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186 Cards in this Set
- Front
- Back
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What is human growth?
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growth is an increase in the size of body parts.
growth can be defined as the progressive development of a living being or any of its parts from its earliest stage to maturity, including the attendant increases in size. growth is the dominant biological activity for the first 2 decades of human life. hyperplasia, hypertrophy, and icnrease intercelluar substance |
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what is development?
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-broad concept incorportating biological and behavioural changes
-changes in an individuals level of functioning -bioloical: differentiation and specialisation of cells -behavioural: development of competence in a variety of domains |
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What is maturation?
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Maturation is a process of developmental change this is characterized by a fixed order of progression genetically determined or influenced by external factors
-reaching a state of maturity -a mature skeletal system is when there is complete ossification of the skeleton |
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The ageing population.
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-projected increase in ageing population
-in australia 2004 16% of the population was over 65 years old -by 2051 it is expected to be over 27% |
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What is the skeletal system and was it is composed of?
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the skeleton is the supportive framework of the body and is composed of bone tissue, cartilage, ligaments, tendinous attactments, blood vessels, marrow, fat, and water
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What is bone tissue composed of?
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the skeleton is approx 17% of our body mass as an adult.
bone marrow is 1/3 skeletal materal and joint tissue is 1/10 skeletal material |
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What makes up bone cells?
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oesteocytes, osteoblasts and osteoclasts
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what is an oesteocyte?
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regulate flow of minerals and nutrients between bone and blood
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what is an ostoblasts?
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bone formation
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what is osteoclast?
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reabsorb bone tissue, minerals from the matrix are released into circulation
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What is the bone composition across the lifespan?
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new borns are 2/3 cartilage with increased flexability of bone to young adults who have strong and tough bones to adults who are 1/10 cartilage and less flexability
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When does bone formation happen?
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most bones are formed prenatally as a cartilage model.
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what are intramembranous bones?
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formed between embryonic membranes
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What are endochondrial bones?
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formed within cartilage
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Primary ossification of a long bone.
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-blood vessels invade the perichondrium surrounding the disphysis cartilage. Osteoblast in the periosteum lay down a collar of bone
-in the center chrondocytes hypertrophy and cartilage calcifies, chrondocytes die and the matrix in the center deteriorates leaving a hallow marrow cavity -the primary ossification center occurs in the diaphysis -the cartilage of the epiphysis and metaphysis continue to proliferate and hypertrophy and the area nearer to the diaphysis ossifies |
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where does secondary ossification occur?
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occurs at the epiphysis forming trabeculae bone in the epiphysis. some larger bones have several secondary ossification centers.
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where is the growth plate?
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also called the epiphyseal place and it is the area of cartilage between the epiphysis and the metaphysis.
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where does the both grow in length?
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in the metaphysis and the growth plate area
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What is epipyseal union?
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it is the calcification of the area creating closure of the plates. after the union the bone no longer grows in length
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Where are centers for ossification ?
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-the first center appears in the shaft of the clavicle.
-there are over 800 in the human body -secondary centers mostly appear after birth and continue to 18 years -appear early in females and complete approx 2 years earliar |
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what affects bone growth?
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-its shape is genetically determined
-it is influenced by the environment -controlled by hormones -activity affects mineral density but does not usually affect the maturation and length of bones -requires adequate diet and weight bearing activity -compact and trabeculae bone -trabeculae bone eventually patterned to resist forces |
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What is the difference between male and female skeletal development?
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during adolescent growth spurt there are noticeable changes in male to female growth
.males have increased development in should width and muscle mass .females have increase in hip breadth and fat mass |
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What happens with bone deposition and bone growth with ageing
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bone deposition occurs more rapidly than bone resorption during growth
during adulthood they usually remain in equilibrium in old age bone resportion is more rapid than bone depostition |
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what is bone mineral density and what does it primarily consist of?
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-mineral is the major component of bone tissue and is is primarily calcium and phosphate.
-bmd is ratio of bone mineral to bone area -dexa technology is used to estimate BMD -5-7% of bone mass is recycles |
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What is Bone failure?
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soft tissue = crumple zone
-decreased BMD can increase the risk of fractures -osteoporotic bones take longer to heal -hip fractures reduce mobility -repair requires adequate nutrition |
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When does ageing of the skeletal system happen and what happens
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ageing starts at about 40 years old
-decreased bone density -increased concavity of the vertebrae, height loss -increased collagen cross linking -increased brittleness -lowered calcium absorption with older age, added effect |
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Why does your posture stoop, head and neck forward, rolled in shoulders, hips in flexion, upper limbs bent?
