21-dec-15introduction to physiology1 introduction to physiology dr. robert mbelwa...

Apr 21, 2023 Introduction to Physiology 1

Introduction To Introduction To PhysiologyPhysiology

Dr. Robert MbelwaDr. Robert Mbelwa

07158320050715832005

07856756760785675676

drrobertmbelwa@gmaildrrobertmbelwa@gmail

Learning ObjectivesLearning Objectives Define physiology and its various specialtiesDefine physiology and its various specialties Identify the major levels of organization in Identify the major levels of organization in

organisms .organisms . Identify the 11 organ systems of the body and Identify the 11 organ systems of the body and

their major components.their major components. Explain the concept of homeostasis, including Explain the concept of homeostasis, including

both positive and negative feedback.both positive and negative feedback.


Physiology Physiology

The term physiology is derived The term physiology is derived from the Greek word from the Greek word PHYSIOLOGICOSPHYSIOLOGICOS– PHYSIS – Nature; LOGOS – StudyPHYSIS – Nature; LOGOS – Study

Inquiry to NatureInquiry to Nature– Physiology is the study of normal Physiology is the study of normal

function and phenomenon of function and phenomenon of living thingsliving things


Physiology Physiology

Aims at Describing, Explaining and Aims at Describing, Explaining and UnderstandingUnderstanding– How living things work or function;How living things work or function;– The intricate control system and The intricate control system and

regulatory mechanismsregulatory mechanisms» How and why plants grow?How and why plants grow?» What makes bacteria divideWhat makes bacteria divide» How do fish obtain and use oxygenHow do fish obtain and use oxygen» How is food digestedHow is food digested» What makes the heart beatWhat makes the heart beat


Interrelation With Interrelation With Other SpecialtiesOther Specialties

In order to discover how living In order to discover how living things workthings work– We need to know the actual structure We need to know the actual structure

of the bodyof the body»The bones, muscles and their The bones, muscles and their

attachments, nerves different organs attachments, nerves different organs and their location (ie. Gross and their location (ie. Gross anatomy)anatomy)

The physiologist can then explain, The physiologist can then explain, for example how a limb movesfor example how a limb moves



Limb moves because Limb moves because – Particular set of muscles contractParticular set of muscles contract

But this is not the end of storyBut this is not the end of story– Further questions ariseFurther questions arise

» Why? And how? Do the muscles contractWhy? And how? Do the muscles contract

To answer these questions, the To answer these questions, the physiologist must knowphysiologist must know– The structure of the muscle The structure of the muscle (Histology)(Histology)



– What is happening at the cellular What is happening at the cellular level (ie Biochemistry)level (ie Biochemistry)

There is an inter-relationship There is an inter-relationship between the biological between the biological sciencessciences– In order to understand In order to understand

physiology one needs to have physiology one needs to have knowledge of a number of other knowledge of a number of other biological sciencesbiological sciences


Branches of PhysiologyBranches of Physiology

Several branches of physiology Several branches of physiology according to the different according to the different types of living thingstypes of living things– Physiology of plants, birds, Physiology of plants, birds,

insects, fish, insects, fish, mammals ; of which mammals ; of which human physiologyhuman physiology is of special is of special interest for Health Sciences interest for Health Sciences SpecialtiesSpecialties


Branches of PhysiologyBranches of Physiology

Human physiology can be Human physiology can be further subdividedfurther subdivided

– according to the different according to the different systemssystems»circulation, respiration, circulation, respiration, muscles, digestion, muscles, digestion, reproduction, nervous reproduction, nervous system, endocrine systemsystem, endocrine system


Comparative Comparative physiologyphysiology

Studied in a variety of speciesStudied in a variety of species– emphasis on how a particular organ or emphasis on how a particular organ or

system function in different speciessystem function in different species– Most of the knowledge about human Most of the knowledge about human

physiology originated from physiology originated from experimentation on different animals.experimentation on different animals.


