1. THE HUMAN BODY AN ORIENTATION
An Overview of Anatomy and Physiology

2. Anatomy
Study of the structure of body parts and their relationships to each other
Anatomy: Greek meaning to cut apart

3. Physiology Study of the function of body parts
How all the body parts work and carry out their life-sustaining activities

4. Topics of Anatomy
Gross (macroscopic) anatomy: the study of structures large enough to be seen with the naked eye
Regional anatomy: all the body structures (muscles, bones, blood vessels, nerves, etc.) in a given body region , such as the abdomen or leg, are examined at the same time
Systemic anatomy: body is studied system by system
Example: when studying the cardiovascular system, you would examine the heart and the blood vessels of the entire body
Surface anatomy: internal body structures as they relate to the overlying skin
Used when identifying the bulging muscles beneath a bodybuilder’s skin, and clinicians use it to locate appropriate blood vessels in which to feel pulses and draw blood

5. Topics of Anatomy
Microscopic anatomy: the study of structures that are too small to be seen with the naked eye
Cytology: study of individual cells
Histology: study of tissues
Developmental anatomy: the study of the change in body structures over the course of a lifetime
Embryology: concerns developmental changes that occur before birth

6. Topics of Anatomy Specialized Branches of Anatomy
Pathological anatomy: study of structural changes associated with disease
Radiographic anatomy: study of internal structures using specialized visualization techniques (X-rays or special scanning devices)
Molecular biology: study of biological molecules

7. Topics of Physiology Considers the function of specific organ systems:
Examples:
Renal physiology: concerns kidney function and urine production
Neurophysiology: explains the workings of the nervous system
Cardiovascular physiology: examines the operation of the heart and blood vessels
While anatomy provides us with a static image of the body’s architecture, physiology reveals the body’s dynamic nature

8. Topics of Physiology Focuses on cellular and molecular events:
Individual cells and the chemical reactions that go on within them
Principles of physics which helps to explain electrical currents, blood pressure, and the way muscles use bones to cause body movements

9. Complementarity of Structure and Function
Function is dependent on structure, and the form of a structure relates to its function:
What a structure can do depends on its specific form
Examples:
Bones can support body organs because they contain hard mineral deposits
Blood flows in one direction through the heart because the heart has valves that prevent backflow
Lungs can serve as a site for gas exchange because the walls of their air sacs are extremely thin

10. Levels of Structural Organization
(1):Chemical level is the simplest level of organization:
Atoms, tiny building blocks of matter, combine to form molecules such as water and proteins
Molecules combine in specific ways to form organelles, which are the basic unit of living cells
Cells are the smallest units of living things
All cells have some common functions, but individual cells vary widely in size and shape, reflecting their unique functions in the body

11. Levels of Structural Organization
(2):Cellular level: smallest unit of life, and varies widely in size and shape according to the cell’s function
(3):Tissue level: groups of similar cells having a common function
Four basic tissue types: each tissue type has a characteristic role in the body
Epithelium: covers the body surface and lines its cavities
Muscle: provides movement
Connective: supports and protects body organs
Nervous: provides a means of rapid internal communication by transmitting electrical impulses

12. Levels of Structural Organization
(4):Organ level: made up of discrete structures that are composed of a least two groups of tissues that work together to perform a specific function in the body
Stomach: epithelium lining, muscles, blood vessels, connective tissues, nerve fibers, etc.
(5):Organ system level: a group of organs that work closely together to accomplish a specific purpose
Respiratory and circulatory system, digestive and circulatory systems
(6):Organismal level: the total of all structures working together to promote life
The living human being

13. Levels of Structural Organization

14. Maintaining Life Necessary Life Functions
(a): Maintaining Boundaries: allows an organism to maintain separate internal and external environments, or separate internal chemical environments
Integumantary System or Skin
(b): Movement: allows the organism to travel through the environment, and allows transport of molecules within the organism
Skeletal, Circulatory, Muscular Systems
(c): Responsiveness: or irritability, is the ability to detect changes in the internal or external environment and respond to them
Muscular System

15. ORGAN SYSTEMS

16. Maintaining Life Necessary Life Functions
(d): Nervous System:
Responsiveness to external and internal environments by activating muscles and glands
(e): Endocrine System:
Regulating body functions such as: growth, reproduction, and nutrition
(f): Cardiovascular System:
Transportation of nutrients, waste, gases, and hormones throughout the body

17. ORGAN SYSTEMS

18. Maintaining Life Necessary Life Functions
(g): Lymphatic System/Immunity:
Body defenses
(h): Respiratory System:
External and internal gas exchanges
(i): Digestive System:
Breakdown and absorption of nutrients

