1. Basic Paediatric Anatomy and Physiology

2. CHILDREN ARE NOT SMALL ADULTS!
Differences between children, adolescents and adults
physiological
anatomical
cognitive
social
and emotional
Growth and development consists of a continuum of biologic events that includes somatic growth or neurobehavioral maturation.
This is related to changes in
body composition
development of organs and organ systems
and change in these organs’ functions

3. Physiology is the science relating how the body functions.
Three branches of science provide the foundation for understanding the biophysical development of children:
Physiology is the science relating how the body functions.
Embryology is the science concerned with the origins and development of the human organism from unicellular embryo or zygote to the birth of a unique human being.
Anatomy is the science of body structures and parts, and the relationship among these structures.

4. Age groups
Newborn or Neonate - birth to 28 days
Infant - 1 to 12 months
Toddler - 1 to 3 years
Preschooler - 3 to 6 years
School Age - 6 to 11 years
Preteen or Tween - 11 to 12 years
Teen - 13 and older

5. Differences between children, adolescents and adults in
physical appearance
skeletal system
nervous system
cardiovascular system /CVS/
respiratory system
renal system
digestive system
reproductive system

6. most dramatic difference is physical size
PHYSICAL APPEARANCE
Standard weight of full-term baby:
2.7–4.1 kg (6 – 9 lbs) average weight of 3.5 kg (7.7 lbs)
The normal length of a full-term baby:
50–53 cm average length of 51cm
midpoint in length on child is umbilicus
midpoint in length on an adult is the symphysis pubis
head is large compared to the adult
often in newborns it exceeds the circumference of the chest
arms and legs are shorted and underdeveloped at birth

7. PHYSICAL APPEARANCE
How body proportions change with age

8. PHYSICAL APPEARANCE
The first 2–3 years of postnatal life is a period of rapid growth and development.
Body weight doubles by 5 months triples by 1 year
Body length increases by 50 % during the first year doubles by 4 years
Growth velocity decreases rapidly from 25 % per month at birth to 4 % at 1 year, and down to 1 % for most of the rest of childhood

9. PHYSICAL APPEARANCE
changes in body composition
TBW: 70–75 % in term neonates  60 % at 4 months, than constant ECW: decreases all through childhood Fat: 12 % of body weight in a term neonate; doubles by 4–5 months of age Muscle mass: increases from 20 % in the term neonate to 50 % in the adult

10. body surface area (BSA) can be computed using West nomogram
Mosteller and Du Bios formula
average BSA:
avg adult BSA: 1.73 m2
BSA is a better indicator of metabolic mass than body weight
clear distinction in regard to pharmacokinetic between children ≥2 years of age and infants <2 years of age

11. Fried’s rule for children up to 2 yrs
 adult dose =
150
age (months)
approx dose for child
Young’s rule for children  2 yrs
 adult dose =
age (yrs) + 12
age (yrs)
approx dose for child
Clark’s rule
 adult dose =
150
weight (lbs)
approx dose for child
Child’s dosage based on BSA
 adult dose =
1.73 m2 (avg adult BSA)
BSA of child (m2)
approx dose for child

12. SKELETAL SYSTEM
bone growth occurs at different rates throughout the body, which affects anatomical landmarks
e.g. in the neonate, the imaginary line joining the iliac crests occurs at S1, not at L4 as in adults
sacrum is not fused normally at birth
at birth spinal column has only the anterior curvature
cervical and lumbar curvature begin with holding head up and walking

13. SKELETAL SYSTEM
skull bones thin
facial bones small
skull possess fontanels soft spots allowing the scull to grow
nose is flat
jaw is tiny (which helps baby with sucking)
small children have small facial sinuses, they reach adult size at the age of 10/12 years
teeth develop during the embryonic stage of development
primary teeth: set of 20
erupt at age of 6 months, eruption continues until month

14. Dentition in humans includes a temporary dentition and a permanent dentition
primary dentition will be completed between the second and third years of age
some primary teeth will remain in the mouth until about 12 years of age

