Organization of the Body

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Lecture Outline

1.1 The Human Body

The structure of a part suits the function of a part

o  Anatomy – structure of a part o  Physiology – function of a part

Organization of Body Parts

o  Levels of Organization •  Chemical •  Cellular •  Tissue •  Organs •  Organ Systems •  Organism

1.2 Anatomical Terms

Used to describe: o  Location of body parts o  Regions of the body o  Imaginary planes by which the

body can be sectioned

Anatomical Terms

Anatomical position – common reference point for all anatomical terms

Anatomical Terms

Directional Terms o  Anterior (ventral)/Posterior

(dorsal) o  Superior/Inferior o  Medial/Lateral o  Proximal/Distal o  Superficial/Deep o  Central/Peripheral o  Ipsilateral/Contralateral

Anatomical Terms

Regions of the Body o  Axial portion – head, neck, and

trunk o  Appendicular portion – upper and

lower limbs

Anatomical Terms

Planes and Sections of the Body o  Sagittal (median) plane – divides

body into right and left portions o  Frontal (coronal) plane – divides

body into anterior and posterior portions

o  Transverse (horizontal) plane – divides body into superior and inferior portions

1.3 Body Cavities and Membranes

o  Posterior (dorsal) •  Cranial cavity – contains the brain •  Vertebral canal – contains the spinal

cord •  Meninges – membranous layers lining

dorsal body cavity

Body Cavities and Membranes

o  Anterior (ventral) •  Thoracic cavity

  Medial portion (mediastinum) – contains the heart, thymus gland, trachea, esophagus, and other structures

  Right and left portions – contain the lungs

Body Cavities and Membranes

o  Anterior (ventral) •  Abdominopelvic cavity

  Superior portion (abdominal cavity) – contains the stomach, liver, spleen, gallbladder, and most of the small and large intestines

  Inferior portion (pelvic cavity) – contains the rectum, urinary bladder, internal reproductive organs, and the rest of the large intestine

Body Cavities and Membranes

o  Parietal serous membrane – line walls of anterior body cavities

•  Thoracic cavity   Parietal Pleura – lines thoracic cavity   Parietal pericardium – creates pericardial

cavity

•  Abdominopelvic cavity   Parietal peritoneum – lines the wall of the

abdominal cavity

Body Cavities and Membranes

o  Visceral serous membrane – covers organs of the anterior body cavity

•  Thoracic cavity   Visceral pleura – covers lung tissue   Visceral pericardium – covers heart

•  Abdominopelvic cavity   Visceral peritoneum – covers many

organs in abdominopelvic cavity

Body Cavities and Membranes

o  Abdominopelvic regions •  Nine regions •  Four quadrants

1.4 Organ Systems

Support, Movement, and Protection o  Integumentary System o  Skeletal System o  Muscular System

Organ Systems

Integration and Coordination o  Nervous System o  Endocrine System

Organ Systems

Maintenance of the Body o  Cardiovascular System o  Respiratory System o  Digestive System o  Urinary System

Organ Systems

Reproduction and Development o  Male Reproductive System o  Female Reproductive System

1.5 Homeostasis

Homeostasis is the relative constancy of the body’s internal environment

o  External conditions may change dramatically

o  Internal conditions stay within a narrow range

o  Dynamic equilibrium – internal conditions are not absolutely constant

o  Illness results if internal conditions change to any great degree

Homeostasis

o  Components of homeostatic mechanisms

•  Sensor – detects a change in the internal environment

•  Control center – activates the effector •  Effector – produces a response to the

change

Homeostasis

Negative Feedback o  Primary homeostatic mechanism o  Effector reverses the change in the

internal environment

Homeostasis

Positive Feedback o  Effector continues to stimulate the

sensor so that a greater change in the internal environment occurs

o  Helps in completing a process that has a cutoff point

•  Blood clotting •  Childbirth

o  Can be harmful

Homeostasis

Homeostasis and Body Systems o  All body systems contribute towards

maintaining homeostasis o  Disease occurs when homeostasis fails

•  Local disease – restricted to a specific part of the body

•  Systemic disease – affects several organ systems or the entire body

•  Acute diseases – occur suddenly and last a short time

•  Chronic diseases – develop slowly and are long term