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thought to be due to
muscle shrinkage -decreased elasticity and calcification of ligaments -shrinking of tendons -vertebral column degeneration and flattening of discs |
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What happens to connective tissue with ageing?
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decreased elastin productions which starts in puberty and is replaced by collagen.
-the fluid content has decreased glycoprotiens which leads to dehydration |
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What happens to Hyaline Cartilage with ageing?
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decreased production of hyaluronic acid causes increased viscosity and joint friction
-decreased glycoproteins -decreased nutrient and waste transport -decreased o2 concentration -increased procollagen thereby hyaline cartilage is converted to fibrocartilage |
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What is osteoporosis?
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less than 2.5 standard deviations below the normal BMD
-weakening of bones due to calcium loss -50% of all women over 70 years -women have 20% less bone mass -increased risk of fracture -prolonged recovery |
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what does osteoporosis effect?
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initially effects spongy (trabecular) bone but later compact bone
-decrease the risk by increasing bone mass prior to peak bone mineral density -compact bone 40 years and spongy bone 25 years |
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What is arthritis?
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imflammatory degenerative disease.
-stiff, swollen, and chronically painful joints -more than 100 type of arthritis but the main types are osteoarthritis and rheumatoid arthritis |
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What is the most common type of arthritis and who does it affect?
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osteoarthritis is the most common and affects 85% of 70-79 year olds
-it has a slow irreversible progression -years of compression and abrasion lead to destruction of cartilage -anti-imflammatory pain relief -exercise beneficial for mobility |
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What is rheumatoid arthritis?
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autoimmune disease attacking joints
-infiltration of T lymphocytes and other cells into synovial fluid -imflammation and pain -progressive cartilage erosion and formation of scar tissue -ossification of scar tissue can fuse bones -hot/cold compression for pain relief. |
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when is height velocity stable?
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between 5-6 years and 9-10 years
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what does ageing create?
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inevitable loss in density and increased brittleness of bones
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What is a healthy musculoskeletal system?
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-weight bearing activity. normal childhood activity is sufficient for skeletal development
-sufficient diet -build calcium stores and BMD before 40 years |
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What is skeletal muscle tissue?
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-muscle is the largest tissue mass in the body
-there are more than 500 skeletal muscles in the body -composed of muscle fibers |
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what does a muscle fiber contains?
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between 100-1000 myofibrils packed with nuclei, mitochondria and sarcoplasmic constituents
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What happens to muscle growth between the last trimester and 4 months old? what about at full term?
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in the foetus fibers are small and few in number
-the number of muscle fibers double between the last trimester and 4 months -at full term the muscles are small but greater in number -muscle of newborn is 25% of TBW |
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muscle growth post natal?
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increase in muscle girth is primarily form hypertrophy
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how much muscle do adult male and females have?
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tbw 40-5 % for females and 42-54% for males
-low extremity of 45% of lean body mass - |
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head and trunk of a new born compared to adult?
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newborn is 40+% TBW and about is 25-30% decreasing center of mass
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when do all skeletal and cardiac muscle fibers form?
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before birth
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How does muscle growth occur?
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growth in length occurs via changing number of sacomeres. stretch and shortening
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when does the differentiation and maturation of muscle fibers occur?
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the chemical composition of muscle fibers is suggested to reach maturity during adolescence.
-most fibers are undifferentiated before 30 weeks of gestation -by age 1 little differenence in relative fiber type is seen |
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When does adipose tissue appear?
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adipose tissue appears in the foetus at 3.5 months old
-large gains in adipose tissue occurs during the last few months of gestation and the first 6 months after birth -increase in cell # appear to occur during puberty and when pregnat |
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explain the difference in the amount of visceral fat and subcutaneous fat as you get older
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-during childhood visceral fat increases faster than subcananeous fat
-increases until age 12-13 for boys and continues to increase for girls -in adolescence boys tend to lose subcutaneous fat -both males and females tend to gain fat during adult years and tend to be in the abdomen region |
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what happens to the muscular system while you age?
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increase collagen compared to elastin
-cartilage is converted to fibrocartilage -decreased ability to import and store nutrients -decrease in power output -disuse leads to further atrophy of muscles |
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What is sarcopenia?
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-loss of fiber size primarily in type 2 fibers
-50-80 years decrease in mass -loss in number of fibers |
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what causes sarcopenia?
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reduced mitochondria
decreased protein synthesis decreased repair ability decreased nerve supply |
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What happens to heart size?
