The structural and functional characteristics of all organisms are determined by their cellular makeup.their chemical level of organization involves interaction between atoms,which are tiny building blocks of matter.Atoms can combine to form molecules,such as water,sugar,fats,proteins,and deoxyribose nucleic acid (DNA).The function of a molecule is related intimately to its structure.For example,collagen molecules are strong,ropelike fibers that give skin structural strength and flexibility.With old age,the structure of collagen changes,and the skin becomes fragile and torn more easily.
Cellular Level
the animal cell(celula animals) click image to enlarge
Cells are basic structural and functional units of organisms,such as plants and animals.Molecules can combine to form organelles,which are the small structures that make up cells.for example,the nucleus contains the cell's hereditary information and mitochondria manufacture adenosine triphosphate (ATP),which is used by cells as a source of energy.although cell types differ in their structure and funtion,they have many characteristics in common.knowledge of these characteristics and their variations is essential to basic understanding of anatomy and physiology.
Tissue Level
simple squamous epithelial tissue click image to enlarge
A tissue is a group of similar cells and the materials surrounding them.The characteristics of the cells and surrounding materials determinehte functions of the tissue.The many tissues that make up the body are classified into four tissue types:epithelial,connective,muscle and nervous. Organ Level
left kidney
An organ is composed of two or more tissue types that together perform one or more common functions.the urinar bladder,skin,stomach,eye,heart are examples of organs. Organ System Level
human skeletal system
An organ system is a group of organs classified as a unit because of a common function or set of functions.For example,the urinary system consist of the kidneys,ureter,urinary bladder, and urethra.The kidney produces urine,which is transported by the ereters to the urinary bladder,where it is stored until eliminated from the body by passing through the urethra. Organism Level
An organism is any livng thing considered as a whole-whether composed of one cell,such as bacterium,or trillions if cells,such as humans.The human organnism is a complex of organ systems that are mutually dependent on one another
Homeostasis
HOMEOSTASIS
=>Is the maintanance of a relatively constant environment within the body.
SET POINT
=>homeostatic mechanisms normally maintain the normal value.
That normal value is called "Set Point".
NORMAL RANGE
=>note that these mechanisms are not able to maintain precisely at the set point.
instead,a range that is when mechanisms remain within these range,hemeostasis is maintained.
That range is the NORMAL RANGE.
NEGATIVE FEEDBACK
=>Any deviation from the set point is made smaller or resisted.
negative feedback does not prevent deviation within the normal range.
example:maintanance of blood pressure. normal blood pressure is necesssary for the movement of heart to the tissues.
the blood supplies the tissues with oxygen and nutrients and removes waste products,thus maintaining tissue homeostasis.
POSITIVE FEEDBACK
=>When a deviation from a normal values occurs,the response to the system is to make the deviation even greater.
example:inadequate delivery of blood to cardiac.contraction of cardiac muscle generartes blood pressure and moves blood
through blood vessels to tissues.A system of blood vessels on the outside of the heart produces cardiac muscle with blood supply
sufficient to allow normaal contranctions to occur.
but with extreme blood loss, inadequation to blood results the heart pumps less blood,causing death to organs and cells.
DIRECTIONAL TERMS
SUPERIOR-INFERIOR
those words denote vertical levels of position
>a structure located above is superior.
example:the mouth is superior to chin.
>a structure located below is inferior.
example:chin is inferior to mouth.
ANTERIOR-POSTERIOR
>Anterior is the one that is the most forward to surface of the body.
example:canine teeth are anterior to premolars.
>posterior is the one that is following the anterior,much like its opposite.
example:premolars are posterior to canine teeth(notice that it was much like just vice versa?)
CEPHALIC-CAUDAL
>cephalic is an anatomical direction that is close to head
>caudal is an antomical direction that pertains to posterior end of body
DORSAL-VENTRAL
>Dorsal is a direction to the back(back of head,back of chest,etc.)
>ventral is a direction to the front(chest,palms,etc.)
PROXIMAL-DISTAL
>Point of reference of attachment to other part of body
(proximal-one nearer to attachment)
(distal-one farther to attachment)
MEDIAL-LATERAL
>Medial is the one closest to the midline of the body.
(midline is the imaginative vertical line at the center of the body.)
>lateral is the one farther to the midline of the body.
BODY PLANES SAGITTAL SECTION
divides the body into left and right portion by cutting
the midsagittal part(a cut in midline.)
TRANSVERSE SECTION
(It is also known as a cross section)
cuts the body into top and bottom part by cutting
the body in horizontal cut.
FRONTAL SECTION
divides the body into front and back part.
