Lecture Eight Flashcards

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1
Q

What is Growth?

A
  • An increase in size of the whole body or parts of the body
  • Dominates the first 20 years of life
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2
Q

How does growth occur?

A
  • Increase in cell number (hyperplasia)
  • Increase in cell size (hypertrophy)
  • Increase in intercellular substances (acceleration)
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3
Q

What does growth focus on?

A

-Focuses on the size attained at a given time

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4
Q

What is Maturation?

A

-The process of becoming mature or the process towards a mature biological state

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5
Q

Where does it occur and what varies between individuals?

A
  • Occurs in all organs and their systems and tissues
  • e.g. skeletal maturity = fully ossified adult skeleton
  • Timing and Tempo of maturation varies between individuals
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6
Q

What are the developmental contexts?

A
  • Biological
  • The development of stem cells into functional cells and systems
  • Behavioural
  • The development of behavioural competence:
  • Motor/skill acquisition
  • Socially acceptable behaviours
  • Intellectual
  • Emotional
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7
Q

What is the definition of Chronological Age, Biological Age & Prenatal?

A
  • Chronological Age = How many years old you are
  • Biological Age = The age of your biological maturation
  • Prenatal = period of growth and development prior to birth (~9 months)
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8
Q

Define Germinal, Embryonic, & Foetal Periods

A
  • Germinal Period = fertilisation to end of germ layer formation (weeks 1 – 2 of development)
  • Embryonic Period = days 14-56 (weeks 3-8) after fertilisation
  • Developing human is called an Embryo
  • Foetal Period = 56 days to birth (last 30 weeks)
  • Developing human is called a Foetus
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9
Q

What are the Dermatomes?

A
  • The dermatome is an area of skin supplied by nerves from a single spinal root
  • Each spinal nerve innervates a particular known area of skin
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10
Q

What are the Myotomes?

A

-A group of muscles that a single nerve innervates

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11
Q

What does the mother provide and remove to the baby?

A

-Mother provides O2 and nutrients to the foetus and removes CO2 and waste products

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12
Q

Function of the Placenta?

A

Allows exchange to occur without mixing of the mothers and foetuses blood

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13
Q

Function of the Umbilical Vein?

A

Carries O2 and nutrients from the placenta to the foetus

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14
Q

Function of the Umbilical Arteries?

A

Transports venous blood from foetus to placenta for re-oxygenation and elimination of wastes

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15
Q

What are the foetuses lungs are heart doing while in the womb?

A
  • Foetuses lungs do not function - they are filled with fluid
  • The foetuses’ heart does pump blood but only 10-15% of the blood pumped by heart goes through the lungs
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16
Q

How does blood get from one side of the heart to the other in the foetus? What is the Ductus Venosa and its function?

A
  • Two shunts which shift blood from the right to left side of the heart thus bypassing the lungs:
  • Ductus Venosa – temporary vessel from umbilical vein to inferior vena cava
  • Allows oxygenated blood from maternal circulation to pass directly from the umbilical vein to the inferior vena cava – bypassing the live
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17
Q

What is the Foramen Ovale and its function?

A
  1. One way opening in the septum separating the right and left atria
    - Allows blood to bypass the right ventricle to go straight to the left atria
    - Once blood has moved through the right atrium the pressure in the left closes the valve thus preventing back flow
18
Q

What is the Ductus Arteriosus and its function ?

A
  1. Small vessel which connects the pulmonary artery to the aorta
    - Serves as a right to left shunt. Allows the small amount of blood pumped by the right ventricle to the lungs to be diverted to the aorta
19
Q

What are the circulatory changes after birth?

A

-Metabolic link between Mother and Foetus is severed at birth
-Large inflation of lungs at birth
= Expansion of lungs
= reduced resistance to blood flow through lungs
= increased blood flow through pulmonary arteries
= more blood from right atrium to right ventricle to pulmonary artery
= less through the foramen ovale also
-more blood returns to left atrium via pulmonary veins
= increased pressure in the left atrium
= closure of the foramen ovale (fossa ovalis)
-Constriction of ductus arteriosus = complete permanent closure = replaced with connective tissue = ligamentum arteriosum
-Cutting of the umbilical cords = no more blood flow through and the umbilical veins and arteries degrade = no blood through ductus venosus = ligamentum venosum

20
Q

What are the age groups?

A

-Postnatal = period after birth
-Infancy = first year of birth (0-1 year)
oPerinatal = the first week
oNeonatal = the first month
oPostnatal = the remainder of the first year
oChildhood = 1 year – adolescence
-Early Childhood = preschool years (1 – 4 years)
-Middle Childhood = elementary school years (5 years to adolescence)
oAdolescence = generally between 10-18 years
-Onset and termination of adolescence is highly variable
-Males: 10 - 22 years
-Females: 8 - 19 years
-Adulthood = Age 20 to death
oYoung Adult = 20-40 yrs
oMiddle age = 40-65 yrs
oOlder Adult = 65 yrs to death
-Three generations:
-65-75
-75-85
-85+

21
Q

What is Infancy & Childhood?

A

-Infancy = period of rapid growth of most systems
-Childhood
oEarly childhood = continued rapid growth but at a decelerating rate
oMiddle childhood = steady progress

22
Q

After birth what happens to the heart?

