1. The Human Body: An Orientation1
P A R T A
The Human Body: An Orientation

2. Overview of Anatomy and Physiology
Anatomy – (Greek – to cut up) - the study of the structure of body parts and their relationships to one another
Gross or macroscopic
Microscopic
Developmental
Physiology – (Greek – study of nature) - the study of the function of the body’s structural machinery; explains physical & chemical processes that direct body activities

3. Gross Anatomy
Regional – all structures in one part of the body (such as the abdomen or leg)
Systemic – gross anatomy of the body studied by system
Surface – study of internal structures as they relate to the overlying skin

4. Developmental Anatomy
Microscopic Anatomy
Cytology – study of the cell
Histology – study of tissues
Developmental Anatomy
Traces structural changes throughout life
Embryology – study of developmental changes of the body before birth

5. Specialized Branches of Anatomy
Pathological anatomy – study of structural changes caused by disease
Radiographic anatomy – study of internal structures visualized by specialized scanning procedures such as X-ray, MRI, and CT scans
Molecular biology – study of anatomical structures at a subcellular level

6. Physiology Considers the operation of specific organ systems
Renal – kidney function
Neurophysiology – workings of the nervous system
Cardiovascular – operation of the heart and blood vessels
Focuses on the functions of the body, often at the cellular or molecular level

7. Understanding physiology also requires a knowledge of physics, which explains
electrical currents
blood pressure
the way muscle uses bone for movement

8. Principle of Complementarity
Function always reflects structure
What a structure can do depends on its specific form
Core theme - Structure (anatomy) determines what functions (physiology) can take place; if structure changes, the function must also change

9. 6 Levels of Structural Organization
Chemical – atoms combine to form molecules which combine to form cells
Cellular – smallest unit of life; human composed of trillion cells; combine to form tissues
Tissue – groups of cells that perform a common function; four types = epithelial, connective, muscular, & nervous
Organ – composed of two or more tissue types that perform a specific function; most contain all 4 tissue types
Organ system – group of organs that cooperate to accomplish a common purpose; ex. circulatory system, digestive system, etc.
Organismal – highest level of structural organization; all systems of body working together

10. Levels of Structural Organization1
Molecules
Atoms
Chemical level
Atoms combine to
form molecules.
Figure 1.1

11. Figure 1.1 Smooth muscle cell Molecules 2 Cellular level
Atoms
Cellular level
Cells are made up of
molecules.
Chemical level
Atoms combine to
form molecules.
Figure 1.1

12. Figure 1.1 1 2 3 Smooth muscle cell Molecules Atoms Smooth muscle
tissue
Cellular level
Cells are made up of
molecules.
Tissue level
Tissues consist of
similar types of cells.
Chemical level
Atoms combine to
form molecules.
Figure 1.1

13. Figure 1.1 1 2 4 3 Smooth muscle cell Molecules Atoms Smooth muscle
tissue
Epithelial
Connective
Blood
vessel
(organ)
Cellular level
Cells are made up of
molecules.
Tissue level
Tissues consist of
similar types of cells.
Organ level
Organs are made up
of different types
of tissues.
Chemical level
Atoms combine to
form molecules.
Figure 1.1

14. Figure 1.1 1 2 4 5 3 Smooth muscle cell Molecules Atoms Smooth muscle
tissue
Epithelial
Heart
Blood
vessels
Connective
vessel
(organ)
Cardiovascular
system
Cellular level
Cells are made up of
molecules.
Tissue level
Tissues consist of
similar types of cells.
Organ level
Organs are made up
of different types
of tissues.
Organ system level
Organ systems consist of
different organs that
work together closely.
Chemical level
Atoms combine to
form molecules.
Figure 1.1

15. Figure 1.1 1 2 4 5 6 3 Smooth muscle cell Molecules Atoms Smooth
tissue
Epithelial
Heart
Blood
vessels
Connective
vessel
(organ)
Cardiovascular
system
Cellular level
Cells are made up of
molecules.
Tissue level
Tissues consist of
similar types of cells.
Organ level
Organs are made up
of different types
of tissues.
Organ system level
Organ systems consist of
different organs that
work together closely.
Organismal level
The human organism
is made up of many
organ systems.
Chemical level
Atoms combine to
form molecules.
Figure 1.1

