Chapter 1
Orientation to the Human Body
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Definitions
 Anatomy: The study of the structures of the
body
 Physiology: The study of how the body
functions
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Organization of the Body
 Arranged in a hierarchy
 Ranges from the very simple to the very
complex
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Organization of the Body (continued_1)
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Organization of the Body (continued_2)
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Question
The smallest living units that make up the
body’s structure are:
A. molecules.
B. organelles.
C. atoms.
D. cells.
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Answer
Correct answer: D
Rationale:
 Molecules and atoms come together to form
cells, which are the smallest living units.
 Organelles are metabolic units within cells
but are not living units on their own.
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Organ Systems
 The body consists of 11 organ systems.
 The organs of each system contribute to a
particular function.
 Some organs belong to more than one
system.
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Integumentary System
Skin, hair, nails
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Skeletal System
Bones, cartilage, and ligaments
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Muscular System
Primarily skeletal muscles
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Lymphatic System
Lymph nodes, lymphatic vessels, lymph,
thymus, spleen, and tonsils
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Respiratory System
Nose, pharynx, larynx, trachea,
bronchi, and lungs
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Urinary System
Kidneys, ureters, urinary bladder, and urethra
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Nervous System
Brain, spinal cord, and sense organs
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Endocrine System
Pituitary gland, adrenals, pancreas, thyroid,
parathyroids, and other organs
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Circulatory System
Heart, arteries, veins, and capillaries
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Digestive System
Stomach, small and large intestines,
esophagus, liver, mouth, and pancreas
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Male Reproductive System
Testes, vas deferens, prostate, seminal
vesicles, and penis
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Female Reproductive System
Ovaries, fallopian tubes, uterus,
vagina, and breasts
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Question (continued_1)
Which organ system supplies the body with
immune cells?
A. Integumentary system
B. Lymphatic system
C. Endocrine system
D. Nervous system
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Answer (continued_1)
Correct answer: B
Rationale:
 The integumentary system offers the body
protection but does not supply immune cells.
 The endocrine system consists of a variety of
organs that secrete hormones.
 The nervous system consists of the brain, spinal
cord, and nerves.
 Both the endocrine and nervous systems
influence other systems, but they do not supply
immune cells.
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Anatomical Terms
Directional terms:
Grouped in pairs of
opposites
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Directional Terms
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Body Planes
Sagittal plane
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Body Planes (continued_1)
Transverse plane
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Body Planes (continued_2)
Frontal plane
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Body Regions
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Body Regions (continued)
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Question (continued_2)
A cut on the leg just above the ankle is said to
be:
A. distal to the knee.
B. proximal to the knee.
C. anterior to the knee.
D. medial to the knee.
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Answer (continued_2)
Correct answer: A
Rationale:
 A cut proximal to the knee would be on the
upper portion of the leg.
 A cut anterior to the knee would be on the
front of the knee.
 A cut medial to the knee would be on the
inside portion of the knee.
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Body Cavities
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Body Cavities (continued)
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Question (continued_3)
The heart is located in the:
A. ventral cavity.
B. mediastinum.
C. pleural cavity.
D. dorsal cavity.
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Answer (continued_3)
Correct answer: B
Rationale:
 The ventral cavity is a more general location
that includes the mediastinum.
 The pleural cavities contain the lungs.
 The dorsal cavity is located at the back of the
body; it consists of the cranial and vertebral
cavities.
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Abdominal Regions
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Abdominal Quadrants
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Homeostasis
 Homeostasis is the state of dynamic
equilibrium of the internal environment of
the body.
 The body operates within a narrow range of
temperature, fluids, and chemicals.
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Homeostatic Regulation
Involves a(n):
1. Receptor: Detects change
2. Control center: An area of the body that
receives and processes information from
the receptor
3. Effector: Sends signals (feedback) that
either oppose or enhance the stimulus
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Definitions
 Negative feedback: When the effector
opposes the stimulus and reverses the
direction of change
 Positive feedback: When the effector
reinforces the stimulus and amplifies the
direction of change
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Negative Feedback
 A falling temperature signals the thermostat.
 The thermostat (which has a “set point” of
68°) sends a message to the furnace.
 The furnace generates heat, raising the
temperature.
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Negative Feedback in the Body
 The outside temperature falls.
 Temperature receptors in the skin send a
message to the brain.
 The hypothalamus sends nerve impulses to
the muscles.
 The muscles shiver, raising body temperature.
View animation on “Negative feedback (homeostasis)”
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Question (continued_4)
The body maintains equilibrium through the
process of:
A. homeostasis.
B. negative feedback.
C. positive feedback.
D. shivering.
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Answer (continued_4)
Correct answer: B
Rationale:
 Homeostasis is a state of being, not a process.
 Positive feedback is rarely beneficial to the
body, and therefore does not promote
homeostasis.
 Shivering may be used to increase
temperature, but it is not a process for
achieving equilibrium.
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