19. ORGAN SYSTEMS

20. Maintaining Life Necessary Life Functions
(j): Urinary System:
Absorption of waste from the blood and elimination
(k): Male Reproductive System:
Production of sperm
(l): Female reproductive System:
Production of eggs

21. ORGAN SYSTEMS

22. Maintaining Life Necessary Life Functions
Digestion is the process of breaking down food into molecules that are usable by the body
Metabolism includes all chemical reactions that occur in the body
Excretion is the process of removing wastes
Reproduction is the process of producing more cells or organisms
Growth is an increase in size in body parts or the whole organism

23. Examples of selected interrelationships among body organ systems
Integumentary system protects the body as a whole from the external environment
Digestive and respiratory systems, in contact with the external environment, take in nutrients and oxygen, respectively, which are then distributed by the blood to all body cells
Elimination of metabolic wastes is accomplished by the urinary and respiratory systems

24. ORGAN SYSTEMS

25. Survival Needs
The ultimate goal of all body systems is to maintain life
Life is extraordinarily fragile and requires that several factors be present:
These factors are called survival needs and include:
Nutrients: consumed chemical substances that are used for energy and cell building
Oxygen: required by the chemical reactions that release energy from foods
Water: most abundant chemical substance in the body, provides an environment for chemical reactions and a fluid for secretions and excretions
Normal body temperature: required for the chemical reactions of the body to occur at the proper rate
Atmospheric pressure: must be within an appropriate range so that proper gas exchange occurs in the lungs

26. Homeostasis
The ability of the body to maintain a relatively constant internal environment, regardless of environmental changes:
Body temperature
Blood pH

27. Homeostatic Control Mechanisms
Communication within the body is essential for homeostasis
Accomplished chiefly by the nervous and endocrine systems
All homeostatic control mechanisms have at least three interdependent components:
1. Receptor: type of sensor that monitors the environment and responds to changes, called stimuli, by sending information (input) to the second component (control center)

28. Homeostatic Control Mechanisms
2. Control Center:
Information flows from the receptor to the control center along the afferent pathway
Structure that determines the set point (level or range at which a variable is to be maintained) for a variable, analyzes input, and coordinates an appropriate response
Variable: the regulated factor or event

29. Homeostatic Control Mechanisms
3. Effector:
Provides the means for the control center’s response (output) to the stimulus
Structure that carries out the response directed by the control center
Information flows from the control center to the effector along the efferent pathway
The results of the response then feed back to influence the stimulus, either depressing it (negative feedback) so that the whole control mechanism is shut off or enhancing it (positive feedback) so that the reaction continues at an even faster rate

30. CONTROL SYSTEM

31. Negative Feedback Mechanisms
Most homeostatic control mechanisms are negative feedback mechanisms
In these systems, the output shuts off the original stimulus or reduces its intensity
These mechanism cause the variable to change in a direction opposite to that of the initial change, returning it to its “ideal” value
Both the nervous system and the endocrine system are important to the maintenance of homeostasis
The goal of negative feedback mechanisms is to prevent sudden, severe changes in the body

32. Negative Feedback Mechanisms
Home heating system connected to a temperature-sensing thermostat
Thermostat houses BOTH the receptor and the control center
If thermostat is set at 20oC (68oF), the heating system (effector) is triggered ON when the house temperature drops below that setting
As the furnace produces heat and warms the air, the temperature rises, and when it reaches 20oC or slightly higher, the thermostat triggers the furnace OFF
This process results in a cycling of “furnace-ON” and “furnace-OFF” so that the temperature in the house stays very near the desired temperature of 20oC
Your body thermostat, located in a part of your brain called the hypothalamus, operates in a similar fashion

33. Negative Feedback Mechanisms
To carry out normal metabolism, body cells need a continuous supply of glucose, their major fuel for producing cellular energy, or ATP
Blood sugar levels are normally maintained around 90 milligrams (mg) of glucose per 100 millimeters (ml) of blood
Rising glucose levels stimulate the insulin-producing cells of the pancreas, which respond by secreting insulin into the blood
Insulin accelerates the uptake of glucose by most body cells
It also encourages storage of excess glucose as glycogen in the liver and muscles
Consequently, blood sugar levels ebb back toward the normal set point, and the stimulus for insulin release diminishes

34. NEGATIVE FEEDBACK

35. Negative Feedback Mechanisms
Glucagon, another pancreatic hormone, has the opposite effect of insulin
Its release is triggered as blood sugar levels decline below the set point
Glucagon secretion is stimulated
Glucagon targets the liver, causing it to release its glucose reserves from glycogen into the blood
Consequently, blood sugar levels increase back into the homeostatic range
There are hundreds of Negative Feedback Mechanisms (regulation of heart rate, blood pressure, rate and depth of breathing, and blood levels of oxygen, carbon dioxide, and minerals)

