Chapter 1

Human Body

Orientation

Anatomy• Study of structure

– Types• Gross Anatomy: the study of large body

structures visible to the naked eye such as the heart or lungs

• Microscopic Anatomy: the study of structures too small to be seen without a microscope such as tissues and cells

• Developmental Anatomy: the study of structural changes that occur in the body throughout the lifespan

Physiology

• The study of the function of the body– Types

• Renal Physiology: kidney function and urine production

• Neurophysiology: nervous system• Cardiovascular Physiology: heart and blood

vessels

Structure determines Function

• How a cell looks determines what the cell does. (ex. Long dendrites on a nerve cell allows it to send signals quickly)

• How an organ looks determines how well it functions.

Levels of Structural Organization

• 1. chemical level (atoms & molecules)• 2. cellular level (cells & organelles)• 3. tissue level (groups of similar cells that have

a common function)• 4. organ level (discrete structures composed of

at least two tissue types)• 5. organ system (organs work together to

accomplish a common purpose)• 6. organismal level (the sum total of all

structural levels)

Necessary Life Functions

• 1. maintaining boundaries: internal boundaries remain distinct from external environment

• 2. movement: activities of the muscular system, etc.• 3. responsiveness: the ability to sense changes

(stimuli) and respond to them• 4. digestion: breaking down food to simple molecules• 5. metabolism: chemical reactions in the body• 6. excretion: removing wastes• 7. reproduction: cellular or organismal• 8. growth: increase in the size of cells, body parts, or

the organism itself

Survival Needs

• 1. nutrients: contain the chemical substances used for energy and cell building

• 2. oxygen: allows cellular respiration to occur• 3. water: accounts for 60-80% of body weight,

needed for chemical reactions• 4. normal body temperature: maintains

metabolic reactions• 5. atmospheric pressure: needed for proper

breathing and gas exchange in the lungs

Homeostasis

• The ability to maintain a stable internal environment

• Every organ system plays a role in maintaining the constancy of the internal environment

Negative Feedback

• The output shuts off the original stimulus or reduces its intensity (prevents sudden severe changes in the body)

• These mechanisms cause the variable to change in a direction opposite to that of the initial change

• Ex. Body temperature and blood volume

Positive Feedback • The response enhances

the original stimulus so that the activity is accelerated

• The change that occurs is in the same direction as the initial disturbance

• Ex. Oxytocin: intensifies labor contractions

Response to Environment

• Nervous system – electrochemical– Afferent pathway – (arriving) receptor stimuli

to control center– Efferent pathway – (exiting) control center

• Ex. hot stove and hand

• Endocrine system – hormones

• Ex. insulin and glucose

Orientation and Direction

• Cranial• Caudal• Ventral• Dorsal• Superior• Inferior• Medial• Lateral• Proximal• Distal

Body Planes and Sections

• Sagittal: divides body into right and left

• Median: sagittal along the midline

• Frontal (coronal): divides body into anterior and posterior

• Transverse: horizontal; divides body into superior and inferior parts

Body Cavities• Dorsal

– Cranial & vertebral

• Ventral– Thoracic

• Pleural cavities – houses lungs

• Mediastinum – houses heart, trachea, esophagus

– Abdominal-- Pelvic

Membranes of Body Cavities

• Serous membranes– Covering on organs

• Parietal serosa: lines the cavity walls

• Visceral serosa: covers the organs

• Serous fluid: lubricating fluid

• Peritonitis- inflammation of the membrane lining of the abdominal cavity

Abdominopelvic Quadrants

Other Body Cavities

• 1. oral and digestive• 2. nasal• 3. orbital• 4. middle ear• 5. synovial

11 Systems

• Cardiovascular• Skeletal• Integumentary• Lymphatic• Urinary• Muscular• Digestive• Respiratory• Reproductive• Nervous• Endocrine