Human OrganizationHuman Organization

Chapter 1: Introduction to Human Chapter 1: Introduction to Human A&PA&P

Unit 1: Levels of OrganizationUnit 1: Levels of Organization

Human OrganizationHuman Organization

The body can be considered conceptually at The body can be considered conceptually at nine structural levels:nine structural levels:

– Chemical (atom, molecule, macromolecule)Chemical (atom, molecule, macromolecule)

-Organelle-Organelle

-Cell-Cell

-Tissue-Tissue

-Organ-Organ

-Organ System-Organ System

-Complete -Complete OrganismOrganism

““The Break Down”The Break Down”

Chemicals consists of invisible Chemicals consists of invisible particles called particles called atomsatoms, which join , which join to form to form moleculesmolecules..

– Small molecules can combine to Small molecules can combine to form larger molecules called form larger molecules called macromoleculesmacromolecules.. CarbohydratesCarbohydrates LipidsLipids ProteinsProteins Nucleic AcidsNucleic Acids

““The Break Down” The Break Down” Cont.Cont. The basic unit of structure and The basic unit of structure and

function is a function is a cellcell (composed of (composed of various macromolecules)various macromolecules)

– Human cells contain Human cells contain organellesorganelles that that carry out specific activitiescarry out specific activities

When cells are organized into layers When cells are organized into layers or masses that have a common or masses that have a common function they become function they become tissuestissues..

““The Break Down” The Break Down” Cont.Cont. Groups of different tissues that Groups of different tissues that

interact form interact form OrgansOrgans

– Groups of organs that function Groups of organs that function closely together comprise closely together comprise Organ Organ SystemsSystems..

Organ systems make up an Organ systems make up an Organism.Organism.

Important Note!Important Note!

Body parts can be thought of as having Body parts can be thought of as having different levels of organization:different levels of organization:

– i.e. atomic level, molecular level, cellular i.e. atomic level, molecular level, cellular level, etc…level, etc…

Body parts vary in complexity from Body parts vary in complexity from one level to the next:one level to the next:

– i.e. atoms are less complex than i.e. atoms are less complex than molecules, molecules are less complex molecules, molecules are less complex than organelles, tissues are less complex than organelles, tissues are less complex than organs, and so forththan organs, and so forth

Anatomical Positioning Anatomical Positioning and Directional Termsand Directional Terms Directional terms Directional terms

always refer to the always refer to the body in the anatomic body in the anatomic position, which is a position, which is a person standing erect person standing erect with the feet facing with the feet facing forward, arms forward, arms hanging to the sides, hanging to the sides, and palms facing and palms facing forward with the forward with the thumbs to the outsidethumbs to the outside

Body PlanesBody Planes

Medical professionals often refer Medical professionals often refer to sections of the body in terms of to sections of the body in terms of anatomical planes (flat surfaces)anatomical planes (flat surfaces)

– These planes are imaginary lines-These planes are imaginary lines-vertical or horizontal-drawn through vertical or horizontal-drawn through the upright body. Think of them as the upright body. Think of them as cutting the body into sections.cutting the body into sections.

The terms are used to describe a The terms are used to describe a specific body part.specific body part.

Sagittal SectionSagittal Section

Coronal SectionCoronal Section

Transverse SectionTransverse Section

Organization of the Organization of the Human BodyHuman Body

A human body is composed of parts A human body is composed of parts within parts, which vary in within parts, which vary in complexity.complexity.

– Its major features include several body Its major features include several body cavities, layers of membranes within cavities, layers of membranes within these cavities, and a variety of organ these cavities, and a variety of organ systems.systems.

Body DivisionsBody Divisions

Human organization can be divided into 2 Human organization can be divided into 2 portions:portions:

1. 1. Appendicular PortionAppendicular Portion: upper & : upper &

lower limbslower limbs

2. 2. Axial PortionAxial Portion: head, neck & trunk: head, neck & trunk

-Can be divided into 2 main body-Can be divided into 2 main body

cavities:cavities:

--Dorsal CavityDorsal Cavity

--Ventral CavityVentral Cavity

Dorsal Body CavityDorsal Body Cavity

Has 2 main divisions:Has 2 main divisions:

1.1. Cranial CavityCranial Cavity: the space inside : the space inside the bony skullthe bony skull

2.2. Spinal CavitySpinal Cavity: extends from the : extends from the cranial cavity nearly to the end of cranial cavity nearly to the end of the vertebral columnthe vertebral column

Ventral CavityVentral Cavity

The cavity is much larger than The cavity is much larger than the dorsal cavity, and contains the dorsal cavity, and contains all the structures within the all the structures within the chest and abdomen.chest and abdomen.

– 2 subdivisions:2 subdivisions:

1. 1. Thoracic CavityThoracic Cavity

2. 2. Abdominopelvic CavityAbdominopelvic Cavity

Thoracic CavityThoracic Cavity

A superior cavity separated from A superior cavity separated from the rest of the ventral cavity by a the rest of the ventral cavity by a dome-shaped muscle called the dome-shaped muscle called the DiaphragmDiaphragm..

– The lungs, heart, trachea, The lungs, heart, trachea, esophagus, and thymus gland are esophagus, and thymus gland are found in this cavity.found in this cavity.

Abdominopelvic CavityAbdominopelvic Cavity

Inferior to the diaphragm.Inferior to the diaphragm.

– Some anatomists separate this cavity Some anatomists separate this cavity into the abdominal cavity and the into the abdominal cavity and the pelvic cavitypelvic cavity

Abdominal CavityAbdominal Cavity: contains the : contains the stomach, liver, intestines, colon and other stomach, liver, intestines, colon and other organs.organs.

Pelvic CavityPelvic Cavity: contains the reproductive : contains the reproductive organs, bladder, and rectumorgans, bladder, and rectum

Abdominal CavityAbdominal Cavity

The abdomen can be divided into The abdomen can be divided into four quadrants or nine regions.four quadrants or nine regions.

– These division are useful for locating These division are useful for locating internal organs or describing the internal organs or describing the location of a pain or tumor.location of a pain or tumor.