A

After birth, left side size grows more rapidly compared to the right

23
Q

Why does the left side of the heart grow more rapidly than the right side?

A

Left ventricle pumps blood against a higher pressure or resistance than the right

24
Q

Describe the hearts size from birth to 2years

A

Size continues to grow until young adulthood

  • Birth = 40 cm3
  • 6 months = doubled
  • 2 years = x 4
25
Q

How does Heart Rate change after birth?

A

-Recall HR = rate at which the heart contracts per minute (bpm)
-Foetal HR begins week 4, prenatal
oHR is rapid
-Labour contractions can cause a foetal HR of 200 bpm
-Newborn HR = 140 ± 20 bpm
oNewborn crying HR can reach 170 bpm
-Over a year HR will decline by ~40 bpm
-6 years HR = ~80 bpm
-10 years HR = ~70 bpm

26
Q

Why do infants & children have higher HR’s compared to adults?

A

oSmaller amount of blood volume
-Still requires blood to reach large surface area
oMyocardium is less contractile / heart produces less forceful contractions
-Due to heart not fully developed
-All these factors contribute to a small SV therefore higher HR is required to maintain cardiac output (CO)

27
Q

Why does HR decline as the child grows?

A

As the heart grows and as blood volume increases the SV increases therefore HR can decrease to maintain CO

28
Q

How is stroke volume affected

A
  • Heart size
  • Contractile force
  • Vascular resistance (vasodilation/vasoconstriction) to blood flow
  • Venous return - rate at which blood is returned to the right side of the heart
  • Infants are not bipedal = limited venous muscular pump
29
Q

Why is stroke volume lower in infants/children?

A

Due to smaller heart size and blood volume

  • Birth SV = 3-4 ml per contraction
  • By Adolescence SV is increased to = 60 ml per contraction
30
Q

How does Cardiac Output change at birth?

A

-Recall CO = blood ejected from the left ventricle in one-minute
CO (Q) = SV x HR
-CO less in children in both resting and exercise
-Newborn = 0.5 L / min
-Children (3-12 years) = 3.6-4.8 L / min
-Children have higher HR’s than adults but not enough to compensate for the reduced SV therefore still a lower CO compared to adults

31
Q

Why is no breathing required in the womb?

A
  • Prenatal lungs filled with fluid = pulmonary resistance is very high, and no gas exchange occurs
  • No breathing movements are required because the foetal blood is oxygenated by the mother, so the brain doesn’t tell the breathing muscles to move therefore decreasing the O2 demand
32
Q

What occurs at the first breath?

A
  • This fluid is pushed out when thorax is compressed during birth
  • Decreased O2, increased CO2, light, mild cooling, sound and touch stimulate the respiratory centre in the brain to take the first breath
  • Alveoli expand and fill with air
  • Pulmonary vessels allow more blood flow
33
Q

What are the breathing rates from birth to 6years old?

A

oBirth = 40 / min
o1 year = 30 / min
o5-6 yrs = 22 / min
-Respiratory tree fully developed by 8 years of age

34
Q

What is thermoregulation in infants and children?

A

-Body surface area (BSA)-to-mass ratio is important for thermoregulation
oThis changes as one grows = 33% decline b/w 2 yrs – 16 yrs
oAn infant and child has:
> BSA to mass ratio
= faster rate of heat dissipation which is advantageous particularly if the skin temp is higher than the environment
-Not advantageous in cold climates
-Low evaporative capacity
oLower sweating rate (particularly in males)
oSweat glands produce less
= lower sweating rate per BSA
-Pre pubertal sweat rate is less compared to post puberty in males
oHigher sweating threshold
-Sweating activated at higher intensities or higher core temperatures
Therefore, children rely on more cutaneous blood flow
oRely on heat loss via convection
-Poorly developed vasoconstriction mechanisms
oMinimal subcutaneous fat
oShivering mechanism not matures

35
Q

What is Lactase?

A

Enzyme required for milk digestion is high at birth and gradually declines = milk diet

36
Q

How does digestion change at birth?

A
  • Number of digestive enzymes increases as the infant gets older
  • Full set of deciduous teeth (n=20; no molar teeth) are present by 30 months
  • Blunt and limits chewing = reduced mechanical breakdown of food
  • Capacity of the stomach increases with age
  • Lower oesophagus sphincter is immature = contributes to reflux
37
Q

How does the Growth Hormone work?

A
  • Growth promoting effects from the hormone directly on target tissues
  • Stimulates production of insulin like growth factors produced from the liver
38
Q

What are the Insulin Growth Factors?

A

Insulin like growth factors (growth promoting molecules)
oIGF1 – Regulation of linear growth – long bone development, protein synthesis, increases cell proliferation
oIGF2 – Particularly important during the foetal period for organ creation and muscle differentiation

39
Q

What does Thyroid Hormone influence?

A

-GH requires thyroxine to function
-Influences growth and maturation
oSkeletal growth and maturation
oSexual maturation
oMuscle development

40
Q

What happens at birth to Thyroid Stimulating Hormone levels?

A
  • Accelerates most biological processes
  • TSH are at the their highest in infancy and childhood
  • Levels fall from birth
41
Q

Function of the Adrenal Medulla and Cortex?

A
  • Adrenal Medulla = for normal growth and development

- Adrenal Cortex = regulation of growth and development