1. An Orientation and Introduction
Chapter 1:
The Human Body…
An Orientation and Introduction

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

4. Figure 1.2 Examples of interrelationships among body organ systems.
Digestive system
Takes in nutrients, breaks them
down, and eliminates unabsorbed
matter (feces)
Respiratory system
Takes in oxygen and
eliminates carbon dioxide
Food O2
CO2
Cardiovascular system
Via the blood, distributes oxygen
and nutrients to all body cells and
delivers wastes and carbon
dioxide to disposal organs
Blood
CO2 O2
Urinary
system
Eliminates
nitrogenous
wastes and
excess ions
Heart
Nutrients
Interstitial fluid
Nutrients and wastes pass
between blood and cells
via the interstitial fluid
Integumentary system
Protects the body as a whole
from the external environment
Feces
Urine

5. Figure 1.3a The body’s organ systems and their major functions.
Hair
Skin
Nails
(a) Integumentary System
Forms the external body covering, and
protects deeper tissues from injury.
Synthesizes vitamin D, and houses
cutaneous (pain, pressure, etc.)
receptors and sweat and oil glands.

6. Figure 1.3b The body’s organ systems and their major functions.
Bones
Joint
(b) Skeletal System
Protects and supports body organs,
and provides a framework the muscles
use to cause movement. Blood cells
are formed within bones. Bones store
minerals.

7. Figure 1.3c The body’s organ systems and their major functions.
Skeletal
muscles
(c) Muscular System
Allows manipulation of the environment,
locomotion, and facial expression. Main-
tains posture, and produces heat.

8. Figure 1.3d The body’s organ systems and their major functions.
Brain
Nerves
Spinal
cord
(d) Nervous System
As the fast-acting control system of
the body, it responds to internal and
external changes by activating
appropriate muscles and glands.

9. Figure 1.3e The body’s organ systems and their major functions.
Pineal gland
Pituitary
gland
Thyroid
gland
Thymus
Adrenal
gland
Pancreas
Testis
Ovary
(e) Endocrine System
Glands secrete hormones that regulate
processes such as growth, reproduction,
and nutrient use (metabolism) by body
cells.

10. Figure 1.3g The body’s organ systems and their major functions.
Red bone
marrow
Thymus
Lymphatic
vessels
Thoracic
duct
Spleen
Lymph
nodes
(g) Lymphatic System/Immunity
Picks up fluid leaked from blood vessels
and returns it to blood. Disposes of debris
in the lymphatic stream. Houses white
blood cells (lymphocytes) involved in
immunity. The immune response mounts
the attack against foreign substances
within the body.

11. Figure 1.3f The body’s organ systems and their major functions.
Heart
Blood
vessels
(f) Cardiovascular System
Blood vessels transport blood,
which carries oxygen, carbon
dioxide, nutrients, wastes, etc.
The heart pumps blood.

12. Figure 1.3h The body’s organ systems and their major functions.
Nasal
cavity
Pharynx
Bronchus
Larynx
Trachea
Lung
(h) Respiratory System
Keeps blood constantly supplied with
oxygen and removes carbon dioxide.
The gaseous exchanges occur through
the walls of the air sacs of the lungs.

13. Figure 1.3i The body’s organ systems and their major functions.
Oral cavity
Esophagus
Liver
Stomach
Small
intestine
Large
intestine
Rectum
Anus
(i) Digestive System
Breaks down food into absorbable
units that enter the blood for
distribution to body cells. Indigestible
foodstuffs are eliminated as feces.

14. Figure 1.3j The body’s organ systems and their major functions.
Kidney
Ureter
Urinary
bladder
Urethra
(j) Urinary System
Eliminates nitrogenous wastes from the
body. Regulates water, electrolyte and
acid-base balance of the blood.

15. Figure 1.3k-l The body’s organ systems and their major functions.
Mammary
glands (in
breasts)
Prostate
gland
Ovary
Penis
Testis
Ductus
deferens
Scrotum
Uterine
tube
Uterus
Vagina
(k) Male Reproductive System
(l) Female Reproductive System
Overall function is production of offspring. Testes produce sperm and male sex
hormone, and male ducts and glands aid in delivery of sperm to the female
reproductive tract. Ovaries produce eggs and female sex hormones. The remaining
female structures serve as sites for fertilization and development of the fetus.
Mammary glands of female breasts produce milk to nourish the newborn.