15. NERVOUS SYSTEM
the brain at birth is 1/10 the body weight ( g, 1/4 of future adult weight)
75% of eventual weight in 2, yrs, 90% in 6 yrs
immature BBB
neuronal development finishes as age 12
myelination is not complete until age 3
primitive reflexes (Moro, grasp) disappear with myelination

16. NERVOUS SYSTEM
The most active parts of the brain at birth:
sensorimotor cortex
thalamus
brain stem and
cerebellum
all the major surface features of the cerebral hemispheres present at birth
the cerebral cortex is only half its adult thickness
about 35 reflexes at birth

17. autonomic nervous system is developed at birth, though immature
parasympathetic system is intact and fully functional
pronounced vagal reflexes
lower end of the cord is at L3 at birth (receeds to L1 by 1 year of age)
dural sac shortens from S3 to S1 by 1 y/o
In infants, the more caudad termination of the dural sac makes it more likely to have an inadvertent dural puncture during performance of a single-shot caudal block if the caudal needle is advanced too far into the caudal epidural space.

18. NERVOUS SYSTEM – development of integration
Five predefined functional networks:
DA: dorsal attention network
DF: default network
FPC: fronto-parietal control network
MS: motor-sensory network
V: visual network
spatial evolution across the first 2 yrs
in neonates, motor-sensory network (red) and visual network (blue) already well organized
three higher-order cognitive networks rather scattered
synchronization of higher-order cognitive networks takes a more prolonged time

19. NERVOUS SYSTEM – psychomotor development
sign of nervous system maturation
eexpresses the becoming of different areas of the nervous system of a child in particular periods of life
motorics - purposeful manipulation activity of a child
statics - fixation and holding of definite parts of the body in necessary position
sensory reactions - formation of corresponding reactions on light, sound, pain, touch
speech - expressive speech and understanding the speech
psychic development - positive and negative emotions, formation of social age

20. NERVOUS SYSTEM – development of cognition

21. CARDIOVASCULAR SYSTEM
oxygenation for the foetus occurs in the placenta
the foetus is always hypoxic with an aortic arterial oxygenation saturation of 60 to 70 per cent of the neonate
to maintain adequate oxygen delivery, foetal cardiac output is thus higher, at 440– ml/kg/min, than in the neonate in order to maintain blood supply to the foetal brain
At birth:
umbilical flow is halted
foramen ovale and ductus arteriosus close
heart rate (HR) is approximately 140 bpm in the first 15 minutes
then reduces to a 90–175 bpm range depending on external stimuli and activity level

22. CARDIOVASCULAR SYSTEM
myocardium relatively stiff
stroke volume (SV) is relatively fixed
increasing preload will not increase cadiac output (CO)
CO (L/min) = SV (L/min)  HR (beats/min)
to increase CO, you must increase HR
parasympathetic cardiac innervation
completely developed at birth
sympathetic innervation sparse,
but functional
the resting HR declines postnatally
due to increased parasympathetic activity

23. CARDIOVASCULAR SYSTEM
Normal paediatric cardiac output (CO) and stroke volume (SV):
The heart weight at birth:
girls – 19 g
boys – 24 g
The heart weight:
doubles in the first year of life
6-fold by the age of 9 yrs
CO: Infant at birth = 400 mL/kg/min         Infant after 1st few weeks = 200 mL/kg/min         Adolescent =100 mL/kg/min
SV: Neonate = 1.5 mL/kg/beat         Adolescent = mL/beat
Over childhood cardiac muscle fibres increase 7 times in size. The number of cardiac blood vessels supplying cardiac musce increases as well.
The newborn heart has right ventricle dominance with right thickening in the muscle wall, but, as pulmonary resistance falls in change from foetal circulation, it thins. At four weeks the right ventricle equals the left ventricle in weight

24. CARDIOVASCULAR SYSTEM Heart rates in childhood
Blood pressure changes over childhood

25. CARDIOVASCULAR SYSTEM - hematology
HbF = 70-90% of the haemoglobin molecules HbF at birth % (max. 5%) at 3 months, HbA predominates
haemoglobin level in a newborn  g/dl
haemoglobin levels at 3-6 months  9-12 g/dl
haematocrit  0.6
CARDIOVASCULAR SYSTEM - hematology

