Organization of the Body

 

 Anatomy and Physiology: structure and function.

 

1)    Structural Levels of Organization

Chemical level: atoms, molecules, and macromolecules (biomolecules; proteins, fats, even carbohydrates)

          Cells: smallest living units of structure and function in the body, contain organelles

          Tissues: organization of similar cells that unite to perform a common function

          Organs: group of tissues that act as a single unit to perform a special function

          Systems: groups of organs that together perform complex functions

          The body as a whole: The big unit

 

2)    Anatomical Position

          Erect, arms at sides, palms forward

          *Supine: lying face upward; not in anatomical position

          *Prone: lying face downward: also not in anatomical position

 

3)    Anatomical directions

          Superior and inferior

          Anterior and posterior

          Medial and lateral

          Proximal and distal

          Superficial and deep

          Central and peripheral

 

 

4)    Planes or Body Sections

Sagittal: front to back, divides into left and right (midsagittal plane creates equal halves)

          Frontal (coronal): side to side, divides body into anterior and posterior

          Transverse: horizontal, divides into superior and inferior.

          Longitudinal and cross sections

 

 

5)    Body Regions

          Axial – head, neck, and trunk (torso; thorax, abdomen, and pelvis

                  

          Appendicular - limbs   

 

See figure 1-3 for list of smaller regions

 

 

6)    Body Cavities

          Ventral

                   Thoracic

                             Mediastinum - heart

                             Pleural (right and left) – lungs

 

                   Abdominopelvic: separated from thoracic by diaphragm

Abdominal – liver, gallbladder, stomach, spleen, pancreas, small intestine, parts of large intestine

 

                             Pelvic – sigmoid colon, rectum, urinary bladder, reproductive organs

 

 

 

 

 Serosa - double membrane lining abdominopelvic cavity (peritoneum), lungs (pleura), and surrounding the heart (pericardium)

Serous fluid between layers acts as lubricant

Parietal layer - attaches to cavity wall

Visceral layer - attaches to organ

 

Divisions of the abdominopelvic cavity:

                             9 regions

                                      Upper abdominopelvic regions: above level of 9th rib cartilages

 

                                      Right hypochondriac              epigastric            left hypochondriac

 

                                      Middle regions: between 9th rib cartilages and iliac crest

 

                                      Right lumbar                           umbilical              left lumbar

 

                                      Lower regions: below iliac crest

 

                                      Right iliac (inguinal)                hypogastric                   left iliac

 

                             Quadrants: Right upper, left upper, right lower, left lower; center is                                                     umbilicus

 

 

          Dorsal

                   Cranial

                   Spinal

 

ORGAN SYSTEMS

 

A.   Integumentary system

1.    Structure – organs

a.     Skin – largest and most important in Integumentary system; 16% body weight

b.    Hair

c.     Nails

d.    Sense receptors; pain, pressure, touch, changes in temperature

e.    Sweat glands

f.       Oil glands

 

2.    Functions

a.     Protection

b.    Regulation of body temperature

c.     Synthesis of chemicals

d.    Sense organ

 

Support and Movement

 

B.   Skeletal system

1.    Structure

a.     Bones

b.    Joints

c.     Ligaments, tendons, cartilage

 

2.    Functions

a.     Support

b.    Movement (with joints and muscles)

c.     Storage of minerals

d.    Blood cell formation

 

C.   Muscular system

1.    Structure

a.     Muscles

·        Voluntary or striated

·        Involuntary or smooth

·        Cardiac

b.  Tendons

 

2.    Functions

a.     Movement

b.    Maintenance of body posture

c.     Production of heat

 

Integration and Coordination

 

D.   Nervous system

1.    Structure

a.     Brain

b.    Spinal cord

c.     Nerves

d.    Sense organs

 

2.    Functions

a.     Communication – nerve impulses, sensory and motor

b.    Integration – brain or spinal cord

c.     Control – motor impulses

d.    Recognition of sensory stimuli

 

3.    System functions by production of nerve impulses caused by stimuli of various types

 

