Unit 12 Key dates & submission points

1. Unit 12 Key dates & submission points All work submitted by the deadline has now been marked. Next submissions; Sub 3 for P2/D1 (Fluid & acid balance) – 14th Feb Sub 3 for P3/M2 (Nervous system) – 14th Feb Sub 2 for P4/M3/D2 (Hormonal system) – 14th Feb Further submission for P1 (Kidneys) will also be 14th Feb If you have not met M1 but are determined to get a merit/distinction you MUST now pass all other merits for the unit before I will come back and mark resubmissions – do the work now and upload it to show you are able to keep up. If you miss 2 final deadlines for M/D criteria you and yourr PC will be informed that you are no longer able to get that grade in this unit. The only way to over turn this decision is to meet all lower criteria and have ALL submissions outstanding completed to a high standard and ready for marking at time of appeal.

2. Assignment support • Over the next 6 week term we will complete P5/M4/D3. • There will NOT be an assignment support session till the last week of this term. • If you need my help with completing assignments for resubmission you MUST complete the current criteria for this half term (P5/M4/D3) in lessons and as HW to allow yourself time in lessons to get help on past assignments. • Any questions?

3. Assignment 5: Homeostatic Mechanisms and Malfunctions Leading to Disorders (P5,M4,D3)

4. Criteria • P5 - Describe the mechanisms of the homeostatic system • M4 - Explain positive and negative feedback in homeostasis, using examples from the human body • D3 - Explain how malfunctions in the homeostatic mechanisms can lead to disorders

5. P5 - Describe the mechanisms of the homeostatic system • Task 1: Describe homeostasis and explain its importance in controlling our internal environment referring to examples. • Task 2: Identify and describe the systems that regulate homeostasis. • Task 3: Describe the mechanisms of homeostasis; include the terms input, output, receptor, effectors: • Complete the flow chart, include the terms input, output, receptor, effector, negative feedback. • Describe the homeostatic mechanism shown in the flow chart.

6. M4 - Explain positive and negative feedback in homeostasis, using examples from the human body • Explain positive and negative homeostatic feedback. • Identify and describe the stimuli, receptors, effectors, output and feedback mechanisms involved with: • Labour • Regulation of blood glucose • Regulaton of body temperature • Regulation of water levels in the body Diagrams will be useful to help here!

7. D3 - Explain how malfunctions in the homeostatic mechanisms can lead to disorders • Using the regulation of: • Blood glucose • Water – (Diabetes inspidus) • Temperature • Explain how malfunctions in these homeostatic mechanisms can lead to disorders. • For each factor: • Identify the disease • Describe the abnormal homeostatic mechanism • Explain the effects of the abnormality on the normal body conditions • Explain the effects on health

8. What does your body need to keep the same for you to stay alive and be healthy? On your white board list as many things as you can!!

9. What needs to be controlled? • Glucose concentration. • Water and salt concentration. • Carbon dioxide level. • Oxygen level. • Temperature. • Waste products in the blood, such as urea. Why?

10. Watch Tim and Moby as they explain what HOMEOSTASIS is.

11. Try to write an explanation of homeostasis on your white boards.

12. Homeostasis Homeo - stasis = same - state • Maintaining a constant internal environment • E.g. Temperature: enzymes need constant temperature to function properly

13. Homeostasis Definition: Metabolic equilibrium actively maintained by several complex biological mechanisms that operate via the autonomic nervous system to offset disrupting changes

14. What is Homeostasis? • Regulation of: • Internal temperature • Glucose concentration inblood and tissue fluid • H2O content of blood. • Homeostasis provides cells within the body with a relatively constant environment. • This helps cells work efficiently, irrespective of external environment…

15. Constant Environment • Homeostasis provides cells with a relatively constant environment. • What does this mean? • If air temperature is 43°C (e.g. summer in Dubai) the temperature around your liver cells will still be ~37°C. • Similarly, however much/little carbohydrate in diet, glucose concentration in body fluids remains around 800mg/dm3 • How are these parameters controlled?

16. What systems control homeostasis? • Which body systems help to control your internal conditions? • Nervous system • Hormonal/endocrine system

17. Nervous system • When you get cold how do you know? • The nervous system uses receptors around the body to collect and relay information about internal conditions to the brain/CNS. This then sends out signals to effectors which will act to counter act these changes • Skin receptors sense a drop in temp  signalled to CNS via sensory neurones  brain sends signal to muscles  muscles contract = shivering to increase body temp.

18. Hormonal system • How is your blood sugar controlled? • The hormonal system is made up of a series of glands which release hormones into the blood stream, these hormones trigger responses in specific cells/tissues/organs. • Eat a meal  blood sugar rises  sensed by cells in the pancreas  insulin released  travels through blood stream to liver  liver removes glucose from blood stream and stores it as glycogen blood sugar falls to normal levels.

19. Lets get on • Open P5 brief and use your notes and knowledge to complete Task 1 and Task 2!!

20. Task 3 - preparation • On your white boards explain what these works mean: • Input • Output • Receptor • Effector • Negative feedback Once you have done this try and add a example of each

21. Group reading • OCR AS/A2 Human Biology Book  • Page 238 • Starting at front!

22. How would we complete this flow chart, including the terms input, output, receptor, effector, negative feedback To complete P5 T3 you need to give an example of a system in the body using these terms

23. Which systems use negative feedback?

24. P5 - Describe the mechanisms of the homeostatic system • Task 1: Describe homeostasis and explain its importance in controlling our internal environment referring to examples. • Task 2: Identify and describe the systems that regulate homeostasis. • Task 3: Describe the mechanisms of homeostasis; include the terms input, output, receptor, effectors: • Complete the flow chart, include the terms input, output, receptor, effector, negative feedback. • Describe the homeostatic mechanism shown in the flow chart. Have you completed P5? Task 1, Task 2 & Task 3

25. Group differentation • Pass only students will use the following lessons to complete P5 and then go back and work on any re-submissions for P1,P2,P3 and P4. • These students are … • Merit/Distinction students will work in groups to produce posters containing the information needed to meet the merit criteria.

