Groeth And Ageing Flashcards
What does growth involve
Hyperplasia
Hypertrophy
What is hyperplasia
Increase in cell numbers
What is hypertrophy
Increase in cell size
Give examples of some cells that can regenerate
Liver, skin, blood cells
Give some examples of cells that cannot regenerate
Neurons
What is growth effected by
- genes, heredity
- enviroment
What is included in enviroment
- nutrition
- disease
- growth factors, such as hormones
What are hormones that influence growth
- thyroid hormones
- growth hormones
- sex hormones
Describe thyroid hormones
- 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
- indirect, rather than direct effects on growth
Facilitates actions of growth hormones and systematic nervous system
What is hypothyroidism
- overactive thyroid
- fetal/ neonate hypothyroidism
- sparse hair
- large tongue
- permanent mental impairments
How does hypothyroidism effect the tooth eruption
Delayed tooth eruption
What is the function of growth hormone
Has metabolic and growth promoting actions
What are the metabolic actions of growth hormone
- increase in blood glucose levels
- decrease in glucose uptake by cells
- increase in lipolysis, making fatty acids available for energy production
- facilitates uptake of amino acids for protein synthesis
Why is orthodontic treatment carried out under the age of 12
Because the face is still growing
When does the brain finish growing
About 8 years old
What is the effect of insulin like growth factor
Cartilage proliferation in long bones, until epiphyses (growth centres) close
What are examples of sex hormones
Testosterone and oestrogen
What are sex hormones responsible for
Responsible for pubertal growth spurt
What are the effects of the sex hormones mediated by
Mediated by increased secretion of GH and IGF-1
What are the effects of testosterone
Anabolic effects on protein synthesis, increasing muscle bulk
Is the anabolic steroid
What is the effect of sex hormones on bones
Stimulates bone growth, but accelerate the closure of epiphyseal growth plates
What can hypothyroid cause in children
Dwarfism, infant proportions, overweight
What does a hypopituitary dysfunction cause in an 8 year old boy
Dwarfism, slimmer
What are some other hormones that can affect growth
- insulin
- corticosteroids
- vitamin D
- parathyroid hormone
Describe how insulin contributes to growth
- promoting foetal growth
- promoting post natal growth by stimulating IGF-1
- facilitating protein synthesis (by making glucose available for energy production)
When present at higher than normal levels cortisol can…
Inhibit growth
What are the functions of cortisol in growth
- stimulates protein catabolism
- supresses bone growth and promotes Reabsorption
Raised levels of cortisol in stress and illness account for the growth retarding effects of childhood illness
How does vitamin D and PTH contribute to growth
Vitamin D is responsible for Calcium absorption in the gut
PTH raises plasma calcium levels
They are responsible for ensuring adequate amounts of calcium and phosphate for bone formation
Excess growth hormone in childhood does what
Accelerates normal growth - gigantism
What happens when there is excess growth hormone in adults
- appositional growth in the extremities
- hands and feet and jaw increase in bulk, acromegaly
What is acromegaly
Excess growth hormone leads to hands, feet and jaw increase in bulk
What is achondroplasia
- defective cartilage growth
- affects long bones and cartilage growth centres eg spheno-occipital synchondrosis in cranial base
What is diastema
Spaces in between teeth
Food may get stuck
What can patients that have acromegaly have
Increased risk of tumor of the pituitary gland
What does ageing involve
Gradual detioration of all parts of the body
Complicated by disease
What does an individuals life span depend on
- genetics
- enviroment
- no evolutionary advantage in old age
What is included in the enviroment pod longevity
- good nutrition
- lifestyle
- absence of disease
Describe cellular ageing
Decline in the ability of cells to divide over time
Accumulation of damage as the cells divide in old age
Give some examples of apoptosis
- in development, tooth germ, nervous system
- to replace worn out cells
- to destroy tumour cells
