Digestive System - Hyperexcision

Last updated: November 12, 2024

Name the type of papillae on the dorsal surface of the tongue and state their respective locations on the tongue
- Filiform papillae: anterior dorsal tongue
- Fungiform papillae: Tip of the tongue
- Circumvallate papillae: Anterior to the sulcus terminalis
- Foliate papillae: Lateral edges of the tongue
Name the cell types of the taste bud
- Neuroepithelial (Sensory) cells: Elongated cells that have microvilli on their apical surface and are connected with afferent endings of CN VII, CN IX and CN X at their base
- Supporting cells: Similar to sensory but they do not synapse with afferent nerve endings.
- Basal cells: Stem cells for sensory and supporting cells.
Describe the histological structure of the ductal and secretory part of a mixed salivary gland
- Secretory part: Mucous cells with Serous demilunes (Fr. half-moon)
- Ductal part
  - Intercalated ducts
    - Low cuboidal lining
    - Bicarbonate secretion and Cl- absorption
    - *Carbonic anhydrase activity
  - Striated ducts
    - simple cuboidal lining that gradually becomes columnar
    - Na+ reabsorption
    - K+ and bicarbonate secretion
  - Excretory ducts
    - simple cuboidal → pseudostratified columnar/ stratified cuboidal → stratified squamous lining
    - Opens into the oral cavity
Describe the histological structure of the oesophagus
- Mucosa
  - Non-keratinizing stratified squamous epithelium
  - Diffuse lymphatic tissue the in lamina propria
  - Muscularis mucosa (longitudinal smooth muscles)
- Submucosa
  - Dense irregular connective tissue
  - Submucosal (Meissner’s) plexus
- Muscularis Externa
  - Longitudinal and circular muscle layers
  - Myenteric (Auerbach’s) plexus
- Adventitia (thoracic part) or Serosa (Visceral peritoneum in the abdominal part)
Describe the histological appearance of the parenchyma of the parotid gland
1. Acinus
  - Serous acini
  - Pyramid shaped serous cells
2. Intercalated duct
  - Well developed
  - Low cuboidal epithelial cells
3. Striated duct
  - Well developed
  - Simple cuboidal epithelium that gradually becomes columnar as it approaches the excretory duct – basal infoldings w/elongated mitochondria and basolateral folds
4. Excretory duct
  - simple cuboidal → pseudostratified columnar/stratified cuboidal → stratified squamous epithelium
Describe the gastric pit and gland with reference to the distribution of cells and function
- Gastric pits (foveolae) are openings visible on the stomach mucosa at higher magnifications.Surface:
  - Surface mucous cells: Mucin secretion
  Isthmus
  - Undifferentiated adult stem cells: regeneration
  Neck
  - Parietal cell: HCl and Intrinsic factor secretionMucous neck cells: Mucin secretionEnteroendocrine cells: Hormone secretion
  Fundus
  - Chief cells: Zymogen secretionParietal cellsEnteroendocrine cells

Describe the parts and respective functions of the ductal system of salivary glands
- Intercalated ducts: Leads from the acinus
  - Low cuboidal lining
  - Bicarbonate secretion and Cl- absorption
  - *Carbonic anhydrase activity
- Striated ducts: because of the presence of striations in the basal aspect
  - simple cuboidal lining that gradually becomes columnar
  - Na+ reabsorption
  - K+ and bicarbonate secretion
- Excretory ducts: larger ducts that empty into the oral cavity
  - simple cuboidal → pseudostratified columnar/ stratified cuboidal → stratified squamous lining
  - Opens into the oral cavity
Name the cell types of the gastric gland epithelium and state their respective functions
- Mucous neck cells – mucin secretion
- Chief cells – pepsinogen and weak lipase secretion
- Parietal cells – HCl and intrinsic factor secretion
- Enteroendocrine cells – hormone secretion
- Undifferentiated adult stem cells – regeneration

State the structural differences in parietal cells between its active and inactive forms

	Active parietal cell	Inactive parietal cell
Microvilli in canaliculi	Increased	Decreased
Tubulovesicular system	Reduced in number or disappear as they are inserted into the cell membrane	Present in the cytoplasm
Mitochondria	Numerous with complex cristae	Reduced in number

Name the cell types of the duodenal epithelium and state their respective functions
- Enterocytes – absorption
- Goblet cells – mucin secretion
- Paneth cells – antimicrobial substance secretion
- Enteroendocrine cells – produce various paracrine and endocrine hormones
- M cells (Microfold cells) – selective endocytosis of antigens and transport to intraepithelial lymphocytes and macrophages which then travel to lymphoid tissue to mount immune responses
Describe the lamina propria of the small intestine
- Mucosal glands: extend into the lamina propria
- Blood and lymphatic vessels: Fenestrated capillaries and lymphatic capillaries that absorb metabolites, lipids, and proteins
- Lymphatic tissue: Lymphocytes, plasma cells, macrophages, eosinophils, mast cells
  - Diffuse lymphatic tissue (GALT): Diffusely arranged Lymphocytes and plasma cells
  - Peyer’s patches: Aggregated lymphocytes that occupies the lamina propria and submucosa.
What is a “collagen table’ in the large intestines? State its significance
- A thick layer of collagen and proteoglycans that lies between the basal lamina of the epithelium and that of the fenestrated absorptive venous capillaries
- Regulates water and electrolyte transport from the intercellular compartment of the epithelium to the vascular compartment
Describe the mucosa of the rectum and give one clinical correlate
- Glands: Straight, tubular intestinal glands
- Epithelium: Simple columnar epithelium
- Lamina propria: Has a collagen table, pericryptal fibroblast sheath, GALT and lymphatics
- Clinical correlate: Colorectal cancer