For the purpose of your For the purpose of your coursecourse

You will be concerned with You will be concerned with Human physiologyHuman physiology– During the first & second During the first & second

semesters you will be taught semesters you will be taught Basic & an aspect of clinical Basic & an aspect of clinical Physiology Physiology

The course will be offered in The course will be offered in ten modulesten modules


Basic PhysiologyBasic Physiology

Semester 1Semester 1– Covers modules 1-7 Covers modules 1-7 – Fluid and circulationFluid and circulation

»The cell and its immediate internal The cell and its immediate internal environment, Body fluids, environment, Body fluids, homeostasishomeostasis

»BloodBlood»The excitable tissueThe excitable tissue»The cardiovascular systemThe cardiovascular system


Basic Physiology Basic Physiology

– Metabolism and excretory systemsMetabolism and excretory systems» The Respiratory systemThe Respiratory system» The renal systemThe renal system» The Digestive systemThe Digestive system

Semester 2Semester 2– Modules covered 8-10Modules covered 8-10

» ReproductionReproduction» Neuroendocrine systemNeuroendocrine system

The Endocrine systemThe Endocrine system The nervous systemThe nervous system

– Sensory, motor, autonomic and special Sensory, motor, autonomic and special sensessenses


Method of TeachingMethod of Teaching Mainly Lectures Mainly Lectures

– Provide only the backbone informationProvide only the backbone information– They are intended to stimulate and guide the They are intended to stimulate and guide the

students into a more detailed private study on students into a more detailed private study on the topics coveredthe topics covered

Practical Practical – Actual practical or practical demonstrationActual practical or practical demonstration

Others Others Seminars, tutorials, student’s presentationsSeminars, tutorials, student’s presentations

– Intended to help the individuals toIntended to help the individuals to» revise materials coveredrevise materials covered» Cover new avenues related to what has Cover new avenues related to what has

already been coveredalready been covered


Recommended TextbooksRecommended Textbooks

Textbook of Medical PhysiologyTextbook of Medical Physiology, by , by

Arthur C. Guyton, 10Arthur C. Guyton, 10thth edition edition Review of Medical Physiology, Review of Medical Physiology, by by

William F. Ganong, 20William F. Ganong, 20thth edition edition

Physiology ,Physiology , by Berne, Robert &Mathew by Berne, Robert &Mathew


Recommended TextbooksRecommended Textbooks

OthersOthers – Human Physiology, the Mechanisms of body Human Physiology, the Mechanisms of body

Function; Function; by Vander, Sherman,& Luciano. 6by Vander, Sherman,& Luciano. 6thth edition edition– Essentials of Medical Physiology, Essentials of Medical Physiology, by Johnson, by Johnson,

Leonard R. 2Leonard R. 2ndnd edition edition– Physiology, NMS, Physiology, NMS, by Bullock, Boyles, Wang. 3by Bullock, Boyles, Wang. 3rdrd

editionedition

Others SourcesOthers Sources– There are several books on systemic There are several books on systemic

physiologyphysiology» Respiratory physiologyRespiratory physiology» Cardiovascular physiology, etcCardiovascular physiology, etc

– From the InternetFrom the Internet


Assessment Assessment

Continuous assessment testsContinuous assessment tests– Mainly at the end of moduleMainly at the end of module– End of Semester university End of Semester university

examinationexamination Mode of examinationMode of examination

– Mixture of multiple choices Questions, Mixture of multiple choices Questions, matching items & short answers, matching items & short answers, essaysessays

Organization Organization

of the of the

human bodyhuman body


Levels of structural Levels of structural organizationorganization

The human The human body exhibitsbody exhibits 6 6 levels of levels of structural structural complexity :complexity :1.1. ChemicalChemical

2.2. CellularCellular

3.3. TissueTissue

4.4. OrgansOrgans

5.5. System LevelSystem Level

6.6. Organismic Organismic LevelLevel

Levels of Structural Organization Levels of Structural Organization cont’d cont’d

1- 1- Chemical level Chemical level the simplest level the simplest level

of structural of structural ladderladder

At this level atoms At this level atoms combine to form combine to form molecules such as molecules such as water, sugar, & water, sugar, & proteinsproteins


Levels of Structural Organization Levels of Structural Organization cont’dcont’d

2- Cellular level 2- Cellular level the smallest the smallest

functional/living functional/living units of living units of living things .things .



3- Tissue level 3- Tissue level groups of similar groups of similar

cells that have a cells that have a common function common function (4 basic types)(4 basic types)a.a. EpitheliumEpithelium

b.b. MuscleMuscle

c.c. Connective Connective tissuetissue

d.d. nervenerve



4- Organ level, 4- Organ level, an organ is a an organ is a structure structure composed of 2 composed of 2 or more tissue or more tissue types that types that performs a performs a specific specific function .function .


