Integumentary System

InCheat Sheets / Histology

Name the layers of the epidermis and state the key histological features of each layer
- Stratum basale: Mitotically active cells – stem cells
- Stratum spinosum: Short processes extending from cell-to-cell
- Stratum granulosum: Keratinocytes have numerous intensely staining granules
- Stratum lucidum: Limited to thick skin: a subdivision of the stratum corneum
- Stratum corneum: Keratinized cells
Name the cell types of the epidermis and their respective functions
- Keratinocytes: Highly specialized cells; separate the organism from its external environment
- Melanocytes: Produce melanin (pigment)
- Langerhan’s cells: Antigen presenting cells
- Merkel’s cells: Sensitive mechanoreceptor cells that contact sensory nerve endings
Describe the layers of the dermis
- Papillary dermis: More superficial. Contains loose connective tissue containing Type I and Type III collagen. Thinner and forms dermal papillae and dermal ridges.
- Reticular dermis: Deeper. Contains thick irregular connective tissue containing type I collagen and elastic fibres. Thicker than the papillary dermis. Responsible for Langer’s lines.
Distinguish between apocrine and eccrine sweat glands Eccrine Sweat glands Apocrine sweat glands Lumen Narrower Wider Mechanism of secretion Merocrine secretion Merocrine secretion (previously believed to be apocrine) Contents of secretion Watery secretion Protein-rich secretion containing pheromones Autonomic innervation Adrenergic Cholinergic Stimulus Heat and stress Emotional and sensory stimuli
Describe the structure and function of the neural elements in skin
- Unencapsulated nerve endings
  - Free nerve endings: fine touch, heat, cold, pain
  Encapsulated nerve endings
  - Pacinian corpuscles: pressure changes and vibrationMeissner’s corpuscles: Sensitivity to light touchRuffini’s corpuscles: Sensitive to skin stretch and torque

Dr Jeffrey Kalei

Author and illustrator for Hyperexcision. Interested in emergency room medicine. I have a passion for medical education and drawing.

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Biochemistry

Adrenocorticotrophic hormone	P: <80 ng/L
Alanine aminotransferase (ALT)	P: 5–35 U/L
Albumin	P: 35–50 g/L
Aldosterone	P: 100–500 pmol/L
Alkaline phosphatase	P: 30–130 U/L (adults)
α-Amylase	P: 0–180 IU/dL
α-Fetoprotein	S: <10 kU/L
Angiotensin II	P: 5–35 pmol/L
Antidiuretic hormone (ADH)	P: 0.9–4.6 pmol/L
Aspartate transaminase	P: 5–35 U/L
Bicarbonate	P: 24–30 mmol/L
Bilirubin	P: 3–17 μmol/L
BNP	P: <50 ng/L
C-reactive protein	P: <10 mg/L
Calcitonin	P: <0.1 mcg/L
Calcium (ionized)	P: 1.0–1.25 mmol/L
Calcium (total)	P: 2.12–2.60 mmol/L
Chloride	P: 95–105 mmol/L
Cholesterol	P: <5.0 mmol/L
VLDL	P: 0.128–0.645 mmol/L
LDL	P: <2.0 mmol/L
HDL	P: 0.9–1.93 mmol/L
Cortisol	P: AM 450–700 nmol/L, Midnight 80–280 nmol/L
Creatine kinase (CK)	P: ♂ 25–195 U/L, ♀ 25–170 U/L
Creatinine	P: 70–100 μmol/L
Ferritin	P: 12–200 mcg/L
Folate	S: 2.1 mcg/L
FSH	P/S: 2–8 U/L ♂ (luteal); >25 U/L menopause
Gamma-glutamyl transpeptidase	P: ♂ 11–51 U/L, ♀ 7–33 U/L
Glucose (fasting)	P: 3.5–5.5 mmol/L
Growth hormone	P: <20 mu/L
HbA1C (DCCT)	B: 4–6%
HbA1C (IFCC)	B: 20–42 mmol/mol
Iron	S: ♂ 14–31 μmol/L, ♀ 11–30 μmol/L
Lactate	P: Venous 0.6–2.4 mmol/L, Arterial 0.6–1.8 mmol/L
Lactate dehydrogenase (LDH)	P: 70–250 U/L
Lead	B: <1.8 mmol/L
LH	P: 3–16 U/L (luteal)
Magnesium	P: 0.75–1.05 mmol/L
Osmolality	P: 278–305 mosmol/kg
Parathyroid hormone (PTH)	P: 0.8–8.5 pmol/L
Potassium	P: 3.5–5.3 mmol/L
Prolactin	P: ♂ <450 U/L, ♀ <600 U/L
PSA	P: 0–4 mcg/mL
Protein (total)	P: 60–80 g/L
Red cell folate	B: 0.36–1.44 μmol/L
Renin	P: Erect 2.8–4.5, Recumbent 1.1–2.7 pmol/mL/h
Sodium	P: 135–145 mmol/L
TBG	P: 7–17 mg/L
TSH	P: 0.5–4.2 mU/L
Thyroxine (T4)	P: 70–140 nmol/L
Free T4	P: 9–22 pmol/L
Total iron-binding capacity	S: 54–75 μmol/L
Triglycerides (fasting)	P: 0.50–2.3 mmol/L
Triiodothyronine (T3)	P: 1.2–3.0 nmol/L
Troponin T	P: <0.1 mcg/L
Urate	P: ♂ 210–480 μmol/L, ♀ 150–390 μmol/L
Urea	P: 2.5–6.7 mmol/L
Vitamin B12	S: 0.13–0.68 nmol/L
Vitamin D	S: 50 nmol/L

