1. Ch. 1 The Human Body: An Orientation Anatomy & Physiology

2. Overview of Anatomy and Physiology Anatomy and Physiology are subdivisions of Biology ▫They explore many of the topics of how our bodies are put together and how they work Anatomy is the study of the structure and shape of the body, body parts and their relationships to one another ▫Gross anatomy is the large, easily observable structures

3. ▫Microscopic anatomy examines very small structures (cells and tissues) in the body Physiology is the study of how the body and its parts work or function ▫There are many subdivisions to physiology: neurophysiology (workings of the nervous system), cardiac physiology (function of the heart muscle) A relationship exists between anatomy and physiology ▫The parts of the body form a well organized unit, and each of those parts has a job to do to make the body operate as a whole ▫Structure determines what function can take place

4. Levels of Structural Organization There are several levels of structural complexity in the human body The levels from simplest to most complex are as follows: ▫Chemical Level ▫Cellular Level ▫Tissue Level ▫Organ Level ▫Organ System Level ▫Organismal Level

5. Chemical Level ▫This level was examined over the summer in Chapter 2 with basic Chemistry ▫At this level, atoms combine to form molecules ▫Molecules associate to form microscopic cells Cellular Level ▫This level was also examined over the summer in Chapter 3 with the study of the cell ▫Individual cells vary widely in size and shape, reflecting their particular functions in the body Tissue Level ▫Tissues consist of groups of similar cells that have a common function

6. Organ Level ▫An organ is a structure, composed of two or more tissue types, that performs a specific function for the body ▫At the organ level, extremely complex functions become possible ▫All of the body’s organs are grouped into a number of organ systems ▫An organ system is a group of organs that cooperate to accomplish a common purpose Organ System Level ▫Group of organs that cooperate to accomplish a common purpose Organismal Level ▫11 organ systems make up the living body, the organism, which represents the highest level

8. Organ System Overview There are 11 organ systems in the human body Integumentary System ▫This makes up the external covering of the body ▫It waterproofs the body, cushions and protects the deeper tissues from injury ▫Regulates body temperature and alerts us by way of receptors at to what is happening at the body surface

9. Skeletal System ▫Consists of bones, cartilages, ligaments, and joints ▫It supports the body and provides a framework that the muscles can use to cause movement Muscular System ▫The muscles of the body have only one job and that is to contract or shorten causing movement ▫Skeletal muscles form the muscular system which are distinct from muscles of the heart and other hollow organs Nervous System ▫The body’s fast-acting control system that allows the body to respond to stimuli ▫Consists of the brain, spinal cord, nerves, and sensory receptors

10. Endocrine System ▫Controls body activities, but it acts much more slowly ▫The glands produce hormones and release them into the blood to travel to distant organs Cardiovascular System ▫Carries oxygen, nutrients, hormones and other substances to and from tissue cells where exchanges are made Lymphatic System ▫The organs of this system help to cleanse the blood and house the cell involved in immunity

11. Respiratory System ▫Keeps the body constantly supplied with oxygen and removes carbon dioxide Digestive System ▫Organs break down food and deliver the products to the blood for dispersal to the body cells Urinary System ▫Removes nitrogen-containing wastes from the blood and flushes them from the body in the urine ▫Also helps to maintain the body’s water and salt balance and regulate the acid-base balance of the blood Reproductive System ▫Primary function is to produce offspring

12. Maintaining Life Organ systems do not work in isolation; instead they work together to promote the wellbeing of the entire body There are several necessary life functions that must occur in the human body: ▫1) Movement – includes all the activities promoted by the muscular system plus the movement of blood, digested food and urine through the various system

13. ▫2) Responsiveness – the ability to sense stimuli in the environment and then react to them ▫3) Digestion – the process of breaking down ingested food into simple molecules that can then be absorbed into the blood for delivery to all body cells ▫4) Metabolism – refers to all chemical reactions that occur within body cells ▫5) Excretion – the process of removing wastes from the body ▫6) Reproduction – the production of offspring (cellular and organismal level) ▫7) Growth – increase in size, usually accomplished by an increase in the number of cells

