The Human Body: An Orientation

1The Human Body: An Orientation

P A R T A

Overview of Anatomy and Physiology

• Anatomy – (Greek – to cut up) - the study of the structure of body parts and their relationships to one another

• Gross or macroscopic• Microscopic• Developmental

• Physiology – (Greek – study of nature) - the study of the function of the body’s structural machinery; explains physical & chemical processes that direct body activities

Gross Anatomy

• Regional – all structures in one part of the body (such as the abdomen or leg)

• Systemic – gross anatomy of the body studied by system• Surface – study of internal structures as they relate to the overlying

skin

Microscopic Anatomy

• Cytology – study of the cell• Histology – study of tissues

Developmental Anatomy• Traces structural changes throughout life• Embryology – study of developmental changes of the body before

birth

Specialized Branches of Anatomy

• Pathological anatomy – study of structural changes caused by disease• Radiographic anatomy – study of internal structures visualized by

specialized scanning procedures such as X-ray, MRI, and CT scans• Molecular biology – study of anatomical structures at a subcellular

level

Physiology

• Considers the operation of specific organ systems• Renal – kidney function• Neurophysiology – workings of the nervous system• Cardiovascular – operation of the heart and blood vessels

• Focuses on the functions of the body, often at the cellular or molecular level

• Understanding physiology also requires a knowledge of physics, which explains

• electrical currents• blood pressure• the way muscle uses bone for movement

Principle of Complementarity

• Function always reflects structure• What a structure can do depends on its specific form• Core theme - Structure (anatomy) determines what functions

(physiology) can take place; if structure changes, the function must also change

6 Levels of Structural Organization

1. Chemical – atoms combine to form molecules which combine to form cells

2. Cellular – smallest unit of life; human composed of 60-100 trillion cells; combine to form tissues

3. Tissue – groups of cells that perform a common function; four types = epithelial, connective, muscular, & nervous

4. Organ – composed of two or more tissue types that perform a specific function; most contain all 4 tissue types

5. Organ system – group of organs that cooperate to accomplish a common purpose; ex. circulatory system, digestive system, etc.

6. Organismal – highest level of structural organization; all systems of body working together

1

Molecules

Atoms

Chemical levelAtoms combine toform molecules.

Levels of Structural Organization

Figure 1.1

1

2

Smooth muscle cellMolecules

AtomsCellular levelCells are made up ofmolecules.


Figure 1.1

1

2

3


Atoms

Smoothmuscletissue

Cellular levelCells are made up ofmolecules.

Tissue levelTissues consist ofsimilar types of cells.


Figure 1.1

1

2

4

3


Atoms

Smoothmuscletissue

Epithelialtissue

Smoothmuscletissue

Connectivetissue

Bloodvessel(organ)



Organ levelOrgans are made upof different typesof tissues.


Figure 1.1

1

2

4

5

3


Atoms

Smoothmuscletissue

Epithelialtissue

Heart

Bloodvessels

Smoothmuscletissue

Connectivetissue

Bloodvessel(organ)

Cardiovascularsystem




Organ system levelOrgan systems consist ofdifferent organs thatwork together closely.


Figure 1.1

1

2

4

5

6

3


Atoms

Smoothmuscletissue

Epithelialtissue

Heart

Bloodvessels

Smoothmuscletissue

Connectivetissue

Bloodvessel(organ)

Cardiovascularsystem




Organ system levelOrgan systems consist ofdifferent organs thatwork together closely.

Organismal levelThe human organismis made up of manyorgan systems.


Figure 1.1

10 Necessary Life Functions1. Maintaining boundaries – the internal environment remains distinct from the external environment

• Cellular level – accomplished by plasma membranes• Organismal level – accomplished by the skin

2. Organization – structure & functions is determined by genetics

3. Movement – locomotion, propulsion (peristalsis), blood, breathing, molecules, and contractility

4. Responsiveness – ability to monitor internal or external conditions and react to changes

5. Digestion – breakdown of ingested foodstuffs; process by which complex substances are converted to simpler forms so that they can be absorbed through intestinal wall & transported by blood

6. Metabolism – all the chemical reactions that occur in the body; releases energy, creates body heat, enables cells to synthesize & secrete molecules

7. Excretion – removal of wastes produced by metabolism

8. Reproduction – cellular and organismal levels• Cellular – an original cell divides and produces two identical

daughter cells• Organismal – sperm and egg unite to make a whole new person

9. Growth – increase in size of a body part or of the organism

10. Differentiation – result in structurally and functionally distinct organs

Survival Needs• Nutrients – needed for energy and cell building• Oxygen – 20% of air; needed for release of energy

during cellular respiration and for metabolic reactions

• Water – min. 60% of body weight; provides the necessary environment for chemical reactions

