TELEMATICS WEDNESDAY, 28 MAY 2014

1. TELEMATICS WEDNESDAY, 28 MAY 2014 HOMEOSTASISNEGATIVE FEEDBACK MECHANISMS[TSH & THYROXIN; INSULIN & GLUCAGON]CONTROL OF CARBON DIOXIDE, WATER & SALTS

2. WHAT IS HOMEOSTASIS? • Greek, homeoor "constant", • stasisor "stable" • means remaining stable or remaining the same. C G OPPELT AND LORRAINE KUUN FOR TELEMATICS 2014

3. HOMEOSTASIS = DEFINITION The process of maintaining a constant, internal environment within narrow limits, despite changes that take place internally and externally. Homeostasisrefers to maintaining internal stability within an organism and returning to a particular stable state after a fluctuation. C G OPPELT AND LORRAINE KUUN FOR TELEMATICS 2014

4. IN HUMANS…… • MANY HIGHLY COMPLEX INTERACTIONS • MUST BE MAINTAINED WITHIN A NORMAL RANGE C G OPPELT AND LORRAINE KUUN FOR TELEMATICS 2014

5. COORDINATION – 2 SYSTEMS • the nervous system (involving nerves) and the endocrine system (involving hormones) as two components that help us respond to stimuli from the environment C G OPPELT AND LORRAINE KUUN FOR TELEMATICS 2014

6. NERVOUS AND ENDOCRINE • Work together for communication and homeostasis in the body • HOMEOSTASIS – maintenance of a CONSTANT internal environment regardless of the changes in our external environment • Vital – organisms only function within a specific range of condition e.g.temp. C G OPPELT AND LORRAINE KUUN FOR TELEMATICS 2014

7. WHAT IS A STIMULUS? • Any internal or external environmental change to which an organism responds: • Light • Sound • Touch • Pressure • Taste • Temperature • chemicals C G OPPELT AND LORRAINE KUUN FOR TELEMATICS 2014

8. THE NEED FOR A NERVOUS SYSTEM IN HUMANS • Reaction to stimuli (stimuli can be external and internal) • Coordination of the various activities of the body C G OPPELT AND LORRAINE KUUN FOR TELEMATICS 2014

9. WHAT IS NERVOUS COORDINATION? • When RAPID responses are required, impulses are conducted in NERVES C G OPPELT AND LORRAINE KUUN FOR TELEMATICS 2014

10. Nervous System: Functions EXAMPLE OF WAKING UP IN THE MORNING.1.INPUT: the sound of the alarm clock is conveyed to your brain by your ears. 2.PROCESSING: your brain knows the past experience that it is time to get up. 3.OUTPUT: your brain directs the muscle of your arm and hand to reach out and shut off the alarm clock. C G OPPELT AND LORRAINE KUUN FOR TELEMATICS 2014

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13. ENDOCRINE SYSTEM AND NEGATIVE FEEDBACK MECHANISMS

14. The difference between an exocrine and endocrine gland • Exocrine gland • Ducts • Lumen and surfaces • Endocrine gland • Chemical messengers • Blood stream C G OPPELT AND LORRAINE KUUN FOR TELEMATICS 2014

15. NEGATIVE FEEDBACK • NEGATIVE FEEDBACK mechanisms operate in the human body to detect changes or imbalances in the internal environment and to restore the balance. C G OPPELT AND LORRAINE KUUN FOR TELEMATICS 2014

16. 3. 2. Message is sent to control centre 4. Target organ carries out corrective action 1.Imbalance is detected 5.Balance is restored C G OPPELT AND LORRAINE KUUN FOR TELEMATICS 2014

17. STEPS IN A NEGATIVE FEEDBACK CONTROL SYSTEM…… • STEP 1: An IMBALANCE is DETECTED • STEP 2: A message is sent to the CONTROL CENTRE • STEP 3: Control centre RESPONDS • STEP 4: MESSAGE/INSTRUCTION sent to TARGET ORGAN/EFFECTOR • STEP 5: Target organ RESPONDS (carries out corrective action) • STEP 6: It OPPOSES/REVERSES the imbalance • STEP 7: BALANCE is RESTORED C G OPPELT AND LORRAINE KUUN FOR TELEMATICS 2014

18. THE REGULATION OF THYROXIN • 2 Glands involved • GLAND 1: THYROIDGLAND (releases Thyroxin) • GLAND 2: PITUITARYGLAND (releases TSH) C G OPPELT AND LORRAINE KUUN FOR TELEMATICS 2014

