UNIT 1:LEVELS OF ORGANIZATION

Chapter 1: Introduction to Human Anatomy

and Physiology

ADDITIONAL HISTORICAL POINTS TO PONDER (1.1)

Primitive people were hunter-gatherers.Killed when hungry and ate their kills

Gathered wild plants which contained and provided chemicals that naturally fought infections

ADDITIONAL HISTORICAL POINTS TO PONDER

• Introduction of Agriculture• Brought exposure to pin, hook,

and tape worms in the fertilizer – animal manure• The ability to grow crops

lessened the need to rely on wild plants. This decreased the ability to fight infections naturally through the chemicals in the wild plants

ADDITIONAL HISTORICAL POINTS TO PONDER

• Urbanization• Leaving the country and

forming towns increased the number and severity of infectious illnesses as well as malnutrition• People became sedentary and

altered their diets• Evidence documented in

bones and teeth (p. 11)

LEARNING OUTCOME 1.1

Identify some of the early discoveries that lead to our current understanding of the human body.

Ana- (up) + -tomy (to cut or break) = AnatomyThe study of the structure (morphology

and form) of body partsLiterally to cut up or break apart the

body into its partso Physio- (relationship to nature) + -ology (to

study) = Physiology• The study of the function of body parts

• What they do and how they do it – the study of what and how each body part does naturally

ANATOMY & PHYSIOLOGY (1.2)

ANATOMY & PHYSIOLOGYThese 2 sciences

are very closely related

Structure determines functions; therefore

ANATOMY DETERMINES PHYSIOLOGY

ULTRASONAGRAPHY

MAGNETIC RESONANCE IMAGING (MRI)

CT IMAGING

LEARNING OUTCOME 1.2

Explain how anatomy and physiology are related.

LEVELS OF STRUCTURAL ORGANIZATION (1.3)

Subatomic particles

ProtonsNeutronsElectrons

Subatomic particles

Atom The smallest particle of an element

Subatomic particles

Atom

MoleculeA particle composed of 2 or more joined atoms

Subatomic particles

Atom

Molecule

Macromolecule A large molecule composed of lots of molecules – lipids, carbohydrates, DNA

Macromolecule

Subatomic particles

Atom

Molecule

Organelle

A small organ of a cell which performs a particular function

Subatomic particles

Atom

Molecule

Macromolecule

Organelle

Cell

The basic unit of structure and function of living organisms

Subatomic particles

Atom

Molecule

Macromolecule

Organelle

Tissue

A group of similar cells that performs a specialized function

Subatomic particles

Atom

Molecule

Macromolecule

Organelle

Cell

Organ

A structure consisting of a group of tissues that performs a specialized function

Subatomic particles

Atom

Molecule

Macromolecule

Organelle

Organ system

A group of organs that act together to carry out a specialized function

Organ system

Subatomic particles

Atom

Molecule

Macromolecule

Organelle

CellTissue

Organism

The most complex level of

organization – an

individual living thing

LEARNING OUTCOME 1.3

List the levels of organization in the human body and the characteristics of each

10 CHARACTERISTICS OF LIFE (1.4)

Movement- change in position of the body or body part; motion of an internal organ

Responsiveness- reaction to a change inside or outside the body

Growth- increase in size without a change in general shape

Reproduction- production of offspringDigestion- process of breaking down foodExcretion- process of removing waste

10 CHARACTERISTICS OF LIFEo Respiration – exchange of gases between the

atmosphere and the body cellso Absorption – passage of substances through

membranes and into body fluidso Circulation – movement of substances in body

fluidso Assimilation – chemically changing absorbed

substances in the body

These processes that obtain, release, and use energy are largely metabolism – all the chemical reactions in an organism that support life.

