THE HUMAN BODY: AN ORIENTATION CH. 1A -...

Copyright © 2010 Pearson Education, Inc.

THE HUMAN BODY: AN

ORIENTATION CH. 1A


Overview of Anatomy and Physiology

• Anatomy: Study of the structure/parts

• Physiology: The study of function at many

levels

• Function always reflects structure; What a

structure can do depends on its specific form


Levels of Structural Organization

• Chemical: atoms and molecules

• Cellular: cells and their organelles

• Tissue: groups of similar cells

• Organ: contains two or more types of tissues

• Organ system: organs that work closely

together

• Organismal: all organ systems


Cardiovascular

system

Organelle Molecule Atoms

Chemical level

Cellular level

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.

Smooth muscle cell

Smooth muscle tissue

Connective tissue

Blood vessel (organ)

Heart

Blood

vessels

Epithelial

tissue

Smooth muscle tissue

1

2

3

4

5 6

Figure 1.1


Survival Needs

1. Nutrients

• Chemicals for energy and cell building

• Carbohydrates, fats, proteins, minerals,

vitamins

2. Oxygen

• Essential for energy release (ATP

production)


Survival Needs

3. Water

• Most abundant chemical in the body

• Site of chemical reactions

4. Normal body temperature

• Affects rate of chemical reactions

5. Appropriate atmospheric pressure

• For adequate breathing and gas exchange in the lungs


Homeostasis

• Definition: Maintenance of a relatively stable

internal environment despite continuous

outside changes


Components of a Homeostatic Control

Mechanism

1. Receptor (sensor)

• Monitors the environment

• Senses stimuli

2. Control center

• Receives input from receptor

• Determines the set point at which the variable is

maintained

• Determines appropriate response


Components of a Control Mechanism

3. Effector

• Receives output from control center

• Provides the means to respond

• Response acts to reduce or enhance the

stimulus (feedback)


Stimulus

produces change in variable.

Receptor

detects change.

Input: Information sent along afferent pathway to control center.

Output:

Information sent along efferent pathway to effector.

Response

of effector feeds back to reduce the effect of stimulus and returns variable to homeostatic level.

Receptor Effector

Control

Center

BALANCE

Afferent

pathway

Efferent

pathway

1

2

3 4

5

Figure 1.4


Negative Feedback

• The response reduces or shuts off the original

stimulus

• Example:

• Regulation of body temperature

Copyright © 2010 Pearson Education, Inc. Figure 1.5

Sweat glands activated

Shivering

begins

Stimulus

Body temperature

rises BALANCE

Information sent

along the afferent

pathway to control

center

Information sent

along the afferent

pathway to control

center

Afferent

pathway

Afferent

pathway

Efferent

pathway

Efferent

pathway

Information sent

along the efferent

pathway to

effectors

Information sent

along the efferent

pathway to effectors

Stimulus

Body temperature falls

Receptors

Temperature-sensitive

cells in skin and brain

Receptors

Temperature-sensitive

cells in skin and brain

Effectors

Sweat glands

Effectors

Skeletal muscles

Control Center

(thermoregulatory

center in brain)

Control Center

(thermoregulatory

center in brain)

Response

Evaporation of sweat

Body temperature falls;

stimulus ends

Response

Body temperature rises;

stimulus ends


Positive Feedback

• The response enhances or exaggerates the

original stimulus

• Rare in biological systems

• Example:

• Enhancement of labor contractions by oxytocin


CHAPTER 1B


Anatomical Position

• Purpose:

• Standard anatomical body position:

• Body erect

• Feet slightly apart

• Palms facing forward


Regional Terms

• Regional Terms:


Cervical

(a) Anterior/Ventral

Pubic

Orbital Nasal Oral

Thoracic

Axillary

Sternal

Abdominal

Umbilical

Pelvic

Inguinal

Upper limb

Acromial Brachial (arm) Antecubital Antebrachial

(forearm) Carpal (wrist)

