1. AP1HumanBodyOrientation

7/30/2019 1. AP1HumanBodyOrientation

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THE HUMAN BODY

AN ORIENTATION

An Overview

ofAnatomy and Physiology


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Anatomy

Study of the structure of body parts andtheir relationships to each other

Anatomy: Greek meaning to cut apart


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Physiology

Study of the function of body parts

How all the body parts work and carryout their life-sustaining activities


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Topics of Anatomy

Gross (macroscopic) anatomy: the study of structures largeenough to be seen with the naked eye

Regional anatomy: all the body structures (muscles, bones, bloodvessels, nerves, etc.) in a given body region , such as the abdomen

or leg, are examined at the same time Systemic anatomy: body is studied system by system Example: when studying the cardiovascular system, you would examine

the heart and the blood vessels of the entire body

Surface anatomy: internal body structures as they relate to theoverlying skin

Used when identifying the bulging muscles beneath a bodybuildersskin, and clinicians use it to locate appropriate blood vessels in which tofeel pulses and draw blood


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Topics of Anatomy

Microscopic anatomy: the study of structuresthat are too small to be seen with the naked eye

Cytology: study of individual cells

Histology: study of tissues

Developmental anatomy: the study of thechange in body structures over the course of a

lifetime

Embryology: concerns developmental changes thatoccur before birth


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Topics of Anatomy

Specialized Branches of Anatomy

Pathological anatomy: study of structuralchanges associated with disease

Radiographic anatomy: study of internalstructures using specialized visualization

techniques (X-rays or special scanning

devices) Molecular biology: study of biological

molecules


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Topics of Physiology

Considers the function of specific organsystems: Examples:

Renal physiology: concerns kidney function and urine

production Neurophysiology: explains the workings of the nervous

system

Cardiovascular physiology: examines the operation of theheart and blood vessels

While anatomy provides us with a staticimage of the bodys architecture, physiologyreveals the bodys dynamic nature


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Complementarity of Structure and

Function

Function is dependent on structure, and theform of a structure relates to its function:

What a structure can do depends on its specific

form Examples:

Bones can support body organs because they contain hard

mineral deposits

Blood flows in one direction through the heart because the

heart has valves that prevent backflow

Lungs can serve as a site for gas exchange because the

walls of their air sacs are extremely thin


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Levels of Structural Organization

(1):Chemical level is thesimplest level oforganization: Atoms, tiny building blocks of

matter, combine to formmolecules such as water and

proteins Molecules combine in

specific ways to formorganelles, which are thebasic unit of living cells

Cells are the smallest unitsof living things

All cells have some commonfunctions, but individual cellsvary widely in size and shape,reflecting their uniquefunctions in the body


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(2):Cellular level: smallest unit oflife, and varies widely in size andshape according to the cellsfunction

(3):Tissue level: groups of similarcells having a common function

Four basic tissue types: eachtissue type has a characteristicrole in the body

Epithelium: covers the bodysurface and lines its cavities

Muscle: provides movement Connective: supports and

protects body organs

Nervous: provides a means ofrapid internal communication bytransmitting electrical impulses


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(4):Organ level: made up of discretestructures that are composed of aleast two groups of tissues that worktogether to perform a specific functionin the body Stomach: epithelium lining, muscles,

blood vessels, connective tissues,nerve fibers, etc.

(5):Organ system level: a group oforgans that work closely together toaccomplish a specific purpose Respiratory and circulatory system,

digestive and circulatory systems

(6):Organismal level: the total of allstructures working together to promotelife The living human being


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Maintaining Life

Necessary Life Functions (a): Maintaining Boundaries: allows an organism to

maintain separate internal and external environments, orseparate internal chemical environments Integumantary System or Skin

(b): Movement: allows the organism to travel throughthe environment, and allows transport of moleculeswithin the organism Skeletal, Circulatory, Muscular Systems

(c): Responsiveness: or irritability, is the ability todetect changes in the internal or external environmentand respond to them Muscular System


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ORGAN SYSTEMS


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Maintaining Life

Necessary Life Functions

(d): Nervous System:

Responsiveness to external and internal

environments by activating muscles and glands

(e): Endocrine System: Regulating body functions such as: growth,

reproduction, and nutrition

(f): Cardiovascular System:

Transportation of nutrients, waste, gases, and

hormones throughout the body


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Maintaining Life


(g): Lymphatic System/Immunity:

