Human Physiology

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How to study physiology?How to study physiology?

1. 1. Take note :Take note :2.2. Ask: Ask: what what

whywhyhowhow

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Chapter one Chapter one

INTRODUCTION INTRODUCTION

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I. Definition of physiologyI. Definition of physiology

Physiology is one of the biological Physiology is one of the biological sciences which deals with the sciences which deals with the mechanisms of the mechanisms of the normal normal functionsfunctions of the living organism. of the living organism.

Goal of physiology :Goal of physiology :

to explain the physical and chemical factors to explain the physical and chemical factors that are responsible for the origin, that are responsible for the origin, development, and progression of lifedevelopment, and progression of life

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PhysiologyPhysiology

Plant PhysiologyPlant Physiology

Animal PhysiologyAnimal Physiology

Viral PhysiologyViral Physiology

Bacterial PhysiologyBacterial Physiology

human Physiologyhuman Physiology

In human physiology, we are concerned with the In human physiology, we are concerned with the specific characteristics and mechanisms of the specific characteristics and mechanisms of the human body that make it a living being. human body that make it a living being.

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One may ask often:One may ask often:

How does the heat beat?How does the heat beat?

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How does the skeletal muscle How does the skeletal muscle contract?contract?

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How does the lung breathe in OHow does the lung breathe in O22 and remove COand remove CO22 from the body? from the body?

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How is the urine How is the urine formed in the kidney ?formed in the kidney ?

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How is the food digested and How is the food digested and absorbed in the digestive systemabsorbed in the digestive system ? ?

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How are all bodily functions How are all bodily functions regulated by our nervous regulated by our nervous

system and endocrine system?system and endocrine system?

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II. The relationship between II. The relationship between physiology and clinical medicinephysiology and clinical medicine

Physiology is the basis of clinical medicine.Physiology is the basis of clinical medicine.

Duty of doctor: to prevent, diagnose and cure Duty of doctor: to prevent, diagnose and cure diseases , to keep healthdiseases , to keep health

For example : HypertensionFor example : Hypertension

BP: concept, normal value, formation and BP: concept, normal value, formation and its influencing factorits influencing factor

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III. History of PhysiologyThe Greek philosopher Aristotle (384–322 B.C.)

speculated on the function of the human body.Galen (A.D. 130–201) wrote widely on the subject

and was considered the authority until the advent of the Renaissance.

Physiology became a fully experimental science with the revolutionary work of the English physician William Harvey (1578–1657), who demonstrated that the heart pumps blood through a closed system of vessels.

However, the father of modern physiology is the French physiologist Claude Bernard (1813–1878), -homeostasis

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III. Foundation of PhysiologyIII. Foundation of Physiology

William HarveyWilliam Harvey

English English (1578–1657),

Famous physician and Famous physician and

Physiologist Physiologist

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the Motion of the Heart and Blood in Animals (1628)

1. The valves in the heart allowed blood to flow in only 1. The valves in the heart allowed blood to flow in only one direction. one direction.

2. The left and the right ventricles contracted together. 2. The left and the right ventricles contracted together. 3. Harvey 3. Harvey removed the heart from a living animal, it the heart from a living animal, it

continued to beat : pump. continued to beat : pump. 4. Harvey also used mathematical data to prove that 4. Harvey also used mathematical data to prove that

the blood was not being consumed: the blood was not being consumed: the heart could hold two ounces of blood. the heart could hold two ounces of blood. the amount of blood pumped was far greater the amount of blood pumped was far greater

than the amount that the body could make. than the amount that the body could make. He also estimated how much food and He also estimated how much food and

liquids a person could eat during a day. liquids a person could eat during a day. Blood had to be flowing through a 'closed circuit' . Blood had to be flowing through a 'closed circuit' .

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IV.IV. Fundamental characteristics Fundamental characteristics of living organismof living organism

MetabolismMetabolismGrowthGrowthDevelopmentDevelopmentReproductionReproductionExcitabilityExcitability

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1. Metabolism1. Metabolism

Definition: Definition: The complex of physical and chemical The complex of physical and chemical processes occurring within a living cell or processes occurring within a living cell or organism that are necessary for the organism that are necessary for the maintenance of life. maintenance of life.

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1. Metabolism1. Metabolism

Anabolism Anabolism the synthesis of complex molecules from simpler ones

CatabolismCatabolismthe breakdown of larger, more complex the breakdown of larger, more complex molecules into smaller, simpler molecules into smaller, simpler molecules, during which energy is molecules, during which energy is released for the activity of the body.released for the activity of the body.

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2. EXCITABILITY2. EXCITABILITYchanges of changes of

body functionbody function

StimulusStimulusstimulationstimulation

Response Response Reaction Reaction

Environmental Environmental ChangesChanges bodybody

Stimulus:Stimulus: the environmental change the environmental change that can induce a change of the body that can induce a change of the body functionsfunctionsResponse:Response: …………

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(1) Definition of excitability(1) Definition of excitability

The property that living organisms can The property that living organisms can react to stimulireact to stimuli is defined as excitability .is defined as excitability .

