PM-154 Homeostasis (2025) PDF

PM-154 Introduction to Homeostasis Dr. Luke Davies SMART - Servier Medical ART  Learning Outcomes: ⬢ Describe human physiology ⬢ Outline the structure and function of key systems ⬢ Describe homeostasis ⬢ Explain positive and negative feedback systems...

PM-154 Introduction to Homeostasis Dr. Luke Davies SMART - Servier Medical ART  Learning Outcomes: ⬢ Describe human physiology ⬢ Outline the structure and function of key systems ⬢ Describe homeostasis ⬢ Explain positive and negative feedback systems 2 1 Human Physiology The Science of Life  MRS. NERG Physiology – Study of life processes I. Movement V. Nutrition - Metabolism – all chemical reactions within the body > Movement of substances > Production of energy > Locomotion > Making body structures II. Respiration > Gas exchange VI. Excretion > Elimination of waste from metabolic III. Sensation - Responsiveness reactions > Ability to sense changes and react VII. Reproduction > Production of future generation IV. Nutrition - Digestion VIII. Growth > Increasing of cell size or number > Break-down and delivery of nutrients 4  Physiology: Structural Organisation 1. Molecular 2. Cellular 3. Tissue 4. Organ 5. Organ System 6. Organism 5 Physiology: Structural Organisation Physiology requires understanding of anatomy and explains it 6 2 Homeostasis Organ system level  Homeostasis ⬢ Maintenance of a stable internal environment = a dynamic state of equilibrium Homeo- = Greek ‘The same’ -stasis = Greek ‘Equilibrium’ – it is NOT static, but attempts this 8  Homeostasis ⬢ Maintenance of a stable internal environment = a dynamic state of equilibrium Homeo- = Greek ‘The same’ -stasis = Greek ‘Equilibrium’ – it is NOT static, but attempts this ⬢ Homeostasis must be maintained for normal body functioning and to sustain life 9  Homeostasis ⬢ Maintenance of a stable internal environment = a dynamic state of equilibrium Homeo- = Greek ‘The same’ -stasis = Greek ‘Equilibrium’ – it is NOT static, but attempts this ⬢ Homeostasis must be maintained for normal body functioning and to sustain life ⬢ Homeostatic imbalance – a disturbance in homeostasis resulting in disease (a.k.a. Pathophysiology) 10  Homeostasis of organ systems Nervous Endocrine Blood Muscular Respiratory Musc Cardiovascular Digestive Reproductive Skeletal Urinary 11  The Muscular System ▪ Allows locomotion, facial expression ▪ Maintains posture – supports other organ systems ▪ Thermoregulation - Produces heat Dr Sarah Rees 12  The Cardiovascular System ▪ Heart and vessels that transport blood (Control of blood pressure) Dr Christian Cobbold ▪ Blood – Haematology (Maintains nutrient balance + immunity) Dr Nia Davies 13  The Respiratory System ▪ Gas homeostasis ▪ Adds oxygen and removes carbon dioxide Dr Christian Cobbold 14  The Digestive System ▪ Breaks down food + Esophagus absorbs nutrients Abdominal aorta ▪ Maintains blood nutrient Liver Stomach homeostasis Gall bladder Spleen Duodenum Pancreas ▪ Eliminates indigestible Colon material (excretion) Small intestine Ileum Dr Christian Cobbold Appendix Rectum 15  The Nervous System ▪ Fast-acting control system ▪ Responds to internal and external change ▪ Activates muscles and glands ▪ Controls homeostasis of multiple systems Dr Luke Roberts 16  The Endocrine System Thymus ▪ Slightly slower acting control system ▪ Controls sleep and wakefulness ▪ Controls homeostasis of multiple systems Adrenal Pituitary Dr Sarah Prior Pancreas 17  The Urinary System ▪ Eliminates nitrogenous wastes Kidneys ▪ Maintains acid–base balance Ureters ▪ Maintains osmolarity Bladder Dr Luke Davies Urethra 18 Organ systems are connected 19  Terminology: Gastr- Stomach Cerebro- Brain Hepa- Liver Cardio- Heart Nephr- Kidney Pneumo- Lung Entero- Instestine Derm- // Cut- Skin Medical Dictionary of Health Terms: A-C - Harvard Health 20 3 Homeostatic control Homeostatic control mechanism 22 Example: Glucostatic control 23 Example: Glucostatic control 24 Example: Glucostatic control 25  Terminology: 1. Gluconeogenesis ⬢ Gluco- or glyco- comes from the Greek word glykys meaning "sweet". 2. Glycogenolysis ⬢ Geno- comes from the Greek word genesis meaning "birth, origin, creation". 