Arterial Blood Gases

pH	7.35–7.45
PaCO₂	4.7–6.0 kPa
PaO₂	>10.6 kPa
Base excess	±2 mmol/L

Urine

Cortisol (free)	<280 nmol/24h
Hydroxyindole acetic acid	16–73 μmol/24h
Hydroxymethylmandelic acid	16–48 μmol/24h
Metanephrines	0.03–0.69 μmol/mmol creatinine
Osmolality	350–1000 mosmol/kg
17-Oxogenic steroids	♂ 28–30 μmol/24h, ♀ 21–66 μmol/24h
17-Oxosteroids (neutral)	♂ 17–76 μmol/24h, ♀ 14–59 μmol/24h
Phosphate (inorganic)	15–50 mmol/24h
Potassium	14–120 mmol/24h
Protein	<150 mg/24h
Protein/creatinine ratio	<3 mg/mmol
Sodium	100–250 mmol/24h

Haematology

WCC	4.0–11.0 ×10⁹/L
Red cell count	♂ 4.5–6.5 ×10¹²/L, ♀ 3.9–5.6 ×10¹²/L
Haemoglobin	♂ 130–180 g/L, ♀ 115–160 g/L
PCV / Haematocrit	♂ 0.4–0.54 L/L, ♀ 0.37–0.47 L/L
MCV	76–96 fL
MCH	27–32 pg
MCHC	300–360 g/L
RDW	11.6–14.6%
Neutrophils	2.0–7.5 ×10⁹/L (40–75%)
Lymphocytes	1.0–4.5 ×10⁹/L (20–45%)
Eosinophils	0.04–0.44 ×10⁹/L (1–6%)
Basophils	0–0.10 ×10⁹/L (0–1%)
Monocytes	0.2–0.8 ×10⁹/L (2–10%)
Platelet count	150–400 ×10⁹/L
Reticulocyte count	0.8–2.0% / 25–100 ×10⁹/L
ESR	Depends on age
Prothrombin time	10–14 s
APTT	35–45 s

Paediatric

Pulse Rate (beats per minute)
Neonate (<1 month)	140–160
Infant (<1 year)	120–140
1–5 years	110–130
5–12 years	80–120
>12 years	70–100
Temperature
Normal range	36.6–37.2 °C
38.0 °C	Fever (infant)
38.5 °C	Fever (>3 months)
Respiratory Rate (tachypnoea)
Neonate (0–2 months)	≥60 breaths/min
2–12 months	≥50 breaths/min
1–5 years	≥40 breaths/min
>5 years	≥30 breaths/min
Blood Pressure (mmHg)
Term	65/45
1 year	75/50
4 years	85/60
8 years	95/65
10 years	100/70
Head Circumference
Term	35 cm ± 2
1 year	+1 cm/month
2–3 years	+2 cm/year
4–5 years	+1 cm/year
5 years	~53 cm
10 years	56–57 cm
Height
Term	52–55 cm
1 year	75 cm
2–12 years	6a + 77 cm
Weight Formulas
3–12 months	(a + 9)/2 kg
1–6 years	2a + 8 kg
>6 years	(7a − 5)/2 kg
Developmental Milestones
Social smile	1.5 months
Head control	4 months
Sits unsupported	7 months
Crawls	10 months
Stands unsupported	10–12 months
Walks	12–13 months
Talks	18 months
MUAC (6 months–5 years)
Obese	>17.5 cm
Normal	13.5–17.4 cm
At risk	12.5–13.4 cm
Moderate malnutrition	11.5–12.4 cm
Severe malnutrition	<11.5 cm
Blood Transfusion
Whole blood	20 mL/kg
pRBC	10 mL/kg
Formula	6 × (weight in kg) × Hb deficit
Normal Paediatric Lab Values
Haemoglobin (g/dL)	Hematocrit (%)
Term newborn: 13–20	40–58
1 month: 11–18	32–54
2 months: 10–15	28–44
1–2 years: 10–13	32–40
>2 years: 11–14	33–42
CSF WBC (/mm³)
Term newborn	0–25
>2 weeks	0–5

Dr Jeffrey Kalei

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