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ch 5 Development and aging of the body system
|individual structure, is living tissue
|the natural process of bone formation
|The site where bone begins to form
|two types of ossification centers
|Primary and Secondary
|The primary ossification centers
|in the midportion of the shafts of long bones, from the Center outward to form bone shafts
|Active secondary ossification centers
|are found at the end of the bone shafts -indicated on X rays by a line that is a layer of cartilage cells -Also called a pressure epiphysis
|when does almost all epiphyseal plates are close?
|by age 18-19
|epiphyseal plates close at younger ages in girls or boys?
|girls 15.5 but boys at 18.1
|Appositional bone growth
|(physical thickness) involves addition of new layers on previously formed layers so that a bone grows in girth
|irritation of the traction epiphysis where the patellar tendon attaches to the shin bone below the knee
|Imagine you are the parent of a youth boy who is the pitcher on his youth baseball team. He already practices once a week and plays weekly games. The coach wants him to join another 2nd team to get more pitching experience. Would you consent?
|Does it depend on what the kid wants? What’s a young boy? How much pitching during each game ?Overuse elbow joint, Right mechanics, Same motion each time , Motivation
|new bone is formed faster than older bone is resorbed, allowing for growth
|-bone formation begins to slow -loss of bone tissue from mid-20s at 1% of bone mass per year
|Older adults have how much more inorganic material?
|Why does bone loss with aging occur?
|-Related to changes in hormone levels, dietary deficiencies, and decreased exercise -Decreased levels of estrogen in post-menopausal women --> more likely to get Osteoporosis
|is a major bone mineral disorder characterized by a bone mineral density significantly below the average -higher in adult women - decreased estrogen levels
|As the bone becomes Porous what happens?
|it increases the risk of fractures and complicates fracture repair
|complete bone death
|What Strategies we can implement to minimize the bone loss in adulthood?
|think lines, grooves, or dents on the muscle line
|lose muscle mass
|Early Development of the Muscular System – Male
|During and after adolescence, muscle mass increases rapidly up to about age 17 (54% of body weight)
|Early Development of the Muscular System - female
|Only add muscle mass until age 13 (45% of body weight)
|Type 1 muscle fiber
|-slow twitch -endurance activities
|Type 2 muscle fiber
|-fast twitch -intense short duration activities
|Between the mid-20s and age 50 how much skeletal muscle is lost ?
|Only 10% is lost
|what decreases accounting for the muscle loss?
|Both the number of fibers and the size of the fibers
|where do boys gain fat?
|add more subcutaneous fat to their trunks than to their limbs
|Where do girls gain fat?
|increased subcutaneous fat at both slides
|What is the difference between the primary and secondary ossification centers? As it relates to the skeletal?
|-Bone development -Primary: Center --> more dense -Secondary: Ends points of long bones --> length
|Ossification differ by sex?
|-Female growth rate is sooner -Males grow for longer & faster
|What is appositional bone growth?
|Youth skeletal muscle
|New bone growth
|Adults skeletal muscle
|Bone formation begins to slow & bone mass loss
|Why does bone loss with aging occur
|Dietary deficiencies , Hormonal
|How do muscle fibers grow?
|Hypertrophy (size) & Hyperplasia (# of cells)
|Muscle growth occurs predominantly by what?
|hypertrophy @ birth
|Why do we lose muscle mass as we age?
|Life style changes
|Is the presence of adipose tissue bad?
|T/F A fat baby will become a fat child
|False, , but not until childhood years of age it becomes an indicator
|Differences in how we put on fat tissue based off of sex.
|Trunk – similar between boys and girls Extremities – higher for girls than boys
|Is the increase in fat weight with aging inevitable?
|This system chemically controls the various functions of cells, tissues, and organs through the secretion of hormones
|are chemical substances secreted into body fluids by a gland
|-Stimulates Protein anabolism so that new tissue can be built -Secreted by the anterior pituitary gland and influences growth in childhood and adolescence
|Secreted by the thyroid gland, located in the anterior neck region, and influence whole-body growth and skeletal growth
|Affect growth and sexual maturation (particularly during adolescence) by stimulating development of the secondary sex characteristics and the sex organs
|Androgens also play a role in the adolescent growth spurt of muscle mass. Who is it more pronounced in?
|-Men secrete both testosterone and adrenal androgens (in men) -Women only produce the adrenal androgens
|-Influences glucose metabolism which indirectly affects development -Produced in the pancreas
|Gradual imbalance (cause of aging) theories
|suggests that over time the nervous system, endocrine system, and immune system gradually fail to function
|hypothyroidism = acceleration of aging systems; increased thyroid hormone levels = congestive heart failure risk
|Gonadal hormone levels ↓ with age
|estrogen levels ↓ after menopause which can lead to osteoporosis
|Diabetes incidence ↑s with age
|likely related to inability of body to use insulin
|What can we do to counteract these hormonal effects of aging?
|hormonal replacement theory
|This system controls movement and speech and is the site of thinking, analysis, and memory
|are the cells of the nervous system that receive and transmit information
|neurons are in the final location by
|the sixth prenatal month, and then specialize
|is a connection between two neurons; it is made by the release of chemicals called neurotransmitters from an axon
|Assume you have just found out you will be a new mother. What
|Sushi, tuna (mercury), raw meats, caffeine, deli meats, raw unpasteurized milk
|The migration of neurons and the branching of their processes are susceptible to effects of environmental factors delivered via ...
|the fetal nourishment system
|↑ risk of mental retardation
|fetal alcohol syndrome
|At birth how heavy is the brain ?
|25% of adult weight and this increases to 80% by 4 years of age
|support and nourish the neurons
|insulating sheath around the axons
|Does brain function declines with age due to loss of neurons, synapses?
|-Yes, these losses happen with age and likely contribute to changes in motor behavior. -But a lot of new research said the brain is quite plastic, adaptable and malleable
|what can play a key role in minimizing the loss of neurons and synapses with aging?
|Regular vigorous Exercise