16. 10 Necessary Life Functions
Maintaining boundaries – the internal environment remains distinct from the external environment
Cellular level – accomplished by plasma membranes
Organismal level – accomplished by the skin
Organization – structure & functions is determined by genetics
Movement – locomotion, propulsion (peristalsis), blood, breathing, molecules, and contractility

17. Responsiveness – ability to monitor internal or external conditions and react to changes
Digestion – breakdown of ingested foodstuffs; process by which complex substances are converted to simpler forms so that they can be absorbed through intestinal wall & transported by blood
Metabolism – all the chemical reactions that occur in the body; releases energy, creates body heat, enables cells to synthesize & secrete molecules
Excretion – removal of wastes produced by metabolism

18. Reproduction – cellular and organismal levels
Cellular – an original cell divides and produces two identical daughter cells
Organismal – sperm and egg unite to make a whole new person
Growth – increase in size of a body part or of the organism
Differentiation – result in structurally and functionally distinct organs

19. Survival Needs Nutrients – needed for energy and cell building
Oxygen – 20% of air; needed for release of energy during cellular respiration and for metabolic reactions
Water – min. 60% of body weight; provides the necessary environment for chemical reactions
Normal body temperature – necessary for chemical reactions to occur at life-sustaining rates
Atmospheric pressure – required for proper breathing and gas exchange in the lungs

20. Homeostasis
Homeostasis – ability to maintain a relatively stable internal environment in an ever-changing outside world
The internal environment of the body is in a dynamic state of equilibrium
Chemical, thermal, and neural factors interact to maintain homeostasis; necessary for survival and good health; its loss results in illness or disease

21. Homeostatic Control Mechanisms
Variables produce a change in the body
The three interdependent components of control mechanisms:
Receptor (sensor) – responds to a stimuli (environmental change) by sending information to the control center
Control center – determines the set point at which the variable is maintained; usually consists of brain, spinal cord, or endocrine gland; assesses multiple stimuli, determines deviations from standard set points, and produces a response by increasing or decreasing the activity of the effector
Effector – muscles or glands; provides the means to respond to stimuli

22. Homeostatic Control Mechanisms
Variable (in homeostasis)
Figure 1.4

23. Stimulus:
Produces
change
in variable
Variable (in homeostasis)
Imbalance 1
Figure 1.4

24. Change
detected
by receptor
Stimulus:
Produces
change
in variable
Receptor (sensor)
Variable (in homeostasis)
Imbalance 2 1
Figure 1.4

25. Change
detected
by receptor
Stimulus:
Produces
change
in variable
Input:
Information
sent along
afferent
pathway to
Receptor (sensor)
Control
center
Variable (in homeostasis)
Imbalance 2 3 1
Figure 1.4

26. Change
detected
by receptor
Stimulus:
Produces
change
in variable
Input:
Information
sent along
afferent
pathway to
Receptor (sensor)
Effector
Control
center
Variable (in homeostasis)
Output:
Information sent
along efferent
Imbalance 2 3 4 1
Figure 1.4

27. Homeostatic Control Mechanisms
Change
detected
by receptor
Stimulus:
Produces
change
in variable
Input:
Information
sent along
afferent
pathway to
Receptor (sensor)
Effector
Control
center
Variable (in homeostasis)
Response of
effector feeds
back to
influence
magnitude of
stimulus and
returns variable
to homeostasis
Output:
Information sent
along efferent 2 3 4 5 1
Figure 1.4

28. Negative Feedback
In negative feedback systems, the output shuts off the original stimulus
Most control systems involve negative feedback systems which act to reduce or stop the initial stimulus; ex. maintenance of body temperature
- antagonistic actions – opposite actions; allow for fine tuning of homeostatic conditions
Example: Regulation of room temperature

29. Signal wire turns
heater off
Set
point
Control center
(thermostat)
Receptor-sensor
(thermometer in
Thermostat)
Heater
off
Effector
(heater)
Stimulus:
rising room
temperature
Response;
temperature
drops
Imbalance
Balance
Response;
temperature
rises
Stimulus:
dropping room
temperature
Imbalance
Heater on
Effector
(heater)
Set
point
Receptor-sensor
(thermometer in
Thermostat)
Signal
wire turns
heater on
Control center
(thermostat)
Figure 1.5

30. Balance
Figure 1.5

31. Stimulus: rising room temperature Imbalance Balance Imbalance
Figure 1.5

32. Set point Receptor-sensor (thermometer In thermostat) Stimulus:
rising room
temperature
Imbalance
Balance
Imbalance
Figure 1.5

