Chapter 1 An Introduction to the Human Body

1. Chapter 1An Introduction to the Human Body • Anatomy • science of structure • relationships revealed by dissection (cutting apart) • imaging techniques • Physiology • science of body functions • normal adult physiology studied in this text • some genetic variations described • Subdivisions of A & P = Table 1.1

2. Clinical Observational Techniques • Palpation • feel body surface with hands • pulses and breathing rates • Auscultation • listen to body sounds with stethoscope • abnormal fluid in lungs • Percussion • tap on body surface and listen to echo • air in intestines

3. Levels of Organization • Chemical • Cellular • Tissue • Organs • System Level • Organismic Level

4. 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

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

6. Interaction of Organ Systems • All major body systems will be examined • Interaction of different systems of the body • skin produces vitamin D needed for calcium absorption and bone growth • bone marrow produces cells which help the skin resist infection.

7. Life Processes • Metabolism = sum of all chemical processes • breakdown of large molecules into small • building new structural components (proteins) • providing chemical energy for cells • Responsiveness • detect & respond to changes in internal or external environment • some typical responses • muscle contraction, electrical signals, hormone or glandular secretion

8. Life Processes • Movement at any structural level • the body, an organ, a cell or cell component • Growth • increase in number or size of cells or the material found between cells • Differentiation • specialization of cells for a specific function • stem cells give rise to cells that specialize • Reproduction • formation of new cells or new individuals

9. Autopsy • Postmortem examination of body by dissection • Purpose • confirm or determine cause of death • support findings of other tests • provide information on effects of drug usage • educate healthcare students • reveal congenital defects

10. Homeostatis • Maintaining the internal environment within physiological limits • First described by French physiologist, 1813-1878 • Process named by Walter Cannon, 1871-1945 • Example • blood glucose level is kept within narrow range 70-110/100ml

11. Homeostasis of Body Fluids • Delineation of fluid compartments • intracellular fluid (ICF) = within cells • extracellular fluid (ECF) = outside cells • intercellular fluid = tissue fluid = interstitial fluid • plasma = fluid portion of blood • Composition of fluids change as substances move between compartments • nutrients, oxygen, ions and wastes move in both directions across capillary walls

12. Control of Homeostasis • Homeostasis is continually being disrupted by • external stimuli or • intense heat, cold , and lack of oxygen • internal stimuli • psychological stresses • exercise • Disruptions are usually mild & temporary • If homeostasis is not maintained, death may result

13. Neural and Endocrine Controls • Process of maintaining a controlled condition • sensory receptors detect change in a monitored variable • nervous system and/or endocrine system responds • Example of control of blood gas level • exercise increases blood CO2 levels • sensory receptors detect change • nervous system increases heart and breathing rates to remove excess CO2 • adrenal gland releases epinephrine to increase heart and breathing rates

14. Components of Feedback Loop • Receptor • monitors a controlled condition • Control center • determines next action • Effector • receives directions from the control center • produces a response that changes the controlled condition

15. Negative & Positive Feedback Loops • Negative feedback loop • original stimulus reversed • most feedback systems in the body are negative • used for conditions that need frequent adjustment • body temperature, blood sugar levels, blood pressure • Positive feedback loop • original stimulus intensified • seen during normal childbirth

16. Homeostasis of Blood Pressure • Pressure receptors in walls of certain arteries detect an increase in BP • blood Pressure = force of blood on walls of vessels • Brain receives input and signals heart and blood vessels • Heart rate slows and arterioles dilate (increase in diameter) • BP returns to normal

17. Positive Feedback during Childbirth • Stretch receptors in walls of uterus send signals to the brain • Brain releases 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

18. Homeostatic Imbalances • Disorder = abnormality of function • Disease = homeostatic imbalance with distinct • symptoms---changes in body function felt by the patient such as nausea and • signs----changes in body function that can be observed by the doctor such as rash or fever • Diagnosis---skill of distinguishing one disease from another • Epidemiology----how disease is transmitted • Pharmacology --- how drugs used to treat disease

19. Basic Anatomical Terminology • Anatomical position • Regions of the body • Anatomical planes, sections and directional terms

20. 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 • Prone position = lying face down • Supine position = lying face up anatomical position?