3. Lipolysis ⬢ Lipo- comes from the Greek word lipos meaning "fat". ⬢ Lysis comes from the Greek word lyein meaning "to unfasten, loose, untie". 4. Glycogenesis ⬢ Neo- comes from the Greek word neo meaning "new, recent". 5. Lipogenesis Medical Dictionary of Health Terms: A-C - Harvard Health 26 Systems working in harmony The stress response 27  Homeostasis ⬢ Negative Feedback Loops – most homeostatic processes 28  Homeostasis ⬢ Negative Feedback Loops – most homeostatic processes ⬢ Positive Feedback Loops – special scenarios e.g. blood clotting 29  Example of Positive feedback: Auto-amplification of cytokines in immunity Cytokines e.g. TNF Chemokines e.g. CCL2 30  Example of Positive feedback: Auto-amplification of cytokines in immunity Positive Cytokines e.g. TNF feedback Chemokines e.g. CCL2 31  Example of Positive feedback: Auto-amplification of cytokines in immunity Positive Cytokines e.g. TNF feedback Positive feedback Chemokines e.g. CCL2 32  Example of Positive feedback: Auto-amplification of cytokines in immunity Positive Cytokines e.g. TNF feedback Positive feedback Positive feedback Chemokines e.g. CCL2 33  Example of Negative feedback: Suppressors of cytokine signalling Cytokines e.g. TNF Inbuilt negative feedback 34 Homeostasis maintained in immunity Inbuilt negative feedback Cytokines e.g. TNF Inbuilt negative feedback Gradient is lost Chemokines e.g. CCL2 35  Homeostasis ⬢ Negative Feedback Loops – most homeostatic processes ⬢ Positive Feedback Loops – special scenarios e.g. blood clotting Always have inbuilt or external negative feedback loops – there is no exception in human physiology E.g. clotting – if you don’t stop it – the entire vasculature will clot Positive feedback loops can shift homeostatic set-point to a new level IMPORTANTLY - Homeostasis must be maintained even if this is at a different level 36  New homeostatic set-points ⬢ Homeostasis = Dynamic equilibrium (Not static) 37  Homeostasis - Dynamic equilibrium Multifactorial Circadian rhythms Hormone rhythms (e.g. menstrual cycle) Varying environment NOT 38 Homeostasis – Equilibriums vary Steady state over a day Blood glucose Cotisol release Blood pressure Core body temperature 39  New homeostatic set-points ⬢ Homeostasis = Dynamic equilibrium (Not static) ⬢ New set points occur in both Physiology and Pathophysiology ⬢ Usually as a response to triggers by a ‘regulatory system’ or failure of one ⬢ Examples – Type II diabetes and the immune response 40  Immune response – Sepsis ‘Normal’ JCI - Sepsis-induced immune dysfunction: can immune therapies reduce mortality? 41  Immune response – Sepsis ‘Normal’ New homeostatic set- point (shorter term) JCI - Sepsis-induced immune dysfunction: can immune therapies reduce mortality? 42  Immune response – Sepsis ‘Normal’ New homeostatic set-point (long term) New homeostatic set- point (shorter term) JCI - Sepsis-induced immune dysfunction: can immune therapies reduce mortality? 43  Regulatory system = Extremely complex and poorly understood (immune response itself and hormones e.g. cortisol) Immune response – Sepsis ‘Normal’ New homeostatic set-point (long term) New homeostatic set- point (shorter term) JCI - Sepsis-induced immune dysfunction: can immune therapies reduce mortality? 44 Regulatory system = Insulin production (dysfunctional) and glucose sensitivity (receptors – sensor failure) Diabetes – Type 2 Dynamic equilibrium Diabetic ‘Normal’ (Western) Healthy 45 Regulatory system = Insulin production (Almost completely gone at end-stage of disease) Diabetes – Type 1 Diabetic coma – dependent on sugar from diet 600 Loss of regulation results in a new homeostatic set-point (dynamic) Not tolerated by body organs (e.g. Brain) - Pathophysiology 46  Homeostasis and Pathophysiology In terms of homeostasis - pathophysiology is an imbalance in ‘normal’ homeostasis that is not tolerated 47  Homeostasis and Pathophysiology In terms of homeostasis - pathophysiology is an imbalance in ‘normal’ homeostasis that is not tolerated This can be due to: A new homeostatic set-point caused by a permeant or long lasting alteration in regulation (e.g. type 2 diabetes) An acute imbalance that overloads the system – regulatory systems cant cope (e.g. glycotoxicity) 48  Principles of 4 Physiology Homeostasis a main principle of physiology  Principles of physiology: I. The functions of organ systems are coordinated with each other. 