26. RESPIRATORY SYSTEM
Paediatric airway:
head is large and neck is short
supine, the chin meets the chest
tongue is large and occupies entire oropharynx
absence of teeth further predisposes the infant to airway obstruction
obligate nose breathers because of the close proximity of the epiglottis to the soft palate
mouth breathing occurs only during crying
obligate nose breathing is vital for respiration during feeding
the pharynx is almost completely soft tissue

27. RESPIRATORY SYSTEM
Larynx: smaller, shaped differently, opposite 2nd and 3rd cervical vertebrae (not 4th and 5th)
Epiglottis flat, more omega or U shaped, softer and harder to pick up
Glottis: ½ cartilage , not ¼
Vocal cords: concave, not horizontal, pink rather than white

28. RESPIRATORY SYSTEM - lungs
Maturation not complete until age 8

29. RESPIRATORY SYSTEM - lungs
maturation not complete until age 8
alveoli grow and increase in number to age 8
surfactant production begins at weeks, but really increases between weeks
breathing movements begin in utero, to prepare for the big event
by 36 weeks, regular breathing movements of 70/min are noted
the alveoli are thick walled at birth.
only 10% of the total number of alveoli found in adults, alveoli clusters develop over the first 8 years of life 
lungs of the foetus are collapsed and filled with fluid until delivery 
lungs expand after alveolar fluid clearence

30. RENAL SYSTEM
immature kidney function at birth  vulnerable to water loss nad dehydration
weigh about 23 g at birth
doubles in 6 months of life triple by the end of the first year adult size by puberty (10-fold increase from birth)
the same number of nephrons as adults
glomeruli are much smaller than in adults
glomerular filtration rate in the newborn is 28–30 ml/min/m2, approx. 100 ml/min/m2 at 9 months, reaching 50% of adult GFR at 1-2 years
tubular immaturity leads to a relative inability to concentrate urine
fluid turnover is 7 times greater than that of an adult

31. RENAL SYSTEM
Immature, small nephrons with short Loops of Henle till the end of 1st year:
NO ADDITIONAL SALT (they cannot excrete the excess to requirements easily)

32. RENAL SYSTEM – keeping the fluid balance
neonate: 20–35 ml of urine 4 times a day
established milk production in the mother: urine 100–200 ml /10 times/day by the 10th day of life
young babies need to feed little and often
older babies can take larger amounts of fluid less often (stomach volume is larger)
fluid intake adjusted for ambient temperatures and the condition of the baby
the newborn has BSA relatively 2-3 times that of the adult  greater water loss through the skin and during increased breathing rates (more rapid dehydration)

33. RENAL SYSTEM – keeping the fluid balance
Daily average fluid requirements for children calculated by body weight

34. DIGESTIVE SYSTEM
small mouth
short tongue, wide, fills the entire cavity of the mouth.
flat and soft hard palate; short, horizontally located
thin mucous membrane, easily damaged, dry
salivary glands secrete sticky saliva containing α-amylase
activity of it increases in months
esophagus: poorly developed narrowing

35. DIGESTIVE SYSTEM - stomach
stomach high in the abdomen
orientated transversely rather than vertically as in the older (7-10 yrs)
capacity of the stomach changes with age
gastric pH is alkalotic at delivery
gastric pH close to adult range by 2nd day of life
acid secretion increases till 3rd year

36. DIGESTIVE SYSTEM – predisposition to regurgitation/reflux
gastroesophageal reflux is common until 5 months of age:
horizontal position of the stomach
small volume of the stomach
pylorus is wide
the cardiac sphincter is not sufficiently developed
pyloric part is well-developed
crus of the diaphragm not tightly surround the esophagus
positioning of the baby (60°)
thickening agents to milk or formula (rice) medication (proton pump inhibitors, prokinetics) surgical terapy (funduplication)

37. DIGESTIVE SYSTEM - liver
large size – 1/3-1/2 of the abdominal cavity in newborns liver lobule not enough demarcated
gallbladder hidden by the liver, different shape
the final formation up to 8 years
thin fibrous capsule
5% of the mass are the blood-forming cells
choleresis delayed,concentration of bile acids high (the newborn may develop obstructive cholestasis)
enzyme systems exist but have not been sensitised or induced
gluconeogensis is deficient
neonates rely on limited supply of stored fats