14. Survival Needs The goal of nearly all body systems is to maintain life Several factors (survival needs) have to be available: ▫1) Nutrients – contain the chemicals used for energy and cell building ▫2) Oxygen – all chemical reactions that release energy from food requires oxygen ▫3) Water – the single most abundant chemical substance in the body (60% – 80% of body weight); provides the fluid base for body secretions and excretions

15. ▫4) Body Temperature – must be maintained at around 98 o F; drastic changes will have a fatal outcome ▫5) Atmospheric Pressure – breathing and the exchange of oxygen and carbon dioxide in the lungs depends on appropriate atmospheric pressure

16. Homeostasis Homeostasis is the body’s ability to maintain relatively stable internal conditions It indicates a dynamic state of equilibrium (a balance in which internal conditions change and vary, but always within relatively narrow limits) In general, the body is in homeostasis when its needs are being adequately met and it is functioning smoothly Every body system plays a role in maintaining homeostasis

17. Homeostatic Control Mechanisms Communication within the body is essential for homeostasis and is accomplished chiefly by the nervous and endocrine systems All homeostatic control mechanisms have at least three components: ▫1) Receptor – some type of sensor that monitors and responds to stimuli in the environment by sending information (input) to the control center ▫2) Control Center – determines the level at which a variable is to be maintained, analyzes the information received and then determines the appropriate response or action

18. ▫3) Effector – provides the means for the control center’s response (output) to the stimulus Information flows from the control center to the effector along the efferent pathway The results of the response then feed back to influence the stimulus ▫The influence can either depress it (negative feedback) so that the whole control mechanism is shut off, or enhancing it (positive feedback) so that the reaction continues at an even faster rate Most homeostatic control mechanisms are negative feedback mechanisms

19. Homeostatic Imbalance Homeostasis is so important that most disease is regarded as a result of its disturbance As we age our body organs become less efficient, and our internal conditions become less and less stable These events place us at an ever greater risk for illness and produce the changes we associate with aging

20. Language of Anatomy Anatomical Position and Directional Terms ▫To accurately describe body parts and position, we must have an initial reference point and use directional terms ▫Standard position, called anatomical position, is always assumed so that there is no confusion  Anatomical position means that the body is erect with the feet parallel and the arms hanging at the sides with the palms facing forward

21. ▫Directional terms used by medical personal and anatomists allow them to explain exactly where one body structure is in relation to another ▫There are many visible landmarks on the surface of the body these are referred to as anterior body landmarks and posterior body landmarks Body Planes and Sections ▫When looking at internal structures of the body a section must be made first ▫When the section is made through the body wall or organ, it is made along an imaginary line called a plane ▫Since the body is three-dimensional, we can refer to three types of planes or sections that lie at right angles to each other

22.  Sagittal section is a cut made along the lengthwise plane of the body dividing it into right and left parts  Midsagittal (median) section occurs when the cut is made down the middle of the body dividing it into equal right and left parts  The frontal section is a cut made along a plane that divides the body (or organ) into anterior and posterior parts  Also called a coronal section  A transverse section is a cut made along a horizontal plane, dividing the body or organ into superior and inferior parts  Also called a cross section

24. Body Cavities The body has two sets of internal cavities that provide different degrees of protection to the organs within them Dorsal Body Cavity ▫The dorsal body cavity has two subdivisions, which are continuous with each other  The cranial cavity is the space inside the bony skull  The spinal cavity extends from the cranial cavity nearly to the end of the vertebral column

25. Ventral Body Cavity ▫The ventral body cavity is much larger than the dorsal body cavity ▫It contains all the structures within the chest and abdomen ▫The thoracic cavity contains the heart and lungs and is separated from the rest of the ventral cavity by the diaphragm ▫Below the thoracic cavity is the abdominopelvic cavity  The superior abdominal cavity contains the stomach, liver, intestines  The inferior pelvic cavity contains the reproductive organs, bladder, and rectum

26. Divisions of the abdominopelvic cavity ▫Since the cavity is large and contains many organs, it is helpful to divide it up into smaller areas for study ▫The cavity can be divided up into four fairly equal quadrants:  Right upper quadrant; right lower quadrant; left upper quadrant; left lower quadrant ▫The cavity can also be divided up into nine separate regions: ▫Right hypochondriac region; epigastric region; left hypochondriac region; right lumbar region; umbilical region; left lumbar region; right iliac region; hypogastric region; left iliac region