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-left ventricle grows rapidly after birth
-heart volume increases until adulthood -heart volume at birth is approximately 40 cm increasing to 600-800 by adulthood -growth curve similar to muscle mass |
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what happens to heart mass/body mass
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ratio of heart mass to body mass declines exponentially during childhood and adolescence
-from 8 to 18 years the heart volume is related to body mass, remaining approx 10cm/kg -increase in heart volume is greater than heart mass during growth |
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What happens to Left ventricular mass in kids
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LVM and volume is influenced by work performed
-LVM is similar in boys and girls until age 9-12, then it grows faster in boys -adolescent endurance athletes have an increased LVM as well as increased heart volume |
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What is the heart rate for newborns to adults?
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newborn-140 plus or minus 20
1 year old is 100 b |
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heart rate as you get older
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new born plus or minus 20 from 140
1 year- 100bpm 6 year- 80bpm 10 year 70 bpm adults male 57-60 bpm female 52-62 -at 10 years slight difference of 3-5 bpm higher for girls -HR drops 10-20 bpm between 5-15 years -max HR decrease with age |
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Stroke volume and Cardiac output as you age
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stroke volume increases during childhood and adolescence from 3-4 ml at birth to 40 ml pre adolescence
-young adult males; SV=approximately 60ml at rest -cardiac output from newborn to young adult male is .5L/min increasing 5L/min |
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Blood pressure as you age
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-pulmonary arterial pressure decreases in neonate
-the same time there is an increase in peripheral vascular resistance -SBP varies from approx 40-75 mm/hg at birth -SBP continually rises -by 10 years difference in SBP between male and female is apparent. Males approx 10mm/hg higher |
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Blood volume, hematocrit, RBC, heamoglobin,leukocytes, and placelet difference between newborn adult male and adult female
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-blood volume is 300-400 ml as a newborn to 5L male and 4-5L female
-Hemacrit is 50% dropping to 30% after birth and its 40-45% male and 38-42% female -RBC 4-4.5 million fropping to 3 million by age 2 and 5.5 million is male and 4.6 million in female -heamoglobin. 20g dropping to 10g between 3-6 months. 16 g male and 14 g female -leukocytes 40,000 newborn and 8000 female and male -placelets- 350,000 for all newborn, male and females |
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what is forced vital capacity?(FVC)
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expiration as hard as possible
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what is inspiratory capacity (IC)?
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maximal vol of gas inhaled
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What is functional residual capacity? (FRC)
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volume of gas remaining after a normal expiration
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Forced-expiratory vol (FEV1.0)
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air expired in 1 second. important indices of resistance of airways to airflow
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Maximal voluntary ventilation (MVV)
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maximal volume of expired air, breathing as deeply as possible
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Total lung capacity (TLC)
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includes maximal inspiration and residual volume
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What is Residual volume?
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volume of gas remaining in lungs after maximal expiration
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Tidal Volume (TV)
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average volume of air expired during each cycle of normal breathing
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inspiratory reserve volume (IRV)
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maximum volume of gas inspired from the normal inspiratory level of TV
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expiratory reserve volume? (ERV)
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max volume of gas that can be expired from the normal expiratory level of TV
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Vital Capacity (VC)
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maximum volume of gas expelled from the lungs after a maximal inspiration VC= TV+IRV+ ERV
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What happens to the expiratory system during growth?
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-lungs expand with the onset of respiration
-lung tissue grows 10 fold before maturity is attained -growth of lungs is mostly proportional to growth in height -the lungs of a newborn can inhale 3ml air per gram of tissue -mature lungs inhald 8-10ml/g |
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Respiration Rate in children
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there is a reduced lung compliance and greater airway resistance in children
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What effects the cardio-vascular system as you age?
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-primary and secondary ageing effects
-little change in heart function at rest in healthy adults -moderate cardiac enlargement may occur |
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What happens to the cardiovascular system as you age?
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-increased peripheral resistance
-increased SBP and DBP -max heart rate declines about 1 beat per year after 20 years -reduce stroke volume -overall decline in cardiac output |
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peripheral factors of ageing and the cardio-vascular system
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-decreased capillary to muscle fiber ratio and reducted arterial cross-sectional area reduces blood flow to active muscle
-increased postural hypotension due to decreased baroreceptor reflex function |
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How does ageing affect the respiratory system?
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-age related decrease in efficiency limit maximum capacity
-reduction is lung elasticity -reduced alveolar surface area -decreased VC, FEV1,/FVC raion, increased FRC and RV -Vo2 max declines about 1-2.5 % each year |
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What happens to the muscle pump with ageing and the respiratory system?