LEARNING OUTCOME 1.4

List and describe the major characteristics of life

Give examples of metabolism

MAINTENANCE OF LIFE (1.5) Nutrients- chemicals used for energy and cell

building Oxygen- chemical reactions that release energy

from foods require oxygen – cellular respiration Water- 60 to 80 % of the body weight – for most

metabolic reactions, lubrication Heat – needed to maintain body temperature-

98.6°F Too low: metabolic reactions slow down until they stop Too high: metabolic reactions speed up until proteins all

break down Atmospheric Pressure- weight of air – needed for

breathing and filtering blood through the kidneys

HOMEOSTASIS The body’s maintenance of a relatively stable

internal environment despite external changes• This is done by keeping conditions in a

homeostatic range compatible with life, near a “set point” value

Most life processes and metabolic reactions work to maintain homeostasis

HOMEOSTASISINTERNAL ENVIRONMENT

o Anatomically – the conditions inside the body but surrounding the cells (outside)

o Cells act in ways that keep the internal environment relatively constant and stable

o Consists of fluid that surrounds cells (extracellular fluid)

o Protects our cells from external changes that would kill isolated cells

HOMEOSTASISAll homeostatic mechanisms – self-regulating control systems - have three components in nature

1. Receptor – senses change in the environment

2. Control Center – regulates set point of variables

3. Effector – organ that acts in response to changes

HOMEOSTASIS

5. Response – return to homeostasis(Change is corrected.)

1. Stimulus(Change occursin internalenvironment.)

(Change is comparedto the set point.)

Control center(set point)

Effectors(muscles or glands)

Receptors(sensor)

3. Input information sent along afferent pathway

2. Change detected by receptor

4. Output information sent along efferent pathway to activate

HOMEOSTASIS Most homeostatic mechanisms are regulated

by negative feedback – brings conditions back toward set point - Automatic (regulates body temp, heart rate, blood pressure, breathing rate, blood levels of: oxygen, glucose, carbon dioxide, minerals)

Sometimes conditions are purposely moved away from the set point – positive feedback - RARE in human body Control events that happen explosively “fight-or-flight”, childbirth, blood clotting

HOMEOSTASISNEGATIVE FEEDBACK

Control centerThermostat detectsdeviation from setpoint and signalseffectors.

ReceptorsThermostat inroom detects change.

too high

Normal roomtemperature

Thermostatset point

too low

EffectorsHeater turns on;air conditionerturns off.

Control centerThermostat detectsdeviation from setpoint and signalseffectors.

ReceptorsThermostat inroom detects change.

StimulusRoom temperaturedrops below set point.

ResponseRoom temperaturereturns toward set point.

EffectorsHeater turns off; airconditioner turns on.

StimulusRoom temperature risesabove set point.

ResponseRoom temperaturereturns towardset point.

HOMEOSTASISPOSITIVE FEEDBACK

Control centerThe hypothalamusdetects the deviationfrom the set point andsignals effector organs.

ReceptorsThermoreceptorssend signals to thecontrol center.

EffectorsSkin blood vesselsdilate and sweat glandssecrete.

too high

too low

Normal bodytemperature37°C (98.6°F)

ReceptorsThermoreceptorssend signals to thecontrol center.

EffectorsSkin bloodvessels constrictand sweat glandsremain inactive.

Control centerThe hypothalamusdetects the deviationfrom the set point andsignals effector organs. If body temperature

continues to drop,control center signalsmuscles to contractinvoluntarily.

StimulusBody temperaturerises above set point.

StimulusBody temperaturedrops below set point.

ResponseBody heat is conserved, temperaturereturns toward set point.

ResponseBody heat is lost tosurroundings, temperaturereturns toward set point.

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ANIMATION: POSITIVE AND NEGATIVE FEEDBACK

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HOMEOSTATIC IMBALANCE

Disturbance in homeostasis occursAs we age our body organs become less

efficient and our internal conditions become less stable.

Any disease or abnormal condition in the body.

LEARNING OUTCOME 1.5 List and describe the major

requirements of organisms Explain the importance of

homeostasis to survival Describe the parts of a homeostatic

mechanism and explain how they function together