36. NEGATIVE FEEDBACK

37. Positive Feedback Mechanisms
Result or response enhances the original stimulus so that the activity (output) is accelerated
A positive feedback mechanism causes the variable to change in the same direction as the original change, resulting in a greater deviation from the set point
Positive feedback mechanisms typically activate events that are self-perpetuating
Once initiated, have an amplifying effect
Most positive feedback mechanisms are not related to the maintenance of homeostasis
Homeostatic imbalance often results in disease

38. Positive Feedback Mechanisms
Examples:
Enhancement of labor contractions during birth:
Oxytocin, a hypothalamic hormone, intensifies labor contractions during the birth of a baby
Causes the contractions to become more frequent and more powerful until the baby is finally born, an event that ends the stimulus for oxytocin release and shuts off the positive feedback mechanism

39. Positive Feedback Mechanisms
Examples:
Blood clotting:
Blood clotting is a normal response to a break in the lining of a blood vessel
1. Once vessel damaged has occurred
2. Blood elements called platelets immediately begin to cling to the injured site
3. Platelets release chemical that attract more platelets
4. This rapidly growing pileup of platelets initiates the sequence of events that finally forms a clot

40. POSITIVE FEEDBACK

41. Homeostatic Imbalance
Homeostasis is so important that most disease is regarded as a result of its disturbance, a condition called Homeostatic Imbalance
Causes:
As we age, our body’s control systems become less efficient
Negative feedback mechanisms become overwhelmed and destructive positive feedback mechanisms take over

42. Language of Anatomy Anatomical Position and Directional Terms
To describe body parts and position accurately, we need an initial reference point and must indicate direction
The anatomical reference point is a standard body position called the Anatomical Position
Anatomical Position: position in which the body is:
Erect with feet only slightly apart
Palms face forward
Thumbs point away from the body

43. REGION TERMS

44. REGION TERMS

45. Language of Anatomy Anatomical Position and Directional Terms
In anatomical position, right and left refer to the right and left sides of the person viewed—NOT those of the observer
In anatomy, anatomical position is always assumed, regardless of the actual position of the body

46. Language of Anatomy Anatomical Position and Directional Terms
Directional terms are used to explain exactly where one body part is in relation to another
Example:
The ears are located on each side of the head to the right and left of the nose
Using anatomical terminology, this condenses to,:
The ears are lateral to the nose
Saves words and is less ambiguous
Anatomical meanings are VERY PRECISE

47. Orientation and Directional Terms

48. Orientation and Directional Terms

49. Orientation and Directional Terms

50. Regional Terms There are two fundamental divisions of the body:
Axial region:
Makes up the main axis of our body
Includes the head, neck, and trunk
Appendicular region:
Consists of the appendages, or limbs
Attached to the body’s axis
Consists of the upper and lower limbs
Regional terms are used to designate specific areas within the major body divisions
The common term for each of these body regions is provided (in parentheses)

51. REGION TERMS

52. REGION TERMS

53. Body Planes and Sections
For anatomical studies, the body is often sectioned (cut) along a flat surface called a plane
Body planes are flat surfaces that lie at right angles to each other
Sagittal plane: a vertical plane that separates the body into right and left parts
Median, or midsagittal plane: lies exactly along the body’s midline
Parasagittal plane (para=near): lies offset from the midline
Frontal plane: a vertical plane that separates the body into anterior and posterior parts
Transverse, or horizontal, plane: a plane that runs horizontally from right to left, and divides the body into superior and inferior parts

54. BODY PLANES

55. Body Planes and Sections
Transverse, or horizontal, plane: a plane that runs horizontally from right to left, and divides the body into superior and inferior parts
Many different transverse planes exist, at every possible level from head to foot
Transverse section, or cross section, is a cut made along the transverse plane
Oblique sections are cuts made at angles between the horizontal and vertical planes
The ability to interpret sections made through the body, especially transverse sections, is important in the clinical sciences
New medical imaging devices produce sectional images rather than three-dimensional images

56. BODY PLANES

57. Body Cavities and Membranes
Within the axial portion of the body are two large cavities called the dorsal and ventral body cavities
Body cavities are spaces within the body that are closed to the outside and contain the internal organs

58. BODY CAVITIES

59. BODY CAVITIES

60. Dorsal Body Cavity
The space that houses the central nervous system, and has two subdivisions: the cranial cavity and the vertebral cavity
Cranial cavity is within the skull, and encases the brain
Vertebral, or spinal, cavity is within the vertebral column, and encloses the spinal cord

