A&P I - Intro to the Human Body PDF

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A&P I
The Human Body: An Orientation...

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The Human Body: An Orientation: Overview of Anatomy and Physiology • Anatomy: The study of structure • Subdivisions: • Gross or macroscopic (e.g., regional, surface, and systemic anatomy) • Microscopic (e.g., cytology and histology) • Developmental (e.g., embryology)

• Essential tools for the study of anatomy: • Mastery of anatomical terminology • Observation • Manipulation • Palpation • Auscultation

• Physiology: The study of function at many levels • Subdivisions are based on organ systems (e.g., renal or cardiovascular physiology)

• Essential tools for the study of physiology: • Ability to focus at many levels (from systemic to cellular and molecular) • Basic physical principles (e.g., electrical currents, pressure, and movement) • Basic chemical principles

Principle of Complementarity • Anatomy and physiology are inseparable. • Function always reflects structure • What a structure can do depends on its specific form

Levels of Structural Organization • Chemical: atoms and molecules (Chapter 2) • Cellular: cells and their organelles (Chapter 3) • Tissue: groups of similar cells (Chapter 4) 1|Page

• Organ: contains two or more types of tissues • Organ system: organs that work closely together • Organismal: all organ systems Overview of Organ Systems • Note major organs and functions of the 11 organ systems (Fig. 1.3) REVIEW ORGAN SYSTEMS PAGES 6-7 Organ Systems Interrelationships • All cells depend on organ systems to meet their survival needs • Organ systems work cooperatively to perform necessary life functions Necessary Life Functions 1 Maintaining boundaries between internal and external environments • Plasma membranes • Skin

2 Movement (contractility) • Of body parts (skeletal muscle) • Of substances (cardiac and smooth muscle)

3 Responsiveness: The ability to sense and respond to stimuli • Withdrawal reflex • Control of breathing rate

4 Digestion • Breakdown of ingested foodstuffs • Absorption of simple molecules into blood

5 Metabolism: All chemical reactions that occur in body cells • Catabolism and anabolism

6 Excretion: The removal of wastes from metabolism and digestion • Urea, carbon dioxide, feces

7 Reproduction • Cellular division for growth or repair • Production of offspring 2|Page

8 Growth: Increase in size of a body part or of organism Survival Needs 1 Nutrients • Chemicals for energy and cell building • Carbohydrates, fats, proteins, minerals, vitamins

2 Oxygen • Essential for energy release (ATP production)

3 Water • Most abundant chemical in the body • Site of chemical reactions

4 Normal body temperature • Affects rate of chemical reactions

5 Appropriate atmospheric pressure • For adequate breathing and gas exchange in the lungs

Homeostasis • Maintenance of a relatively stable internal environment despite continuous outside changes • A dynamic state of equilibrium Homeostatic Control Mechanisms • Involve continuous monitoring and regulation of many factors (variables) • Nervous and endocrine systems accomplish the communication via nerve impulses and hormones Components of a Control Mechanism 1 Receptor (sensor) • Monitors the environment • Responds to stimuli (changes in controlled variables) 2 Control center • Determines the set point at which the variable is maintained • Receives input from receptor • Determines appropriate response

3 Effector • Receives output from control center 3|Page

• Provides the means to respond • Response acts to reduce or enhance the stimulus (feedback)

Negative Feedback • The response reduces or shuts off the original stimulus • Examples: • Regulation of body temperature (a nervous mechanism) • Regulation of blood volume by ADH (an endocrine mechanism)

Negative Feedback: Regulation of Blood Volume by ADH • Receptors sense decreased blood volume • Control center in hypothalamus stimulates pituitary gland to release antidiuretic hormone (ADH) • ADH causes the kidneys (effectors) to return more water to the blood Positive Feedback • The response enhances or exaggerates the original stimulus • May exhibit a cascade or amplifying effect • Usually controls infrequent events e.g.: • Enhancement of labor contractions by oxytocin (Chapter 28) • Platelet plug formation and blood clotting

Homeostatic Imbalance • Disturbance of homeostasis • Increases risk of disease • Contributes to changes associated with aging • May allow destructive positive feedback mechanisms to take over (e.g., heart failure)

Anatomical Position •Standard anatomical body position: •Body erect •Feet slightly apart •Palms facing forward

Regional Terms 4|Page

•Two major divisions of body: •Axial •Head, neck, and trunk •Appendicular •Limbs

•Regional terms designate specific areas Body Planes •Plane: Flat surface along which body or structure is cut for anatomical study •Sagittal plane •Divides body vertically into right and left parts •Produces a sagittal section

•Midsagittal (median) plane •Lies on midline

•Parasagittal plane •Not on midline

•Frontal (coronal) plane •Divides body vertically into anterior and posterior parts

•Transverse (horizontal) plane •Divides body horizontally into superior and inferior parts •Produces a cross section

•Oblique section •Cuts made diagonally

Anatomical Variability •Over 90% of all anatomical structures match textbook descriptions, but: •Nerves or blood vessels may be somewhat out of place •Small muscles may be missing

Body Cavities •Dorsal cavity •Protects nervous system

•Two subdivisions: •Cranial cavity •Encases brain 5|Page

•Vertebral cavity •Encases spinal cord

•Ventral cavity •Houses internal organs (viscera) •Two subdivisions (separated by diaphragm): •Thoracic cavity •Abdominopelvic cavity

Ventral Body Cavities •Thoracic cavity subdivisions: •Two pleural cavities •Each houses a lung •Mediastinum •Contains pericardial cavity •Surrounds thoracic organs •Pericardial cavity •Encloses heart

•Abdominopelvic cavity subdivisions: •Abdominal cavity •Contains stomach, intestines, spleen, and liver •Pelvic cavity •Contains urinary bladder, reproductive organs, and rectum

Serous Membrane (Serosa) •Thin, double-layered membrane separated by serous fluid •Parietal serosa lines internal body walls •Visceral serosa covers the internal organs

Abdominopelvic Regions •Nine divisions used primarily by anatomists Abdominopelvic Quadrants •Divisions used primarily by medical personnel Other Body Cavities •Oral and digestive cavities •Nasal cavity 6|Page

•Orbital cavities •Middle ear cavities •Synovial cavities

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