1. The Human Body: An Orientation Ch. 1a

2. 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

3. 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

4. Cardiovascular system
Organelle
Atoms
Molecule
Smooth muscle cell 2
Cellular level 1
Chemical level
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.
Organismal level The human organism is made up of many organ systems. 6 5
Organ system level Organ systems consist of different organs that work together closely.
Figure 1.1

5. 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

6. Components of a Homeostatic Control Mechanism
Receptor (sensor)
Monitors the environment and senses stimuli
Control center
Receives input from receptor
Determines the set point at which the variable is maintained
Determines appropriate response
Effector
Receives output from control center
Provides the means to respond
Response acts to reduce or enhance the stimulus (feedback)

7. Output: Information sent along efferent pathway to effector. 4 3
Input: Information sent along afferent pathway to control center.
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
IMBALANCE
Stimulus produces change in variable.
BALANCE
IMBALANCE
Figure 1.4

8. 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

9. Temperature-sensitive Temperature-sensitive
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)
Figure 1.5

10. 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

11. Standard anatomical body position:
Anatomical Position
Purpose:
Standard anatomical body position:
Body erect
Feet slightly apart
Palms facing forward

12. Table 1.1

13. Table 1.1

14. Table 1.1

15. Table 1.1

16. Table 1.1

17. Upper limb Acromial Orbital Brachial (arm) Nasal Antecubital Oral
Antebrachial
(forearm)
Cervical
Carpal (wrist)
Thoracic
Axillary
Digital
Sternal
Abdominal
Lower limb
Umbilical
Coxal (hip)
Pelvic
Femoral (thigh)
Inguinal
Patellar
Crural (leg)
Pubic
Fibular
Tarsal (ankle)
Thorax
Abdomen
Back (Dorsum)
(a) Anterior/Ventral
Figure 1.5

18. Upper limb Cephalic Acromial Brachial (arm) Occipital (back of head)
Olecranal
Cervical
Back (dorsal)
Scapular
Vertebral
Digital
Lumbar
Sacral
Femoral (thigh)
Gluteal
Popliteal
Sural (calf)
Fibular
Calcaneal
Plantar
(b) Posterior/Dorsal
Figure 1.5

19. 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

20. Frontal (coronal) plane
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

21. Median (midsagittal) plane
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
Figure 1.6

22. Dorsal cavity encloses the CNS
Body Cavities
Two Large Cavities:
Dorsal cavity encloses the CNS
Two subdivisions:
Cranial cavity
Encases brain
Vertebral cavity
Encases spinal cord

23. Body Cavities Ventral cavity Houses soft internal organs (viscera)
Two subdivisions (separated by diaphragm):
Thoracic cavity
Abdominopelvic cavity

24. Cranial
cavity
Cranial
cavity
Dorsal body cavity
Ventral body cavity
Vertebral
cavity
Dorsal
body
cavity
Thoracic
Cavity
Vertebral
cavity
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
Figure 1.7

25. Thoracic cavity subdivisions:
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

26. Abdominopelvic cavity subdivisions:
Ventral Body Cavities
Abdominopelvic cavity subdivisions:
Abdominal cavity
Contains stomach, intestines, spleen, and liver
Pelvic cavity
Contains urinary bladder, reproductive organs, and rectum

27. Thoracic cavity Cranial cavity Vertebral cavity Cranial cavity
Dorsal body cavity
Ventral body cavity
Vertebral
cavity
Thoracic
cavity
Dorsal
body
cavity
Vertebral
cavity
Ventral body
cavity
Diaphragm
Abdominal cavity
Abdomino-
pelvic
cavity
Pelvic cavity
(a) Lateral view
(b) Anterior view
Figure 1.7

28. Nine Abdominopelvic Regions
Liver
Diaphragm
Right
hypochondriac
region
Left
hypochondriac
region
Epigastric
region
Gallbladder
Stomach
Right
lumbar
region
Left
lumbar
region
Ascending colon of
large intestine
Transverse 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
Figure 1.12