Transcript Ch. 1 The Human Body An Orientation

THE HUMAN BODY: AN
ORIENTATION CH. 1A
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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
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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
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Atoms
Organelle
Smooth muscle cell
Molecule
2 Cellular level
1 Chemical level
Smooth muscle tissue
Cardiovascular
system
Heart
Blood
vessels
3 Tissue level
Tissues consist of similar
types of cells.
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.
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5 Organ system level
Organ systems consist of different
organs that work together closely.
Figure 1.1
Homeostasis
• Definition: Maintenance of a relatively stable
internal environment despite continuous
outside changes
• Homeostasis is maintained by homeostatic
control mechanisms which involve at least
three components: receptor, control center,
effector
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Components of a Homeostatic Control Mechanism
1. Receptor (sensor)
•
Monitors the environment and senses stimuli
2. Control center
•
Receives input from receptor
•
Determines the set point at which the variable is maintained
•
Determines appropriate response
3.
Effector
•
Receives output from control center
•
Provides the means to respond
•
Response acts to reduce or enhance the stimulus
(feedback)
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3 Input: Information
sent along afferent
pathway to control
center.
2
Receptor
detects
change.
Receptor
4 Output:
Control
Center
Afferent
Efferent
pathway
pathway
1
Stimulus
produces
change in
variable.
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BALANCE
Information sent along
efferent pathway to
effector.
Effector
5
Response
of effector
feeds back
to reduce
the effect of
stimulus
and returns
variable to
homeostatic
level.
Figure 1.4
Negative Feedback
• When the response of a control mechanism
reduces or shuts off/stops the original
stimulus, this is called negative feedback
• Example:
• Regulation of body temperature
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Control Center
(thermoregulatory
center in brain)
Information sent
along the afferent
pathway to control
center
Afferent
pathway
Information sent
along the efferent
pathway to
effectors
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
Response
Body temperature rises;
stimulus ends
Body temperature falls
Receptors
Temperature-sensitive
cells in skin and brain
Effectors
Skeletal muscles
Shivering
begins
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Efferent
pathway
Information sent
along the efferent
pathway to effectors
Afferent
pathway
Control Center
(thermoregulatory
center in brain)
Information sent
along the afferent
pathway to control
center
Figure 1.5
Positive Feedback
• When the response of a control mechanism
enhances or exaggerates the original
stimulus, this is called positive feedback
• Example:
• Enhancement of labor contractions by oxytocin
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Anatomical Position
• Purpose:
• Standard anatomical body position:
• Body erect
• Feet slightly apart
• Palms facing forward
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Table 1.1
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Table 1.1
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Table 1.1
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Table 1.1
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Table 1.1
Upper limb
Acromial
Brachial (arm)
Antecubital
Antebrachial
(forearm)
Carpal (wrist)
Orbital
Nasal
Oral
Cervical
Thoracic
Axillary
Sternal
Abdominal
Umbilical
Pelvic
Inguinal
Pubic
Thorax
Abdomen
Back (Dorsum)
Digital
Lower limb
Coxal (hip)
Femoral (thigh)
Patellar
Crural (leg)
Fibular
Tarsal (ankle)
(a) Anterior/Ventral
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Figure 1.5
Upper limb
Acromial
Brachial (arm)
Olecranal
Digital
Femoral (thigh)
Popliteal
Sural (calf)
Fibular
Cephalic
Occipital (back
of head)
Cervical
Back (dorsal)
Scapular
Vertebral
Lumbar
Sacral
Gluteal
Calcaneal
Plantar
(b) Posterior/Dorsal
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Figure 1.5
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
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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
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Frontal plane
Median (midsagittal) plane
Transverse plane
(a) Frontal section
(through torso)
(b) Transverse section
(through torso,
inferior view)
Pancreas
(c) Median section
(midsagittal)
Aorta
Spleen
Left and
Liver Heart Spleen
right lungs
Stomach
Arm
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Liver
Spinal cord
Body wall
Subcutaneous fat layer
Intestines
Rectum
Vertebral
column
Figure 1.6
Body Cavities
• Two Large Cavities:
• Dorsal cavity encloses the CNS
• Two subdivisions:
• Cranial cavity
• Encases brain
• Vertebral cavity
• Encases spinal cord
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Body Cavities
• Ventral cavity
• Houses soft internal organs (viscera)
• Two subdivisions (separated by diaphragm):
• Thoracic cavity
• Abdominopelvic cavity
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Cranial
cavity
Cranial
cavity
Dorsal body cavity
Ventral body cavity
Vertebral
cavity
Thoracic
Cavity
Dorsal
body
cavity
Vertebral
cavity
Ventral body
cavity
(thoracic and
Abdomino- abdominopelvic
pelvic
cavities)
cavity
Diaphragm
Abdominal cavity
(contains digestive
viscera)
(a) Lateral view
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Pelvic cavity
(contains urinary
bladder, reproductive
organs, and rectum)
(b) Anterior view
Figure 1.7
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
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Ventral Body Cavities
• Abdominopelvic cavity subdivisions:
• Abdominal cavity
• Contains stomach, intestines, spleen, and
liver
• Pelvic cavity
• Contains urinary bladder, reproductive
organs, and rectum
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Cranial
cavity
Cranial
cavity
Dorsal body cavity
Ventral body cavity
Vertebral
cavity
Thoracic
cavity
Dorsal
body
cavity
Vertebral
cavity
Ventral body
cavity
Diaphragm
Abdominal cavity
Abdominopelvic
cavity
Pelvic cavity
(a) Lateral view
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(b) Anterior view
Figure 1.7
Nine Abdominopelvic Regions
Right
Epigastric
hypochondriac
region
region
Right
lumbar
region
Umbilical
region
Right iliac Hypogastric
(inguinal) (pubic)
region
region
Left
hypochondriac
region
Left
lumbar
region
Left iliac
(inguinal)
region
(a) Nine regions delineated by four planes
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Liver
Diaphragm
Gallbladder
Stomach
Ascending colon of
large intestine
Transverse colon
of large intestine
Small intestine
Descending colon
of large intestine
Cecum
Appendix
Initial part of
sigmoid colon
Urinary bladder
(b) Anterior view of the nine regions showing the superficial organs
Figure 1.12