Organ level - Organ level - consists of two or consists of two or more types of more types of primary tissues primary tissues that function that function together to together to perform a perform a particular function particular function or functionsor functions


– Example: StomachExample: Stomach» Inside of stomach Inside of stomach

lined with lined with epithelial tissueepithelial tissue

» Wall of stomach Wall of stomach contains smooth contains smooth musclemuscle

» Nervous tissue in Nervous tissue in stomach controls stomach controls muscle contraction muscle contraction and gland and gland secretionsecretion

» Connective tissue Connective tissue binds all the above binds all the above tissues togethertissues together



5- Organ System 5- Organ System is a group of is a group of organs that work organs that work together to together to accomplish a accomplish a common purpose common purpose – each organ has each organ has

its own job to doits own job to do

sometimes an sometimes an organ is part of organ is part of more than one more than one systemsystem



6- organismic level 6- organismic level Comprises of one Comprises of one

living individualliving individual represents the represents the

highest level of highest level of structural structural organizationorganization

consists of Groups of consists of Groups of organs that perform organs that perform related functions and related functions and interact to accomplish interact to accomplish a common activity a common activity essential to survival of essential to survival of the whole bodythe whole body

Do not act in isolation Do not act in isolation from one anotherfrom one another– Human body has 11 Human body has 11

systemssystems


summarysummary

1.1. Integumentary systemIntegumentary system2.2. Nervous systemNervous system3.3. Skeletal systemSkeletal system4.4. Endocrine systemEndocrine system5.5. Muscular systemMuscular system6.6. Cardiovascular systemCardiovascular system7.7. Lymphatic systemLymphatic system8.8. Urinary systemUrinary system9.9. Respiratory systemRespiratory system10.10. Digestive systemDigestive system11.11. Reproductive systemReproductive system

Body systems:The human body has 11 systems

Homeostasis Homeostasis &&

Feedback systems for Feedback systems for controlling body functionscontrolling body functions


HomeostasisHomeostasis Describes the body’s ability to maintain Describes the body’s ability to maintain

relatively stable internal conditions relatively stable internal conditions even though the outside world is even though the outside world is continuously changingcontinuously changing

The literal translation of homeostasis is The literal translation of homeostasis is “unchanging,”( homeo= the same, “unchanging,”( homeo= the same, stasis = standing still which is not stasis = standing still which is not true). true).

Homeostasis cont’dHomeostasis cont’d The term does not really mean a static, The term does not really mean a static,

or unchanging, state. or unchanging, state. Rather, it indicates a dynamic state of Rather, it indicates a dynamic state of

equilibrium, or a balance, in which equilibrium, or a balance, in which internal conditions vary, but always internal conditions vary, but always within relatively narrow limits. within relatively narrow limits.

In general, the body is in homeostasis In general, the body is in homeostasis when its needs are adequately met and when its needs are adequately met and it is functioning smoothly.it is functioning smoothly.

Homeostasis is essential for survival Homeostasis is essential for survival and function of all cellsand function of all cells

If homeostasis is not maintained, death If homeostasis is not maintained, death may resultmay result

Control of HomeostasisControl of Homeostasis

Autoregulation or intrinsic regulation – Autoregulation or intrinsic regulation – results when cell, organ or system adjusts results when cell, organ or system adjusts its activity automatically.its activity automatically.

Extrinsic regulation - results from activity of Extrinsic regulation - results from activity of nervous system or endocrine system nervous system or endocrine system

Homeostasis cont’dHomeostasis cont’d

•Two general points within Two general points within homeostasishomeostasis

Homeostatic Control Homeostatic Control MechanismsMechanisms

Communication within the body is Communication within the body is essential for homeostasis. essential for homeostasis.

Communication is accomplished chiefly Communication is accomplished chiefly by the by the nervousnervous and and endocrine systemsendocrine systems

which use neural electrical impulses or which use neural electrical impulses or blood borne hormones, respectively, as blood borne hormones, respectively, as information carriers.information carriers.

Regardless of the factor being Regardless of the factor being regulated(the variable)all homeostatic regulated(the variable)all homeostatic control mechanisms have control mechanisms have at least three at least three interdependent components .interdependent components .