Digital

Lower limb

Coxal (hip) Femoral (thigh) Patellar Crural (leg) Fibular

Tarsal (ankle) Thorax

Abdomen Back (Dorsum)


Cervical

Back (dorsal)

(b) Posterior/Dorsal

Scapular Vertebral Lumbar Sacral Gluteal

Upper limb

Acromial Brachial (arm) Olecranal

Digital

Femoral (thigh) Popliteal Sural (calf) Fibular

Calcaneal Plantar

Cephalic

Occipital (back

of head)


Body Planes and Sections

• Sagittal plane

• Divides body vertically into right and left parts

• Produces a sagittal section

• Midsagittal (median) plane

• Lies on midline

• Parasagittal plane

• Not on midline


Body Planes

• Frontal (coronal) plane

• Divides body vertically into anterior and posterior parts

• Transverse (horizontal) plane

• Divides body horizontally into superior and inferior parts

• Produces a cross section


Transverse plane

Median (midsagittal) plane

Frontal plane

Liver

Spleen

Pancreas

Aorta

Vertebral

column

Spinal cord

Subcutaneous fat layer Body wall

Rectum Intestines Left and

right lungs

Liver Heart

Stomach

Spleen

Arm

(a) Frontal section

(through torso)

(b) Transverse section

(through torso,

inferior view)

(c) Median section

(midsagittal)


Body Cavities

• Two Large Cavities:

• Dorsal cavity encloses the CNS

• Two subdivisions:

• Cranial cavity

• Encases brain

• Vertebral cavity

• Encases spinal cord


Body Cavities

• Ventral cavity

• Houses soft internal organs (viscera)

• Two subdivisions (separated by diaphragm):

• Thoracic cavity

• Abdominopelvic cavity


Cranial

cavity

Dorsal

body

cavity

Vertebral

cavity

Cranial

cavity

Vertebral

cavity

Abdomino-

pelvic

cavity

Ventral body

cavity

(thoracic and

abdominopelvic

cavities)

Abdominal cavity

(contains digestive

viscera)

Diaphragm

Pelvic cavity

(contains urinary

bladder, reproductive

organs, and rectum)

Thoracic

Cavity

(a) Lateral view (b) Anterior view

Dorsal body cavity

Ventral body cavity


Ventral Body Cavities

• Thoracic cavity subdivisions:

• Two pleural cavities

• Each houses a lung

• Mediastinum

• Contains pericardial cavity

• Also contains the esophagus and aorta

• Pericardial cavity

• Encloses heart


Ventral Body Cavities

• Abdominopelvic cavity subdivisions:

• Abdominal cavity

• Contains stomach, intestines, spleen, and

liver

• Pelvic cavity

• Contains urinary bladder, reproductive

organs, and rectum


Cranial

cavity

Dorsal

body

cavity

Vertebral

cavity

Cranial

cavity

Vertebral

cavity

Abdomino-

pelvic

cavity

Ventral body

cavity

Abdominal cavity

Diaphragm

Pelvic cavity

Thoracic

cavity

(a) Lateral view (b) Anterior view

Dorsal body cavity

Ventral body cavity


Abdominopelvic Regions

• Nine divisions:


Epigastric

region

Umbilical

region

Right

lumbar

region

Left

lumbar

region

Right

hypochondriac

region

Left

hypochondriac

region

Hypogastric

(pubic)

region

Right iliac

(inguinal)

region

Left iliac

(inguinal)

region

Liver

Gallbladder

Ascending colon of

large intestine

Small intestine

Appendix

Cecum

Diaphragm

Stomach

Descending colon

of large intestine

Transverse colon

of large intestine

Initial part of

sigmoid colon

Urinary bladder

(a) Nine regions delineated by four planes (b) Anterior view of the nine regions showing the superficial organs

THE HUMAN BODY: AN ORIENTATION CH. 1A -...

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