61. BODY CAVITIES

62. BODY CAVITIES

63. Ventral Body Cavity
Is anterior to and larger than the dorsal cavity and has two main subdivisions: the thoracic cavity, and the abdominopelvic cavity
Houses the body organs collectively called the viscera (viscus=an organ in a body cavity), or visceral organs
Thoracic cavity:
Is a superior division of the ventral cavity that is further subdivided into the lateral pleural cavities that surround the lungs
Thoracic cavity also contains the medulla mediastinum, which includes the pericardial cavity surrounding the heart and the space surrounding the other thoracic structures (esophagus, trachea, and others)
Diaphragm Muscle separates the Thoracic and Abdominopelvic Regions
Abdominopelvic Regions and Quadrants:
Inferior to the Thoracic Cavity
There are nine abdominopelvic regions used primarily by anatomists
There are four quadrants used primarily by medical personnel

64. BODY CAVITIES

65. BODY CAVITIES

66. Membranes in the Ventral Body Cavity
The walls of the ventral body cavity and the outer surfaces of the organs it contains are covered by a thin, double-layered membrane, the serosa, or serous membrane
Serous membranes, or serosae, cover the inner walls of the ventral cavity and the outer surfaces of organs
Serous membranes secrete and are separated by a thin layer of lubrication fluid called serous fluid, which allows organs to slide without friction along cavity walls and between each other
Parietal serosa lines the body cavity walls, and is named for the specific cavities it is associated with
Visceral serosa covers the outer surfaces of organs, and is named for the specific organs it is associated with
Parietal pericardium lines the pericardial cavity
Visceral pericardium covers the heart within that cavity
Parietal pleura lines the walls of the thoracic cavity
Visceral pleura covers the lungs
Parietal peritoneum is associated with the walls of the abdominalpelvic cavity
Visceral peritoneum covers most of the organs within that cavity

67. SEROUS MEMBRANE Parietal pericardium lines the pericardial cavity
Visceral pericardium covers the heart within that cavity

68. SEROUS MEMBRANE

69. Membranes in the Ventral Body Cavity
You can visualize the relationship between the serosal layers by pushing your fist into a limp balloon
The part of the balloon that clings to your fist can be compared to the visceral serosa clinging to the organ’s external surface
The outer wall of the balloon then represents the parietal serosa that lines the walls of the cavity

70. SEROUS MEMBRANE

71. Homeostatic Imbalance
When serous membranes are inflamed, they typically produce less lubricating serous fluid
This leads to excruciating pain as the organs stick together and drag across one another, as anyone who has experienced pleurisy (inflammation of the pleurae: thoracic cavity) or peritonitis (inflammation of the peritoneal: abdominal cavity)

72. Abdominopelvic Regions
Because the abdominopelvic cavity is large and contains several organs, it helps to divide it into smaller areas for study
Cavity divided into 9 regions
Umbilical region: centermost region deep to and surrounding the umbilicus (navel)
Epigastric region: located superior to the umbilical region (epi=upon, above; gastri=belly)
Hypogastric (pubic) region: located inferior to the umbilical region (hypo=below)

73. ABDOMINAL REGION

74. ABDOMINAL REGIONS

75. Abdominopelvic Regions
Right and left iliac, or inguinal regions: located lateral to the hypogastric region (iliac=superior part of the hip bone)(inguinal=groin: between thigh and trunk)
Right and left lumbar regions: lie lateral to the umbilical region (lumbus=loin: between ribs and pelvis)
Right and left hypochondriac regions: flank the epigastric region laterally (chondro=cartilage)

76. ABDOMINAL REGION

77. ABDOMINAL REGIONS

78. Quadrants
Medical personnel usually use a simpler scheme to localize the abdominopelvic cavity organs
In this scheme, one transverse and one median sagittal plane pass through the umbilicus at right angles
The resulting quadrants are named according to their positions from the subject’s point of view:
Right upper quadrant (RUQ)
Left upper quadrant (LUQ)
Right lower quadrant (RLQ)
Left lower quadrant (LLQ)

79. ABDOMINAL REGION

80. Other Body Cavities
Oral and digestive cavities are continuous cavities that extend from the mouth through the digestive system to the anus
Nasal cavity is within and posterior to the nose
Part of the respiratory system
Orbital cavities (orbits) in the skull house the eyes
Middle ear cavities are within the skull just medial to the eardrums, and house the bones that transmit sound vibrations to the inner ears
Synovial cavities are joint cavities
Enclosed within fibrous capsules that surround movable joints (elbow and knee)
Lined with a lubricating fluid-secreting membranes
Secrete a lubricating fluid that reduces friction as the bones move across one another

81. OTHER CAVITIES

82. Medical Imaging X-ray (radiograph) CAT: Ccomputerized axial tomography
Xenon CT
DSR: Dynamic spatial reconstruction
DSA: Digital subtraction angiography
PET: Positron emission tomography
Sonography (ultrasound imaging)
MRI: Magnetic resonance imaging
MRS: Magnetic resonance spectroscopy

83. IMAGING