homeostatic regulation homeostasis maintains stable internal conditions temperature ionic...

Homeostatic Regulation

Homeostasis

• Maintains stable internal conditions

• Temperature

• Ionic concentrations

• Blood sugar levels, etc.

Utilizes negative feedback mechanisms

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


Regulation depends on:• Receptor - sensitive to a particular

stimulus• Control Center - receives and

processes information from the receptor

• Effector - that responds to the commands of the control center which have been affected by the same stimulus



HOMEOSTASISNormalroom

temperature

Figure 1-3

2 of 6


RECEPTOR

Thermometer

STIMULUS:Room temperature

rises

Normalconditiondisturbed


temperature

Figure 1-3

3 of 6


RECEPTOR

Thermometer


rises



temperature

Informationaffects

CONTROL CENTER(Thermostat)

20o 30o 40o

Figure 1-3

4 of 6


RECEPTOR

Thermometer


rises



temperature

EFFECTOR

Air conditionerturns on

Sendscommands

to

Informationaffects


20o 30o 40o

Figure 1-3

5 of 6

RECEPTOR

Thermometer


rises



temperature

RESPONSE:Room temperature

dropsNormal

conditionrestored

EFFECTOR

Air conditionerturns on

Sendscommands

to

Informationaffects


20o 30o 40o


Figure 1-3

6 of 6


Negative Feedback:• Variation outside normal limits

triggers automatic corrective response• Response negates disturbance



Negative Feedback Example - thermoregulation• Altering the relationship between

heat loss and heat production



STIMULUS

Body temperaturerises above 37.2oC(99oF)

Controlmechanismwhen bodytemperature

rises

CONTROLCENTER

Thermoregulatorycenter in brain

Figure 1-4

2 of 10


RECEPTOR

Body’stemperature

sensorsSTIMULUS



rises

CONTROLCENTER


Informationaffects

Figure 1-4

3 of 10


RECEPTOR

Body’stemperature

sensorsSTIMULUS



rises

EFFECTOR

Blood vesselsand sweat

glands in skin

Sendscommands

to

CONTROLCENTER


Informationaffects

Figure 1-4

4 of 10


RECEPTOR

Body’stemperature

sensorsSTIMULUS


RESPONSEIncreased blood flowto skinIncreased sweatingStimulus removedHomeostasis restored


rises

EFFECTOR


glands in skin

Negativefeedback

Sendscommands

to

CONTROLCENTER


Informationaffects

Figure 1-4

5 of 10


STIMULUSBody temperaturefalls below 37.2oC(99oF)


falls

CONTROLCENTER


Figure 1-4

6 of 10


RECEPTOR

Body’stemperature

sensors STIMULUSBody temperaturefalls below 37.2oC(99oF)


falls

CONTROLCENTER


Informationaffects

Figure 1-4

7 of 10


RECEPTOR

Body’stemperature



falls

EFFECTOR

Blood vesselsand sweat glands

in skinSkeletal muscles

Sendscommands

to

CONTROLCENTER


Informationaffects

Figure 1-4

8 of 10


RECEPTOR

Body’stemperature


RESPONSEDecreased blood flowto skinDecreased sweatingShiveringStimulus removedHomeostasis restored


falls

EFFECTOR



Negativefeedback

Sendscommands

to

CONTROLCENTER


Informationaffects

Figure 1-4

9 of 10

Figure 1-4

10 of 10Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

RECEPTOR

Body’stemperature

sensorsSTIMULUS


RESPONSE

Increased blood flowto skinIncreased sweatingStimulus removedHomeostasis restored

Controlmechanismwhen body

temperaturerises

EFFECTOR


glands in skin

Negativefeedback

Sendscommands

to

Informationaffects

Informationaffects

CONTROLCENTER


Sendscommands

to

EFFECTOR



Negativefeedback

Controlmechanismwhen body

temperaturefalls

RECEPTOR

Body’stemperature

sensors STIMULUS

Body temperaturefalls below 37.2oC(99oF)

RESPONSE

Decreased blood flowto skinDecreased sweatingShiveringStimulus removedHomeostasis restored


Positive Feedback:• Stimulus produces response

that reinforces the stimulus• Response rapidly completes

critical process



Figure 1-5


Remember:• Negative feedback: negates the

disturbance – opposes the limit from normal limits• Positive feedback: reinforces

the stimulus



Homeostasis and Disease • Failure of homeostatic regulation

causes• Symptoms to appear• Organ system to malfunction



Key Note

Physiological systems work together to maintain a stable internal environment. They monitor and adjust internal conditions.


The Language of Anatomy

Surface Anatomy• Anatomical Position

• Hands at side• Palms forward• Feet together

• Supine: Face up

• Prone: Face down



Figure 1-6(a)


Figure 1-6(b)


Anatomical Regions• Two methods to map abdominal and

pelvic regions

• Four abdominopelvic quadrants

• Nine abdominopelvic regions



Figure 1-7(a)


Figure 1-7(b)


Figure 1-7(c)


A few anatomical directions:• Anterior (= ventral)• Posterior (= dorsal)• Superior• Inferior• Lateral• Medial• Proximal• Distal



Figure 1-8


Sectional Anatomy: Planes and Sections

• Transverse plane• Transverse section

• Frontal plane• Frontal section

• Sagittal plane• Sagittal section



Figure 1-9


Ventral body cavity

• Protects delicate organs

• Permits organ growth and movement

• Surrounds:

• Respiratory

• Cardiovascular

• Digestive

• Urinary

• Reproductive organsCopyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings


Diaphragm subdivides ventral cavity:

• Thoracic cavity

• Pleural cavities (R and L)• Pericardial cavity

• Abdominopelvic cavity

• Abdominal cavity

• Pelvic cavity

• Peritoneal membrane



Key Note

Anatomical descriptions refer to an

individual in the anatomical position:

standing, with the hands at the sides,

palms facing forward, and feet together.



Figure 1-10(a)


Radiological Procedures

• X-rays

• CT Scans

• MRIs

• Ultrasound


X-Rays

Figure 1-11(a)

X-Rays

Figure 1-11(b)

Common Scanning Techniques

Figure 1-12(a)


Figure 1-12(b)


Figure 1-12(c)


Figure 1-12(d)

homeostatic regulation homeostasis maintains stable internal conditions temperature ionic...

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normal limits

receptor sensitive

processes information