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decreased muscle pump
-increased chest wall stiffness -decreased respiratory muscle strength -decrease sensitivity to respiratory controls centers in the central nervous system |
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heart disease.
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the leading cause of death
-atherosclerosis is the most important underlying factor and it begins in infancy |
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coronary heart disease
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narrowing arteries and reducing blood supply to heart
-main causes are unclear -atherosclerotic plaques build up in blood vessels -can begin in infants 2-4 months old -heart attack occur due to prolong ischemia(inadequate blood supply to an organ) |
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hypertension
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-blood pressure greater than 140/90
-indicates blood flow to vital organs -increased risk of heart attack, heart failure, and stroke -kidney damage is related -lifestyle modification, exercise and diet effect BP |
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congestive heart failure
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-circulatory congestion produced via impaired muscle pump of the heart
-often involves hypertrophy and failure of the left ventricle -associated with hypertension and CHD -results in blood pooling in tissues |
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pulmonary heart disease
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-damage to capillary beds in the lungs
-blood backs up between the lungs and the right side of the heart leading to right ventricular hypertrophy -results in obstructive lung disease |
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summary on skeletal muscle changes.
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-growth is not uniform
-ageing skeletal muscle lose size strength and power and loss of elasticity -disuse leads to further -males have an increase in muscle mass during adolescence |
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summary on cardio-vascular and respirtatory changes?
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-heart mass and volume grow proportionally to body weight
-lungs grow proportionally to height -heart rate decreases by about 50% from birth to young adult, cardiac output increases 10 folds in this time |
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endocrine system first 8 weeks and what do endocrine glands do?
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-endocrine functions change with age
-the endocrine system is not responsible for growth in the first 8 weeks of foetal development -endocrine glands produce hormones that play an important role in growth and maturation; as do hormone liek molecules produced in other tissue and organs |
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how do endocrine hormones circulate and what are there functions?
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endocrine hormones circulate via the blood stream.
-all cells are potentially exposed; response is receptor specific -receptor cell concentration vary throughout life -function is to maintain homeostasis, morphogenesis, co-ordinate cellular responses |
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Where are hormones produced?
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-protein derivatives are produced in the pituitary, parathyroid and pancreas
-steriods which are cholesterol derivatives are produced in the adrenals, ovaries, and testes amines ware produced in the thyroid and adrenal medulla |
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How is the endocrine system regulated?
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-hormonal response takes longer than nervous system control
-effect last longer -regulated by change in blood ion or nutrient levels, neural stimuli, and other hormones either present or absent |
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what is the pituitary and hypothalamus relationship and what hormones are produced
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-the hypothalamus moderates the release of anterior pituitary hormones
-hormones from the hypothalamus are the growth hormone releasing hormone somatotropin releasing hormone thyrotropin releasing hormone corticotropin releasing hormone Gonadotropin releasing hormone |
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How are pituitary hormones released and regulated
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hypothalamic releasing hormones are secreted from hypothalamic neurons into the vascular network or the pituitary portal system
-released in episodic burst -neuroendocrine system - regulated via neural pathways, circulating hormones, circadian factors and environmental conditions |
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Where is the growth hormone secreted from, what does it influence, and what happens to it with ageing?
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secreted from the anterior pituitary gland
-it influences protein, carbs, and fat metabolism and mobilises lipids from adipose tissue -present in foetus but not essential for foetal growth, required for growth postnatal -the gh content of the pituitary increases from birth till adulthood then decreases with ageing |
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What effects GH?
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effected by activity, nutrition and stress
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What is hypersection?
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the production of excess GH after closure of the epiphyseal plate. results in acromegaly and giantism
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What is hyposecretion?
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results in pituitary dwarfism
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How is the growth mediated?
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IGF-I (insulin like growth factors)
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What is the GH/ IFG-1 axis
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it is the central basis for growth being an integral and integrated pathway that involves a large number of factors affecting growth
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What does GH stimulate and from where? how can GH be inhibited
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-GH stimulates the production of IGF-I from the liver.
-GH can be inhibited by somatostatin, and regulated by thyroxine and cortisol |
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Where is IGF-1 formed and what happens with age?
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-peptides formed in the liver adn other tissues such as bone tissue
-igf-i levels are stable throughout the day -95% IGF -1 is bound to proteins, primarily protein 3, this prolongs its life and increases reactivity -surge of IGF-I in adolescent growth spurt parallels the increase in GH bursts -levels reach 415 ng/ml in girls at 13-14 years and 430 ng/ml in boys age 15-16 years |
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what does IGF do?
