1. Introduction to Physiology

2. Chapter Outline What Is Physiology? Organization of the Body
Challenging Homeostasis: Thermoregulation
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings.

3. Organization of the Body
Levels of organization
Cell
Tissue
Organ
System
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings.

4. Organization of the Body
Simplify by classifying
Body has over 200 different cell types
Cells can be put into four groups
Neurons
Muscle cells
Epithelial cells
Connective tissue cells
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings.

5. Major Tissue Types Based primarily on cell function
Correspond to four major cell types
Nerve tissue
Muscle tissue
Epithelium (epithelial tissue)
Connective tissue
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings.

6. Neurons and Nerve Tissue
Transmit signals for communication
Have branches to receive or transmit
Receive information from receptors
Transmit information to muscles or glands
Some neurons process information
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings.

7. Neurons and Nerve Tissue
Figure 1.2a
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings.

8. Muscle Cells Specialized to contract Can be voluntary or involuntary
Examples of contraction
Flexing of forearm
Pumping of blood
Mixing of food in the stomach
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings.

9. Muscle Cells
Figure 1.2b
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings.

10. Epithelial Cells and Epithelium
Epithelium = sheet-like layer of cells
Line external body surfaces
Line hollow body tubes and organs
Function as a barrier
Function as a transport membrane
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings.

11. Epithelial Cells and Epithelium
Figure 1.2c
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings.

12. Epithelium: Glands Glands Major classes of glands
Formed from epithelium
Manufacture a product
Major classes of glands
Exocrine glands
Have ducts
Endocrine glands
No ducts, product into blood
Product = hormone
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings.

13. Epithelium: Glands Figure 1.3a
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings.

14. Epithelium: Glands Figure 1.3b
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings.

15. Connective Tissue Most diverse of the four tissues
Characterized by extracellular matrix
Anchors and links structures of body
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings.

16. Connective Tissue Examples of connective tissue Bone Tendons Fat Blood
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings.

17. Connective Tissue Figure 1.2d
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings.

18. Organ System Tissues contain similar cells Organs Organ System
Composed of at least two tissue types
Perform specific functions
Organ System
Collection of organs
Perform particular task
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings.

19. Organ Systems
Table 1.1
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings.

20. A Simplified Body Plan Figure 1.4
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings.

21. Body Fluids and Compartments
Figure 1.5a–c
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings.

22. Body Fluids and Compartments
Figure 1.5c–e
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings.

23. Body Fluid Compartments
Internal environment = fluid surrounding cells = extracellular fluid (ECF)
70 kg man
- Total body water = 42 liters
28 liters intracellular fluid (ICF)
14 liters extracellular fluid (ECF)
Three liters plasma
11 liters interstitial fluid (ISF)
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings.

24. Homeostasis
Ability to maintain a relatively constant internal environment
Conditions of the internal environment which are regulated include
Temperature
Volume
Composition
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings.

25. Homeostasis: Terms Negative feedback
If a regulated variable decreases,
System responds to make it increase, and vice versa
Tends to be self correcting
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings.

26. Homeostasis: Terms Set point Expected value of regulated variable
Examples
Core body temperature = 37º C
Blood glucose (sugar) = 100 mg/dL
Blood pH = 7.4
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings.

27. Homeostasis: Terms Error signal
Difference between value of set point and regulated variable
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings.

28. Homeostasis: Terms Figure 1.6c–d
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings.

29. Homeostasis: Components
Structures enabling homeostasis
Components include
Receptors
Integrating Centers
Effectors
Signals
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings.

30. Homeostasis: Components
Receptors
Sensors which detect stimuli
Receptors include
Thermoreceptors
Chemoreceptors
Baroreceptors
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings.

31. Homeostasis: Components
Integrating center
Orchestrates an appropriate response
Often particular sets of neural circuits in brain
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings.

32. Homeostasis: Components
Effectors
Responsible for body responses
Effectors include
Muscles (smooth, striated, and cardiac)
Glands
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings.

33. Homeostasis: Components
Signals
Allow components to communicate
Input signal is from a receptor to an integrating center
Output signal is from an integrating center to an effector
Signals are chemical or via neurons
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings.

34. Negative Feedback Loop
Figure 1.7
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings.

35. Positive Feedback Loop
Positive feedback loops cause a rapid change in a variable.
Figure 1.8
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings.

36. Homeostasis: Thermoregulation
Core body temperature
Humans: 37º C (98.6º F)
Hypothermia = decrease in body temperature
Hyperthermia = increase in body temperature
Above 41º C is dangerous
Above 43º C is deadly
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings.

37. Homeostasis: Thermoregulation
Mechanisms of heat transfer between body and external environment
Radiation—thermal energy as electromagnetic waves
Conduction—thermal energy through contact
Evaporation—heat loss through evaporation of water
Insensible water loss
Sweating
Convection—heat transfer by movement of fluid or air
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings.

38. Thermoregulation: Components
Receptors = thermoreceptors
Central: found in CNS (hypothalamus)
Peripheral: found in PNS (mainly skin)
Effectors
Glands: sweat glands
Muscles: skeletal muscles, and smooth muscle of cutaneous blood vessels
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings.

39. Thermoregulation: Components
Integrating center
Thermoregulatory center in hypothalamus
Signals
Nerve impulses via neurons
Chemicals via hormones
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings.

40. Thermoneutral Zone
Range of outside temperature where alterations in blood flow alone regulates body temperature—25-30ºC
Body temperature increase
Blood flow to skin increases
Body temperature decrease
Blood flow to skin decreases
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings.

41. Thermoregulation Negative feedback control of body temperature
Figure 1.9a, b
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings.

42. Thermoregulation Figure 1.9c
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings.

43. Fever Rise in core body temperature Accompanies infection
White blood cells secrete pyrogens
Body temperature set point increases
Fever enhances immune response
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings.