HUMAN Anatomy (Intro to Human anatomy)

ANATOMY

 is the study of internal and external structures of the human body. Given that specific structures perform specific functions, therefore, structure determines function.

The BRANCHES of ANATOMY include:

• MICROSCOPIC ANATOMY (fine anatomy) – the study of body structures that cannot be viewed without magnification; includes cytology (the study of cells) and histology (the study of tissues)
  

• GROSS ANATOMY (macroscopic anatomy) – the study of body structures which are visible without the aid of magnification; subclasses include surface anatomy (the study of shapes and markings on the body surface), regional anatomy (the study of all structures in a single body region, superficial or deep) and systemic anatomy (the study of all organs with related functions, i.e. study one organ system at a time)
  

• DEVELOPMENTAL ANATOMY – the study of structural changes that occur from conception to physical maturity; its subclass is embryology (the study of structural formation and development before birth)
  
  

• COMPARATIVE ANATOMY – the study of the anatomy of different types of animals
  

• PATHOLOGICAL ANATOMY – the study of structural changes in cells tissues, and organs caused by disease
  

• RADIOGRAPHIC ANATOMY – the study of internal body structures by using noninvasive imaging techniques, such as X-ray imaging and ultrasound
  

SURGICAL ANATOMY – the study of anatomical landmarks, which are important to surgical procedures

A. LEVELS of STRUCTURAL ORGANIZATION of the human body (microscopic to macroscopic)

1. CHEMICAL LEVEL: atoms (building blocks of matter) combine to form small molecules (such as water and carbon dioxide) and larger macromolecules (carbohydrates, lipids, proteins and nucleic acids); i.e., Chemicals (molecules) comprise the entire body.
   

2. CELLULAR LEVEL: cells are comprised of molecules; they are the smallest living units in the body; cellular organelles are their functional subunits.
   

3. TISSUE LEVEL: similar types of cells, with a common function, combine to form tissues. Four primary tissue types comprise all organs of the human body.
   

4. ORGAN LEVEL: more than one tissue type (often all four tissues) combine to form organs; extremely complex physiological processes occur at this level.
   

5. ORGAN SYSTEM LEVEL: organs that work closely together combine to form an organ system, to accomplish a common purpose; there are 11 organ systems of the human body.
   

HUMAN ORGANISM (or organismal level): the highest level of structural organization; this is the combination of all the organ systems functioning together to sustain the life of the organism.

Absorption:

the route through which substances (only very small molecules) can enter the body, dependent upon catabolic reactions

Adaptability:

 long-term responsiveness

Adaptation

the change in living organisms that allow them to live successfully in an environment

Differentiation

the process by which a less specialized cell becomes a more specialized cell type

Excretion

the process of removing metabolic waste products and other useless materials from within an organism

Growth:

refers to an increase in some quantity over time, often due to an increase in the size and/or number of individual cells

Metabolism

•  the set of chemical reactions that occur in living organisms in order to maintain life
  

  • Anabolism refers to the construction of molecules, via metabolic pathways, from smaller units
    

Catabolism refers to the breakdown of molecules, via metabolic pathways, into smaller units, consequently releasing energy

Reproduction:

the process through which new individual organisms are produced; therefore, it is essential to the continuity of life

Supine:

 The patient is lying down with the face up.

Prone:

The patient is lying down with the face down.

Responsiveness:

 the ability of an organism to change activity or functioning, based upon the application of a stimulus; also referred to as irritability

Integumentary System

forms the cutaneous membrane (epidermis and dermis),

the external body covering; provides protection and thermoregulation;

synthesizes vitamin D; provides cutaneous reception through sensory receptors;

additional accessory structures are hair follicles, nails, sweat (sudoriferous) glands and oil (sebaceous) glands

Skeletal System –

provides protection and support to the body organs;

provides skeletal framework for the muscles to attach, hence, causing movement;

stores minerals; blood cell formation occurs within bones

Muscular System

produces motion;

maintains posture by providing support;

produces heat

Nervous System

 control center of the body, which directs immediate responses to stimuli and coordinates the other organ systems; i.e. responds to internal and external stimuli by activating appropriate muscles and glands