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-increase cartilage cell proliferation at the growth place
-nitrogen retention -stimulate protein synthesis -cell proliferation |
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What is the relationship between GH/IGF-I and insulin
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-insulin is required for GH, IGF-1, and IGF-2 to exert a full effect on protein synthesis
-insulin and GH have opposite effect on fat -under nutrition= decreased GH receptors and decreased IGF-1 results in inhibiting growth and protein synthesis -Obesity- decreased GH with increased GH receptors, and increased IGF-I with increased insulin results in accelerated growth in height, fat, and lean mass |
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What is insulin essential for, where is it secreted, what stimulates it?
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-essential for carbs metabolism
-secreted from the beta cells of the islets of langerhans in the pancreas -increase in blood sugar stimulates the release of insulin -the autonomic nervous system stimulation of the beta cells also controls the release of insulin -lower blood sugar, increasing glucose uptake in skeletal muscle, adipose cells and other tissues |
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what does insulin maintain, what is it important for and what does it interact with?
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-maintain appropriate blood glucose levels
-insulin is important for normal growth and maturation -insulin interacts with GH for protein synthesis -insulin deficiency can decrease protein synthesis |
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Where is Glucagon secreted and what does it stimulate?
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-secreted in the alpha cells when the blood glucose is low
-increase glycogen breakdown(glycogenolysis) in the liver = increased blood glucose -stimulates breakdown of triglycerides in fat stores increasing fatty acids |
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What does the thyroid consist of and what happens during adolescents?
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consist of two lobes and enlarges during adolescence
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What does the thyroid hormone stimulate and what does it effect?
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-stimulates oxygen uptake and energy expenditure
-effects bodies sensitivity to other hormones -accelerates most biological functions |
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What happens in a hypothyroid child?
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skeletal and sexual maturation is delayed
-if servere mental and physical retardation -causes is iodine deficiency, auto immune thyroiditis, congenital defects |
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What happens in a hyperthyroid child?
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initial excessive growth followed by weight loss
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Where is calcitonin released from, what does it do, what can it inhibit and who does it work with?
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-released from the thyroid gland, .decreases circulating calcium
.calcitonin can inhibit osteoclast activity and increase osteoblast activity .work with the parathyroid hormone to regulate blood calcium and is essential to skeletal growth |
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Where are parathyroid hormones located, what are they essential and what are they vital for?
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-located at the dorsal portion of the thyroid gland
-essential for regulating calcium and phosphate metabolism -vital for normal.. and dental growth and maturation |
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what are the functions of the parathyroid hormone and what does it stimulate and reduce?
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-maintain plasma calcium concentration via direct action on the kidneys and bones
-stimulate osteoclast activity when blood calcium is low -reduces renal clearance of calcium -increase intestinal absorption of calcium |
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where are the adrenal glands located, what happens during growth and what is it innervated with?
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-small glands located on the superior portion of the kidneys
-adrenals initially decrease in size between birth and 6 months of age, then increase through childhood -undergo growth spurt during adolescence returning to there original size -the adrenal medulla is innervated by the sympathetic nervous system |
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Where are the adrenal hormones produced and which ones?
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-medulla produces epinephrine and norepinephrine
-adrenal cortex produces gluccocorticoid- cortisol mineralocorticoids- aldosterone androgens - testosterone |
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What are the testes and ovaries responsible for?
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the production of gamate as well as secreting hormones
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what is the release of androgens and oestrogens dependant upon?
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from release from the testes and ovaries is dependant upon hormones released from the anterior pituitary gland termed gonadotropins
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what are the Gonadotropins?
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FSH- follicle stimulating hormone
LH- luteinizing hormone |
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what is the FSH responsible for?
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-oestrogen synthesis and ovarian follicles in females
-growth of seminiferous tubules and sperm production in males |
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What is the LH responsible for?
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-maturation of ovarian follicles; ovulation, oestrogen and progesterone secretion from ovaries in females
-stimulate testosterone production |
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what is the hypothalmis-pituitary-gonadal axis?
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-gonadotropin releasing hormones(GnRH) are released to the anterior pituitary gland
-stimulating production and secretion of FSH and LH -the axis is moderated with both negative and positive feedback loops |
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Androgen in males?
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males have a higher proportion of androgens than females
-testosterone is the most abundant androgen - |
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what is dihydrotestosterone?
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-derived from testosterone
-synthesized from adrenal precursor androstenedione |
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oestrogen in females?
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-females have a higher level of oestrogen than males
-oestradiol is the most potent oestrogen -most other oestrogens result from peripheral conversion of ovarian and adrenal precursors -testosterone and dihydrotestosterone are present in females in smaller quantities than in males |
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characteristics of androgen?