Body defenses

(h): Respiratory System:

External and internal gas exchanges

(i): Digestive System:

Breakdown and absorption of nutrients


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ORGAN SYSTEMS


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Maintaining Life


(j): Urinary System:

Absorption of waste from the blood and

elimination

(k): Male Reproductive System:

Production of sperm

(l): Female reproductive System:

Production of eggs


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ORGAN SYSTEMS


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Maintaining Life


Digestion is the process of breaking down foodinto molecules that are usable by the body

Metabolism includes all chemical reactions

that occur in the body Excretion is the process of removing wastes

Reproduction is the process of producing more

cells or organisms Growth is an increase in size in body parts or

the whole organism


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Examples of selected interrelationships

among body organ systems

Integumentary systemprotects the body as a wholefrom the external environment

Digestive and respiratorysystems, in contact with the

external environment, take innutrients and oxygen,respectively, which are thendistributed by the blood to allbody cells

Elimination of metabolic

wastes is accomplished by theurinary and respiratorysystems


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ORGAN SYSTEMS


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Survival Needs

The ultimate goal of all body systems is to maintain life

Life is extraordinarily fragile and requires that severalfactors be present: These factors are called survival needs and include:

Nutrients: consumed chemical substances that are used for energyand cell building

Oxygen: required by the chemical reactions that release energyfrom foods

Water: most abundant chemical substance in the body, provides anenvironment for chemical reactions and a fluid for secretions and

excretions Normal body temperature: required for the chemical reactions of

the body to occur at the proper rate

Atmospheric pressure: must be within an appropriate range sothat proper gas exchange occurs in the lungs


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Homeostasis

The ability of the body to maintain a

relatively constant internal environment,

regardless of environmental changes:

Body temperature

Blood pH


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Homeostatic Control Mechanisms

Communication within thebody is essential forhomeostasis Accomplished chiefly by the

nervous and endocrinesystems

All homeostatic controlmechanisms have at leastthree interdependentcomponents:

1. Receptor: type of sensorthat monitors the environment

and responds to changes,called stimuli, by sendinginformation (input) to thesecond component (controlcenter)


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2. Control Center: Information flows from

the receptor to thecontrol center along theafferent pathway

Structure that determinesthe set point (level or rangeat which a variable is to bemaintained) for a variable,analyzes input, andcoordinates an appropriateresponse

Variable: the regulatedfactor or event


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3. Effector: Provides the means for the control

centers response (output) to thestimulus

Structure that carries out theresponse directed by the controlcenter

Information flows from thecontrol center to the effectoralong theefferent pathway

The results of the responsethen feed back to influence thestimulus, either depressing it(negative feedback)so that thewhole control mechanism is

shut off or enhancing it(positive feedback)so that thereaction continues at an evenfaster rate


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CONTROL SYSTEM


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Negative Feedback Mechanisms

Most homeostatic control mechanisms arenegative feedback mechanisms

In these systems, the output shuts off theoriginal stimulus or reduces its intensity

These mechanism cause the variable to change ina direction oppositeto that of the initial change,returning it to its ideal value

Both the nervous system and the endocrinesystem are important to the maintenance ofhomeostasis

The goal of negative feedback mechanisms isto prevent sudden, severe changes in the body


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Home heating system connected to a temperature-sensing thermostat Thermostat houses BOTH the receptor and the control center

If thermostat is set at 20oC (68oF), the heating system (effector)is triggered ON when the house temperature drops below thatsetting

As the furnace produces heat and warms the air, thetemperature rises, and when it reaches 20oC or slightly higher,the thermostat triggers the furnace OFF

This process results in a cycling of furnace-ON and furnace-OFF

so that the temperature in the house stays very near the desiredtemperature of 20oC

Your body thermostat, located in a part of your brain calledthe hypothalamus, operates in a similar fashion


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To carry out normal metabolism,body cells need a continuoussupply of glucose, their major fuel forproducing cellular energy, or ATP

Blood sugar levels are normallymaintained around 90 milligrams (mg)of glucose per 100 millimeters (ml) ofblood

Rising glucose levels stimulate theinsulin-producing cells of the pancreas,which respond by secreting insulin intothe blood Insulin accelerates the uptake of

glucose by most body cells It also encourages storage of excess

glucose as glycogen in the liver and

muscles Consequently, blood sugar levels

ebb back toward the normal setpoint, and the stimulus for insulinrelease diminishes


