Chapter 9 Flashcards
What are the 5 body systems that we talk about in this course?
- Skeletal
- Muscular
- Adipose
- Endocrine
- Nervous
What is a rate-limiting constraints?
a system that lags in development can be a developmental rate limiter
Where does ossification begin? (prenatal)
- primary ossification centers in the midportions of long bones
How many primary ossification centers are present before birth and after birth?
around 400 before the baby is born and another 400 of them show up after birth
What is ossification?
Bone formation
process by which new bone is produced
Where does growth in bone length occur?
secondary ossification centers at the end of the bone shaft
What are secondary ossification centers also known as?
- epiphyseal plates
- growth plates
- pressure epiphyses
How do small round bones ossify
from the centre out
what is increase in bone girth called?
appositional bone growth
What are traction epiphyses
where muscle tendons attach to bones
What happens to bone as you get older?
- bone growth slows
- fails to keep pace with resorption
- results in loss of bone mass
- bone becomes more brittle
Why do women have more of a risk for severe bone structure changes?
menopause, don’t have as much osteoblastic activity
What does prenatal muscle fiber growth involve?
hyperplasia (number of cells) and hypertrophy (size of the cells)
What pattern does muscle growth follow?
sigmoid pattern
how does muscle increase in diameter and length?
the addition of sarcomeres
What kind of growth happens posnatally?
hypertrophy
at what age do you start losing muscle mass?
- minimal until 50 years
- still lots of variability
- by 80, on average an additional 30% of muscle mass is lost
what heart ventricle is larger at birth?
the right ventricle but the left catches up
what happens to the heart in old age?
- heart can lose elasticity and valves become more fibrotic
When does adipose tissue first appears in a fetus?
at about 3.5 months
how much does adipose tissue account for of body weight at birth?
about 0.5 kg of body weight
What is adipose tissue used for?
energy storage
insulation
protection
at what age does subcutaneous fat increase?
6-7 years until age 12 or 13 in both sexes
what is the difference between males and females in regards to subcutaneous fat ?
subcutaneous fat continues to increase in females
males tend to lose subcutaneous fat mid-adolescence
What is subcutaneous fat?
a type of fat that’s stored just beneath your skin
What is the main purpose of the endocrine system
- plays a role in regulating growth and maturation through hormones
what do these hormones stimulate?
protein anabolism (constructive metabolism/tissue building)
What are the major hormones involved in growth?
- growth hormones (GH)
- Thyroid hormones (TH)
- gonadal hormones - estrogen, androgens (including testosterone
what role does insulin play?
indirect role and is vital for carbohydrate metabolism and for the full functioning of GH
what happens when you have a insulin deficiency?
can decrease protein synthesis, which is detrimental at any point in the lifespan, but particularly during growth
What are the locations of the endocrine glands? (3)
- Pituitary gland (anterior and posterior)
- thyroid gland
- adrenal glands (medulla and cortex)
where is the growth hormone secreted?
Anterior pituitary gland
what does the growth hormone do?
necessary for normal growth
stimulates protein anabolism = new tissue built
What can a deficiency of growth hormone lead to?
can result in growth abnormality
Where are the thyroid hormones secreted from?
thyroid gland
what do the 3 types of thyroid hormones influence?
2 types influence whole-body
the 3rd one plays a role in skeletal growth
What are gonadal hormones?
influences growth, sexual maturation (sex organs, secondary sex characteristics)
what are the 2 types of gonadal hormones?
androgens and estrogen
What are androgens? What are the roles of androgens?
- secreted by testes (males), adrenal glands (both sexes)
- hasten epiphyseal growth plate closure
- promote growth of muscle mass by increasing nitrogen retention and protein synthesis
What is estrogen and what are the roles of estrogen?
- secreted by ovaries (females) adrenal cortex (both sexes)
- hastens epiphyseal growth plates closure
- promotes accumulation of fat
What is the frontal lobe’s responsibility?
- Voluntary movement
- Language
- Higher level executive function
○ Collection of having higher level talkative skills
○Control responses
What is the prefrontal cortex’s responsibility?
- For infants it helps them to be able to recognize faces, voices, favourites
- For older individuals
○ Key in planning,
prioritizing
○One of the last
things to
develop
What is the parietal lobe’s responsibility?
- Helps us receive and process sensory input
○ Touch
○ Pressure
○ Heat/cold
○ Paint - Body awareness
- Create a mental map
- Spatially coordination
What is the temporal lobe’s responsibility?
- Important for emotions
- Processing information from your senses
- Storing and retrieving memory
- Understanding language
What is the occipital lobe’s responsibility?
- Visual processing
○ Get spatial information
○ Distance and depth perception
○ Discern colours
○ Object and face recognition
○ Memory formation
What is the diencephalon’s responsibility?
- Very crucial body function
○ Coordinate the endocrine system
○ Relays sensory and motor signals
○ Circadian rhythm
○ Breathing, consciousness, BP, HR - Blends into the brain stem
What is the brain stems responsibility?
- Consciousness
- the control centre
What is the cerebellum’s responsibility?
- motor control **
- posture maintenance
- balance
what is the cerebral cortex?
outer layer of the brain that lays across the cerebellum
What are the roles and responsibilities of the cell body?
- compared to a trees root system
- dendrites reach out to get the nutrients
- messages are converted into electrical impulses
What are the roles and responsibilities of the axons?
- Trees trunk
- Nutrients transfer up the trunk
- Axon terminal
○ Buds that are at the end of a tree branch
○ Electrical impulses are transferee here to be picked up by another nerve cell
where is the myelin sheath located?
surrounding the axon
What sort of extrinsic factors fine-tune the system
teratogens might disturb normal mitigation and branching
What happens to the nervous system prenatally?
The formation of neurons, their differentiation into a general type, and their migration to a final position in the nervous system
What % of the adult weight of the brain does a baby have at birth?
25% of the adult weight
What factors is involved in growth?
- increases in size of neurons
- prolific branching to form synapses
- increases in glial cells for support and nourishment of neurons
- increases in myelin to insulin axons
What are some major changes in both structure and function occur within childhood?
- changes due to maturation as well as neural pruning
- second surge of neuronal growth right before puberty
- continued refinement up to 25 years of age
What is neurogenesis?
division and propagation of neurons
What is the neural network model?
- one theory of aging that suggestios that breaks in neural network links cause detours and therefore slowing
- with advancing age, more links break and as a result there is a longer signaling time
