Sherwood 1

Human Physiology by Lauralee Sherwood ©2007 Brooks/Cole-Thomson Learning

Chapter 1Homeostasis: The Foundation of Physiology

Chapter 1 Homeostasis: The Foundation of Physiology Human Physiology by Lauralee Sherwood ©2007 Brooks/Cole-Thomson Learning

Outline

• Physiology

• Levels of organization

• Basic Cell function

• Tissues/ organs/systems


Outline

• Homeostasis– Fluid compartments– Variables controlled– contributions of systems– Control systems

• intrinsic/extrinsic• Feedfoward/ feedback• Positive/negative

• Disruptions of homeostasis


Physiology• Study of body functions• Two processes explain body functions

– Teleological• Explanations are in terms of meeting a bodily need

– Mechanistic• Explanations are in terms of cause and effect

sequences– Body is viewed as a machine


Anatomy• Study of the structure of the bodyPhysiological mechanisms are possible

through structural designStructure-Function relationships of the body

include• Heart receiving and pumping blood• Teeth tearing and grinding food


Functional Organization of the BodyLevels of organization• Chemical

– Molecules composed of atoms

• Cellular– Cells are basic unit of life

• Tissue• Organ• Body system• Organism


1

2

3

4

65

1 Chemical level

2 Cellular level

4 Organ level

3 Tissue level

5 Body system level

6 Organism level

Fig. 1.1, p.

3

Stepped art


Basic Cell Functions• Obtain nutrients and oxygen from

surrounding environment• Perform chemical reactions that provide

energy for the cell• Eliminate carbon dioxide and other wastes

to surrounding environment• Synthesize needed cellular components


Basic Cell Functions• Control exchange of materials between

cell and its surrounding environment• Sensing and responding to changes in

surrounding environment• Reproduction

– Exception• Nerve cells and muscle cells lose their ability to

reproduce during their early development


Tissues• Groups of cells with similar structure and

specialized function• Four primary types of tissues

– Muscle tissue– Nervous tissue– Epithelial tissue– Connective tissue


Tissues• Muscle tissue

– Specialized for contracting and generating force– Three types of muscle tissue

• Skeletal muscle– Moves the skeleton

• Cardiac muscle– Pumps blood out of the heart

• Smooth muscle– Encloses and controls movement of contents through

hollow tubes and organs


Tissues• Nervous tissue

– Consists of cells specialized for initiating and transmitting electrical impulses

– Found in brain, spinal cord, and nerves

• Epithelial tissue– Consists of cells specialized for exchanging

materials between the cell and its environment– Organized into two general types of structures

• Epithelial sheets• Secretory glands


Tissues• Connective tissue

– Connects, supports, and anchors various body parts

– Distinguished by having relatively few cells dispersed within an abundance of extracellular material

– Examples• Tendons• Bone• Blood


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Chapter 1 Homeostasis: The Foundation of Physiology Human Physiology by Lauralee Sherwood ©2007 Brooks/Cole-Thomson LearningHyaline cartilage. X64.

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Chapter 1 Homeostasis: The Foundation of Physiology Human Physiology by Lauralee Sherwood ©2007 Brooks/Cole-Thomson LearningCollagen or dense connective tissue. X155.

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Chapter 1 Homeostasis: The Foundation of Physiology Human Physiology by Lauralee Sherwood ©2007 Brooks/Cole-Thomson LearningReticular fibers, silver preparation. X100.

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Chapter 1 Homeostasis: The Foundation of Physiology Human Physiology by Lauralee Sherwood ©2007 Brooks/Cole-Thomson LearningHuman unilocular (white) fat and adipose (adult fat). H&E stain. LM X100.

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Human pseudostratified columnar epithelium lining the bronchus of the lung. H&E stain. X180.


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Chapter 1 Homeostasis: The Foundation of Physiology Human Physiology by Lauralee Sherwood ©2007 Brooks/Cole-Thomson LearningStratified squamous epithelium from mouth mucosa. H&E stain. LM X100.