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NEGATIVE FEEDBACK


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Glucagon, another pancreatichormone, has the opposite effect ofinsulin Its release is triggered as blood sugar

levels decline below the set point

Glucagon secretion is stimulated

Glucagon targets the liver, causing it torelease its glucose reserves from

glycogen into the blood Consequently, blood sugar levels

increase back into the homeostaticrange

There are hundreds of NegativeFeedback Mechanisms (regulationof heart rate, blood pressure, rateand depth of breathing, and bloodlevels of oxygen, carbon dioxide,and minerals)


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NEGATIVE FEEDBACK


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Positive Feedback Mechanisms

Result or response enhances the original stimulus sothat the activity (output) is accelerated

A positive feedback mechanism causes the variable tochange in the same direction as the original change,

resulting in a greater deviation from the set point Positive feedback mechanisms typically activate events

that are self-perpetuating Once initiated, have an amplifying effect

Most positive feedback mechanisms are not relatedto the maintenance of homeostasis Homeostatic imbalance often results in disease


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Examples:

Enhancement of labor contractions duringbirth:

Oxytocin, a hypothalamic hormone, intensifieslabor contractions during the birth of a baby

Causes the contractions to become more frequentand more powerful until the baby is finally born, anevent that ends the stimulus for oxytocin release andshuts off the positive feedback mechanism


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Examples: Blood clotting:

Blood clotting is a normalresponse to a break in thelining of a blood vessel

1. Once vessel damaged

has occurred 2. Blood elements called

platelets immediatelybegin to cling to theinjured site

3. Platelets releasechemical that attract moreplatelets

4. This rapidly growingpileup of platelets initiatesthe sequence of eventsthat finally forms a clot


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POSITIVE FEEDBACK


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Homeostatic Imbalance

Homeostasis is so important that mostdisease is regarded as a result of itsdisturbance, a condition called

Homeostatic Imbalance Causes:

As we age, our bodys control systems become

less efficient Negative feedback mechanisms become

overwhelmed and destructive positive feedback

mechanisms take over


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Language of Anatomy

Anatomical Position and Directional Terms

To describe body parts and positionaccurately, we need an initial reference pointand must indicate direction

The anatomical reference point is a standardbody position called the Anatomical Position

Anatomical Position: position in which thebody is:

Erect with feet only slightly apart Palms face forward

Thumbs point away from the body


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REGION TERMS


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REGION TERMS


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Language of Anatomy


In anatomical position, right and left referto the right and left sides of the personviewedNOT those of the observer

In anatomy, anatomical position is always

assumed, regardless of the actual position

of the body


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Language of Anatomy


Directional terms are used to explain

exactly where one body part is in relation

to another

Example:

The ears are located on each side of the head to

the right and left of the nose

Using anatomical terminology, this condenses to,:

The ears are lateral to the nose

Saves words and is less ambiguous

Anatomical meanings are VERY PRECISE


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Orientation and Directional Terms


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Orientation and Directional Terms


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Regional Terms

There are two fundamental divisions of thebody: Axial region:

Makes up the main axis of our body

Includes the head, neck, and trunk

Appendicular region: Consists of the appendages, or limbs

Attached to the bodys axis

Consists of the upper and lower limbs

Regional terms are used to designate specificareas within the major body divisions The common term for each of these body regions

is provided (in parentheses)


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REGION TERMS


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REGION TERMS


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BODY PLANES


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Body Planes and Sections

Transverse, or horizontal, plane: a plane that runshorizontally from right to left, and divides the body intosuperior and inferior parts Many different transverse planes exist, at every possible level

from head to foot

Transverse section, or cross section, is a cut made along thetransverse plane

Oblique sections are cuts made at angles between the horizontal andvertical planes

The ability to interpret sections made through the

body, especially transverse sections, is important inthe clinical sciences New medical imaging devices produce sectional images

rather than three-dimensional images


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BODY PLANES


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Body Cavities and Membranes

Within the axial portion of the body are two

large cavities called the dorsal andventral body cavities

Body cavities are spaces within the bodythat are closed to the outside and contain

the internal organs


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BODY CAVITIES


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BODY CAVITIES


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Dorsal Body Cavity

The space that houses the central nervous

system, and has two subdivisions: the

cranial cavity and the vertebral cavity

Cranial cavity is within the skull, andencases the brain

Vertebral, or spinal, cavity is within the

vertebral column, and encloses the spinalcord


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BODY CAVITIES


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BODY CAVITIES


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Ventral Body Cavity

Is anterior to and larger than the dorsal cavity and has two mainsubdivisions: the thoracic cavity, and the abdominopelvic cavity Houses the body organs collectively called the viscera (viscus=an organ

in a body cavity), orvisceral organs Thoracic cavity:

