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Ch. 1 – Characteristics of Life & Organization of the
Human Body
What is the difference between Anatomy and Physiology?
A. Anatomy- study of the structures of an organism
-Examples of 4 subcategories:
1. Gross anatomy- large, what you can see
2. Microscopic anatomy - tiny
Cytology= study of cells
Histology= tissues
3. Developmental Anatomy-structure of an embryo (embryology)
4. Pathological anatomy- diseased structures
B. Physiology- study of the functions of an organism
What are the levels of organization in the human body?
-chemical (subatomic, atomic, molecules, macromolecules)
-organelles
-cells (differentiated to perform unique functions) 100 Trillion!
-tissues
-organs
-organ system (see below)
-organism (human)
Virtually all processes in the body occur in order to maintain
Homeostasis• What is Homeostasis?
Homeostasis- an organism’s maintenance of a relatively constant internal state
within set ranges.
Examples: Temp.= ~ 98.6 °Fb.p.= ~ 120/80 mmHgglucose= ~ 90-130 mg/dlBlood pH= 7.4hydration= ~60% H2O
MANY, MANY more!
Homeostatic control mechanisms- -known as a feedback control loop-virtually all of the body’s organ systems can be involved -there are three basic components:
-Sensor – senses a change (a “stimulus”)-Integrator, (control center) – interpret the change-Effector – responds to the change
Example:SENSOR: pressure sensor in the walls of the heart and major arteries senses low blood pressure and sends a signal to the brain.INTEGRATOR: Medulla oblongata in the brain determines degree in which b.p. must be corrected and send a signal back to the heart. EFFECTOR: the heart begins to beat faster thereby increasing pressure.
NEGATIVE feedback mechanism-
-creates a response that opposes the initial disturbance. (reverses the change)
-work to stabilize physiological variables
-are responsible for maintaining homeostasis
POSITIVE feedback mechanism-
-amplifies or reinforces the change that is occurring
-can be harmful or disasterous CANCER!
-very few normal positive feedback mechanisms-childbirth, bloodclotting, a sneeze