Development and growth of the tooth

 Initiation Stage (Dental Lamina Stage)

Primitive oral cavity lined by stratified squamous epithelium

Formation of Primary Epithelial Band

Divides into:

Dental lamina → forms teeth

Vestibular lamina → forms oral vestibule

Dental Lamina

Appears at 6th week of intrauterine life

Forms tooth buds of all primary teeth

Gives rise to:

Successional lamina → permanent successors

Accessional lamina → permanent molars

Remnants of dental lamina = Rests of Serres

2. 🔹 Role of Ectomesenchyme

Derived from neural crest cells

Responsible for:

Formation of dentin, pulp, cementum

3. 🔹 Morphological Stages of Tooth Development

1. 🟢 Bud Stage

First sign of tooth development

Proliferation of dental lamina into ectomesenchyme

Structures:

Enamel organ (early)

Ectomesenchymal condensation

Cells:

Peripheral cuboidal cells

Central polygonal cells

2. 🟡 Cap Stage

Enamel organ becomes cap-shaped

Components formed:

Enamel organ

Dental papilla → dentin + pulp

Dental sac (follicle) → cementum, PDL

Layers in enamel organ:

Outer enamel epithelium (OEE)

Inner enamel epithelium (IEE)

Stellate reticulum ⭐

3. 🟠 Early Bell Stage

Histodifferentiation & morphodifferentiation begin

New layer:

Stratum intermedium

Important changes:

IEE → differentiates into ameloblasts

Dental papilla → forms odontoblasts

Nuclear polarity reversal

4. 🔴 Advanced Bell Stage (Apposition Stage)

Hard tissue formation begins

Sequence:

Odontoblasts form dentin first

Then ameloblasts form enamel

👉 Key Point: Dentin formation precedes enamel formation

Other features:

Stellate reticulum collapses

Enamel and dentin deposition continues

4. 🔹 Root Formation (Hertwig’s Epithelial Root Sheath - HERS)

Forms after crown formation

Function:

Shapes root

Induces dentin formation in root

Breakdown leads to:

Cementum formation

👉 Remnants of HERS = Rests of Malassez

Development of oral cavity mind map

 

Protein metabolism mind map

 

PROTEIN METABOLISM – COMPLETE REVISION NOTES

1. METABOLISM OF AMINO ACIDS

🔹 A. Transamination

Transfer of amino group from amino acid → keto acid

Enzymes: Transaminases

⭐ Salient Features:

Requires coenzyme: Pyridoxal phosphate (PLP)

Occurs in pairs:

Alanine transaminase (ALT)

Aspartate transaminase (AST)

No free NH₃ released

Reversible process

Helps in:

Synthesis of non-essential amino acids

Gluconeogenesis

🔹 B. Deamination

Removal of amino group → helps in urea formation

Types:

1. Oxidative Deamination

Substrate: Glutamate

Enzyme: Glutamate dehydrogenase

Products:

α-ketoglutarate

NH₃

Site: Liver mitochondria

Coenzyme: NAD⁺

2. Reductive Deamination

Removal of amino group by reduction

Substrate: Keto acids / Imino acids

Enzyme: Reductase

Product: NH₃ released

Coenzyme: NADPH

2. TRYPTOPHAN METABOLISM

🔹 Features:

Essential amino acid

Contains β-indole ring

🔹 Pathways:

1. Kynurenine Pathway

Steps: Tryptophan

→ N-formylkynurenine

→ Kynurenine

→ 3-hydroxykynurenine

→ 3-hydroxyanthranilic acid

Clinical:

Pellagra → 3 D’s:

Dermatitis

Diarrhea

Dementia

Products:

Melatonin (sleep regulation)

2. Serotonin Pathway

Steps: Tryptophan

→ 5-hydroxytryptophan

→ Serotonin

Functions:

Mood regulation

Depression link

3. PHENYLALANINE & TYROSINE METABOLISM

🔹 Characteristics:

Aromatic amino acids

🔹 Conversion:

Phenylalanine

→ Tyrosine

Enzyme: Phenylalanine hydroxylase

Converts essential → non-essential amino acid

🔹 Functions of Tyrosine:

Melanin synthesis

Thyroid hormone synthesis

Catecholamine synthesis

🔹 Tyrosine Degradation Pathway:

Tyrosine

→ p-Hydroxyphenylpyruvate

→ Homogentisate

→ Maleylacetoacetate

→ Fumarylacetoacetate

→ Fumarate + Acetoacetate

Final Fate:

Fumarate → TCA cycle → Glucose

Acetoacetate → Fat

4. UREA CYCLE

🔹 Key Points:

End product of protein metabolism

80–90% nitrogen excreted via urine

🔹 Steps:

CO₂ + NH₄⁺

→ Carbamoyl phosphate

(Enzyme: Carbamoyl phosphate synthetase)

