clinical introduction to endocrine system

What is a hormone?

chemical messengers secreted directly into the bloodstream

Key characteristics of hormones

- travel via circulatory system to target organs
- bind to specific receptors on target cells
- trigger cellular responses through signal transduction

- subject to feedback control mechanisms

Types of Hormonal Signalling:

• endocrine - Distance signalling via bloodstream

• Paracrine - Local cell-to-cell communication

• Autocrine - Self-signalling

What are the major endocrine glands?

• Hypothalamus - Master regulator
• Pituitary gland - Master gland
• Thyroid gland - Metabolism control
• Parathyroid glands - Calcium homeostasis
• Adrenal glands - Stress response
• Pancreas - Glucose regulation
• Gonads (ovaries/testes) - Reproduction

Key functions of the endocrine system

• Control of growth and differentiation
• Maintenance of homeostasis
• Regulation of reproduction
• Metabolism regulation

What are the functions of the hypothalamus?

- produces releasing and inhibiting hormones
- links nervous and endocrine systems
- controls pituitary gland function

where in the body the endocrine glands are

yes

what re the key hormones in the hypothalamus

• CRH (Corticotropin-Releasing Hormone)

• TRH (Thyrotropin-Releasing Hormone)

• GnRH (Gonadotropin-Releasing Hormone)

• GHRH (Growth Hormone-Releasing Hormone)

• Somatostatin, Dopamine

what are the key hormones in the pituitary gland

• Anterior: TSH, ACTH, LH, FSH, GH, Prolactin

• Posterior: ADH, Oxytocin

What are the 3 classifications of hormones?

pepide, steroid, monoamine

Structure, examples and characteristics of peptide hormones

- structure: modified amino acids, peptide/protein chains
- examples: insulin, glucagon, growth hormone
- characteristics: water soluble, cannot cross cell membrane

Structure, examples and characteristics of steroid hormones

- structure: derived from cholesterol
- examples: cortisol, testosterone, estrogen
- characteristics: lipid soluble, cross cell membrane easily

Structure, examples and characteristics of monoamine hormones

- structure: derived from aromatic amino acids
- examples: thyroid hormones, epinephrine
- characteristics: variable solubility

What is the hormone signalling mechanism of a water soluble hormone?

- bind to cell surface receptors
- activate second messenger systems
- rapid response (secs to mins)

What is the hormone signalling mechanism of a lipid soluble hormone?

- cross cell membrane freely
- bind to intracellular receptors
- slower response (hours to days)

What are the two feedback loop mechanisms?

- negative feedback: product inhibits its own production, maintains homeostasis
- positive feedback: product stimulates its own production, creates amplification

what is the pathway and mechanism for the hypothamic-pituatry-adrenal axis

• hormal response that controls cortisol release linking the hypothalamus, anterior pituitary, and adrenal cortex

what is the function of cortisol

• Increases blood glucose (gluconeogenesis)

• Anti-inflammatory effects

• Immune system suppression

• Stress response coordination

• Circadian rhythm (peak morning levels)

what are the implication of corticosteroid therapy

HPA axis suppression and dental implications

HPA axis suppression:

• Long-term steroids suppress CRH/ACTH

• Adrenal cortex atrophy

• Reduced stress response capability

• Risk of crisis

dental implication

• Delayed healing

• Increased infection risk

• Poor stress tolerance

• Need for steroid cover in surgery

what is the pathway Mechanism of hypothalamic-pituitary-thyroid axis

hormonal control system that regulates thyroid hormone release by linking hypothalamus, anterior pituitary, and thyroid gland

what is the function of thyroid hormone

• Metabolic rate regulation

• Growth and development

• Protein synthesis

• CNS development

• Cardiovascular function

summary of pancreatic endocrine functions

• Pancreatic Islets (Islets of Langerhans):

• Cell Types:

  • α-cells (20%) → Glucagon production

  • β-cells (75%) → Insulin production

  • δ-cells (4%) → Somatostatin production

  • PP cells (1%) → Pancreatic polypeptide

• Glucagon Functions:

  • Stimulates hepatic glycogenolysis

  • Promotes gluconeogenesis

  • Activates lipolysis

  • Response to low blood glucose

• Insulin Functions:

  • Facilitates glucose uptake by cells

  • Promotes glycogen synthesis

  • Stimulates protein and fat synthesis

  • Response to high blood glucose

what are the two responses to glucose homeostasis mechanisms

Hypoglycaemia Response

• Pancreatic α-cells detect low glucose

• Glucagon release increases

• Liver glycogen → glucose

• Amino acids → glucose

• Blood glucose rises

Hyperglycaemia Response

• Pancreatic β-cells detect high glucose

• Insulin release increases

• Enhanced glucose uptake

• Glucose → glycogen storage

• Blood glucose decreases

what are the dental relevance of diabetes, oral manifestations and management

patients can have oral manifestations:

• Oral candidiasis (thrush)

• Xerostomia (dry mouth)

• Increased dental caries risk

• Aggressive periodontal disease

• Delayed wound healing

• Increased infection risk

• Sialosis (salivary gland enlargement)

management considerations:

• Early morning appointments

• Ensure normal meals/medications

• Monitor for hypoglycemia

• Optimise oral hygiene

what are the 2 treatment in endocrinology

hormone replacement

• Replace deficient hormones

• Examples: Insulin (diabetes), levothyroxine (hypothyroid)

• Physiologic dosing preferred

• Monitor response and side effects

hormone suppression

• Block excess hormone production/action

• Examples: Antithyroid drugs, GH antagonists

• Balance efficacy vs. side effects

how do we manage patients with endocrine problems

pre-operative assessments:

• Identify endocrine disorders

• Assess disease control

• Review medications

• Consider stress dosing needs

perioperative care

• Maintain medication schedules

• Monitor glucose levels

• Provide steroid cover if needed

• Watch for complications

what are the dental implications of endocrine disorders

manifestations:

• Diabetes: Candidiasis, xerostomia, periodontal disease

• Thyroid: Delayed eruption (hypo), accelerated caries (hyper)

• Parathyroid: Enamel defects, bone changes

• Adrenal: Pigmentation changes, delayed healing

clinical approach

• Comprehensive medical history

• Recognise oral signs of systemic disease

• Coordinate with medical colleagues

• Modify treatment plans appropriately

what is the future of endocrinology

• Personalised medicine approaches

• Novel therapeutic targets

• Improved diagnostic methods

• Better understanding of hormone resistance

• Integration of technology in care

• Continuous glucose monitoring

• Closed-loop insulin delivery systems

summary