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testosterone
male characteristics fat mobilising increased GH and IGF-I secretion -potent stimulation of anabolism; bone, cartilage and skeletal muscle growth |
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characteristics of ostrogen?
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oestradiol
-female characteristics -adipose distribution pattern -accelerate skeletal maturity (epiphyseal closure) -also stimulates nitrogen retention |
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What is puberty dominated by, what is GnRH key role, and what are the resultant changes?
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-dominated by sex steriods, GH, IGF-I
-GnRH key role, CNS fundamental regulation (stimulate release of GnRH) -changes tempo of growth, size, body composition, height velocity, insulin resistance, muscle mass, cardiac muscle, blood counts. -related to changes to functional capacity |
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when does peak growth in puberty occur in boys and girls
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females- stage 2-3
males stage 3-4 |
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What does leptin do, what is it required for?
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reduces appetite and increases energy expenditure, it is important for long term appetite regulation
-required for normal growth and maturation -leptin is suggested to occur with ageing -cytokinelike molecules synthesized and secreted by adipocytes in proportion to fat mass |
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What are leptin concentrations correlated with? what happens with absense of leptin? what is it inversely related to?
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-leptin concentrations are correlated with subcutaneous fat, especially abdominal obesity
- absense of leptin is related to serve obesity - deficiency is related to increased risk of type 2 diabetes -exercise depletes leptin -leptin is inversely related to cortisol and ACTH |
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Relationship between growth and exercise? What does PA enhance ?
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-physical activity is important for normal growth and maturation
-physical activity enhances bone mineral density at the sites of mechanical strain but does not influence skeletal maturity -resistance training pre puberty results increased strength without significant muscle hypertrophy -effects of acute and chronic exercise on hormone levels |
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how repetitive exercise affect the hypothalamic-pituitary-gonadal axis?
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its inhibits the axis in highly trained female atheletes. This results in amenorrhea and lack of bone development
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What does aging do to the endocrine system?
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-reduced adrenal cortex output of dehydroepiandrosterone (DHEA)
-decreased IGF-I and GH -thyroid mass and function decrease so BMR decrease, insuffient thyroid hormone is associated with accelerated aging systems however long term increase in thyroid hormone can be related to congestive heart failure |
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What happens to gonadal hormone and ageing
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gonadal hormone decrease
-results in muscle wasting and osteoporosis -testosterone levels decline with age, a decline in testosterone is related to increased abdominal obesity -in the middle of adulthood the gradual decline in sex hormones is termed climacteric -it is more noticeable in women with the cessation of menstration |
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physiological response to stress and what does it result in
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increased neural excitement, cardio-respiratory activity, metabolic activity, protein mobilisation
-results in increased sweating, change in salvation, change in gastrointestinal tone and mobility, vitamin depletion, increased insulin production, increased sodium retention-increased blood pressure |
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symptoms adn illness related to stress
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tight shoulders
anger and irritability fatigue stomach pain digestive decreased immune fuction skin rashes, psoriasis stomach ulcers headaches high blood pressure |
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growth summary
what do GH, IGF 1 and insulin play a major role in? what is the increase in sex hormones at puberty related to? |
play a major and integrated role in protein synthesis, which is essential for growth
-the increase in sex hormones is related to adolescent growth spurts and development of male and female secondary sex characteristics |
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summary of ageing and the endocrine systems
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gradual decline in function of many glands in the endocrine system resulting in decreased hormone production
-decreased androgens result in muscle wasting and osteoporosis |
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Foetal development
how do growth of organs and tissue occur, what two directions does foetal growth proceed in? |
-growth of organ and tissues occurs via hyperplasia and hypertrophy
-two directions- cephalocaudal and proximodistal -although many cells differentiate to perform a specific function, some cells have a high degee of plasticity, such as cells in the CNS |
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development of the nervous system.
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-the nervous system has been described as the essence of an individual
-formation, differentiation and final positioning occurs prenatally |
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nervous system in prenatal development
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-the neurons are usualy in place by the 6th prenatal month
-once the neurons are in place they grow axons to connect to the other neurons -firing of electrical impluses from the neurons strengthen the connections |
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What does some evidence suggest about the nervous system in prenatal development
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suggests that epilepsy, autism and dyslexia are caused by faulty migration
- the nervous system is susceptible to teratogenic exposure during prenatal development |
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in the first year of life each what can each neuron do?
