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The Human Body: An Orientation
Chapter 1
Part 2
Maintaining Life
Necessary Life Functions
Survival Needs
Homeostasis
Necessary Life Functions• Maintaining Boundaries– Inside must be distinct
from outside• Movement– Locomotion– Movement of substances
• Responsiveness– AKA “irritability”– Ability to sense changes in
environment and respond• Digestion– Breakdown and delivery of
nutrients
• Metabolism– Chemical reactions
within body cells• Excretion– Removes wastes from
body and requires many organs
• Reproduction– Production of future
generation• Growth– Increasing of cell size
and number
Survival Needs
• Nutrients– Taken in via diet– Give energy and maintain cells– Chemicals for energy and cell building– Includes carbohydrates, proteins, lipids, vitamins, and
minerals
• Oxygen– Required for chemical reactions
Survival Needs (con’t)
• Water– Obtained through diet– Lose by evaporation from lungs, skin, and excretion– 60 – 80% of body weight– Provides for metabolic reactions
• Normal (stable) body temperature• Atmospheric pressure – must be appropriate
Homeostasis
Describes the ability to maintain relatively stable internal condition even though the
outside world changes continuously.
Indicates a dynamic state of equilibrium, or balance.
Homeostatic Control Mechanisms
• Communication in the body is accomplished chiefly by the nervous and endocrine systems.
• Variable – factor or event being regulated• Receptor – sensor that monitors the environment
and respond to changes• Control center – analyzes the input it receives and
then determines the appropriate response• Effector – provides a means for response to the
stimulus
Negative Feedback Mechanism
• The output of the system shuts off the original stimulus or reduces its intensity.
• This mechanism causes the variable to change in a direction opposite to that of the initial change, returning it to its “ideal” value.
• All negative feedback systems have the same goal: to prevent sudden severe changes.
Positive Feedback Mechanism
• The result of response enhances or exaggerates the original stimulus so that the activity is accelerated.
• “Positive” because the change occurs in the same direction as the initial disturbance, causing the variable to deviate further and further from the original value.
• Control infrequent events that don’t require continuous adjustments!!
The Language of Anatomy
Special terminology is used to prevent misunderstanding
• Exact terms are used for:
• Position
• Direction
• Regions
• Structures
Anatomical Position
• Anatomical reference point
• Body is erect with feet slightly apart
• “Standing at attention” pose
• Palms face forward and thumbs point away from body
Directional Terms
Allow us to explain exactly where one body structure is in relation to another.
Orientation and Directional TermsOrientation and Directional Terms
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Orientation and Directional TermsOrientation and Directional Terms
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Regional Terms
• Used to designate specific areas within the major body divisions.
• Two divisions:1. Axial part – head, neck, and trunk
2. Appendicular part – limbs
BodyBody
LandmarksLandmarks
Anterior
BodyBody
LandmarksLandmarks
Posterior
Body Planes
• Plane – flat surface• Most frequent body planes:– Sagittal Plane
• Vertical plane that divides body into right and left• Midsagittal – exactly on midline• Parasagittal – offset from midline
– Frontal Plane• Divides body into anterior and posterior• AKA “coronal” plane
– Transverse Plane• Horizontal plane• Divides into superior and inferior parts
Body Planes
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Body Cavities
Axial portion of the body:
Dorsal Body Cavity
• Protects nervous system• 2 Subdivisions:– Cranial cavity – encases brain– Vertebral cavity – encases spinal cord
Ventral Body Cavity
• 2 Subdivisions:– Thoracic cavity is subdivided into pleural cavities, the
mediastinum, and the pericardial cavity• Surrounds ribs and muscles• Pleural cavity – houses lungs• Pericardial cavity – houses hearts, esophagus and trachea• Mediastinum – contains the pericardial cavity, and surrounds
the remaining thoracic organs
Ventral Body Cavity
– 2 Subdivisions: (con’t)
– Abdominopelvic cavity• Separated from thoracic cavity by the dome-shaped diaphragm• It is composed of two subdivisions
– Abdominal cavity – contains stomach, intestines, spleen, and liver, and other organs
– Pelvic cavity – lies within the pelvis and the contains bladder, reproductive organs, and rectum
Membranes in the Ventral Body Cavity
• Serosa (serous membrane)– Thin, double-layered membrane– Parietal serosa – membrane lining cavity walls– Visceral serosa – covers organs
• Serous fluid– Separates serous membranes– Allows sliding without friction
Ventral Body Cavity MembranesVentral Body Cavity Membranes
• Parietal serosa covering the body walls
• Visceral serosa covering the internal organs
• Serous fluid separates the serosae
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
Abdominopelvic Regions • 1. Right Hypochondriac: Liver, gall bladder, small intestine,
ascending colon, transverse colon, right kidney • 2. Epigastric: Esophagus, stomach, liver, pancreas, small
intestine, transvers colon, right and left adrenal glands, pancreas, right and left kidneys, right and left ureters, spleen
• 3. Left Hypochondriac: Stomach, tip of liver, tail of pancreas, small intestines, transverse colon, descending colon, pancreas, left kidney, spleen
• 4. Right Lumbar: Tip of liver, gall bladder, small intestine, ascending colon, right kidney
• 5. Umbilical: Stomach, pancreas, small intestine, transverse colon, pancreas, right and left kidneys, right and left ureters
Abdominopelvic Regions (con’t)• 1. Right Hypochondriac: Liver, gall bladder, small intestine,
ascending colon, transverse colon, right kidney • 2. Epigastric: Esophagus, stomach, liver, pancreas, small
intestine, transvers colon, right and left adrenal glands, pancreas, right and left kidneys, right and left ureters, spleen
• 3. Left Hypochondriac: Stomach, tip of liver, tail of pancreas, small intestines, transverse colon, descending colon, pancreas, left kidney, spleen
• 4. Right Lumbar: Tip of liver, gall bladder, small intestine, ascending colon, right kidney
• 5. Umbilical: Stomach, pancreas, small intestine, transverse colon, pancreas, right and left kidneys, right and left ureters
Abdominopelvic Regions
Abdominopelvic Quadrants
• Quadrants are named according to subject’s pt. of view– Right upper– Left upper– Right lower– Left lower