Introduction to the Human Body
A.
B.
C.
D.
E.
F.
G.
H.
Anatomy and physiology defined
Levels of structural organization
Life processes
Anatomical position
Directional terms
Planes and sections
Body cavities
Homeostasis
1. Body fluids and exchange
2. Regulation by nervous and endocrine
mechanisms
3. Feedback systems
Anatomy (Greek “anatome” =to cut up or
dissect
Physiology (Greek “physis” =nature
Levels of Structural
Organization
Life Processes
Metabolism= catabolism + anabolism
Responsiveness
Movement
Growth
Differentiation
Reproduction
Anatomical Position
Directional Terms
Superior vs. Inferior
Anterior vs. Posterior
Medial vs. Lateral
Proximal vs. Distal
Superficial vs. Deep
superior
Proximal
Medial
Lateral
Distal
inferior
Anterior
Posterior
Planes and Sections
1.Sagittal
a. midsagittal
b. parasagittal
2. Frontal (coronal)
3.Transverse (cross)
4.Oblique
Planes of the Body
Sections Through the Body
Body Cavities
Body Cavities (also material
In Atlas A (A. 12-A.22) and
Handout 1-Body Regions
1. Dorsal
a. cranial
b. vertebral (spinal
2. Ventral
a. thoracic
(1) pleural-2
(2) mediastinum
(a) anterior
(b)middle(pericardial)
(c) posterior
b. abdominopelvic
Homeostasis
(Greek “homoi” =same
“stasis” =standing still)
Body Fluids and Exchange
1. Extracellular fluid
(ECF)
a. interstitial fluid
b. plasma
2. Intracellular fluid
The homeostatic responses of the
body are regulated by the combined
effects of the nervous system and
the endocrine system.
REGULATION OF HOMEOSTASIS
Nervous system = electrical messages control
events on a millisecond basis; short-term and
very specific effects
Endocrine system = chemical messages
control events on a minute, hour, daily,
monthly, etc. basis; longer-term and more
widespread effects
Operation of a Feedback
System
Condition
Receptor
Control Center
Effectors
Response
Condition- A stimulus or stress disrupts homeostasis in a
controlled condition which is monitored by a receptor.
Receptor- responds to specific changes in the controlled
condition and sends input to control center.
Control Center- Receives input from receptors, integrates the
information and provides output to specific effectors.
Effectors-respond to output from the control center by
bringing about some type of change in the body that
counteracts the disruption in homeostasis.
Response-the activity of the effectors brings the controlled
condition back into normal homeostasis and the negative
feedback system is shut down.
Feedback System: Main Players
WHAT IS A FEEDBACK SYSTEM?
CONTROLLED CONDITION
some physiologic state
RETURN TO HOMEOSTASIS
RECEPTOR
senses a change in the condition
EFFECTORS
structure that restores homeostasis
CONTROL CENTER
integrates incoming information
WHAT IS A NEGATIVE FEEDBACK SYSTEM?
A feedback loop in which the body senses a change and
activates mechanisms that reverse the change
RETURN TO HOMEOSTASIS
CONTROLLED CONDITION
blood pressure
decreased
blood pressure rises
turns off
increased heart rate
and vasoconstriction
RECEPTOR
baroreceptors in blood
vessels
decreased
activity
CONTROL CENTER
EFFECTORS
heart and arterial smooth
muscle
nervous output
medulla of brain
end
Positive Feedback
WHAT IS A POSITIVE FEEDBACK SYSTEM?
A feedback loop in which the response reinforces the stimulus,
triggering a cycle of ever-increasing response
CONTROLLED CONDITION
level of uterine stretch
reinforcing
effects
RETURN TO HOMEOSTASIS
labor forces baby’s head further into
cervix
increased
RECEPTOR
EFFECTORS
stretch receptors in cervix
uterine smooth muscle contraction
increased
activity
CONTROL CENTER
hypothalamic neurons of brain
oxytocin secretion