Chapter 1 Organization of the Nervous System

1. Chapter 1 Organization of the Nervous System Hypothalamus

2. Outline • Function of the Hypothalamus • Regulation of Body Temperature • Autonomic Nervous System

3. I. Function of the Hypothalamus • Reference • Adina Michael-Titus, et al. System of the Body – The Nervous System. 2nd version, Elsevier Limited, 2011. P19 – 20 • 姚泰主编，8年制及1年制临床医学等专用生理学，第二版，人民卫生出版社，2010年。P 483 – 485。

4. Hypothalamus Tu :19.17

5. Hypothalamic Functions • Food Intake • Water Balance • Sleep/wake cycle • Emotions and behavior • Circadian • Endocrine Functions • Body Temperature • Autonomic Nervous System

6. Food Intake • Ventromedial and Paraventricular Nuclei are satiety centers • Lesion causes obesity • Through disrupting satiety input to the periventricular nucleus • Lateral HT is feeding center • Stimulation cause food and water intake • Lesion causes starvation behavior • Through damage the medial forebrain bundle, leading to neglect syndrome – no motivation to eat

7. Water Balance • Thirst center in the hypothalamus (supraotic nucleus) is stimulated by: • Cellular dehydration • Decreased salivary production • Increased blood osmotic pressure • Decreased blood volume • Thirst center response • Release vasopressin • Cause sensation of thirst

8. Sleep/Wake Cycle: • suprachiasmatic nuc is biological clock • preoptic nuc can initiate sleep • lat HT can change cortical arousal • post HT lesion can cause coma or impaired arousal

9. Emotions and Behavior • Ventromedial lesions can cause viciousness/rage • Posterior HT stimulates sympathetic functions • Anterior HT stimulates parasympathetic functions • Mamillary nuclei recent memory

10. Circadian • Almost all land animals coordinate their behavior according to circadian rhythms • Suprachiasmatic Nuclei (SCN)

11. Circadian Rhythms of Physiological Functions

12. Endocrine Function • Regulation of Adenohypophysis • Secretion of Hormones (Vasopressin and Oxytocin)

13. Functions of the Hypothalamus • Food intake • Water balance • Sleep/wake cycle • Emotions and behavior • Circadian • Endocrine Function • Body temperature • Autonomic Nervous System

14. II Energy metabolism and body temperature

15. Reference • Arthur C. Guyton, John E. Hall. Textbook of Medical Physiology, 11th edition, Elsevier Science, 2006. P 881-900 • 姚泰主编，8年制及7年制临床医学等专用生理学，第二版，人民卫生出版社，2010年。P 483 – 485。

16. Section 1 Energy Metabolism

17. Metabolism Anabolism Catabolism material synthesis require energy material breakdown release energy material metabolism energy metabolism

18. Energy storage, liberation, transfer and utilization

19. Energy balance Energy input = energy output heat Food heat heat ATP cellular functions heat metabolism Food heat

20. Metabolic Rate • The amount of energy liberated from a living organism per unit of time • Expressed in terms of the rate of heat liberation during the chemical reactions

21. Measurement of the metabolic rate • Direct calorimetry • Indirect calorimetry • Caloric value / thermal equivalent of food • Oxygen consumption / thermal equivalent of oxygen （1 L） • Respiratory quotient （CO2 / O2）

24. Factors that affect the metabolic rate • Exercise - increase in metabolic rate • Ingestion of food - Increase metabolic rate • The specific dynamic action of protein • Emotional state • Environmental temperature • 20-30 °C have stable metabolic rate • < 20 or >30°C , metabolic rate is increased • Other factors (sleep, sex, age, etc.)

