk
• testosterone is the anabolic steroid

Question 21

What is the anabolic steroid?

Answer 21

Testosterone

Question 22

What are the effects of sex hormones mediated by?

Answer 22

Growth hormone and IGF-1

Question 23

What hormones are responsible for pubertal growth spurt?

Answer 23

Sex hormones

Question 24

What is IGF-1?

Answer 24

Insulin like growth factors

Question 25

Where is IGF- 1 produced?

Answer 25

Liver

Question 26

What are the effects of IGF-1?

Answer 26

- in cartilage, bone, soft tissues, viscera - IGF-1 leads to cartilage proliferation in long bones until epiphyses close

Question 27

What are epiphyses?

Answer 27

Growth centres

Question 28

Describe the role of insulin in growth

Answer 28

- indirect - promotes foetal growth - promoting postal-natal growth by stimulating IGF-1 secretion - facilitating protein synthesis (making glucose available for energy production)

Question 29

Describe the role of cortisol in growth

Answer 29

- stimulates protein catabolism - suppresses bone regrowth and promotes bone resorption (osteoporosis) - raised level of cortisol in stress and illness accounts for growth retarding effects of childhood illnesses

Question 30

Which hormone if present in higher than normal levels can inhibit growth?

Answer 30

Cortisol

Question 31

Describe the role of vit D and parathyroid hormone in growth

Answer 31

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

Question 32

Which hormone is responsible for Ca2+ absorption in the gut?

Answer 32

Vitamin D

Question 33

Which hormone raises plasma Ca2+ levels?

Answer 33

Parathyroid hormones

Question 34

What is the effect of excess growth hormone in childhood?

Answer 34

Accelerated normal growth - gigantism

Question 35

What is the effect of excess growth hormone in adults?

Answer 35

Hands, feet and jaw increase in bulk - acromegaly - appositional growth occurs in extremities

Question 36

What is appositional growth?

Answer 36

Increase in bone diameter

Question 37

What is acromegaly?

Answer 37

Rare condition in which the body produces too much growth hormone causing body tissues and bone to grow at increased rate

Question 38

What could the effects of a tumour of the pituitary gland be?

Answer 38

- enlarged sella turcica - increased growth of mandible

Question 39

What is achnodroplasia?

Answer 39

Defective cartilage growth

Question 40

What has happened to lifespan?

Answer 40

- more people living to old age - population average age has increased

Question 41

What are the factors which influence an individuals lifespan?

Answer 41

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

Question 42

Describe the biology of ageing

Answer 42

- decline in ability of cells to divide overtime - as they decline there is an accumulation of damage (errors in protein synthesis, abnormal proteins, damage to organelles) - free radicals, shortening of telomeres

Question 43

When does apoptosis occur?

Answer 43

- in development eg tooth germ, nervous system - to replace worn out cells - to destroy tumour cells