An Introduction to the Human Body

1. An Introduction to the Human Body • Anatomy • science of structure • Histology is study of microscopic aspect of anatomy • Physiology • science of body functions • Normal adult physiology changes due to infection by pathogens (disease causing life forms) or disorder (malfunction due to genetic or other factors) Shina Alagia, 2005

2. Levels of Organization • Chemical • Cellular • Tissue • Organs • System Level • Organismic Level Shina Alagia, 2005

3. Levels of Structural Organization • Chemical Level • atomic and molecular level • Cellular level • smallest living unit of the body • Tissue level • group of cells and the materials surrounding them that work together on one task • 4 basic tissue types • epithelium, muscle, connective tissue, and nerve Shina Alagia, 2005

4. Levels of Structural Organization • Organ level • grouping of 2 or more tissue types into a recognizable structure with a specific function. • System • collection of related organs with a common function • sometimes an organ is part of more than one system • Organismic level • one living individual. Shina Alagia, 2005

5. Homeostasis • Maintaining the internal environment within physiological limits (may not be optimal level) • Example: Blood temperature is kept between 100-104 oF(38oC), blood volume is kept between 4-6 L (Male and female) • Two systems that maintain homeostasis are: Nervous system & Endocrine system Shina Alagia, 2005

6. Control of Homeostasis • Homeostasis is continually being disrupted by • external stimuli or • intense heat, cold, lack of oxygen, pathogenic microbes • internal stimuli • psychological stresses • Organ/system malfunction, internal injury etc. • Disruptions can be mild to severe • If homeostasis is not maintained, death may result Shina Alagia, 2005

7. Feedback Loop • Feed back loop is the way of communication to maintain homeostasis. Components are: • Receptor • Structures that monitor a controlled condition and detect changes • Control center • determines next action • Effector • receives directions from the control center • produces a response that restores the controlled condition Shina Alagia, 2005

8. Feed Back Loop Shina Alagia, 2005

9. Feedback Loops: Types • Negative feedback loop • original stimulus reversed • most feedback systems in the body are negative • used for conditions that need frequent adjustment • Positive feedback loop • original stimulus intensified • seen during normal childbirth Shina Alagia, 2005

10. Homeostasis of Temperature • Thermo receptors in walls of blood vessels detect an increase in temp. during exercise • Brain receives input and signals blood vessels and sweat glands • Blood vessels dilate (increase in diameter), sweat released. • Loss of heat by combined action. Temperature turns to normal Shina Alagia, 2005

11. Positive Feedback during Childbirth • Stretch receptors in walls of uterus send signals to the brain • Brain induces release of hormone (oxytocin) into bloodstream • Uterine smooth muscle contracts more forcefully • More stretch, more hormone, more contraction etc. • Cycle ends with birth of the baby & decrease in stretch Shina Alagia, 2005

12. Body Fluids • Delineation of fluid compartments • intracellular fluid (ICF) = within cells • extracellular fluid (ECF) = outside cells - interstitial fluid - plasma = fluid portion of blood • Continuous exchange of substances between compartments • nutrients, oxygen, ions and wastes Shina Alagia, 2005

13. Shina Alagia, 2005

14. Basic Anatomical Terminology • Anatomical position • Regions of the body • Anatomical planes, sections and directional terms Shina Alagia, 2005

15. Anatomical Position • Standardized position from which to describe directional terms • standing upright • facing the observer, head level • eyes facing forward • feet flat on the floor • arms at the sides • palms turned forward anatomical position? Shina Alagia, 2005

16. Common Regional Names Shina Alagia, 2005

17. Planes and Sections • A plane is an imaginary flat surface that passes through the body. • A section is one of the 2 surfaces (pieces) that results when the body is cut by a plane passing through it. Shina Alagia, 2005

18. Frontal Plane • Frontal or coronal plane • divides the body or an organ into front (anterior) and back (posterior) portions Shina Alagia, 2005

19. Sagittal Plane • Sagittal plane • divides the body or an organ into left and right sides • Midsagittal plane • produces equal halves Shina Alagia, 2005

20. Transverse Plane • divides the body or an organ into upper (superior) or lower (inferior) portions Shina Alagia, 2005

21. Major Directional Terms Shina Alagia, 2005

22. Superior or Inferior • Superior • towards the head • The eyes are superior to the mouth. • Inferior • away from the head • The stomach is inferior to the heart. Shina Alagia, 2005

23. Dorsal or Ventral • Dorsal or Posterior • at the back of the body • The brain is posterior to the forehead. • Ventral or Anterior • at the front of the body • The sternum is anterior to the heart. Shina Alagia, 2005

24. Medial or Lateral • Medial • nearer to the midline of the body • The heart lies medial to the lungs. • Lateral • farther from the midline of the body • The thumb is on the lateral side of the hand. Shina Alagia, 2005

25. Dorsal Body Cavities • Near dorsal surface of body 1. cranial cavity • holds the brain • formed by skull 2. vertebral or spinal canal • contains the spinal cord • formed by vertebral column Shina Alagia, 2005

26. Ventral Body Cavities • Near ventral surface of body • thoracic cavity above diaphragm • abdominopelvic cavity below diaphragm • Diaphragm = large, dome-shaped muscle • Organs called viscera • Many sub cavities are present ex. Nasal cavity oral cavity etc. Shina Alagia, 2005

27. Serous Membranes • Thin slippery membrane lines body cavities not open to the outside. Always 2 layers • parietal layer lines walls of cavities • visceral layer covers viscera within the cavities • Ex include pericardial membrane around heart, pleural membrane around lungs, peritoneum within abdomino-pelvic cavity etc. Shina Alagia, 2005

28. Epithelial membranes • Line body cavities/canals open to exterior. Ex. Membrane lining nasal cavity, oral cavity, respiratory tract, urinary tract, vagina etc. • Single layered and fast regenerating Shina Alagia, 2005