• Normal body temperature – necessary for chemical reactions to occur at life-sustaining rates

• Atmospheric pressure – required for proper breathing and gas exchange in the lungs

Homeostasis

• Homeostasis – ability to maintain a relatively stable internal environment in an ever-changing outside world

• The internal environment of the body is in a dynamic state of equilibrium

• Chemical, thermal, and neural factors interact to maintain homeostasis; necessary for survival and good health; its loss results in illness or disease

Homeostatic Control Mechanisms• Variables produce a change in the body• The three interdependent components of control

mechanisms:1. Receptor (sensor) – responds to a stimuli

(environmental change) by sending information to the control center

2. Control center – determines the set point at which the variable is maintained; usually consists of brain, spinal cord, or endocrine gland; assesses multiple stimuli, determines deviations from standard set points, and produces a response by increasing or decreasing the activity of the effector

3. Effector – muscles or glands; provides the means to respond to stimuli

Homeostatic Control Mechanisms

Figure 1.4

Variable (in homeostasis)

Figure 1.4

Stimulus: Produces changein variable


Imbalance

Imbalance

1

Figure 1.4

Change detected by receptor


Receptor (sensor)


Imbalance

Imbalance

2

1

Figure 1.4



Input:Informationsent along afferentpathway to

Receptor (sensor)

Controlcenter


Imbalance

Imbalance

2

3

1

Figure 1.4




Receptor (sensor) Effector

Controlcenter


Output:Information sentalong efferentpathway to

Imbalance

Imbalance

2

34

1

Homeostatic Control Mechanisms

Figure 1.4




Receptor (sensor) Effector

Controlcenter


Response ofeffector feedsback toinfluencemagnitude ofstimulus andreturns variableto homeostasis

Output:Information sentalong efferentpathway to

2

34

5

1

Negative Feedback

• In negative feedback systems, the output shuts off the original stimulus

• Most control systems involve negative feedback systems which act to reduce or stop the initial stimulus; ex. maintenance of body temperature

- antagonistic actions – opposite actions; allow for fine tuning of homeostatic conditions

• Example: Regulation of room temperature

Figure 1.5

Signalwire turnsheater on

Signalwire turnsheater off

Response;temperaturerises

Response;temperaturedrops

Stimulus: rising roomtemperature

Stimulus: dropping roomtemperature

Balance

Effector(heater)

Effector(heater)

Setpoint

Control center(thermostat)

Heateroff

Setpoint

Receptor-sensor(thermometer inThermostat)


Heateron

Imbalance

Imbalance


Figure 1.5

Balance

Figure 1.5


Balance

Imbalance

Imbalance

Figure 1.5


Balance

Imbalance

Imbalance

Receptor-sensor(thermometerIn thermostat)

Setpoint

Figure 1.5


Balance

Imbalance

Imbalance


Setpoint


Figure 1.5




Balance

Effector(heater)



Setpoint


Heateroff

Figure 1.5


Balance

Imbalance

Imbalance

Figure 1.5


Balance

Setpoint


Imbalance

Imbalance

Figure 1.5


Balance

Setpoint



Imbalance

Imbalance

Figure 1.5



Balance

Effector(heater)

Setpoint



Heateron

Imbalance

Imbalance

Figure 1.5




Balance

Effector(heater)

Setpoint



Heateron

Figure 1.5







Balance

Effector(heater)

Effector(heater)

Setpoint


Heateroff

Setpoint



Heateron

Imbalance

Imbalance


Positive Feedback• In positive feedback systems, the output enhances or exaggerates the original stimulus

• Rare in humans; works against homeostasis

• Example: Regulation of blood clotting

• Ex. Oxytocin during labor stimulated by pressure on cervix; causes greater uterine contractions & more pressure on cervix

Figure 1.6

Figure 1.6

Break or tear inblood vessel wall

Feedback cycleinitiated

1

Figure 1.6

Clotting occursas platelets adhere to site and releasechemicals



2

1

Figure 1.6

Releasedchemicalsattract moreplatelets




2

1

3

Figure 1.6





Clotting proceeds; newly formingclot grows

2

1

34

Figure 1.6





Feedbackcycle endsafter clotseals break

Clotting proceeds; newly formingclot grows

2

1

34

Positive Feedback System

Homeostatic Imbalance

• Disturbance of homeostasis or the body’s normal equilibrium• Overwhelming the usual negative feedback mechanisms allows

destructive positive feedback mechanisms to take over

Directional Terms

• Superior and inferior – toward and away from the head, respectively• Anterior and posterior – toward the front and back of the body• Medial, lateral, and intermediate – toward the midline, away from the

midline, and between a more medial and lateral structure• Proximal and distal – closer to and farther from the origin of the body part• Superficial and deep – toward and away from the body surface

Directional Terms

Table 1.1a

Directional Terms

Table 1.1b

Try these !