26. M4 - Explain positive and negative feedback in homeostasis, using examples from the human body • Explain positive and negative homeostatic feedback. • Identify and describe the stimuli, receptors, effectors, output and feedback mechanisms involved with: • Labor • Regulation of blood glucose • Regulation of body temperature • Regulation of water levels in the body Diagrams will be useful to help here!

27. Negative & Positive Feedback • Give specific examples of negative and positive feedback in the human body: • Group 1 - Labour • Group 2 – regulation of blood glucose • Group 3 – regulation of body temperature • Group 4 – regulation of water levels • 35 minutes to researchand produce a information poster. • You will then present your poster to the class (2 min)  and posters will be displayed to help everyone to use to complete the rest of M5 next lesson. • Use the success criteria on your hand out to ensure you cover all needed points!!

28. Example success criteria for M4 Task 2 Research poster for labor:

29. Negative & Positive Feedback Negative feedback isn’t only found in living organisms. Think about how a central heating system regulates itself to keep the temperature in a home constant.

30. Additional slides to help complete your work

31. How is temperature controlled? • What would naturally happen to your body to heat you up and cool you down in the environments below? • Write down your ideas on your white board!

32. Temperature Regulation • Thermo-receptors in the skin & hypothalamus • Hypothalamus secretes TRH • TRH reaches pituitary gland, stimulates TSH • TSH reaches thyroid gland thyroxine secreted • What is the role of the hormone thyroxine?

33. Thermostat • Temperature is controlled by a part of the brain called the hypothalamus • The hypothalamus sends impulses to other parts of the body to initiate mechanisms to either warm up or cool down the body

34. The Skin The skin’s jobs:- • The skin is the biggest organ in the body. An average person has about 2 square metres of skin. • The skin keeps our water in, is tough enough to keep out microbes that might cause disease and has a layer of fat to keep us warm. • The skin has lots of nerve receptors to detect changes in the environment • The skin employs mechanisms to help control temperature by altering blood flow, hair position and the amount of sweating.

36. Too hot • Impulses are also sent to the skin to cause 3 things to happen:-

37. 1. Our hairs lie flat: so letting more heat out.

38. 2. We sweat: the evaporation of this cools us down. 3. More blood goes through the skin: this acts like a radiator to radiate out heat.

39. Too cold • The hypothalamus sends impulses to the liver and cause it to increase respiration and so creates more heat. Like turning up the central heating! • By shivering the muscles make heat by respiration to keep us warm. • The hypothalamus sends other impulses so that the reverse happens:

40. 1.Our hairs stand up: this traps a layer of air which acts like an insulator.

41. 2. We stop sweating: this stops the heat loss by evaporation. 3. less blood goes through the skin: the skin will appear paler and colder. And we put more clothes on. This traps an insulating layer of air near our bodies

42. Hypothermia • This is a gradual cooling of the body caused when the core temp falls below 35°C • Usually caused by prolonged exposure to cold • Normal response – vasoconstriction, shivering & endocrine activity • In hypothermia, the above responses are not sufficient to maintain the normal core temp • A drop of 2ºC will start to affect the brain • Body movements and speech start to slow down • Coma and eventually death may follow

43. MISCONCEPTIONS • Blood vessels DO NOT move up and down in the skin • Capillaries DO NOT constrict or dilate – it’s the arterioles that supply them that constrict and dilate • Sweating itself DOES NOT cool the body – it’s the evaporation of the sweat taking heat energy with it that cools the body.

44. Homeostasis • What is meant by homeostasis? • The maintenance of a constant internal environment. • What factors does the body have to control? • Steady levels of temperature, water, oxygen and CO2. • Why is homeostasis important? • If there is not a constant internal environment, enzymes would not work properly. That would mean that nothing would operate correctly and we would die.  • What is normal body temperature? • 37ºC

45. Why are babies particularly at risk of hypothermia? Babies have a large surface area to volume ratio and are not able to shiver. How do a hot meal and warm clothes help? A hot meal warms the body from within and clothing – especially lots of layers, as they trap and insulating layer of air Why do damp clothes and cold winds cause hypothermia? The body heat causes the water in the wet clothes to evaporate taking heat energy with it. Cold winds also take heat energy.

46. Controlling body temperature - Negative Feedback Blood temperature falls Blood gets too hot Brain switches on cooling mechanisms Normal body temperature 37ºC Normal body temperature 37ºC Blood gets too cold Blood temperature rises Brain switches on warming mechanisms

47. The amount of glucose in our blood is controlled by the hormones insulin and glucagon working with the PANCREAS: Glucose returns to normal Controlling Glucose

48. Positive Feedback: Role of Oxytocin in Childbirth Hypothalamous produces GnRH Anterior lobe of pituitary gland produces LH and FSH Ovaries produces oestrogen and also produces progesterone(after ovulation) Endometrium of uterus (increased vascular tissue) FSH + LH effect the ovaries by increasing the production and secretion of another reproductive hormone by the follicle cells of the ovary. Hormone is oestrogen which targets the uterus and increases the blood vessels of the endometrium of the uterus. GnRH: gonadotropin releasing hormone – targeted to the pituitary gland – results in the pituitary gland secreting into the blood stream – secreting hormones are FSH and LH FSH: Follicle stimulating hormone LH: lutenizing hormone and they both target the ovaries.

49. High blood water content…

50. Low blood water level