33. Control center Set (thermostat) point Receptor-sensor (thermometer
In thermostat)
Stimulus:
rising room
temperature
Imbalance
Balance
Imbalance
Figure 1.5

34. Signal wire turns heater off Control center Set (thermostat) Stimulus:
point
Control center
(thermostat)
Stimulus:
dropping room
temperature
Receptor-sensor
(thermometer
In thermostat)
Heater
off
Effector
(heater)
Stimulus:
rising room
temperature
Response;
temperature
drops
Balance
Figure 1.5

35. Imbalance Balance Imbalance Stimulus: dropping room temperature
Figure 1.5

36. Imbalance Balance Imbalance Stimulus: dropping room temperature Set
point
Receptor-sensor
(thermometer in
Thermostat)
Figure 1.5

37. Imbalance Balance Imbalance Stimulus: dropping room temperature Set
point
Receptor-sensor
(thermometer in
Thermostat)
Control center
(thermostat)
Figure 1.5

38. Imbalance Balance Imbalance Stimulus: dropping room temperature Heateron
Set
point
Effector
(heater)
Receptor-sensor
(thermometer in
Thermostat)
Signal
wire turns
heater on
Control center
(thermostat)
Figure 1.5

39. Balance Response; temperature Stimulus: dropping room rises
Heater on
Set
point
Effector
(heater)
Receptor-sensor
(thermometer in
Thermostat)
Signal
wire turns
heater on
Control center
(thermostat)
Figure 1.5

40. Signal wire turns
heater off
Set
point
Control center
(thermostat)
Receptor-sensor
(thermometer in
Thermostat)
Heater
off
Effector
(heater)
Stimulus:
rising room
temperature
Response;
temperature
drops
Imbalance
Balance
Response;
temperature
rises
Stimulus:
dropping room
temperature
Imbalance
Heater on
Effector
(heater)
Set
point
Receptor-sensor
(thermometer in
Thermostat)
Signal
wire turns
heater on
Control center
(thermostat)
Figure 1.5

41. Positive Feedback
In positive feedback systems, the output enhances or exaggerates the original stimulus
Rare in humans; works against homeostasis
Example: Regulation of blood clotting
Ex. Oxytocin during labor stimulated by pressure on cervix; causes greater uterine contractions & more pressure on cervix
Figure 1.6

42. 1
Break or tear in
blood vessel wall
Feedback cycle
initiated
Figure 1.6

43. 1
Break or tear in
blood vessel wall
Feedback cycle
initiated 2
Clotting occurs
as platelets
adhere to site
and release
chemicals
Figure 1.6

44. 1
Break or tear in
blood vessel wall
Feedback cycle
initiated 2
Clotting occurs
as platelets
adhere to site
and release
chemicals 3
Released
chemicals
attract more
platelets
Figure 1.6

45. 1
Break or tear in
blood vessel wall
Feedback cycle
initiated 2
Clotting occurs
as platelets
adhere to site
and release
chemicals 3
Released
chemicals
attract more
platelets 4
Clotting
proceeds;
newly forming
clot grows
Figure 1.6

46. Positive Feedback System1
Break or tear in
blood vessel wall
Feedback cycle
initiated
Feedback
cycle ends
after clot
seals break 2
Clotting occurs
as platelets
adhere to site
and release
chemicals 3
Released
chemicals
attract more
platelets 4
Clotting
proceeds;
newly forming
clot grows
Figure 1.6

47. Homeostatic Imbalance
Disturbance of homeostasis or the body’s normal equilibrium
Overwhelming the usual negative feedback mechanisms allows destructive positive feedback mechanisms to take over

48. Directional Terms
Superior and inferior – toward and away from the head, respectively
Anterior and posterior – toward the front and back of the body
Medial, lateral, and intermediate – toward the midline, away from the midline, and between a more medial and lateral structure
Proximal and distal – closer to and farther from the origin of the body part
Superficial and deep – toward and away from the body surface

49. Directional Terms
Table 1.1a

50. Directional Terms
Table 1.1b

51. Try these ! The thorax is to the abdomen.
The kidneys are to the intestine.
The navel is on the side of the body.
The legs are to the trunk.
The heart is to the lungs.
The skin is to the muscles.
The ears are to the nose.
The knee is to the foot.
The brain is to the cranium.
The hand is to the elbow.
Superior
Posterior
Anterior
Inferior, distal
Medial, deep
Superficial
Lateral
Superior, proximal
Deep
Distal, inferior