The The firstfirst component, the component, the receptorreceptor, is , is some type of sensor that monitors the some type of sensor that monitors the environment and responds to changes, environment and responds to changes, called called stimulistimuli, by sending information , by sending information (input) to (input) to

thethe second second component, the component, the control control centercenter. Input flows from the receptor to . Input flows from the receptor to the control center along the so-called the control center along the so-called afferentafferent pathway. The control center, pathway. The control center, analyzes the input it receives and then analyzes the input it receives and then determines the appropriate response or determines the appropriate response or course of action.course of action.



The The thirdthird component, the component, the effector effector, , provides the means of response (output) provides the means of response (output) to the stimulus. Information flows from to the stimulus. Information flows from the control center to the effectorthe control center to the effector along along the the efferentefferent pathway. pathway.

The results of the response then The results of the response then feed feed back back to influence the stimulus, either to influence the stimulus, either depressing it (negative feedback) so that depressing it (negative feedback) so that the whole control mechanism is shut off the whole control mechanism is shut off or enhancing it (positive feedback) so or enhancing it (positive feedback) so that the reaction continues at an even that the reaction continues at an even faster rate. faster rate.


•Components of homeostatic control Components of homeostatic control mechanismsmechanisms

Homeostatic control Homeostatic control mechanisms are mechanisms are TWO:TWO:– Negative feedback mechanisms – the net Negative feedback mechanisms – the net

effect of the response to the stimulus is effect of the response to the stimulus is the shut off of the original stimulus or to the shut off of the original stimulus or to reduce its intensity I,e the original reduce its intensity I,e the original stimulus is reversedstimulus is reversed»E.g. – body temp, blood chemical levelsE.g. – body temp, blood chemical levels

– Positive feedback mechanisms – tend to Positive feedback mechanisms – tend to increase the original disturbance increase the original disturbance (stimulus) and push the variable farther (stimulus) and push the variable farther from its original value i.e original from its original value i.e original stimulus is intensifiedstimulus is intensified»E.g. – ovulation, blood clotting, birthE.g. – ovulation, blood clotting, birth

Negative Feedback MechanismsNegative Feedback Mechanisms Most homeostatic control mechanisms Most homeostatic control mechanisms

are negative feedback mechanisms. In are negative feedback mechanisms. In these systems, the output shuts off the these systems, the output shuts off the original stimulus or original stimulus or reduces its intensityreduces its intensity. . These mechanisms cause the variable to These mechanisms cause the variable to change in a direction opposite to that of change in a direction opposite to that of the initial change, returning it to its the initial change, returning it to its “ideal” value; thus the name “negative” “ideal” value; thus the name “negative” feedback mechanismsfeedback mechanisms


Negative Feedback LoopNegative Feedback Loop


A good example of a non-A good example of a non-biological negative feedback biological negative feedback

system system is a home heating system connected to a is a home heating system connected to a

temperature-sensing thermostat . temperature-sensing thermostat . If the thermostat is set at 20°C (68°F), If the thermostat is set at 20°C (68°F),

the heating system (effector) is triggered the heating system (effector) is triggered ON when the house temperature drops ON when the house temperature drops below that setting. below that setting.

As the furnace produces heat and warms As the furnace produces heat and warms the air, the temperature rises, and when the air, the temperature rises, and when it reaches 20°C or slightly higher, the it reaches 20°C or slightly higher, the thermostat triggers the furnace OFF.thermostat triggers the furnace OFF.


Example continuedExample continued This process results in a cycling of This process results in a cycling of

“furnace-ON” and “furnace-OFF” so that “furnace-ON” and “furnace-OFF” so that the temperature in the house stays very the temperature in the house stays very near the desired temperature of 20°C. near the desired temperature of 20°C. Your body “thermostat,” located in a part Your body “thermostat,” located in a part of your brain called the of your brain called the hypothalamushypothalamus, , operates in a similar fashion.operates in a similar fashion.