Endocrine System

comprised of glands, which secrete hormones that regulate processes (such as metabolism, growth, and reproduction) of the other organ systems

Cardiovascular System

comprised of the heart, blood vessels, and blood to transport materials (such as respiratory gases, nutrients and wastes) within the body

Lymphoid (Lymphatic and Immune) System

comprised of the lymphatic vessels, lymphoid organs (lymph nodes, the thymus, and the spleen), lymphocytes, and lymphoid tissue;

returns leaked fluid to blood;

provides defense against pathogens and disease by housing white blood cells (lymphocytes) that function in immunity

Respiratory System

 comprised of the nasal cavities, pharynx, larynx, trachea, bronchi, and the lungs;

maintains the blood’s constant supply of oxygen and removal of carbon dioxide by delivering air to the lungs where gas exchange occurs at the alveoli (air sacs of the lungs)

Digestive System

comprised of the gastrointestinal tract (or alimentary canal) and accessory structures, which together function to process food and absorb nutrients

Urinary System

comprised of the kidneys, ureters, the urinary bladder, and the urethra;

functions to eliminate excess water, salts, and nitrogenous wastes from the body;

regulates water, electrolyte, and acid-base balance of the blood

anatomical position

 the person is standing upright, arms at sides, palms facing forward (little fingers are medial, touching the thighs), feet flat on the floor, face straight ahead)

AXIAL REGION

consists of the head, neck and torso.

APPENDICULAR REGION

 consists of the upper and lower limbs (or extremities

ORIENTATION and DIRECTIONAL TERMS:

• SUPERIOR (cranial or cephalic) – above the point of reference; toward the head end or upper part of a structure or the body
  

• INFERIOR (caudal) – below the point of reference; toward the tail end or toward the lower part of a structure or the body
  

• ANTERIOR (ventral) – toward or at the front of the body; in front of (the front or belly side)
  

• POSTERIOR (dorsal) – toward or at the back of the body; behind (the back side) (n.b. anterior/dorsal and posterior/ventral are interchangeable in humans only, not so in four-footed animals in which dorsal is superior and ventral is inferior)
  

• MEDIAL – toward or at the midline of the body; on the inner side of (e.g. The trachea is medial to the arm.)
  

• LATERAL – away from the midline of the body; toward the sides or on the outer sides of (e.g. The ears are lateral to the nose.)
  

• PROXIMAL – closer to the origin of the body part or the point of attachment of a limb to the body trunk (e.g. The shoulders are proximal to the elbows.)
  

• DISTAL – away from the origin of a body part or the point of attachment of a limb to the body trunk (e.g. The fingers are distal to the wrist.)
  

• SUPERFICIAL (external) – closer to or at the body surface (e.g. The skin is superficial to the heart.)
  

• DEEP (internal) – farther from or away from the body surface; more internal (e.g. The lungs are deep to the skin.)
  

• IPSILATERAL – on the same side (e.g. The right arm and right leg are ipsilateral.)
  

CONTRALATERAL – on opposite sides (e.g. The right arm and left leg are contralateral.)

REGIONAL TERMS (names of specific body parts)

• CEPHALON (cephalic) – area of the head
  
  

• CERVICIS (cervical) – neck region
  
  

• THORACIS (thoracic) – chest region
  
  

• BRACHIUM (brachial) – upper arm
  
  

• ANTEBRACHIUM (antebrachial) – forearm
  
  

• CARPUS (carpal) – wrist
  
  

• MANUS (manual) – hand
  
  

• POLLICIS (pollex) – thumb
  
  

• ABDOMEN (abdominal) – abdominal region
  
  

• UMBILICUS (umbilical) – navel or bellybutton
  
  

• PELVIS (pelvic) – pelvic region
  
  

• PUBIS (pubic) – anterior pelvis or genital region
  
  

• INGUEN (inguinal) – groin
  
  

• LUMBUS (lumbar) – lower back
  
  

• GLUTEUS (gluteal) – buttock region
  
  

• FEMUR (femoral) – thigh
  
  

• PATELLA (patellar) – kneecap
  
  

• CRUS (crural) – anterior leg, from knee to ankle
  
  

• SURA (sural) – posterior, calf of leg
  
  

• TARSUS (tarsal) – ankle
  
  

• PES (pedal) – foot (pedals of a bike)
  
  

• PLANTA (plantar) – the bottom of the foot, sole
  
  

HALLUCIS (hallux) – great toe or big toe

 BODY PLANES

• (a) – FRONTAL (CORONAL) plane – lies vertically and divides the body into an anterior (front) portion and a posterior (back) portion
  

• (b) – TRANSVERSE (HORIZONTAL) plane – lies horizontally and divides the body into a superior (top) portion and an inferior (lower) portion. These sections are also called cross sections.
  