50  Principles of physiology: I. The functions of organ systems are coordinated with each other. II. Most physiological systems are controlled by multiple regulatory systems, often working in opposition. 51  Principles of physiology: I. The functions of organ systems are coordinated with each other. II. Most physiological systems are controlled by multiple regulatory systems, often working in opposition. III. Homeostasis is essential for health and survival. 52  Principles of physiology: I. The functions of organ systems are coordinated with each other. II. Most physiological systems are controlled by multiple regulatory systems, often working in opposition. III. Homeostasis is essential for health and survival. IV. Information flow between cells, tissues and organs is essential – integration of physiological processes. 53  Principles of physiology: V. Controlled exchange of materials occurs between compartments and across cellular membranes. 54  Principles of physiology: V. Controlled exchange of materials occurs between compartments and across cellular membranes. VI. Physiological Processes dictated by laws of chemistry and physics. 55  Principles of physiology: V. Controlled exchange of materials occurs between compartments and across cellular membranes. VI. Physiological Processes dictated by laws of chemistry and physics. VII. Physiological Processes require the transfer and balance of matter and energy. 56  Principles of physiology: V. Controlled exchange of materials occurs between compartments and across cellular membranes. VI. Physiological Processes dictated by laws of chemistry and physics. VII. Physiological Processes require the transfer and balance of matter and energy. VIII. Structure is a determinant of – and has coevolved with – function. 57  Learning Outcomes: ⬢ Describe human physiology ⬢ Outline the structure and function of key systems ⬢ Describe homeostasis ⬢ Explain positive and negative feedback systems 58  Summary ⬢ Physiology is study of processes operating within an organism. 59  Summary ⬢ Physiology is study of processes operating within an organism. ⬢ Organ systems are interconnected and are formulated to maintain life 60  Summary ⬢ Physiology is study of processes operating within an organism. ⬢ Organ systems are interconnected and are formulated to maintain life ⬢ Homeostasis attempts to keep the system in balance 61  Summary ⬢ Physiology is study of processes operating within an organism. ⬢ Organ systems are interconnected and are formulated to maintain life ⬢ Homeostasis attempts to keep the system in balance ⬢ Positive and negative feedback maintain homeostasis by increasing or decreasing signals 62  Compulsory reading Marieb, 10th or 11th Edition Vanders, 12th-15th Edition OR 63 4 Quiz Homeostasis THANKS! Any questions? [email protected] 66  Question 1: The structure of an organism can be explained through understanding of physiology. A. True B. False 67  Question 2: Positive feedback mechanisms exist in biology without any negative feedback. A. True B. False 68  Question 3: Homeostasis is: Choose correct answer. A. A Static process B. Dispensable for life C. A Dynamic process D. Boring 69  Question 4: Organ systems are made up of: Choose correct answer. A. Tissues B. Molecules C. Cells D. Organs E. All of the above 70 Question 5: A researcher thinks they have discovered a new hunger-controlling hormone. Eating seems to decrease the hormone and make you less hungry. In terms of homeostasis, this is an example of… A. A positive feedback loop B. Good Research C. A new weight loss drug D. A negative feedback loop E. A Static Equilibrium 71  Question 6: A disease of an organ only effects that organ system. A. True B. False 72  Question 7: Disease is a loss of homeostasis. A. True B. False 73  Question 8: When a homeostatic set point is not well tolerated this leads to: Choose the best answer. A. Anti-homeostasis B. An Imbalance C. Physiology D. Inflammation E. Pathophysiology F. All of the above 74