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Chapter 1 Homeostasis: The Foundation of Physiology Human Physiology by Lauralee Sherwood ©2007 Brooks/Cole-Thomson LearningSimple columnar epithelium. LM X140.

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Chapter 1 Homeostasis: The Foundation of Physiology Human Physiology by Lauralee Sherwood ©2007 Brooks/Cole-Thomson LearningSimple Squamous Epithelium. LM X75.


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Chapter 1 Homeostasis: The Foundation of Physiology Human Physiology by Lauralee Sherwood ©2007 Brooks/Cole-Thomson LearningAreolar (loose) connective tissue. LM X60.


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Bone section showing osteocytes in lacunae arranged in concentric circles surrounding Haversian canals. LM X75.


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A long bone showing the compact bone (yellow) surrounding the spongy or cancellous bone (orange). Compact bone consist of a dense matrix resembling a solid mass. The spongy region consists of a network of bony spicules called trabeculae. SEM X40.

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Chapter 1 Homeostasis: The Foundation of Physiology Human Physiology by Lauralee Sherwood ©2007 Brooks/Cole-Thomson LearningColony of undifferentiated human embryonic stem cells. LM X5.14

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Chapter 1 Homeostasis: The Foundation of Physiology Human Physiology by Lauralee Sherwood ©2007 Brooks/Cole-Thomson LearningSweat gland duct in the skin. LM X5.

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Chapter 1 Homeostasis: The Foundation of Physiology Human Physiology by Lauralee Sherwood ©2007 Brooks/Cole-Thomson LearningCardiomyocyte differentiated from human embryonic stem cells.

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Organs• Consist of two or more types of primary

tissues that function together to perform a particular function or functions

• Example– Stomach

• Inside of stomach lined with epithelial tissue• Wall of stomach contains smooth muscle• Nervous tissue in stomach controls muscle contraction

and gland secretion• Connective tissue binds all the above tissues together


Body Systems• Groups of organs that perform related

functions and interact to accomplish a common activity essential to survival of the whole body

• Do not act in isolation from one another• Human body has 11 systems


Body Systems• Circulatory System• Digestive System• Respiratory System• Urinary System• Skeletal System• Muscular System

• Integumentary System

• Immune System• Nervous System• Endocrine System• Reproductive System


Body Systems


Homeostasis• Defined as maintenance of a relatively

stable internal environment– Does not mean that composition, temperature,

and other characteristics are absolutely unchanging

• Homeostasis is essential for survival and function of all cells

• Each cell contributes to maintenance of a relatively stable internal environment


Homeostasis


Homeostasis• Body cells are in contained in watery

internal environment through which life-sustaining exchanges are made

• Extracellular fluid (ECF)– Fluid environment in which the cells live (fluid

outside the cells)– Two components

• Plasma, interstitial fluid

• Intracellular fluid (ICF)– Fluid contained within all body cells


Homeostasis


HomeostasisFactors homeostatically regulated include• Concentration of nutrient molecules• Concentration of O2 and CO2

• Concentration of waste products• pH• Concentration of water, salt, and other

electrolytes• Volume and pressure• Temperature


Contributions of Body Systems to Homeostasis

• Circulatory system– Carries materials from one part of the body to

another

• Digestive system– Breaks down dietary food into smaller molecules

that can be distributed to body cells– Transfers water and electrolytes from external

environment to internal environment– Eliminates undigested food residues to external

environment in the feces



• Respiratory system– Gets O2 from and eliminates CO2 to the external

environment– Important in maintenance of proper pH of internal

environment

• Urinary system– Removes excess water, salt, acid, and other

electrolytes from plasma and eliminates them in urine



• Skeletal system– Provides support and protection for soft tissues

and organs– Serves as storage reservoir for calcium– Along with muscular system enables movement

of body and its parts– Bone marrow is ultimate source of all blood cells

• Muscular system– Moves the bones



• Integumentary system– Serves as outer protective barrier– Important in regulating body temperature