1. The thorax is to the abdomen.2. The kidneys are to the intestine.3. The navel is on the side of the body.4. The legs are to the trunk. 5. The heart is to the lungs.6. The skin is to the muscles.7. The ears are to the nose.8. The knee is to the foot.9. The brain is to the cranium.10. The hand is to the elbow.

Anatomical Position and Directional Terms

Anatomical postion = Body erect, feet parallel, eyes forward, arms at side, palmsforward, fingers downward

5 Major Body Regions

1. Head – facial and cranial regions2. Neck – cervical region3. Trunk (torso) – thorax and abdomen4. Upper extremity – shoulder, arm, hand5. Lower extremity – hip, leg, foot

Regional Terms: Anterior View

Figure 1.7a

Nasal (nose)

Oral (mouth)

Cervical (neck)

Frontal (forehead)

Orbital (eye)

Buccal (cheek)

Mental (chin)

(a) Anterior

Figure 1.7a

Nasal (nose)

Oral (mouth)

Cervical (neck)

Acromial(point of shoulder)Axillary (armpit)

Brachial (arm)

Antecubital(front of elbow)

Abdominal(abdomen)

Pelvic (pelvis)

Antebrachial(forearm)

Carpal (wrist)

Palmar(palm)

Pollex(thumb)

Digital(fingers)

Mammary(breast)

Frontal (forehead)

Orbital (eye)

Buccal (cheek)

Sternal(breastbone)Thoracic(chest)

Mental (chin)

Umbilical(navel)

(a) Anterior

Figure 1.7a

Nasal (nose)

Oral (mouth)

Cervical (neck)

Acromial(point of shoulder)Axillary (armpit)

Brachial (arm)

Antecubital(front of elbow)

Abdominal(abdomen)

Pelvic (pelvis)

Antebrachial(forearm)

Carpal (wrist)

Palmar(palm)

Pollex(thumb)

Digital(fingers)

Pubic (genital region)

Patellar(anterior knee)

Crural (leg)

Tarsal (ankle)Pedal(foot) Digital (toes)

Inguinal(groin)

Coxal(hip)

Femoral(thigh)

Fibular, orperoneal(side of leg)

Hallux (great toe)

Mammary(breast)

Frontal (forehead)

Orbital (eye)

Buccal (cheek)

Sternal(breastbone)Thoracic(chest)

Mental (chin)

Umbilical(navel)

(a) Anterior

Regional Terms: Posterior View

Figure 1.7b

Otic (ear)

Occipital (back ofhead or base of skull)

Cephalic(head)

(b) Posterior

Figure 1.7b

Brachial (arm)

Otic (ear)

Occipital (back ofhead or base of skull) Acromial(point of shoulder)Vertebral(spinal column)Scapular(shoulder blade)

Dorsum or dorsal(back)

Olecranal(back of elbow)Lumbar (loin)Sacral(between hips)Manus

(hand)

Upperextremity

Cephalic(head)

(b) Posterior

Figure 1.7b

Brachial (arm)

Otic (ear)

Occipital (back ofhead or base of skull) Acromial(point of shoulder)Vertebral(spinal column)Scapular(shoulder blade)

Dorsum or dorsal(back)

Olecranal(back of elbow)Lumbar (loin)Sacral(between hips)

Gluteal (buttock)

Perineal(region betweenthe anus and external genitalia)Femoral (thigh)

Popliteal(back of knee)

Sural (calf)

Calcaneal (heel)

Plantar (sole)

Manus(hand)

Upperextremity

Cephalic(head)

Lowerextremity

(b) Posterior

Body Planes

• Sagittal – divides the body into right and left parts• Midsagittal or medial – sagittal plane that lies on the midline• Frontal or coronal – divides the body into anterior and posterior parts• Transverse or horizontal (cross section) – divides the body into

superior and inferior parts• Oblique section – cuts made diagonally

Body Planes – cuts to view internal structures

Human Anatomy and Physiology, 7eby Elaine Marieb & Katja Hoehn

Copyright © 2007 Pearson Education, Inc.,publishing as Benjamin Cummings.