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can establish 1,000-100,000 connections
-this period is very susceptible to extrinsic factors -rapid early growth of the brain |
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Myelination of the Central Nervous system during growth
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-at birth neurons of the CNS are largely unmyelinated
-rapid myelination occurs during the first six months of life -neurons of association areas in the cerebral cortex continue myelination through to adulthood |
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myelination in spinal cord and peripheral nerves.
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-sensory fibers are completed first
-descending motor fibers last (start at term finishes about 2 years) |
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Brain size
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-a full new born brain weights 25% of its adult weight
-increases in mass by 4x between birth and maturity -adult weight of 1100-1700gms (2% of TBW) is achieved as early as 7th year but normally after 15th year |
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Skull
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greater part of skull surrounds relatively massive brain, only small part constitutes face. The base is small
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Brain structures with growth
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-lower brain structures are more advanced at birth, respiration, food intake, reflexes, reactions
-periods of maturation of the brain occurs between 15-24 months, 6-8 years, and adolescence -early motor development may be related to an infant growth spurt of the cerebellum |
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infantile movements
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-newborn movements can be classified into random/spontaneous movements and reflex movements
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Categories of reflex movements
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primative reflex
postural reflex locomotor reflex |
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random/spontaneous movements of infants
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are important for future motor development
-they are the building blocks of intentional movement -supine kicking -infant arm movements |
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what are primitive reflexes?
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reflexes that are present at birth or early infancy are extensions of responses established during foetal life
-reflexes are responses to specific external stimuli -they are specific and localised -the same stimuli will illicit the same reflex consistently |
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Where are reflexes controlled?
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as cerebral control develops, reflexes are controlled
- reflexes dont disappear they remain apparent at times of stress, pathology or some still exist in specific situations in healthy adults -individual constraints may account for disappearance or prolonged existence of a reflex |
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What is functional development? what happens to infants?
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early motor development
-infant progresses from reflex movements to control the acquisition of fundamental movements and skills -in first 2 years of life the infant/child gradually gains postural, locomotor, and prehensile control -development occurs in stages |
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When are skills developed and how does it vary in boys and girls?
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most fundamental skills are developed by 6-7 years of age
-the minimal variation between boys and girls in timing of skill attainment -boys tend to attain proficiency in the overarm throw and kicking before girls, and girls attain proficiency at hopping and skipping sooner |
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individual structural constraints. relative growth
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proportions change dramatically throughout life
-at birth the head accounts for one-fourth of height as an adult it accounts for one-eight -the legs make up 3/8 of height at birth and about half as an adult |
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timing of maturation
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-chronological age and maturation are related, as we get older the maturation occurs, however the timing varies among individuals
-maturation status is a better predictor of performance potential: individuals who are further along in maturation are likely to be stronger and more coordinated -expectations of performance should be based on maturation not chronological age |
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visual development.
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-newborns visual acuity is 20/400
- 6 months vision is adequate for locomotion (crawling) -5 years vision is 20/30 -10 years vision is 20/20 -age 40 onset of presbyopia |
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visual perception
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-2 dimensional perception is required for grasping, locomotion, and complex skills
-depth perception is demonstrated by 6 month old infants -infants perceive objects fairly well but not as well as adults -motion perception is not perceived under 8 weeks old |
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auditory development
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-young infants can determine location of sound
- discrimination of sound determined by 10 years old -refinement continues until early teenage years |
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kinaesthetic perception
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development follows cephalocaudal and proximodistal directions
-reflexes respond to kinesthetic receptors -infants clearly respond to touch at birth -body awareness improves between ages 5-8 |
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What are experience and environmental constraints?
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-aduequate playing environment
-climate -culture (will influence diet and supervision) -social-culture constraints can influence functional constraints of movivation, self esteem, and sense of competence |
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What does ageing do to the central nervous system?
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-decline in brain weight
-loss of nerve cells (1,000 per day) -as nerve cells lost- increase in glial cells - 20-30% of CNS cells lost 25-80 years -sulci broaden and gyri flatten -ventricles increase in size -neurofibrillary tangles -thinning of myelin sheath -blood vessels thicken- decrease blood flow- 20% from 30-70 years -decrease in neurotransmitter substance - up to 50% in some areas of CNS -increased fatty granules, increased calcium deposits -decline in neural plasticity -exercise and the ageing brain |
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What does ageing do to the peripheral nervous system?
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-demyelinization
-reinnervation of damaged nerves is slower -number of sensory receptor organs and sensory sibers decrease -loss of motor units -speed of reflexes -nerve conduction velocity slow only slightly -rxn time increases by as much as 50% from 30-70 years to synaptic delay |
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What else goes ageing do to the peripheral nervous system.. vestibular function, hearing and vision?
