B. General Characteristics of Control Mechanisms 1. Established by the nervous and endocrine systems 2. All homeostatic control mechanisms have 3 interdependent components a. control center – interprets input b. receptor – receiver (input) – sends input to control center via afferent pathways c. effector – acts on (output) – causes response via efferent pathway
C. Negative Feedback Mechanisms 1. Increase in output feeds back and decreases input 2. Net effect is decrease of the original stimuli 3. Opposite directional change 4. Examples – heart rate, respiration rate, blood pressure, temperature regulators; control glucose levels
D. Positive Feedback Mechanisms 1. Original stimulus is enhanced so output is accelerated 2. Same directional change 3. Usually controls infrequent events 4. Cascade effect – explosive and self perpetuating 5. Examples – blood clotting, labor contractions
E. Homeostasis Imbalance 1. Effected by disease 2. Effected by aging 3. Effected by destructive positive feedback mechanisms that overwhelm negative feedback mechanisms i.e. heart failure
VIII. Language of Anatomy A. Anatomical Position 1. Human body upright 2. Arms at sides 3. Palms forward
D. Body Planes & Sections 1. Planes a. Sagittal/midsagittal (right & left) b. Frontal ( anterior & posterior) c. Transverse (superior & inferior) d. Oblique - diagonal 2. Sections – different sections give different views
E. Body Cavities & Membranes 1. Dorsal Body Cavity (posterior) a. cranial cavity (brain) b. vertebral cavity (spinal cord) 2. Ventral Body Cavity (anterior) a. Thoracic cavity – heart & lungs b. Abdominopelvic cavity * separated by the diaphragm
3. Membranes – serous (double layered) a. Parietal serosa – cavity walls b. Visceral serosa - organs c. Serous fluid – separates layers d. Named for cavity or organ – i.e. parietal pericardium; visceral pleura
4. Other Body Cavitites a. Oral cavity - buccal b. Nasal cavity c. Orbital cavity - eyes d. Middle ear cavity e. Synovial cavity - joints
F. Abdominopelvic Regions & Quadrants 1. Regions a. Umbilical b. Epigastric c. Hypogastric d. Right & left lumbar e. Right & left hypochondriac f. right & left iliac
2. Quadrants a. Right upper b. Right lower c. Left upper d. Left lower