Growth physiology

Question 1

What is growth

Answer 1

Increase in cell numbers​
-Hyperplasia​

Increase in cell size​
-Hypertrophy

Question 2

What cells cannot grow

Answer 2

Neurons

Question 3

What affects growth

Answer 3

Genes, heredity​

Environment​
-Nutrition​
-Disease​
-Growth factors, such as hormones

Question 4

What hormones typically influence growth

Answer 4

Thyroid hormones​

Growth hormone​

Sex hormones​

Others​
-Insulin​
-Cortisol​
-Vitamin D, parathyroid hormone

Question 5

Why do we have thyroid hormones

Answer 5

Essential for normal development and growth​

Essential for protein synthesis in brain of fetus and infant​

Required for normal development of neurons​

Necessary for childhood growth​

Facilitates actions of Growth hormone and Sympathetic NS

Question 6

What are the affects of hypothyroidism

Answer 6

Fetal / neonate hypothyroidism​

Sparse hair​

large tongue​

Permanent mental impairments

Question 7

What is hypothyroidism

Answer 7

Deficiency of thyroid hormones in childhood impedes both brain development and skeletal growth

Question 8

How can growth effects be rectified

Answer 8

By thyroxine supplements

Question 9

What affects does hypothyroidism have on the teeth

Answer 9

Delayed tooth eruption

Question 10

What are the metabollic actions of growth hormone

Answer 10

Increased blood glucose levels (“anti-insulin”)​

Decreased glucose uptake by cells​

Increased lipolysis, making fatty acids available for energy production​

Facilitates uptake of amino acids for protein synthesis (especially liver, muscle)​

Question 11

What effect does IGF-1 have on bones

Answer 11

Cartilage proliferation in long bones, until epiphysis (growth centres) close

Question 12

What is the anabolic steroid

Answer 12

Testosterone

Question 13

What mediates the effects of sex hormones

Answer 13

Secretion of GH and IGF-1

Question 14

How does insulin contribute to growth

Answer 14

Promoting foetal growth​

Promoting post-natal growth by stimulating secretion of IGF-1​

Facilitating protein synthesis (by making glucose available for energy production)​

Question 15

When are cortisol levels raised

Answer 15

Stress and illness

Question 16

Why may individuals who were ill fora prolonged period of time as children have stunted growth/reduced growth

Answer 16

Increased cortisol levels during period of illness

Question 17

How do the PTH and Vit D increase growth

Answer 17

Ensuring adequate amounts of calcium and phosphate are available for bone formation​

Vitamin D is responsible for Ca2+ absorption from the gut​

PTH raises plasma Ca2+ levels​

Question 18

What does excess growth hormone cause

Answer 18

CHILDHOOD
-gigantism

ADULTHOOD
-acromegaly (hands, feet etc)

Question 19

What is achondroplasia

Answer 19

Defective cartilage growth

Question 20

What is ageing

Answer 20

Involves a gradual deterioration of all parts of the body

Question 21

What impacts lifespan

Answer 21

Genetics​

Environment​
-Good nutrition​
-Lifestyle​
-Absence of disease​

No evolutionary advantage in old age; reproductive ‘fitness’ takes priority

Question 22

What causes ageing

Answer 22

There is a decline in the ability of cells to divide over time​

As they divide, there is accumulation of damage:​
-Errors in DNA sequence​
-Abnormal proteins​
-Damage to organelles (e.g. mitochondria)​

Free radicals; shortening of telomeres​

Question 23

When does apoptosis occur

Answer 23

In development; e.g. tooth germ, nervous system​

To replace ‘worn out’ cells​

To destroy tumour cells

Question 24

What is apoptosis

Answer 24

Programmed cell death​

Cells programmed to ‘self-destruct’

Question 25

What accompanies ageing

Answer 25

Reduced performance of body systems and organs

Question 26

What are the gaps between teeth called

Answer 26

diastema