Planes and Sections of the Body

• Sagittal Plane: Extends lengthwise, divides body into right and left portions.

• Frontal Plane: Extends lengthwise and divides body into anterior and posterior portions.

• Transverse: Runs crosswise to separate body into horizontal sections.

Body Cavities and Membranes

• Posterior (Dorsal) Body Cavity- – Cranial Cavity: Contains the brain.– Vertebral Canal: Contains the spinal cord.– Lined by three membranous layers called

meninges.• Meningitis = Infection of these membranes.

Body Cavities and Membranes

• Anterior (Ventral) Body Cavity-– Thoracic Cavity– Abdominopelvic Cavity– Separated by Diaphragm– Lined by Serous membranes.

• Secrete fluid similar to serum• Reduces friction between organs.

Thoracic Cavity

• Enclosed by rib cage and has three portions.– Mediastinum: Located in the middle and holds

the heart, thymus, trachea and others.

– Right and left portions hold the lungs

– Pleural and Pericardial spaces surround the lungs and heart to provide protection.

Abdominopelvic Cavity

• Abdominal Cavity is superior: Contains most of the digestive organs.

• Pelvic Cavity is inferior: Contains the rectum, bladder and some parts of the large intestines.

• The organs (viscera) in the cavity are covered by membranes and the cavity is lined by a membrane.

• Peritoneal fluid fills the space between.

Abdominopelvic Cavity Cont.

• Broken down into four quadrants.

Organ Systems

• Support, Movement and Protection:– Integumentary– Skeletal– Muscular: Muscles

• Reproduction and Development:– Reproductive system.

• Integration and Coordination:– Nervous– Endocrine

• Maintenance of Body:– Cardiovascular– Lymphatic– Respiratory– Digestive– Urinary

“Balance” in the Body

• Homeostasis: This is the relative constancy of the body’s internal environment.

• Outside environment may change lots, the inside stays very steady.– pH of blood, blood sugar levels, body temp.

Negative Feedback

• Keeps a variable close to a partciular value.

• Three components:– Sensor– Regulatory center– Effector

• Ex. Home heating system, blood pressure, body temperature.

Positive Feedback

• Brings about an ever greater change in the same direction.

Positive Feedback

• Brings about an ever increasing change in the same direction.

• Examples: Blood Clotting, Digestion of proteins in the stomach, muscle contractions during child birth.