4.    Control is fast-acting and of short duration

 

E.   Endocrine system

1.    Structure – ductless glands

a.     Pituitary gland

b.    Pineal gland

c.     Hypothalamus

d.    Thyroid gland

e.    Parathyroid glands

f.       Thymus gland

g.    Adrenal glands

h.     Pancreas

i.        Ovaries

j.        Testes

 

1.    Functions

a.     Secretion of special substances called hormones directly into the blood

b.    Same as nervous system – communication, integration, control

c.     Control is slow and of long duration

d.    Examples of hormone regulation:

·        Growth

·        Metabolism

·        Reproduction

·        Fluid and electrolyte balance

 

Maintenance of the Body

 

F.    Circulatory system (cardiovascular)

1.    Structure

a.     Heart

b.    Blood vessels

 

2.    Functions

a.     Transportation

b.    Regulation of body temperature

c.     Immunity (body defense)

 

G.  Lymphatic system

1.    Structure

a.     Lymph nodes

b.    Lymphatic vessels – interstitial fluid, lymph, return to venous blood

c.     Thymus

d.    Spleen

 

2.    Functions

a.     Transportation

b.    Immunity (body defense)

 

H.   Respiratory system

1.    Structure

a.     Nose

b.    Pharynx

c.     Larynx

d.    Trachea

e.    Bronchi

f.       Lungs

 

2.    Functions

a.     Exchange of waste gas (carbon dioxide) for oxygen in the lungs

b.    Area of gas exchange in the lungs called alveoli

c.     Filtration of irritants from inspired air

d.    Regulation of acid-base balance

 

I.       Digestive system

1.    Structure

a.     Primary organs

·        Mouth

·        Pharynx

·        Esophagus

·        Stomach

·        Small intestine

·        Large intestine

·        Rectum

·        Anal canal

b.    Accessory organs

·        Teeth

·        Salivary glands

·        Tongue

·        Liver

·        Gallbladder

·        Pancreas

·        Appendix

 

2.    Functions

a.     Mechanical and chemical breakdown (digestion) of food

b.    Absorption of nutrients

c.     Undigested waste product that is eliminated is called feces

d.    Appendix is a structural but not a functional part of digestive system

e.    Inflammation of appendix is called appendicitis

 

J.     Urinary system

1.    Structure

a.     Kidneys

b.    Ureters

c.     Urinary bladder

d.    Urethra

 

2.    Functions

a.     “Clearing” or cleaning blood of waste products:  waste product excreted from body is called urine

b.    Electrolyte balance

c.     Water balance

d.    Acid-base balance

e.    In male, urethra has urinary and reproductive functions

 

Reproduction and Development

 

K.   Reproductive system

1.    Structure

a.     Male

·        Gonads – testes

·        Genital ducts – vas deferens, urethra

·        Accessory gland – prostate

·        Supporting structures – genitalia (penis and scrotum)

 

b.    Female

·        Gonads – ovaries

·        Accessory organs – uterus, uterine (fallopian) tubes, vagina

·        Supporting structures – genitalia (vulva), mammary glands (breasts)

 

2.    Functions

a.     Survival of species

b.    Production of sex cells (male: sperm; female: ova)

c.     Transfer and fertilization of sex cells

d.    Development and birth of offspring

e.    Nourishment of offspring

 

7)    The Balance of Body Functions

          Homeostasis: constancy of internal environment

                   Feedback loops:

Stimulus ®Receptor ® regulator center ® effector ®change caused ®eliminates stimulus® control center® shuts down effector or stops stimulating effector

 

 

 

 

                             Negative: control within tight limits

                                      Blood glucose levels: Insulin and glucagon

 

                             Positive:  deal with rare or catastrophic events

                                      Oxytocin and uterine contraction – birth

                                      Blood clotting

 

8)    Disease – loss of homeostasis

 

Local disease – restricted to a specific body part

Systemic – more widespread, involves several organ systems or even the entire body

Acute – sudden occurrence and short duration

Chronic – usually less severe, develop more slowly, last longer