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

2. Overview of Anatomy and Physiology
Anatomy – the study of the structure of body parts and their relationships to one another
Gross or macroscopic
Microscopic
Developmental
Physiology – the study of the function of the body’s structural machinery

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. Microscopic Anatomy
Cytology – study of the cell
Histology – study of tissues

5. Developmental Anatomy
Traces structural changes throughout life
Embryology – study of developmental changes of the body before birth

6. 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

7. Considers the operation of specific organ systems
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

8. Forms the external body covering
Integumentary System
Forms the external body covering
Composed of the skin, sweat glands, oil glands, hair, and nails
Protects deep tissues from injury and synthesizes vitamin D
Figure 1.3a

9. Composed of bone, cartilage, and ligaments
Skeletal System
Composed of bone, cartilage, and ligaments
Protects and supports body organs
Provides the framework for muscles
Site of blood cell formation
Stores minerals
Figure 1.3b

10. Composed of muscles and tendons
Muscular System
Composed of muscles and tendons
Allows manipulation of the environment, locomotion, and facial expression
Maintains posture
Produces heat
Figure 1.3c

11. Composed of the brain, spinal column, and nerves
Nervous System
Composed of the brain, spinal column, and nerves
Is the fast-acting control system of the body
Responds to stimuli by activating muscles and glands
Figure 1.3d

12. Cardiovascular System
Composed of the heart and blood vessels
The heart pumps blood
The blood vessels transport blood throughout the body
Figure 1.3f

13. Picks up fluid leaked from blood vessels and returns it to blood
Lymphatic System
Composed of red bone marrow, thymus, spleen, lymph nodes, and lymphatic vessels
Picks up fluid leaked from blood vessels and returns it to blood
Disposes of debris in the lymphatic stream
Houses white blood cells involved with immunity
Figure 1.3g

14. Composed of the nasal cavity, pharynx, trachea, bronchi, and lungs
Respiratory System
Composed of the nasal cavity, pharynx, trachea, bronchi, and lungs
Keeps blood supplied with oxygen and removes carbon dioxide
Figure 1.3h

15. Breaks down food into absorbable units that enter the blood
Digestive System
Composed of the oral cavity, esophagus, stomach, small intestine, large intestine, rectum, anus, and liver
Breaks down food into absorbable units that enter the blood
Eliminates indigestible foodstuffs as feces
Figure 1.3i

16. Composed of kidneys, ureters, urinary bladder, and urethra
Urinary System
Composed of kidneys, ureters, urinary bladder, and urethra
Eliminates nitrogenous wastes from the body
Regulates water, electrolyte, and pH balance of the blood
Figure 1.3j

17. Male Reproductive System
Composed of prostate gland, penis, testes, scrotum, and ductus deferens
Main function is the production of offspring
Testes produce sperm and male sex hormones
Ducts and glands deliver sperm to the female reproductive tract
Figure 1.3k

18. Female Reproductive System
Composed of mammary glands, ovaries, uterine tubes, uterus, and vagina
Main function is the production of offspring
Ovaries produce eggs and female sex hormones
Remaining structures serve as sites for fertilization and development of the fetus
Mammary glands produce milk to nourish the newborn
Figure 1.3l

19. 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

20. Homeostatic Control Mechanisms
Variables produce a change in the body
The three interdependent components of control mechanisms:
Receptor – monitors the environments and responds to changes (stimuli)
Control center – determines the set point at which the variable is maintained
Effector – provides the means to respond to stimuli

21. 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
Imbalance 2 3 4 5 1
Figure 1.4

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

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

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

25. Homeostatic Control Mechanisms
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. 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)
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
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
Imbalance
Balance
Imbalance
Figure 1.5

35. 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

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

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

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

39. 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

40. 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

41. 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

42. Example: Regulation of blood clotting
Positive Feedback
In positive feedback systems, the output enhances or exaggerates the original stimulus
Example: Regulation of blood clotting
Figure 1.6

43. 1
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

44. 1
Break or tear in
blood vessel wall
Feedback cycle
initiated
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
Figure 1.6

46. 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

47. 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

48. 1
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

49. 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