38. = organ system by which humans reproduce and bear live offspring
sex of a child determined at the time of fertilization
sex non-differentiable up to 8th week
5 weeks: gonadal ridges and 4 ducts: 2 mesonephric (Wolffian), 2 paramesonephric (Müllerian)
9th-12th week: effect of AMH (anti-Müllerian hormone) and androgenes (testosterone)
in males: Müllerian ducts regress, Wolffian ducts develop into spermatic ducts
seminal vesicle and the prostate gland form lately
in females: Wolffian ducts disappear, Müllerian ducts growth promoted  formation of the oviducts, Fallopian tubes, uterus, cervix, and upper vagina
REPRODUCTIVE SYSTEM

39. REPRODUCTIVE SYSTEM

40. REPRODUCTIVE SYSTEM – Tanner scale
Tanner scale = physical measurements of development based on external primary and secondary sex characteristics 9
9-11
14+
10
10 –11.5
13 -15
15+
yrs
yrs

41. REPRODUCTIVE SYSTEM – sex differences in body composition
fat: 25 % of the total weight at birth
boys under the age of 10 yrs 14.4 %, girls %
boys aged yrs: 13.9 %, girls 20.8 %
fat cell numbers tripple in the 1st year of life
than increase of size and number to adult levels throughout puberty
these differences emerge at 3 to 4 years
lean body mass /LBM/ = essential lipid-rich stores in the bone marrow, brain, spinal cord and internal organs
LBM increases from 25 kg at 10 yrs to 42 kg at 16 yrs
muscle mass increases from about 12 kg at 9 ys to 23 kg at 15 yrs
girls attain 2/3 of this LBM compared to boys
girl at the end of puberty: 8–10 % more body fat than boy
her sex specific fat will be about 5 % of her total fat

42. IMMUNE RESPONSES
immune system developing
adaptation from living in sterile environment to exposition to microbial-rich surrounding
cervical plug separates colonized vagina
maternal–foetal membranes of the placenta secrete various antimicrobial proteins and peptides (APPs) into the amniotic fluid
cellular components of immune system initially born in foetal liver, than in bone marrow (white blood cell line)
after 7 weeks of gestation T-cell progenitor cells migrate to the thymus
there differentiate into mature subsets
specific functional defects (compromised chemotaxis, rolling adhesion, transmigration, impairments in microbicidal mechanisms

43. IMMUNE RESPONSES

44. IMMUNE RESPONSES – bacterial colonisation
colonisation in 12 to 24 hours: Enterobacteria, E. coli, and Anaerobes
formula-fed infants: same as above + Bifidobacteria
breastfeeding infants: same as above + Bifidobacteria + Lactobacill
few days after birth: strict anaerobic bacteria community
first month: bifidobacterial species predominate
introduction of solid foods (4–6 months): expansion of clostridial species
by 2–3 years: mainly Bacteroidaceae, Lachnospiraceae, and Ruminococcaceae
remains stable into adulthood
adulthood: 1013 microorganisms about 500 species

45. IMMUNE RESPONSES – Ig protection
main immune protection transferred from mother to child: antibody
passive IgG antibody transferred from the mother = critical early protection against many infectious diseases previously experienced by the mother
transferred across placenta to foetus, then via breast milk
main immunoglobulin class transferred: IgA
works at mucosal surfaces, where it is able to prevent pathogen entry
this passive protection is short lived
decays by the time a child is about months of age

46. IMMUNE RESPONSES – 3 lines of defence
Three lines of defence against pathogenic invasion: 2 innate, 1 adaptive
first line of defence - surface coverage (0-4 h, dry skin, low pH, lysosymes, stomach acid)
second line of defence - when invader gets past the 1st line (4-96 h, phagocytosis, inflammation, fever)
third line of defence – adaptive immunity (>96 h, complement proteins, antigen-presentig cells, T- and B-cells)

47. Thank you for your attention 