Principles of Growth Flashcards
What is Growth?
Process of an increase in size by accretion of tissue based on Cell Hyperplasia, Cell Hypertrophy, and Apoptosis
SKELETAL GROWTH:
When does Osteogenesis begin after birth?
What are the 2 Osteogenic Pathways?
Intramembranous Ossification:
What type of bone does it form?
What’s the 1ST thing that occurs?
What the 2ND thing that occurs?
What the 3RD thing that occurs?
What the 4TH thing that occurs?
Endochondral Ossification:
What type of bone does it form?
What do the Mesenchymal cells differentiate into?
What’s the 1ST thing that occurs?
What the 2ND thing that occurs?
What the 3RD thing that occurs?
What the 4TH thing that occurs?
What the 5TH thing that occurs?
- Week 6-7 after birth
- • Intramembranous Ossification (flat bones)
• Endochondral Ossification (long bones)
- Flat bones
- Mesenchymal cells group into a cluster to form an Ossification centre
- Osteoid is secreted and traps Osteoblasts, which then become Osteocytes
- Trabecular matrix and Periosteum (bone lining) form
- • Compact bone develops around the Trabecular bone
• Crowded blood vessels condense into Red marrow
- Long bones
- Chondrocytes
- Cartilage model of future bone forms
- • Capillaries penetrate cartilage
• Perichondrium becomes the Periosteum
• PRIMARY OSSIFICATION CENTRE forms - • Cartilage and Chondrocytes continue to grow at the ends of the bone
• SECONDARY OSSIFICATION CENTRE forms - Cartilage remains at epiphyseal (growth) plate and at joint surface as Articular cartilage
BONE GROWTH IN LENGTH:
What is the Epiphyseal (Growth) plate composed of? What are they called?
What is growth at this plate under the influence of?
What occurs on the Outer (Epiphyseal) side of the growth plate?
What occurs on the Inner (Diaphyseal) side of the growth plate?
- 4 zones - Reserve zone, Proliferative zone, Maturation and Hypertrophy zone, Calcified matrix
- GH (+Sex hormones at puberty)
- Cartilage forms
- Cartilage is ossified
PRENATAL GROWTH:
What is the 1st period? What’s it characterised by?
What is the 2nd period? What’s it characterised by?
What is the 3rd period? What’s it characterised by?
What occurs in the 1st Trimester?
What occurs in the 2nd Trimester?
What occurs in the 3rd Trimester?
What are the Intrinsic factors affecting Prenatal growth?
What are the Extrinsic factors affecting Prenatal growth?
What is the baby’s size at birth dependent on?
- Zygote - Cell division, but NO increase in mass
- Pre-embryo and Embryo - Cell division with differentiation and migration
- Foetus - Rapid growth
- Differentiation of organs with formation of Embryonic disk (Ectoderm, Endoderm, Mesoderm)
- Cell Hyperplasia (Length increase)
- Cell Hypertrophy and Maturation (Weight increase)
- • Genes - Structural, Regulatory, and Mitochondrial genes
• Hormones - GH, IGFs, TH, Foetal glucocorticoid - • Placenta, Blood flow and Nutrition
• Maternal anatomy
• Teratogens - agent that causes malformation of an embryo
o Biological - Maternal DM, Gestational infection
o Chemical
o Physical - Hyperthermia, Radiation, Mechanical injuries - In-utero environment, varying with gestational age
POSTNATAL GROWTH:
How does its influences differ from Prenatal growth?
What is Infancy?
→ What is weight a good parameter of here?
What is Childhood?
→ What is weight a good parameter of here?
→ What is growth influenced by here?
Karlberg’s ICP Model of Growth:
What does ICP stand for?
What does each growth curve on the model reflect?
→ What are these in each phase of growth?
Canalisation:
What does this concept say?
- Changes from Maternal → Genetic & Environmental
- Birth to 1 year
→ Growth - 1 year to Puberty
→ Non-hormonal factors
→ Hormones (TH, GH) > Nutrition
- Infancy, Childhood, Puberty
- The different hormonal phases of growth
→ Nutritional during Infancy, Hormonal during Childhood, Sex steroids during Puberty
- Infants/Children stay within one or two growth centiles, and therefore, any crossing of height centiles ALWAYS warrants further evaluation
Catch-UP Growth:
What is it?
When does it commonly occur?
Catch-DOWN Growth:
What is it?
When does it commonly occur?
When is investigation needed?
- Height velocity above normal for at least 1 year after a transient period of growth inhibition
- IUGR baby, or a child with Hypothyroidism receiving Thyroxine
- Starts off at a high percentile in early infancy and, over time, becomes reduced to a lower percentile
- Infant of a diabetic mother, or an Overfed infant
- If there’s a fall of >2 major percentiles
During puberty, how does body fat change between boys and girls?
How does adult body fat differ between Men and Women?
- Body fat increases more in girls
- • Men (Apple-shaped) - Increased amounts of brown fat, Enlarged peripheral fat deposits
• Women (Pear-shaped) - Preferential increase of Intra-abdominal fat deposits