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20. Step 1: Thyroxin levels increase above normal limits Step 2: Pituitary gland is stimulated Step 3: Pituitary gland produces lessTSH Step 4: Low TSH level stimulates the thyroid gland Step 5: The thyroid gland secretes less thyroxin Step 6: The thyroxin level thus decreases Step 7: Thyroxin level returns to normal C G OPPELT AND LORRAINE KUUN FOR TELEMATICS 2014

21. Step 1: Thyroxin levels decrease below normal limits • Step 2: Pituitary gland is stimulated • Step 3: Pituitary gland produces more TSH • Step 4: High TSH level stimulates the thyroid gland • Step 5: The thyroid gland secretes more thyroxin • Step 6: The thyroxin level thus increases • Step 7: Thyroxin level returns to normal C G OPPELT AND LORRAINE KUUN FOR TELEMATICS 2014

22. LET’S TAKE A LOOK AT MORE NEGATIVE FEEDBACK LOOPS C G OPPELT AND LORRAINE KUUN FOR TELEMATICS 2014

23. Exocrine and endocrine cells • Acinar cells (forming most of the pancreas) • Exocrine function • Secrete digestive enzymes • Islet cells (of Langerhans) • Endocrine function • secretes hormones directly into blood stream C G OPPELT AND LORRAINE KUUN FOR TELEMATICS 2014

24. INSULIN GLYCOGEN Glucose is removed from the blood Beta cells (Islets of Langerhans) detect the change DECREASES Glucose used for Cellular Respiration DECREASES Alpha cells (Islets of Langerhans) detect the change Glucose is added to the blood PANCREAS GLUCOSE C G OPPELT AND LORRAINE KUUN FOR TELEMATICS 2014

25. CONTROL OF CO2 LEVELS C G OPPELT AND LORRAINE KUUN FOR TELEMATICS 2014

26. Carbon dioxide + water carbonic acid (H2CO3) it breaks down to form hydrogen ions (H+) and bicarbonate ions (HCO3-). Increased H+ will cause a decrease in blood pH and this causes an increase in breathing rate. MEDULLA OBLONGATA C G OPPELT AND LORRAINE KUUN FOR TELEMATICS 2014

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28. CONTROL OF CARBON DIOXIDE LEVELS IN THE INTERNAL ENVIRONMENT C G OPPELT AND LORRAINE KUUN FOR TELEMATICS 2014

29. CONTROL OF CARBON DIOXIDE LEVELS IN THE INTERNAL ENVIRONMENT C G OPPELT AND LORRAINE KUUN FOR TELEMATICS 2014

30. CONTROL OF WATER LEVELS IN THE INTERNAL ENVIRONMENT 1 4 5 3 2 6 8 7 C G OPPELT AND LORRAINE KUUN FOR TELEMATICS 2014

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32. WHEN WATER CONTENT DECREASES • ON WARM DAY…… • Osmoreceptors in Hypothalamus are stimulated…..more ADH secreted • ADH causes walls of distal convoluted tubules and collecting ducts of kidney – MORE PERMEABLE to water • More water is REABSORBED FROM TUBULES – into blood • Urine becomes MORE concentrated and volume decreases • Thirst centre in brain stimulated – more water is taken in • Water content increases – returns to normal C G OPPELT AND LORRAINE KUUN FOR TELEMATICS 2014

33. WHEN WATER CONTENT INCREASES • ON COLD DAY…… • Osmoreceptors in Hypothalamus are NOT stimulated…..less ADH secreted • ADH causes walls of distal convoluted tubules and collecting ducts of kidney – LESS PERMEABLE to water • Less water is REABSORBED FROM TUBULES • Urine becomes LESS concentrated –(dilute) and volume increases • More urine excreted • Water content decreases – returns to normal C G OPPELT AND LORRAINE KUUN FOR TELEMATICS 2014

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35. CONTROL OF SALT LEVELS IN THE INTERNAL ENVIRONMENT More sodium ions reabsorbed Less sodium ions excreted More aldosterone is secreted sodium level rises Sodium level decreases NORMAL SODIUM LEVEL IN BLOOD Sodium levels increases sodium levels drops Less aldosterone secreted Less sodium ions reabsorbed More sodium ions excreted C G OPPELT AND LORRAINE KUUN FOR TELEMATICS 2014

36. 2. MORE Sodium ions reabsorbed – Distal Convoluted Tubule 3. Sodium ions in blood INCREASE 1. MORE Aldosterone is secreted 4. FEWER sodium ions excreted in urine C G OPPELT AND LORRAINE KUUN FOR TELEMATICS 2014

37. 2. FEWER Sodium ions reabsorbed – Distal Convoluted Tubule 3. LESS sodium ions secreted – sodium ions decrease in blood 1. LESS Aldosterone is secreted 4. More sodium ions excreted in urine C G OPPELT AND LORRAINE KUUN FOR TELEMATICS 2014