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-reduced function - loss of receptors in semicircular canal- cerebellar degeneration- gain changes.. smaller steps.. more falls
hearing- presbycusis vision- in very old need 3x more contrast to see stimuli at low frequencies, poor depth perception, lost peripheral vision |
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What happens to cognitive processing of older adults?
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-a break in neural links- increase time required for response to a signal
-disuse or ageing, replaying mastered skills new experiences, overload principle -exercise- increased blood flow to the brain, stimulate neurogenesis, lessens the loss of dendrites, promotes new synaptic connections resulting in improved cognitive function |
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age related diseases
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-parkinsonism
-dementia -alzhemiers disease- neurofibrillary tangles, amyload plaques,loss of neurons -exercise prescription |
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what is neural plasticity and neurogenesis?
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connections of the brain are constantly changing over the lifespan
-the division and propagation of neurons -learning stimulates changes in the nervous system- MRI show and increased brain area devoted to parts that are frequently used |
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What is developement effected by?
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large range of variation in neural maturation and motor development
- development is effected by integration of structural, functional, environmental and task constraints |
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What does ageing result in in the nervous system?
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ageing results in decreased capacity of the nervous system, however stimulation of the nervous system is proposed to assist maintaining neural function
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what is one gait cycle?
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one gait cycle measured from floor contact of one heel to the following same limb heel contact
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what effects the spatio-temporal characteristics in a young adult?
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leg length
velocity stength terrain balance |
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development of gait.. what do toddlers have?
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center of mass
base of support single leg support time step length velocity an candence |
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what are the 5 parameters used to indicate gait maturity?
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duration single limb support
walking velocity cadence step length base of support |
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what is cerebral palsy?
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possible cause of brain injury
-rarely caused by birth -approx 1 in 300 children have CP -large range in disability level |
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what are the three types of cerebral palsy?
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spastic CP, Ataxic CP, and Athetoid CP
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What is spastic CP
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accounts for 50% of CP cases
-stiffened contracted muscles, sometimes paralysis -five types- diplegia, hemiplegia, quadriplegia, monoplegia, triplegia |
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what is ataxis CP?
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muscles are too weak
-shakey and unsteady -approx 10% of CP cases -affect balance coordination, depth perception -unsteady gait, poor fine motor skills |
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What is Athetoid CP?
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-muscles fluctuate between being too tight and too weak
-patients have involuntary movements in the face and arms and difficulty holding them upright -approx 20% of CP cases -difficulty controlling facial muscles and some may experience speech problems and drooling |
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What is parkinsons disease?
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-degenerative disease of the brian that impairs motor skills, speech, and other functions
-chronic and progessive -decreased stimulation of the motor cortex by the basal ganglia, insufficient dopamine production and action |
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what is parkinsonism?
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is the term referring to the syndrome of bradykinesia, tremor, rigidity and postural instability
-secondary cases may occur due to toxicity of drugs, head trauma, other medical disorders |
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what are parkinson disease symptoms?
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TRAP
Tremor - decrease with voluntary movement Ridigity - increase muscle ton Akinesia or bradykinesia Posural instability; loss of postural reflexes |
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What environment conditions interfere with development of pregnacy?
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-prenatal development is largely canalised process
-exposure to teratogens interfere with development -nutritious diet and healthy lifestyle is beneficial for the mother and foetus |
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weight gain during pregnancy
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- 1st trimester - 1.8-2 kg
-2nd trimester- 5-6 kg -3rd trimester- 3-5 kg |
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endocrine changes during pregnancy?
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-increased release of hormones that mediate foetal development and sustain essential functions of the mother and foetus
-increase release of oestrogen, progesterone, and relaxin |
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musculoskeletal changes during pregnancy
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-relative redistribution of mass
-increase forces on joints -increased mobility of joings -variation and spinal curvature -increase weight gain, ligament laxity and altered postural alignment |
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benefits of Physical activity and pregnacy
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-reduced risk of hypertension
-reduced risk of gestational diabetes -maintain body composition -improved mood, well being and increased energy -promote strength and endurance -reduce muscle cramps -reduce oedema -may improve nutrient delivery and overall foetal growth |
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risk of physical activity and pregnacy
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-changing center of gravity may increase chance on falling
-increased joint laxity -risk of injury to mother or foetus in sport is minimal |
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how can gait be analyzed? how do toddlers and older adults walk?
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-gait cycle can be analyzed with distal and spatial- temporal parameters
-toddlers and older adults walk with wider base of support, decrease single leg support time, shorter step length and slower velocity |