Is a superior division of the ventral cavity that is further subdivided into the

lateral pleural cavities that surround the lungs Thoracic cavity also contains the medulla mediastinum, which includes thepericardial cavity surrounding the heart and the space surrounding the otherthoracic structures (esophagus, trachea, and others)

Diaphragm Muscle separates the Thoracic and AbdominopelvicRegions

Abdominopelvic Regions and Quadrants:

Inferior to the Thoracic Cavity There are nine abdominopelvic regions used primarily by anatomists

There are four quadrants used primarily by medical personnel


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BODY CAVITIES


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BODY CAVITIES


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Membranes in the Ventral Body Cavity

The walls of the ventral body cavity and the outer surfaces of the organs itcontains are covered by a thin, double-layered membrane, the serosa, orserous membrane Serous membranes, or serosae, cover the inner walls of the ventral cavity and

the outer surfaces of organs Serous membranes secrete and are separated by a thin layer of lubrication fluid called

serous fluid, which allows organs to slide without friction along cavity walls andbetween each other

Parietal serosa lines the body cavity walls, and is named for the specific cavitiesit is associated with

Visceral serosa covers the outer surfaces of organs, and is named for thespecific organs it is associated with

Parietal pericardium lines the pericardial cavity Visceral pericardium covers the heart within that cavity Parietal pleura lines the walls of the thoracic cavity

Visceral pleura covers the lungs Parietal peritoneum is associated with the walls of the abdominalpelvic cavity Visceral peritoneum covers most of the organs within that cavity


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SEROUS MEMBRANE

Parietal pericardiumlines the pericardial

cavity

Visceral pericardiumcovers the heart

within that cavity


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SEROUS MEMBRANE


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Membranes in the Ventral Body Cavity

You can visualize therelationship betweenthe serosal layers bypushing your fist into alimp balloon The part of the balloon that

clings to your fist can becompared to the visceralserosaclinging to theorgans external surface

The outer wall of theballoon then represents theparietal serosathat linesthe walls of the cavity


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SEROUS MEMBRANE


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Homeostatic Imbalance

When serous membranes are inflamed,they typically produce less lubricatingserous fluid

This leads to excruciating pain as the organsstick together and drag across one another,

as anyone who has experienced pleurisy(inflammation of the pleurae: thoracic cavity)

orperitonitis(inflammation of the peritoneal:abdominal cavity)


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Abdominopelvic Regions

Because the abdominopelviccavity is large and containsseveral organs, it helps todivide it into smaller areas forstudy

Cavity divided into 9 regions

Umbilical region: centermostregion deep to andsurrounding the umbilicus(navel)

Epigastric region: locatedsuperior to the umbilicalregion (epi=upon, above;gastri=belly)

Hypogastric (pubic) region:located inferior to theumbilical region (hypo=below)


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ABDOMINAL REGION


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ABDOMINAL REGIONS


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Abdominopelvic Regions

Right and left iliac, oringuinal regions: locatedlateral to the hypogastricregion (iliac=superior part ofthe hip bone)(inguinal=groin:between thigh and trunk)

Right and left lumbarregions: lie lateral to theumbilical region (lumbus=loin:between ribs and pelvis)

Right and left

hypochondriac regions: flankthe epigastric region laterally(chondro=cartilage)


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ABDOMINAL REGION


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ABDOMINAL REGIONS

Q


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Quadrants

Medical personnel usuallyuse a simpler scheme tolocalize the abdominopelviccavity organs

In this scheme, onetransverse and one mediansagittal plane pass through theumbilicus at right angles

The resulting quadrants arenamed according to theirpositionsfrom the subjectspoint of view:

Right upper quadrant (RUQ)

Left upper quadrant (LUQ)

Right lower quadrant (RLQ)

Left lower quadrant (LLQ)

ABDOMINAL REGION


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ABDOMINAL REGION


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OTHER CAVITIES


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OTHER CAVITIES


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IMAGING


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IMAGING

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