21. Common Regional Names • Clinical terminology based on a Greek or Latin root word.

22. 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.

23. Sagittal Plane • Sagittal plane • divides the body or an organ into left and right sides • Midsagittal plane • produces equal halves • Parasagittal plane • produces unequal halves

24. Other Planes and Sections • Frontal or coronal plane • divides the body or an organ into front (anterior) and back (posterior) portions • Transverse(cross-sectional) or horizontal plane • divides the body or an organ into upper (superior) or lower (inferior) portions • Oblique plane • some combination of 2 other planes

25. Planes and Sections of the Brain(3-D anatomical relationships revealed) • Horizontal Plane • Frontal Plane • Midsagittal Plane

26. Major Directional Terms • See Definitions page 14

27. 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.

28. 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.

29. 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.

30. Proximal or Distal • Proximal • nearer to the attachment of the limb to the trunk • The knee is proximal to the ankle. • Distal • farther from the attachment of the limb to the trunk • The wrist is distal to the elbow.

31. Dorsal Body Cavity • Near dorsal surface of body • 2 subdivisions • cranial cavity • holds the brain • formed by skull • vertebral or spinal canal • contains the spinal cord • formed by vertebral column • Meninges line dorsal body cavity

32. Ventral Body Cavity • Near ventral surface of body • 2 subdivisions • thoracic cavity above diaphragm • abdominopelvic cavity below diaphragm • Diaphragm = large, dome-shaped muscle • Organs called viscera • Organs covered with serous membrane

33. Abdominopelvic Cavity • Inferior portion of ventral body cavity below diaphragm • Encircled by abdominal wall, bones & muscles of pelvis

34. Thoracic Cavity • Encircled by ribs, sternum, vertebral column and muscle • Divided into 2 pleural cavities by mediastinum • Mediastinum contains all thoracic organs except lungs

35. Mediastinum • Midline wall of tissue that contains heart and great vessels, esophagus, trachea and thymus.

36. Serous Membranes • Thin slippery membrane lines body cavities not open to the outside • parietal layer lines walls of cavities • visceral layer covers viscera within the cavities • Serous fluid reduces friction

37. Visceral pleura clings to surface of lungs --- Parietal pleura lines chest wall Visceral pericardium covers heart --- Parietal pericardium lines pericardial sac Pleural & Pericardial Cavities

38. Peritoneum • Visceral peritoneum --- serous membrane that covers the abdominal viscera • Parietal peritoneum --- serous membrane that lines the abdominal wall

39. Abdominopelvic Regions & Quadrants • Describe locations of organs or source of pain • Tic-tac-toe grid or intersecting lines through navel

40. Medical Imaging • Allows visualization of structures without surgery • Useful for confirmation of diagnosis • Examples of imaging techniques

41. Conventional Radiography • A single burst of xrays • Produces 2-D image on film • Known as radiography or xray • Poor resolution of soft tissues • Major use is osteology

42. Computed Tomography (CT Scan) • Moving x-ray beam • Image produced on a video monitor of a cross-section through body • Computer generated image reveals more soft tissue detail • kidney & gallstones • Multiple scans used to build 3D views

43. Digital Subtraction Angiography(DSA) • Radiopaque material injected into blood vessels • Before and after images compared with a computer program • Image of blood vessel is shown on a monitor

44. Ultrasound (US) • High-frequency sound waves emitted by hand-held device • Safe, noninvasive & painless • Image or sonogram is displayed on video monitor • Used for fetal ultrasound and examination of pelvic & abdominal organs, heart and blood flow through blood vessels

45. Magnetic Resonance Imaging (MRI) • Body exposed to high-energy magnetic field • Protons align themselves relative to magnetic field • Pulse of radiowaves used to generate an image on video monitor • Can not use on patient with metal in their body • Reveals fine detail within soft tissues

46. Positron Emission Tomography(PET) • Substance that emits positively charged particles is injected into body • Collision with negatively charged electrons in tissues releases gamma rays • Camera detects gamma rays & computer generates image displayed on monitor