• (c) – SAGITTAL plane – lies vertically and divides the body into a right portion and a left portion.
  

  • If the sagittal plane lies exactly in the midline and the portions are equivalent, it is called a MIDSAGITTAL PLANE, or MEDIAN PLANE.
    

All other sagittal planes (that are offset from the midline and result in unequal portions) are called PARASAGITTAL PLANES.

BODY CAVITIES and MEMBRANES (Dorsal Body Cavity)

a. Cranial cavity – lies within skull (cranium), encasing the brain
b. Spinal cavity – lies within the vertebral column, enclosing the spinal cord

VENTRAL body cavity (COELOM)

provides protection,

allows organ movement, l

ining prevents friction

 a. The THORACIC cavity – superior to diaphragm, contains heart, lungs, blood vessels; surrounded by the ribs and the muscles of the chest wall

• PLEURAL CAVITIES – right and left cavities, which enclose the right and left lungs
  
  

  • parietal pleura (the thin membrane that lines the chest walls) of the serous membrane
    
    

  • visceral pleura (the thin membrane that adheres to the lungs) of the serous membrane
    
    

  • serous fluid fills the pleural cavity between the layers of the serous membrane
    
    

• MEDIASTINAL CAVITY or MEDIASTINUM – a central cavity containing a band of organs, which lies between the pleural cavities; contains the heart (enclosed by the pericardial cavity), esophagus, trachea, and major blood vessels
  
  

  • PERICARDIAL CAVITY – contains the heart
    
    

    • parietal pericardium (the thin membrane that lines the pericardial walls) of the serous membrane
      
      

    • visceral pericardium (the thin membrane that adheres to the heart surface) of the serous membrane
      
      

serous fluid fills the pericardial cavity between the layers of the serous membrane

The ABDOMINOPELVIC CAVITY

lies inferior to the diaphragm and is divided into a superior part and an inferior part
ABDOMINAL cavity – the superior part, which contains the liver, stomach, small intestine, spleen, kidneys, and other organs; extends from diaphragm superiorly to superior border of sacrum

• Many organs in the abdominopelvic cavity are surrounded by a peritoneal cavity.
  

  • parietal peritoneum (the thin membrane that lines the wall) of the serous membrane
    

  • visceral peritoneum (the thin membrane that adheres to the abdominopelvic organs) of the serous membrane
    

• Note that the kidneys, adrenal glands, pancreas, and ureters are retroperitoneal because they are located behind the abdominopelvic cavity.
  

• PELVIC cavity – the inferior part, which is enclosed by the bony pelvis; contains the urinary bladder, some reproductive organs, and the rectum
  

• Peritoneum is continuous with that of the abdominal cavity

The four abdominopelvic quadrants

delineate the abdominopelvic cavity into four segments by drawing one horizontal plane and one vertical plane through the umbilicus.

 ○ Right upper quadrant (RUQ)
○ Right lower quadrant (RLQ)
○ Left upper quadrant (LUQ)
○ Left lower quadrant (LLQ)

The nine abdominopelvic regions

• created by two transverse planes and two parasagittal planes, forming a “tic-tac-toe” grid.
  

○ UMBILICAL region (5) – the center square
○ HYPOCHONDRIAC regions (1–right and 3–left) – superior lateral regions
○ EPIGASTRIC region (2) – medial and superior to the umbilical region
○ LUMBAR regions (4–right and 6–left) – middle lateral regions
○ HYPOGASTRIC region (8) – medial and inferior to the umbilical region
○ INGUINAL (ILIAC) regions (7–right and 9–left) – inferior lateral regions