• Immune system – Defends against foreign invaders and against

body cells that have become cancerous– Paves way for repairing or replacing injured or

worn-out cells



• Nervous system– Controls and coordinates bodily activities that

require rapid responses– Detects and initiates reactions to changes in

external environment• Endocrine system

– Secreting glands of endocrine regulate activities that require duration rather than speed

– Controls concentration of nutrients and, by adjusting kidney function, controls internal environment’s volume and electrolyte composition


Surface epithelium

Pocket epitheliumcells

Fig. 1.2a, p. 5


Surface epithelium

Duct cells

Secretory exocrinegland cell

Fig. 1.2b, p. 5


Surface epithelium

Connecting cellslost during development

Secretory exocrinegland cell

Blood vessels

Fig. 1.2c, p. 5



• Reproductive system– Not essential for homeostasis (not essential for

survival of individual)– Is essential for perpetuating the species


Role of Body Systems in Homeostasis


Homeostatic Control Systems

• In order to maintain homeostasis, control system must be able to– Detect deviations from normal in the internal

environment that need to be held within narrow limits

– Integrate this information with other relevant information

– Make appropriate adjustments in order to restore factor to its desired value



• Control systems are grouped into two classes– Intrinsic controls

• Local controls that are inherent in an organ

– Extrinsic controls• Regulatory mechanisms initiated outside an organ• Accomplished by nervous and endocrine systems



• Feedforward – Term used for responses made in anticipation of

a change

• Feedback – Refers to responses made after change has been

detected– Types of feedback systems

• Negative• Positive



• Negative feedback system– Primary type of homeostatic control– Opposes initial change– Components

• Sensor – Monitors magnitude of a controlled variable

• Control center– Compares sensor’s input with a set point

• Effector – Makes a response to produce a desired effect



• Positive feedback system– Amplifies an initial change– Do not occur as often as negative feedback

system– Example

• Uterine contractions become increasingly stronger until the birth of the baby


Disruptions in Homeostasis

• Can lead to illness and death• Pathophysiology

– Abnormal functioning of the body associated with disease


During the minute that it will take you to read this page

Your heart will beat 70 times,pumping 5 liters of blood to your lungs and another 5 liters to the rest of your body.

Your kidneys will produce 1 ml of urine.

Your eyes will convert the information on this page into electrical signals that will transmit to your brain.

Your digestive system will be processing your last meal for transfer into your bloodstream.

You will breathe in and out about 12 times.

Your cells will consume 250 ml of oxygen and produce 200 ml of carbon dioxide.

You will use about 2 calories of energy.

Your brain will send chemical messengers through your nerves to control your body.

Chapter Opener, p. 1


Information from the external environment relayed through thenervous system

O2

CO2

Urine containingwastes and excess water and electrolytes

Nutrients, water,electrolytesFeces containingundigested foodresidue

Sperm leave maleSperm enter female

EXTERNALENVIRONMENT

BODY SYSTEMS

RESPIRATORY SYSTEM

NERVOUS SYSTEM

URINARY SYSTEM

DIGESTIVE SYSTEM

REPRODUCTIVE SYSTEM

Exchanges with all other systems

CIRCULATORY SYSTEM

Exchanges with all other systems

MUSCULAR AND SKELETAL

SYSTEM

IMMUNE SYSTEM

INTEGUMENTARY SYSTEM

ENDOCRINE SYSTEM

Body systemsmaintainhomeostasis

Keeps internalfluids in

Keeps foreignmaterials out

HOMEOSTASIS

Homeostasisessential forcell survival

CELLS

Cells makeup bodysystem

Enables thebody to interactwith the externalenvironment

Protects againstforeign invaders

Regulate

Fig. 1.6, p. 12


Fig. 1-7a, p. 15


Fig. 1-7b, p. 15


Fig. 1-7c, p. 15

Sherwood 1

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