Hemeostasis .. Foundation of Physiology Ch1

8/3/2019 Hemeostasis .. Foundation of Physiology Ch1

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Fundamentals of Physiology:A Human Perspective, 3e

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Homeostasis: The

Foundation of Physiology

Chapter 1



Physiology is the study of

body functions. There are two

processes to explain body

functions. They are:

• teleological - The explanations are in terms of meeting a bodily need.

• mechanistic - The explanations are in

terms of cause and effect sequences. – The body is viewed as a machine.

– Both processes, for example, can be applied to

body shivering.



Anatomy is the study of the

structure of the body.Physiological mechanisms are

possible through structural

design.

Structure-Function relationships of the body include the:

– heart receiving and pumping blood

– teeth tearing and grinding food



The body is structurally organized into a whole functional unit.

Its levels organization are represented in this hierarchy:

– organism (the whole body)

– body system

– organ

– tissue

– cell

– molecule

– atom (smallest, most specific)



The cell is the basic unit of life.

• Basic cell functions are:

– obtain food and oxygen

–

perform chemical reactions

– eliminate carbon dioxide and wastes

– synthesize proteins and cell components

– control exchange of materials

– moving materials

– sensitive, responsive to environmental changes

– reproduction



Tissues are groups of cells of

similar specializations. There are

four primary tissue types.• muscle - 3 kinds: skeletal, cardiac, and smooth

• nervous - transmits electrical impulses

• epithelial - sheets and glands

connective - few cells dispersed in an extracellular matrix



An organ is made up of several

tissue types. The stomach is

one example of an organ.

• The inside surface of the stomach is lined

with epithelial tissue.• The wall of the stomach contains smooth

muscle.

• Nerve tissue in the stomach controls muscle contraction

• These tissues are bound together by connective tissue.



A body system is a group of

related organs.• The mouth, stomach, and small intestine are

some of the organs of the digestive system.

• The body systems are:

– circulatory

– digestive

– respiratory

– urinary

– skeletal

–

muscular – integumentary

– immune

– nervous

– endocrine

– reproductive



Body systems maintain homeostasis.

They maintain a dynamic steady state

in the internal environment.• The ECF is the internal environment.



Homeostasis is essential for cell survival.

Body systems maintain homeostasis.Cells make up body systems.



Many factors of the internal

environment are homeostatically

regulated. These factors include:• concentration of: nutrient molecules

– oxygen

– carbon dioxide

– waste products

– water

– salts

– other electrolytes

• pH

• temperature

• volume

•

pressure



The human body systems and

their contribution to homeostasis

are:• circulatory - transports materials (e.g., nutrients, gases)

• digestive - breaks dietary food into small nutrient molecules.

•respiratory - obtains oxygen and eliminates carbon dioxide

• urinary - removes and eliminates wastes from the plasma

• skeletal - provides support and protection for soft tissues

• muscular - moves the bones

• integumentary - serves as an outer protective barrier

• immune - defends against foreign invaders

• nervous - controls and coordinates activities rapidly

• endocrine - regulates activities that require duration

• reproductive - perpetuation of the species



Homeostatic control systems

operate locally or bodywide.Homeostatic control systems are:

•intrinsic - inherent in an organ

• extrinsic - outside the organ to alter the activity of the organ

– Extrinsic control is accomplished by thenervous and endocrine systems.



Negative feedback opposes an

initial change. It maintains

homeostasis.• Its components are:

– control center

–

sensor – effector

• The sensor monitors the magnitude of a controlled variable.

• The control center compares a sensor’s input with a set point.

• The effector makes a response to produce

a desired effect.



Positive feedback amplifies an initial change.

An output is enhanced.

A controlled variable moves in the direction of an initial change.

One example occurs during the birth of

a baby.



Disruption in homeostasis can lead to illness and death.

Pathophysiology is the abnormal functioning of the

body during disease.

Hemeostasis .. Foundation of Physiology Ch1

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