16. Information sent along efferent pathway to effector.
Figure 1.4 Interaction among the elements of a homeostatic control system.
Output:
Information sent along
efferent pathway to
effector. 4
Input: Information
sent along afferent
pathway to control
center. 3
Control
Center
Afferent
pathway
Efferent
pathway 2
Receptor
Effector 5
Receptor
detects
change.
Response
of effector
feeds back
to reduce
the effect of
stimulus
and returns
variable to
homeostatic
level. 1
Stimulus
produces
change in
variable.
BALANCE

17. Temperature-sensitive Temperature-sensitive
Figure 1.5 Regulation of body temperature by a negative feedback mechanism.
Control Center
(thermoregulatory
center in brain)
Information sent
along the afferent
pathway to control
center
Information sent
along the efferent
pathway to
effectors
Afferent
pathway
Efferent
pathway
Receptors
Temperature-sensitive
cells in skin and brain
Effectors
Sweat glands
Sweat glands activated
Response
Evaporation of sweat
Body temperature falls;
stimulus ends
Stimulus
Body temperature
rises
BALANCE
Stimulus
Body temperature falls
Response
Body temperature rises;
stimulus ends
Receptors
Temperature-sensitive
cells in skin and brain
Effectors
Skeletal muscles
Efferent
pathway
Afferent
pathway
Shivering
begins
Information sent
along the efferent
pathway to effectors
Information sent
along the afferent
pathway to control
center
Control Center
(thermoregulatory
center in brain)

18. 1 occurs in blood vessel wall. Positive feedback cycle is initiated. 3
Figure 1.6 Summary of the positive feedback mechanism regulating formation of a platelet plug.
Break or tear
occurs in blood
vessel wall. 1
Positive feedback
cycle is initiated. 3
Released
chemicals
attract more
platelets. 2
Platelets
adhere to site
and release
chemicals.
Positive
feedback
loop
Feedback cycle ends
when plug is formed.
Platelet plug
forms. 4

19. Figure 1.7 Regional terms used to designate specific body areas.
Cephalic
Cephalic
Frontal
Otic
Orbital
Occipital (back
of head)
Nasal
Oral
Upper limb
Mental
Acromial
Cervical
Cervical
Brachial (arm)
Thoracic
Antecubital
Sternal
Olecranal
Back (dorsal)
Axillary
Antebrachial
(forearm)
Scapular
Mammary
Carpal (wrist)
Vertebral
Abdominal
Umbilical
Lumbar
Manus (hand)
Pelvic
Pollex
Sacral
Inguinal
(groin)
Metacarpal
Palmar
Gluteal
Digital
Perineal (between
anus and external
genitalia)
Lower limb
Coxal (hip)
Pubic
(genital)
Femoral (thigh)
Patellar
Popliteal
Crural (leg)
Sural (calf)
Fibular or peroneal
Pedal (foot)
Thorax
Tarsal (ankle)
Abdomen
Calcaneal
Back (Dorsum)
Metatarsal
Digital
Plantar
Hallux
(a) Anterior/Ventral
(b) Posterior/Dorsal

21. Median (midsagittal) plane
Figure 1.8 Planes of the body with corresponding magnetic resonance imaging (MRI) scans.
Frontal plane
Median (midsagittal) plane
Transverse plane
(a) Frontal section
(through torso)
(b) Transverse section
(through torso,
inferior view)
(c) Median section
(midsagittal)
Pancreas
Aorta
Spleen
Left and
right lungs
Liver
Heart
Spleen
Liver
Spinal cord
Rectum
Intestines
Body wall
Stomach
Arm
Vertebral
column
Subcutaneous fat layer

22. Figure 1.9 Dorsal and ventral body cavities and their subdivisions.
Cranial
cavity
Cranial
cavity
(contains
brain)
Dorsal body cavity
Ventral body cavity
Vertebral
cavity
Superior
mediastinum
Dorsal
body
cavity
Thoracic
cavity
(contains
heart and
lungs)
Pleural
cavity
Pericardial
cavity within
the mediastinum
Vertebral
cavity
(contains
spinal
cord)
Ventral body
cavity
(thoracic and
abdominopelvic
cavities)
Diaphragm
Abdominal cavity
(contains digestive
viscera)
Abdomino-
pelvic
cavity
Pelvic cavity
(contains urinary
bladder, reproductive
organs, and rectum)
(a) Lateral view
(b) Anterior view

23. Figure 1.11 The four abdominopelvic quadrants.
Right upper
quadrant
(RUQ)
Left upper
quadrant
(LUQ)
Right lower
quadrant
(RLQ)
Left lower
quadrant
(LLQ)

24. Figure 1.12 The nine abdominopelvic regions.
Liver
Diaphragm
Right
hypochondriac
region
Left
hypochondriac
region
Epigastric
region
Gallbladder
Stomach
Transverse colon
of large intestine
Right
lumbar
region
Left
lumbar
region
Ascending colon of
large intestine
Umbilical
region
Small intestine
Descending colon
of large intestine
Cecum
Right iliac
(inguinal)
region
Hypogastric
(pubic)
region
Left iliac
(inguinal)
region
Initial part of
sigmoid colon
Appendix
Urinary bladder
(a) Nine regions delineated by four planes
(b) Anterior view of the nine regions showing the superficial organs

25. Table 1.1 Orientation and Directional Terms (1 of 3)

26. Table 1.1 Orientation and Directional Terms (2 of 3)

27. Table 1.1 Orientation and Directional Terms (3 of 3)