Planes of the body—frontal, transverse, and median (midsagittal) with corresponding magnetic resonance imaging (MRI) scans

Transverse plane

Median (midsagittal) plane

Frontal plane

Frontal section through torso Transverse section through torso(superior view)

Median (midsagittal)section

Posterior

Left andright lung

LiverHeart

StomachSpleen

Liver

Spleen

StomachAorta Vertebral

columnSpinalcord

Subcutaneous fat layer

Rectum

Intestines

Pubic symphysis

(a) (b) (c)

Can you match these up and label them?

2 Principle Body cavities –internal cavities that confine organs that have related functions

1. Dorsal (posterior) cavity protects the nervous system, and is divided into two subdivisions

• Cranial cavity – within the skull; encases the brain• Vertebral cavity – runs within the vertebral column;

encases the spinal cord2. Ventral (anterior) cavity houses the internal organs

(viscera), and is divided into two subdivisions• Thoracic - chest cavity; includes mediastinum,

pleural & pericardial cavities• Abdominopelvic - may be divided into abdominal

cavity and pelvic cavity

Body Cavities

• Thoracic cavity is subdivided into two pleural cavities, the mediastinum, and the pericardial cavity

• Pleural cavities – each houses a lung• Mediastinum – contains the pericardial cavity; surrounds the remaining

thoracic organs• Pericardial cavity – encloses the heart

Body Cavities

• The abdominopelvic cavity is separated from the superior thoracic cavity by the dome-shaped diaphragm

• It is composed of two subdivisions• Abdominal cavity – contains the stomach, intestines, spleen, liver, and other

organs• Pelvic cavity – lies within the pelvis and contains the bladder, reproductive

organs, and rectum

Body Cavities

Figure 1.9a

Cranial cavity(contains brain)

Dorsalbodycavity

Diaphragm

Abdominal cavity(contains digestiveviscera)

Pelvic cavity(contains bladder,reproductive organs,and rectum)

Vertebral cavity(contains spinal cord)

Key:

Dorsal body cavity

Ventral body cavity

Thoraciccavity(containsheartand lungs)

(a) Lateral view

Body Cavities

Figure 1.9b

Ventral body cavity(thoracic and abdomino-pelviccavities)

Abdomino-pelviccavity

Superiormediastinum

Pleuralcavity

Cranialcavity

Vertebralcavity

Pericardialcavity withinthe mediastinum

Diaphragm

Abdominal cavity(contains digestiveviscera)

Pelvic cavity(contains bladder,reproductive organs,and rectum)

Thoraciccavity(containsheartand lungs)

(b) Anterior view

Key:

Dorsal body cavity

Ventral body cavity

Body membranes – thin layers of connective and epithelial tissue that cover, separate, and support

viscera and line body cavities2 types

1. Mucous membranes – secrete thick liquid substance called mucus; lubricates or protects organs; lines cavities that enter or exit the body

2. Serous membranes – line thoracic and adominopelvic cavities and cover visceral organs; secrete watery serous fluid; include: pleurae (lung), pericardial (heart) membranes, & peritoneal (abdominal) membranes

Ventral Body Cavity Membranes

• Parietal serosa lines internal body walls• Visceral serosa covers the internal organs• Serous fluid separates the serosae

Serous Membrane Relationship

Figure 1.10a

Serous membranes of the thorax

Serous membranes of the abdominopelvic cavity

Other Body Cavities

• Oral and digestive – mouth and cavities of the digestive organs• Nasal –located within and posterior to the nose• Orbital – house the eyes• Middle ear – contains bones (ossicles) that transmit sound vibrations• Synovial – joint cavities

Other Body Cavities

Figure 1.13

Abdominopelvic Regions

Figure 1.11a

Organs of the Abdominopelvic Regions

Figure 1.11b

Abdominopelvic Quadrants• Right upper• Left upper• Right lower• Left lower

Figure 1.12

Clinical procedures used to determine anatomical structure and function

1. Inspection – observing body for swelling, rashes, needle marks, irregular breathing, etc.

2. Palpation – applying fingers with firm pressure to surface of body to feel lumps, tender spots, body landmarks, etc.

3. Percussion – tapping sharply on body walls to detect vibrations; used to locate excess fluid or organ abnormalities

4. Auscultation – listening to sounds of various organs; breathing, heartbeat, etc.

5. Reflex testing – observing automatic response to stimulus

The Human Body: An Orientation

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