BIOS5130 Week 8 Slides

Week 8 Lecture Overview

• Module: BIOS5130 – Human Physiology and Disease 2

• Lecturer: Dr. Emma Hargreaves

• Focus: Introduction to the endocrine system

Subject Specific Learning Outcomes

• Physiological Systems

  • Understand structural organization and function of specific physiological systems.

  • Learn how body systems integrate to maintain homeostasis.

• Health and Disease

  • Explore the malfunction of physiological systems causing disease (with examples).

  • Recognize the relationships between physiology, anatomy, and medicine.

Module Convenors and Teachers

• Module Convenor: Dr. Emma Hargreaves (e.j.mead@kent.ac.uk)

• Teachers:

  • Prof. John Dickinson (j.w.Dickinson@kent.ac.uk)

  • Dr. Sam Smith (s.a.smith-75@kent.ac.uk)

  • Dr. Peter Ellis (P.J.I.Ellis@kent.ac.uk)

Weekly Structure

Lecture Topics

• Week 8: Endocrinology, Dr. Emma Hargreaves

• Weeks 9-13: Nervous System, Dr. Emma Hargreaves

• Weeks 15-16: Kidneys, Dr. Emma Hargreaves

• Weeks 17-18: Muscles, Prof. John Dickinson/Dr. Sam Smith

• Week 19: Reproduction, Dr. Peter Ellis

Workshops

• Format: Problem-solving practice in groups (compulsory, no changes allowed).

• Scheduled: Week 11 OR 13

• Assessment: Problem-solving test in ICT slot, Week 15; Exam duration 2 hours.

• Feedback: Week 16 for problem-solving assessment.

Textbook Recommendation

• Title: Human Physiology: An Integrated Approach

• Author: Dee Unglaub Silverthorn

• ISBN: 9781292259628

• Availability: Physical copies in library, 15 e-copies available through library link.

Introduction to Endocrinology

Key Topics

• Hormones and their classification

• Endocrine organs

• Hormone release mechanisms: simple vs. complex

• Endocrine disorders overview

What is a Hormone?

• Definition: A chemical secreted into the bloodstream for transport to distant tissues.

• Mechanism: Hormones bind to target cell receptors, which can be membrane-bound, cytosolic, or nuclear.

• Functions:

  • Alter enzyme reaction rates

  • Regulate transport across membranes

  • Regulate gene expression

• Concentration: Active at very low concentrations (nanomolar 10^-9 or picomolar 10^-12).

Classification of Hormones

Hormone Types by Source and Effect

Hormonal Interactions

• Synergistic Effect: Combined effects are greater than individual effects (e.g., glucagon + cortisol + adrenaline).

• Permissive Effect: One hormone facilitates the action of another (e.g., thyroid hormone needed for sexual maturation).

• Antagonistic Effect: Opposing effects (e.g., insulin lowers blood glucose, glucagon raises it).

Peptide Hormone Production and Action

Peptide Hormone Synthesis Process

1. Preprohormones are synthesized in ribosomes.

2. The signal sequence guides them into the endoplasmic reticulum (ER).

3. Prohormones form within the ER; enzymes chop inactive forms into active peptides.

4. Secretory vesicles transport hormones for exocytosis into the bloodstream.

Steroid Hormone Characteristics

• Synthesis: Derived from cholesterol.

• Primary Action Site: Intracellular receptors (cytoplasm or nucleus).

• Transport: Many bound to plasma proteins, only free hormones act.

• Mechanism: Hormone-receptor complex binds to DNA to modify gene expression.

Amine Hormone Structure

• Derived from: Tyrosine, with catecholamines and thyroid hormones as examples.

• Types of Receptors: G-protein coupled receptors or intracellular receptors.

Regulation of Hormone Release

Mechanisms:

1. Simple Reflexes: One cell senses a stimulus and secretes hormone (e.g., parathyroid hormone).

2. Complex Reflexes: Multiple hormones or integrating centers involved (e.g., hypothalamus/pituitary).

Case Study: Graves' Disease

Overview

• Autoimmune disorder leading to hyperthyroidism (overproduction of thyroid hormones).

• Common symptoms: weight loss, palpitations, irritability, goitre (swelling of the thyroid gland).

• Autoimmunity: Antibodies mimic TSH, stimulating excessive hormone production.

Diagnosis and Treatment

• Diagnostic tests: Include blood tests (T3, T4, TSH levels), ultrasound.

• Treatment options include antithyroid medications, radioactive iodine therapy, and surgical removal of thyroid tissue.