1. Levels of Organization, Homeostasis, Body Cavities
Introduction to A&P
Levels of Organization, Homeostasis, Body Cavities

2. Terminology
Anatomy – the study of internal and external structures of the body, and the physical relationships among body parts. Ex. Studying the parts of the kidney.
Physiology – the study of how living organisms perform their vital functions. Ex. Studying the mechanisms by which the kidneys produce urine.

3. Levels of Organization

4. Levels of Organization
chemical level – lowest – chemicals essential for maintaining life- atoms to molecules to macromolecules to organelles
cellular- basic structural and functional unit; ex. Muscle and nerve cells
tissue- similar cells with same function; ex. Connective tissue, epithelial tissue

5. Levels of Organization
organ- structures of definite form and function composed of 2 or more tissues; ex. Heart, liver
system- association of organs with common function ex. Digestive, nervous
organism – all parts of the body functioning with one another

6. Metabolism
Definition: sum total of all chemical processes occurring in the body
catabolism – breakdown of organic matter, usually with the release of energy
anabolism – buildup of organic matter, usually requiring the input of energy
Example: A catabolic process would be the breakdown of a Carbohydrate for a release of energy to the body. An anabolic reaction would occur when that energy is captured and then used (or required) for something else.

7. Homeostasis
Definition: state of balance in which the body’s internal environment remains in the normal range. Our body is said to be in homeostasis when the needs of its cells are met and its activities are occurring smoothly.
Occurs with a balance of positive and negative feedback.

8. +/- Feedback
negative feedback – when the information decreases the system’s output to bring the system back to its set point
Example: The level of glucose rises after a meal, glucose stimulates the release of insulin, and insulin encourages the passage of glucose in the cells and therefore reduces the glucose level.

9. +/- Feedback
positive feedback – the information returned to the system increase the deviation from the set point
Example: Stimulating a nerve cell causes sodium ions to flow across the membrane into the cell; the sodium flow increases the membrane’s passageways to encourage more sodium ions to flow inward. The result is a nerve impulse.

10. Body Planes

11. Planes of the Body
sagittal – lengthwise plane running from front to back, it divides the body into right and left sides
transverse – refers to a cut that divides the body into superior and inferior portions
Coronal (frontal) – lengthwise plane running from side to side, it divides the body into front (anterior) and back (posterior) portions

12. Body Cavities

13. Body Cavities
The human is divided into an axial portion (head, neck and trunk) and an appendicular portion (upper and lower limbs)
The axial portion has 2 major cavities: a dorsal and a ventral cavity

14. Body Cavities
dorsal – subdivided into the cranial (brain) and spinal (vertebrae and spinal cord) cavities
ventral (divided by the diaphragm) – subdivided into the thoracic (heart, lungs, esophagus) and abdominopelvic ( stomach, intestines, spleen, liver, etc) cavities

15. Body Cavities right hypochondriac epigastric left hypochondriac
thoracic – the mediastinum separates the thoracic cavity into 2 compartments, the left and right lungs. The mediastinum includes the heart, esophagus, trachea, and thymus gland
abdominopelvic cavity includes the upper abdomen and the lower pelvic areas. The abdominal region is subdivided into nine regions
right hypochondriac
epigastric
left hypochondriac
right lumbar
umbilical
left lumbar
right iliac
hypogastric
left iliac region