Negative Feedback: The Control of Negative Feedback: The Control of Body TemperatureBody Temperature

Homeostasis of Blood Homeostasis of Blood PressurePressure

Baroreceptors in Baroreceptors in walls of blood walls of blood vessels detect an vessels detect an increase in BPincrease in BP

Brain receives input Brain receives input and signals blood and signals blood vessels and heartvessels and heart

Blood vessels Blood vessels dilate, HR dilate, HR decreasesdecreases

BP decreasesBP decreases

Some of the variables that need to be Some of the variables that need to be regulated by negativeback mechanisms regulated by negativeback mechanisms includeinclude– Body temperature ,blood volume,Body temperature ,blood volume,heart heart

rate,blood pressure,the rate and depth rate,blood pressure,the rate and depth of breathing, and blood levels of of breathing, and blood levels of oxygen, carbon dioxide, minerals. oxygen, carbon dioxide, minerals. .etc.etc


Positive Feedback MechanismsPositive Feedback Mechanisms In positive feedback mechanisms, the In positive feedback mechanisms, the

result or response enhances the original result or response enhances the original stimulus so that the activity (output) isstimulus so that the activity (output) is acceleratedaccelerated. This feedback mechanism is . This feedback mechanism is “positive” because the change that “positive” because the change that occurs proceeds in the same direction as occurs proceeds in the same direction as the initial disturbance, causing the the initial disturbance, causing the variable to deviate further and further variable to deviate further and further from its original value or range. from its original value or range.


Positive feedback cont’dPositive feedback cont’d In contrast to negative feedback In contrast to negative feedback

controls, which maintain controls, which maintain manymany physiological functions or keep blood physiological functions or keep blood chemicals within narrow rangeschemicals within narrow ranges positive feedback mechanisms usually control positive feedback mechanisms usually control

infrequentinfrequent events that do not require events that do not require continuous adjustmentscontinuous adjustments

However, However, TWOTWO familiar examples of their familiar examples of their use as homeostatic mechanisms are the use as homeostatic mechanisms are the enhancement of enhancement of labor contractions labor contractions during birth during birth and and blood clotting.blood clotting.


Positive Feedback: Blood ClottingPositive Feedback: Blood Clotting

•In positive feedback an initial stimulus produces a response that In positive feedback an initial stimulus produces a response that enhances the change in the original condition. For instance:enhances the change in the original condition. For instance:

• Damage to blood vessel wall will cause release of chemicals.Damage to blood vessel wall will cause release of chemicals.

•Chemicals will trigger blood clottingChemicals will trigger blood clotting

•Clotting process increases release of chemicalsClotting process increases release of chemicals

•More chemicals means accelerated clottingMore chemicals means accelerated clotting

•Accelerated clotting means more chemicalsAccelerated clotting means more chemicals

Positive Feedback during Positive Feedback during ChildbirthChildbirth Stretch receptors in walls of uterus send Stretch receptors in walls of uterus send

signals to the brainsignals to the brain Brain induces release of hormone Brain induces release of hormone

(oxytocin) into bloodstream(oxytocin) into bloodstream Uterine smooth muscle contracts more Uterine smooth muscle contracts more

forcefullyforcefully More stretch, more hormone, more More stretch, more hormone, more

contraction etc.contraction etc. Cycle ends with birth of the baby & Cycle ends with birth of the baby &

decrease in stretchdecrease in stretch

Homeostatic ImbalanceHomeostatic Imbalance Homeostasis is so important that most Homeostasis is so important that most

disease can be regarded as a result of its disease can be regarded as a result of its disturbance, a condition called disturbance, a condition called homeostatic imbalancehomeostatic imbalance. .

As we age, our body’s control systems As we age, our body’s control systems become less efficient, and our internal become less efficient, and our internal environment becomes less and less environment becomes less and less stable. These events increase our risk for stable. These events increase our risk for illness and produce the changes we illness and produce the changes we associate with agingassociate with aging

Examples of homeostatic imbalance are Examples of homeostatic imbalance are provided throughout this course to provided throughout this course to enhance understanding of normal enhance understanding of normal physiological mechanisms. physiological mechanisms.


Final wordFinal word

Hard work is the only cure for Hard work is the only cure for hard lifehard life

I wish you all the best in your I wish you all the best in your academic pursuitacademic pursuit

You will all make itYou will all make it


21-dec-15introduction to physiology1 introduction to physiology dr. robert mbelwa...

Documents

term physiology

aspect of clinical physiology

different speciesmost

different systemscirculation

different animals

system function

muscles contractto

nerves different organs