Anatomy and Physiology Chapter 1

The human organism is made up of structure and function, which are studied by anatomy and physiology respectively.

Systemic anatomy: studies the body by organ systems.
Regional anatomy: studies the body by areas.
Surface anatomy: uses superficial structures to locate deeper structures.
Anatomical imaging: a non-invasive method for examining deep structures using X-ray, MRI, Ultrasound, etc.

Chemical level: the simplest level of the structural ladder, includes atoms and molecules.
Cellular level: the basic structural and functional units of an organism, composed of chemical.
Tissue level: a group of cells that perform the same function.
Organ level: composed of two or more tissues that perform the same function.
System level: a group of related organs with a common function.
Organism level: any living thing considered as a whole.

Metabolism: the ability to use energy.
Movement: the ability to perform physical actions.
Responsiveness: the ability to sense changes in the environment.
Growth: the increase in body size.
Reproduction: the formation of new cells for tissue growth, repair, or requirement.

The existence and maintenance of the balance of the body's internal environment.
Variables: factors being regulated.
Set value points: normal ranges.
Receptors: detect changes and signal the control center.
Control center: analyzes the information and determines the appropriate response.
Effectors: receive output and produce the response.

Body position: standard position called anatomical position.
Directional terms: used to describe the location of structures in the body.
Body planes: imaginary flat surfaces that pass through the body.
Section: an image or view of the body or one of its organs.
Cavities: the body contains many cavities that do not open to the outside of the body.
Serous membranes: line the trunk cavities and cover the organs of these cavities.### Structural and Functional Organization of the Human Body
The human body is organized into six levels: chemical, cell, tissue, organ, organ system, and organism.
There are eleven organ systems: integumentary, skeletal, muscular, lymphatic, respiratory, digestive, nervous, endocrine, cardiovascular, urinary, and reproductive systems.

The characteristics of life are organization, metabolism, responsiveness, growth, development, and reproduction.

Homeostasis is the condition in which body functions, body fluids, and other factors of the internal environment are maintained within a range of values suitable to support life.
Negative-feedback mechanisms maintain homeostasis.
Positive-feedback mechanisms make deviations from normal even greater.

The anatomical position is a human standing erect with the face directed forward, the arms hanging to the sides, and the palms facing forward.
A face-upward position is supine, and a face-downward one is prone.
Directional terms always refer to the anatomical position, regardless of the body’s actual position.

The body can be divided into the head, neck, trunk, upper limbs, and lower limbs.
The abdomen can be divided superficially into four quadrants or nine regions, which are useful for locating internal organs or describing the location of a pain.

A sagittal plane divides the body into left and right parts.
A transverse plane divides the body into superior and inferior parts.
A frontal plane divides the body into anterior and posterior parts.
A longitudinal section divides an organ along its long axis.
A transverse section cuts an organ at a right angle to the long axis.
An oblique section cuts across the long axis at an angle other than a right angle.

The thoracic cavity is bounded by the ribs and the diaphragm, and is divided into two parts by the mediastinum.
The abdominal cavity is bounded by the diaphragm and the abdominal muscles.
The pelvic cavity is surrounded by the pelvic bones.

The trunk cavities are lined by serous membranes.
The parietal part of a serous membrane lines the wall of the cavity, and the visceral part covers the internal organs.
Serous membranes secrete fluid that fills the space between the parietal and visceral membranes.
Serous membranes protect organs from friction.
The pericardial cavity surrounds the heart, the pleural cavities surround the lungs, and the peritoneal cavity surrounds certain abdominal and pelvic organs.
Mesenteries are parts of the peritoneum that hold the abdominal organs in place and provide a passageway for blood vessels and nerves to organs.
Retroperitoneal organs are found “behind” the parietal peritoneum, and include the kidneys, adrenal glands, pancreas, parts of the intestines, and urinary bladder.