52. Anatomical Position and Directional Terms
Anatomical postion =
Body erect, feet parallel, eyes forward, arms at side, palms
forward, fingers downward

53. Head – facial and cranial regions Neck – cervical region
5 Major Body Regions
Head – facial and cranial regions
Neck – cervical region
Trunk (torso) – thorax and abdomen
Upper extremity – shoulder, arm, hand
Lower extremity – hip, leg, foot

54. Regional Terms: Anterior View
Nasal (nose)
Oral (mouth)
Cervical (neck)
Frontal (forehead)
Orbital (eye)
Buccal (cheek)
Mental (chin)
(a) Anterior
Figure 1.7a

55. Figure 1.7a Nasal (nose) Oral (mouth) Cervical (neck) Acromial
(point of shoulder)
Axillary (armpit)
Brachial (arm)
Antecubital
(front of elbow)
Abdominal
(abdomen)
Pelvic (pelvis)
Antebrachial
(forearm)
Carpal (wrist)
Palmar
(palm)
Pollex
(thumb)
Digital
(fingers)
Mammary
(breast)
Frontal (forehead)
Orbital (eye)
Buccal (cheek)
Sternal
(breastbone)
Thoracic
(chest)
Mental (chin)
Umbilical
(navel)
(a) Anterior
Figure 1.7a

56. Figure 1.7a Nasal (nose) Oral (mouth) Cervical (neck) Acromial
(point of shoulder)
Axillary (armpit)
Brachial (arm)
Antecubital
(front of elbow)
Abdominal
(abdomen)
Pelvic (pelvis)
Antebrachial
(forearm)
Carpal (wrist)
Palmar
(palm)
Pollex
(thumb)
Digital
(fingers)
Pubic (genital region)
Patellar
(anterior knee)
Crural (leg)
Tarsal (ankle)
Pedal
(foot)
Digital (toes)
Inguinal
(groin)
Coxal
(hip)
Femoral
(thigh)
Fibular, or
peroneal
(side of leg)
Hallux (great toe)
Mammary
(breast)
Frontal (forehead)
Orbital (eye)
Buccal (cheek)
Sternal
(breastbone)
Thoracic
(chest)
Mental (chin)
Umbilical
(navel)
(a) Anterior
Figure 1.7a

57. Regional Terms: Posterior View
Otic (ear)
Occipital (back of
head or base of skull)
Cephalic
(head)
(b) Posterior
Figure 1.7b

58. Figure 1.7b Otic (ear) Cephalic Occipital (back of (head)
Brachial (arm)
Otic (ear)
Occipital (back of
head or base of skull)
Acromial
(point of shoulder)
Vertebral
(spinal column)
Scapular
(shoulder blade)
Dorsum or dorsal
(back)
Olecranal
(back of elbow)
Lumbar (loin)
Sacral
(between hips)
Manus
(hand)
Upper
extremity
Cephalic
(head)
(b) Posterior
Figure 1.7b

59. Figure 1.7b Otic (ear) Cephalic Occipital (back of (head)
Brachial (arm)
Otic (ear)
Occipital (back of
head or base of skull)
Acromial
(point of shoulder)
Vertebral
(spinal column)
Scapular
(shoulder blade)
Dorsum or dorsal
(back)
Olecranal
(back of elbow)
Lumbar (loin)
Sacral
(between hips)
Gluteal (buttock)
Perineal
(region between
the anus and
external genitalia)
Femoral (thigh)
Popliteal
(back of knee)
Sural (calf)
Calcaneal (heel)
Plantar (sole)
Manus
(hand)
Upper
extremity
Cephalic
(head)
Lower
(b) Posterior
Figure 1.7b

60. Body Planes Sagittal – divides the body into right and left parts
Midsagittal or medial – sagittal plane that lies on the midline
Frontal or coronal – divides the body into anterior and posterior parts
Transverse or horizontal (cross section) – divides the body into superior and inferior parts
Oblique section – cuts made diagonally