🔸 Uses 2 ATP

Carbamoyl phosphate + Ornithine

→ Citrulline

(Ornithine transcarbamoylase)

Citrulline

→ Argininosuccinate

(Argininosuccinate synthetase)

🔸 Uses 1 ATP

Argininosuccinate

→ Arginine + Fumarate

(Argininosuccinase)

Arginine

→ Urea + Ornithine

(Arginase)

🔹 Important Points:

Total energy: 4 ATP used

Fumarate enters:

TCA cycle

Gluconeogenesis

Ornithine is regenerated (cycle continues)

🔥 QUICK SUMMARY (EXAM REVISION)

Transamination → No NH₃, reversible

Deamination → NH₃ released → Urea

Tryptophan → Serotonin + Kynurenine → Pellagra

Phenylalanine → Tyrosine → Hormones & pigments

Urea cycle → Detoxifies ammonia → Uses 4 ATP

Mind map of lipid metabolism

 

🧠 LIPID METABOLISM – Colorful Handwritten Mind Map

🧠 LIPID METABOLISM

                               

🔴 1. Fatty Acid Oxidation (β-Oxidation)

Occurs in mitochondria

Steps

1️⃣ Activation

Fatty acid + CoA + ATP

→ Fatty acyl-CoA

(enzyme: Acyl-CoA synthetase)

2️⃣ Transport

Carnitine carrier system

3️⃣ β-Oxidation Cycle

• Dehydrogenation → FADH₂ formed

• Hydration

• Oxidation → NADH formed

• Cleavage → Acetyl-CoA

Energetics (Palmitate)

7 FADH₂ → 10.5 ATP

7 NADH → 17.5 ATP

8 Acetyl-CoA → 80 ATP

✔ Total = 108 ATP

✔ Net = 106 ATP

🟠 2. Cholesterol Biosynthesis

Location: Cytosol of liver cells

Pathway

Acetyl-CoA

⬇

HMG-CoA

⬇

Mevalonate

⬇

Isoprene units (IPP + DPP)

⬇

Squalene

⬇

Cholesterol

Requirements

18 Acetyl-CoA

36 ATP

16 NADPH

Uses

✔ Bile acids

✔ Steroid hormones

✔ Vitamin D

🟡 3. Lipoproteins

Lipoprotein = Lipid + Protein

Types

Chylomicrons

Transport dietary fat

VLDL

Transport endogenous triglycerides

LDL

Transport cholesterol to tissues

HDL

Reverse cholesterol transport

Lipoprotein Degradation

1️⃣ Lipoprotein + LPL enzyme

2️⃣ Triglyceride hydrolysis

3️⃣ Fatty acid uptake

4️⃣ Chylomicron remnant formation

5️⃣ Uptake by liver

🟢 4. Ketone Bodies

Types

Acetoacetate

β-Hydroxybutyrate

Acetone

✔ Water soluble

✔ Alternative energy source

Ketogenesis (Liver)

2 Acetyl-CoA

⬇

Acetoacetyl-CoA

⬇

HMG-CoA

⬇

Acetoacetate

⬇

Acetone + β-Hydroxybutyrate

Use

During fasting/starvation

Overproduction

Ketonuria / Ketoacidosis

🔵 5. Fatty Liver

Normal liver lipid ≈ 5%

Cause

Excess triglyceride accumulation

Reasons

Increased TG synthesis

Decreased lipoprotein formation

Alcohol / metabolic disorders

🟣 6. Atherosclerosis

✔ Thickening and hardening of arteries

✔ Due to lipid deposition

Result

⬆ Risk of

Coronary heart disease

Heart attack

✅ Memory Trick for Lipid Metabolism Topics

"F C L K F A"

F → Fatty acid oxidation

C → Cholesterol synthesis

L → Lipoproteins

K → Ketone bodies

F → Fatty liver

A → Atherosclerosis

Mind map of carbohydrates metabolism

 

For TCA cycle menomic is used 

C                citrate 

I                isocitrate 

Alpha.      Ketoglutarate 

S.              Succinnyal coa 

S.              Succinate 

F.              Fumarate 

M.            Malate 

O.            Oxyloacetate 

For glycolysis 

Good                        Glucose

Girls                         Glucose-6-phosphate

 Find                         Fructose-6-phosphate

Friends                    Fructose-1,6-bisphosphate

Don't                        Dihydroxyacetone phosphate

  Get                         Glyceraldehyde-3-phosphate

 Big                           1,3-Bisphosphoglycerate

 Problems               3-Phosphoglycerate

  Please                    2-Phosphoglycerate

  Please                   Phosphoenolpyruvate

  Please                    Pyruvate

Mind map of protein

 

Essential amino acid menmonic 

PVT TIM HALL

P – Phenylalanine

V – Valine

T – Tryptophan

T – Threonine

I – Isoleucine

M – Methionine

H – Histidine

L – Leucine

L – Lysine

Ploysaccharide mind map for medical student