With the aid of diagrams outline the classification of liver lobules

Classic Liver Lobule (A): Based on blood flow pattern, with the central vein as the axis
Liver acinus (B): Based on susceptibility to injury. Has 3 zones
Portal lobule (C): Based on biliary drainage, with the portal triad as the axis

Illustrate the zonation of a liver acinus

Describe the following regarding the liver: Space of Disse, Kupffer cells, Ito cells, Glisson’s Capsule, Space of Mal
- Space of Disse: Perisinusoidal space. Found between the hepatocytes and sinusoids
- Kupffer cells: Phagocytic macrophages within the lumen of liver sinusoids
- Ito cells: Hepatic stellate cells that store vitamin A, and differentiate into myofibroblasts during pathological conditions (eg. cause bridging fibrosis by secreting collagen – a feature of liver cirrhosis)
- Glisson’s capsule: Fibrous connective tissue enclosing the liver
- Space of Mal: Periportal space between the stroma of the portal canal and outermost hepatocytes
What are the histological peculiarities of the gall bladder wall
- Absent muscularis mucosae
- Absent submucosa
- Rokitansky-Aschoff sinuses extend through the muscularis externa. They are pathological changes.
- Smooth muscle bundles in muscularis externa are randomly oriented
Name the principal cell types of the islets of Langerhan and state their respective secretions
- A cells – Glucagon production
- B cells – Insulin production
- D cells – Somatostatin production
- PP cells (F cells) – pancreatic polypeptide secretion
- D1 cell – Vasoactive intestinal polypeptide secretion
- EC cell – secretin, motilin and substance P production
- Epsilon cell – Ghrelin production

Reference Intervals ›

Biochemistry

ACTH	P: <80 ng/L
ALT	P: 5–35 U/L
Albumin	P: 35–50 g/L
Aldosterone	P: 100–500 pmol/L
Alk. phosphatase	P: 30–130 U/L
α-Amylase	P: 0–180 IU/dL
α-Fetoprotein	S: <10 kU/L
Angiotensin II	P: 5–35 pmol/L
ADH	P: 0.9–4.6 pmol/L
AST	P: 5–35 U/L
Bicarbonate	P: 24–30 mmol/L
Bilirubin	P: 3–17 μmol/L
BNP	P: <50 ng/L
CRP	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 AM	P: 450–700 nmol/L
Cortisol Midnight	P: 80–280 nmol/L
CK ♂	P: 25–195 U/L
CK ♀	P: 25–170 U/L
Creatinine	P: 70–100 μmol/L
Ferritin	P: 12–200 mcg/L
Folate	S: 2.1 mcg/L
FSH	P: 2–8 U/L ♂; >25 menopause
GGT ♂	P: 11–51 U/L
GGT ♀	P: 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
Iron ♀	S: 11–30 μmol/L
Lactate (venous)	P: 0.6–2.4 mmol/L
Lactate (arterial)	P: 0.6–1.8 mmol/L
LDH	P: 70–250 U/L
LH	P: 3–16 U/L
Magnesium	P: 0.75–1.05 mmol/L
Osmolality	P: 278–305 mosmol/kg
PTH	P: 0.8–8.5 pmol/L
Potassium	P: 3.5–5.3 mmol/L
Prolactin ♂	P: <450 U/L
Prolactin ♀	P: <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 (erect)	P: 2.8–4.5 pmol/mL/h
Renin (recumbent)	P: 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
T4	P: 70–140 nmol/L
Free T4	P: 9–22 pmol/L
TIBC	S: 54–75 μmol/L
Triglycerides	P: 0.50–2.3 mmol/L
T3	P: 1.2–3.0 nmol/L
Troponin T	P: <0.1 mcg/L
Urate ♂	P: 210–480 μmol/L
Urate ♀	P: 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 cr.
Osmolality	350–1000 mosmol/kg
17-Oxogenic steroids ♂	28–30 μmol/24h
17-Oxogenic steroids ♀	21–66 μmol/24h
17-Oxosteroids ♂	17–76 μmol/24h
17-Oxosteroids ♀	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
RBC ♂	4.5–6.5 ×10¹²/L
RBC ♀	3.9–5.6 ×10¹²/L
Hb ♂	130–180 g/L
Hb ♀	115–160 g/L
PCV ♂	0.4–0.54 L/L
PCV ♀	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%)
Platelets	150–400 ×10⁹/L
Reticulocytes	0.8–2.0% / 25–100 ×10⁹/L
Prothrombin time	10–14 s
APTT	35–45 s

Paediatric

Pulse Rate (bpm)
Neonate	140–160
Infant <1yr	120–140
1–5 years	110–130
5–12 years	80–120
>12 years	70–100
Respiratory Rate (tachypnoea)
0–2 months	≥60/min
2–12 months	≥50/min
1–5 years	≥40/min
>5 years	≥30/min
Blood Pressure (mmHg)
Term	65/45
1 year	75/50
4 years	85/60
8 years	95/65
10 years	100/70
Weight Formulas
3–12 months	(a + 9)/2 kg
1–6 years	2a + 8 kg
>6 years	(7a − 5)/2 kg
Haemoglobin (g/dL)
Term newborn	13–20
1 month	11–18
2 months	10–15
1–2 years	10–13
>2 years	11–14
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
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
CSF WBC (/mm³)
Term newborn	0–25
>2 weeks	0–5

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