61. Body Planes – cuts to view internal structures

62. Planes of the body—frontal, transverse, and median (midsagittal) with corresponding magnetic resonance imaging (MRI) scans
Frontal plane
Median (midsagittal) plane
Transverse plane
(a)
Frontal section through torso
(b)
Transverse section through torso
(superior view)
(c)
Median (midsagittal)
section
Posterior
Spleen
Liver
Intestines
Stomach
Left and
right lung
Liver
Stomach
Subcutaneous
fat layer
Rectum
Vertebral
column
Pubic symphysis
Heart
Spleen
Spinal
Aorta
cord

63. Can you match these up and label them?

64. Can you match these up and label them?

65. 2 Principle Body cavities –internal cavities that confine organs that have related functions
Dorsal (posterior) cavity protects the nervous system, and is divided into two subdivisions
Cranial cavity – within the skull; encases the brain
Vertebral cavity – runs within the vertebral column; encases the spinal cord
Ventral (anterior) cavity houses the internal organs (viscera), and is divided into two subdivisions
Thoracic - chest cavity; includes mediastinum, pleural & pericardial cavities
Abdominopelvic - may be divided into abdominal cavity and pelvic cavity

66. Body Cavities
Thoracic cavity is subdivided into two pleural cavities, the mediastinum, and the pericardial cavity
Pleural cavities – each houses a lung
Mediastinum – contains the pericardial cavity; surrounds the remaining thoracic organs
Pericardial cavity – encloses the heart

67. Body Cavities
The abdominopelvic cavity is separated from the superior thoracic cavity by the dome-shaped diaphragm
It is composed of two subdivisions
Abdominal cavity – contains the stomach, intestines, spleen, liver, and other organs
Pelvic cavity – lies within the pelvis and contains the bladder, reproductive organs, and rectum

68. Body Cavities Cranial cavity (contains brain) Thoracic Dorsal body
Diaphragm
Abdominal cavity
(contains digestive
viscera)
Pelvic cavity
(contains bladder,
reproductive organs,
and rectum)
Vertebral cavity
(contains spinal
cord)
Key:
Dorsal body cavity
Ventral body cavity
Thoracic
(contains
heart
and lungs)
(a) Lateral view
Figure 1.9a

69. Body Cavities Key: Cranial Dorsal body cavity Ventral body cavity
(thoracic
and
abdomino-
pelvic
cavities)
Abdomino-
cavity
Superior
mediastinum
Pleural
Cranial
Vertebral
Pericardial
cavity within
the mediastinum
Diaphragm
Abdominal cavity
(contains digestive
viscera)
Pelvic cavity
(contains bladder,
reproductive organs,
and rectum)
Thoracic
(contains
heart
and lungs)
(b) Anterior view
Key:
Dorsal body cavity
Ventral body cavity
Figure 1.9b

70. Body membranes – thin layers of connective and epithelial tissue that cover, separate, and support viscera and line body cavities
2 types
Mucous membranes – secrete thick liquid substance called mucus; lubricates or protects organs; lines cavities that enter or exit the body
Serous membranes – line thoracic and adominopelvic cavities and cover visceral organs; secrete watery serous fluid;
include: pleurae (lung), pericardial (heart) membranes, & peritoneal (abdominal) membranes

71. Ventral Body Cavity Membranes
Parietal serosa lines internal body walls
Visceral serosa covers the internal organs
Serous fluid separates the serosae

72. Serous Membrane Relationship
Figure 1.10a

73. Serous membranes of the thorax

74. Serous membranes of the abdominopelvic cavity

75. Other Body Cavities
Oral and digestive – mouth and cavities of the digestive organs
Nasal –located within and posterior to the nose
Orbital – house the eyes
Middle ear – contains bones (ossicles) that transmit sound vibrations
Synovial – joint cavities

76. Other Body Cavities
Figure 1.13

77. Abdominopelvic Regions
Figure 1.11a

78. Organs of the Abdominopelvic Regions
Figure 1.11b

79. Abdominopelvic Quadrants
Right upper
Left upper
Right lower
Left lower
Figure 1.12

80. Clinical procedures used to determine anatomical structure and function
Inspection – observing body for swelling, rashes, needle marks, irregular breathing, etc.
Palpation – applying fingers with firm pressure to surface of body to feel lumps, tender spots, body landmarks, etc.
Percussion – tapping sharply on body walls to detect vibrations; used to locate excess fluid or organ abnormalities
Auscultation – listening to sounds of various organs; breathing, heartbeat, etc.
Reflex testing – observing automatic response to stimulus