25. Component of Energy Expenditure

27. Basal metabolic rate (BMR) • minimum level of energy required to exist • a person is at basal condition (complete rest) • useful for diagnosing the diseases: • Hyperthyroidism, hypothyroidism

28. Basal conditions • Fasted for at least 12 hours • After a night of restful sleep • No strenuous activity is performed for at least 1 hour before the test • All psychic and physical factors that cause excitement must be eliminated • The temperature 25 – 30 °C • No physical activity is permitted during the test

29. Section 2 Body temperature

30. Skin and Core Temperature • Skin temperature • the temperature of the skin and tissues immediately underlying the skin. rises and falls with the temperature of the surroundings • Core temperature • the temperature of the deep tissues of the body – the “core” of the body. • remains almost constant, varying not more than 1 °C • Rectal T: 36.9-37.9 °C • Oral T: 36.7-37.7 °C • Axillary T: 36.0-37.4 °C

31. Range of Body Temperature

32. Factors affecting normal temperature • Circadian rhythm • In the early morning, the body T is the lowest. • In late afternoon or early evening, it is the highest. • Age • Newborn child > adult > old person • Sex • Women > man 0.3 °C • Muscular activity • Other factors: emotion, eating, change in climate

33. Heat Production • BMR of all the cells • Extra metabolism caused by • muscle activity • hormone (thyroxine, growth hormone and testosterone) • the effect of epinephrine, • norepinephrine and sympathetic stimulation on the cells • increased chemical activity in the cells themselves

34. Heat Loss • The major organ to loss heat is the skin • Blood flow to the skin from the body core provides heat transfer

35. Methods of heat loss from the skin to the surroundings

36. Effect of Environment air Temperature on Conductance of Heat from the Body

37. Evaporation • 1) Insensible perspiration • 2) Sweating • Innervated mainly by sympathetic cholinergic nerve (acetylcholine) • Caused by nervous reflex • Mechanism of sweat secretion • Primary secretion • reabsorption • Sweat (urea, lactic acid, K+ )

38. Regulation of the body temperature • Behavioral control of the body temperature • Autonomic control of the body temperature

40. Feedback mechanisms of regulation of the body temperature • Temperature receptor • Peripheral temperature receptor • Locations: skin, mucous,, abdominal viscera • Types: cold receptor and warmth receptor • cold receptor > warmth receptor • Central temperature receptor • Locations: spinal cord, preoptic and anterior hypothalamic area of the hypothalamus (PO/AH) • Types: heat-sensitive neurons and cold-sensitive neurons • Temperature-regulating center • 1) The thermoregulating center is mainly in the hypothalamus • 2) The PO/AH area is the basic thermostatic temperature controlling center

41. Feedback mechanisms of regulation of the body temperature • Efferent pathways: Control of the heat loss and heat production • Control of the skin vascular tone and sweating by sympathetic nerve system • Changes of the muscular tension by somatic motor nerve system • Control of the metabolic rate by altering the function of endocrine system, mainly the hormone secretion of the thyroid glands or adrenal medulla

42. “Set-point” 37 °C PO/AH area T > 37 °C Production < loss T < 37 °C Production > loss

44. Fever

45. III Autonomic Nervous System • Reference • Adina Michael-Titus, et al. System of the Body – The Nervous System. 2nd version, Elsevier Limited, 2011. P24 – 28 • 姚泰主编，8年制及7年制临床医学等专用生理学，第二版，人民卫生出版社，2010年。P 478 – 482

46. Section 1. Basic of the ANS • Including • parasympathetic • sympathetic • enteric divisions • Coordinates cardiovascular, respiratory, digestive, excretory and reproductive systems • The enteric system • an independent nervous system responsible for regulation of digestive functions.

47. Somatic and Autonomic Nervous System

48. Somatic Skeletal muscle Conscious and unconscious movement Skeletal muscle contracts One synapse Acetylcholine Autonomic Smooth and cardiac muscle and glands Unconscious regulation Target tissues stimulated or inhibited Two synapses Acetycholine by preganglionic neurons and ACh or norepinephrine by postganglionic neurons Somatic and Autonomic Nervous System

49. Sympathetic Division • Preganglionic cell bodies in lateral horns of spinal cord T1-L2

50. Parasympathetic Division • Preganglionic cell bodies in nuclei of brainstem or lateral parts of spinal cord gray matter from S2-S4 • Preganglionic axons from brain pass to ganglia through cranial nerves • Preganglionicaxons from sacral region pass through pelvic nerves to ganglia • Preganglionic axons pass to terminal ganglia within wall of or near organ innervated