1. Some Medical & Applied Sciences
Group 1 – cardiology, cytology, dermatology
Group 2 – endocrinology, epidemiology, gastroenterology
Group 3 – geriatrics, gerontology, gynecology
Group 4 – hematology, immunology, neonatology
Group 5 – nephrology, neurology, obstetrics
Group 6 – oncology, opthalmology, orthopedics
Group 7 – pathology, pediatrics, pharmacology
Group 8 – podiatry, psychiatry, radiology
Group 9 – otolaryngology, toxicology, urology
Mrs. Guzman - histology

3. Homeostasis
All homeostatic control mechanisms have at least three components:
Receptor –Sensor
Control Center –Determines Set Point
Effector –Output (organ)

4. Homeostasis Components of Feedback Mechanisms:
1. Stimulus: The change from ideal or resting conditions.
2. Receptor: The cells or tissue which detects the change due to the stimulus.
3. Relay: The transmission of the message, via nerves or hormones or both, to the effector.
4. Effector: The cells or tissue, usually a gland or muscles, which cause the response to happen.
5. Response: An action, at cell, tissue or whole organism level which would not have occurred in the absence of the stimulus.
6. Feedback: The consequence of the response on the stimulus. May be positive or negative.

6. Homeostasis Components of Feedback Mechanisms:
1. Stimulus: The change from ideal or resting conditions.
2. Receptor: The cells or tissue which detects the change due to the stimulus.
3. Relay: The transmission of the message, via nerves or hormones or both, to theeffector.
4. Effector: The cells or tissue, usually a gland or muscles, which cause the response to happen.
5. Response: An action, at cell, tissue or whole organism level which would not have occurred in the absence of the stimulus.
6. Feedback: The consequence of the response on the stimulus. May be positive or negative.

7. A feedback mechanism starts with a
Stimulus
Receptor
Response
Feedback

8. Homeostasis
Feedback Mechanisms:
Negative
Positive

9. Negative Feedback Most common homeostatic feedback mechanism
The response diminishes the original stimulus
Reduces the output or activity of any organ or system back to its normal range of functioning.

10. Negative Feedback Examples: Body Temperature –Nervous System
Blood Calcium Levels (Normal = mmol/L) –Endocrine System
Blood Pressure: Blood vessels can sense resistance of blood flow against the walls when blood pressure increases. The blood vessels act as the receptors and they relay this message to the brain. The brain then sends a message to the heart and blood vessels, both are the effectors. The heart rate would decrease as the blood vessels increase in diameter (or vasodilation). This change would result in the blood pressure to fall back to its normal range.

12. Positive Feedback Rare homeostatic feedback mechanism
The response enhances the original stimulus

14. Positive Feedback Examples: Hemorrhage
Childbirth (release oxytocin to intensify the contractions that take place during childbirth)
Lactation
Childbirth Positive Feedback Video

15. Choose the true statement regarding positive feedback
It occurs when the heart rate increases during exercise.
It reinforces or strengthens the original stimulus.
Positive feedback mechanisms are usually of long duration.
It produces dilation of surface blood vessels when a person exercises on a hot day.

16. Homeostatic Imbalances in the Body
1. Integumentary System –Burns, Cutaneous Legions (Cold Sores, Impetigo, Psoriasis), Skin Cancer
2. Skeletal System –Rickets, Abnormal Spinal Curvatures (Scoliosis, Kyphosis, Lordosis),Osteoporosis

17. Cutaneous Legion
Rickets

18. Homeostatic Imbalances in the Body
3. Muscular System –Muscular Dystrophy, Myasthenia Gravis
4. Nervous System –Multiple Sclerosis, Huntington’s Disease, Parkinson’s Disease, Alzheimer’s Disease

19. Myasthenia Gravis
Multiple Sclerosis

20. Homeostatic Imbalances in the Body
5. Endocrine System –Goiter, Graves’ Disease, Pituitary Dwarfism, Infertility
6. Cardiovascular System –Pericarditis, Valvular Stenosis, Varicose Veins, Atherosclerosis

21. Goiter Varicose Veins

22. Homeostatic Imbalances in the Body
7. Lymphatic System –Allergies, Immunodeficiencies (SCID, AIDS), Autoimmune Disease (Lupus, Rheumatoid Arthritis, etc)
8. Respiratory System –Sinusitis, Tonsillitis, Pleurisy, Emphysema, Bronchitis, Cystic Fibrosis

23. Rheumatoid Arthritis
Emphysema

24. Homeostatic Imbalances in the Body
9. Digestive System –Gallstones, Heartburn, Gastric Ulcers
10. Urinary System –Kidney Stones, Addison’s Disease, Polycystic Kidney Disease

25. Gastric Ulcer
Kidney Stones

26. Kidney Stone Removal Video

27. Homeostatic Imbalances in the Body
11. Reproductive System –Pelvic Inflammatory Disease, Cervical Cancer, Testicular Cancer