((classic)classic)

The property that living cells can elicit an The property that living cells can elicit an action potential to react to stimuli.action potential to react to stimuli.(Action potential is the index of (Action potential is the index of excitability)excitability)

action potentialaction potential

(modern)(modern)

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(2)(2) EXCITABLE CELL EXCITABLE CELL

The cells that can elicit an action potentialThe cells that can elicit an action potentiali.e. i.e. Muscle cell , neurons and glandular cellMuscle cell , neurons and glandular cell

（（ 33 ）） The types of response :The types of response :

-- an increase in activity-- an increase in activity

-- a decrease in activity-- a decrease in activity

1) 1) Excitation (excitatory Excitation (excitatory response): response):

2) 2) inhibition (inhibitory inhibition (inhibitory response):response):

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threshold

1tyexcitabili

the smallest intensity of stimulus needed to the smallest intensity of stimulus needed to elicit a minimal response or an action elicit a minimal response or an action potentialpotential

TThe higher the threshold needed, the lower he higher the threshold needed, the lower the excitability, vice versa.the excitability, vice versa.

threshold intensitythreshold intensity(Threshold(Threshold ，， threshold of stimulus)threshold of stimulus)

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II. Internal II. Internal environment environment

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Body fluid Body fluid (60% /body weight)(60% /body weight)

Interstitial fluid Interstitial fluid (15%)(15%)

Extracellular fluid (20%)

Intracellular fluid

（ 40%）

Plasma（ 5 ％）

What is the heaviest in our body?What is the heaviest in our body?

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Internal environment Internal environment is the environment in which the cells live, is the environment in which the cells live,

which is made up of which is made up of extracellular fluid..

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Claude BernardClaude Bernard ，， 1813—1878,1813—1878,French French

The father of modern PhysiologyThe father of modern Physiology

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homeostasis homeostasis ：：The Chemical and PhysicalThe Chemical and Physical conditions in conditions in

the internal environment are maintain the internal environment are maintain in a stable state.in a stable state.

stable ≠stable ≠ rigidity, can vary within narrow limitrigidity, can vary within narrow limit (normal physiological range)(normal physiological range)

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Body temperature Body temperature ≈≈3737 ℃ ℃

Arterial pHArterial pH 7.35-7.457.35-7.45

OO22 content content17.2-22.0 ml/100 ml17.2-22.0 ml/100 ml

Total lipidTotal lipid 400-800 mg/100 ml400-800 mg/100 ml

GlucoseGlucose 75-110 mg/100 ml75-110 mg/100 ml

Normal Normal Physiological rangesPhysiological ranges

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Homeostasis is the basis for Homeostasis is the basis for normal function of cells and the normal function of cells and the body.body.

Activities of cells and organs Activities of cells and organs lose homeostasislose homeostasis

Maintaining of homeostasis is Maintaining of homeostasis is depended on the activities of depended on the activities of cells and organscells and organs

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The golden goal of every organ : to mainThe golden goal of every organ : to maintain homeostasistain homeostasis

Organism in homeostasisOrganism in homeostasis

External changeExternal change Internal changeInternal change

Change results in loss of homeostasisChange results in loss of homeostasis

Organism attempts to compensateOrganism attempts to compensate

Compensation fallsCompensation falls

illnessillness

Compensation succeedsCompensation succeeds

wellnesswellness

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Regulation of Regulation of body functionsbody functions

the ability of an organism to maintain a stable internal conditions in a constantly changing environment

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Types of regulationTypes of regulation

I.I. Nervous regulationNervous regulation

II.II. Humoral regulationHumoral regulation

III.III. auto-regulationauto-regulation

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I. Nervous regulation:I. Nervous regulation:

(1) definition of reflex :(1) definition of reflex :

-- -- the the regularregular responses of the organism to responses of the organism to the stimulation under the mediation of the stimulation under the mediation of the the centralcentral nervous system. nervous system.

１１ . the basic manner of nervous . the basic manner of nervous regulation:regulation: reflexreflex

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(2) (2) Structural basis of reflex:Structural basis of reflex:

Receptor

Afferent nerve

Efferent nerve

Reflex Center

Effector

reflex arcreflex arcstimulus

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2. the types of reflex 2. the types of reflex ：：

unconditionedunconditioned conditionedconditionedformationformation congenital, inherited congenital, inherited acquiredacquired

Reflex arcReflex arc simple, fixed simple, fixed complex, variable complex, variable

centercenter low center low center higher centerhigher center

numbernumber limited limited limitlesslimitless

Significance Significance basic adaptation basic adaptation high adaptationhigh adaptation

unconditioned and conditioned reflexunconditioned and conditioned reflex

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II. II. Humoral regulationHumoral regulation

Definition:Definition: Regulation of carried out by Regulation of carried out by special chemicals produced by certain special chemicals produced by certain tissues through body fluid. tissues through body fluid.

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Types of humoral regulationTypes of humoral regulation

(3) (3) Paracrine Paracrine （（ local humoral regulationlocal humoral regulation ））Local Local chemicals →surrounding tissues or cellschemicals →surrounding tissues or cells

(2)(2)NeurocrineNeurocrineNeuronsNeurons secrete hormones →tissues or cells secrete hormones →tissues or cells

(1) (1) telecrine telecrine ：：Endocrine glands → Endocrine glands → hormoneshormones→ → bloodblood→ tissues or → tissues or

cellscells

(4) (4) AutocrineAutocrineChemicals by cells→to itselfChemicals by cells→to itself

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The characteristics of nervous The characteristics of nervous and humoral regulationand humoral regulation

longer longer

diffusediffuse

slowslow

shortershorter

accurate accurate

localizedlocalized

rapid rapid

DurationDuration

responseresponse

onsetonset

humoral humoral regulation :regulation :

nervous nervous regulation :regulation :

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III. auto-regulationIII. auto-regulation

A tissue or organ can respond directly to A tissue or organ can respond directly to the environmental change, depending the environmental change, depending neither on nervous nor on humoral neither on nervous nor on humoral regulation. regulation.

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Control systems of Control systems of the bodythe body

Cybernetics Cybernetics (The theoretical study (The theoretical study of communication and control of communication and control processes in biological, mechanical, processes in biological, mechanical, and electronic systems, especially and electronic systems, especially the comparison of these processes the comparison of these processes in biological and artificial systems.)in biological and artificial systems.)

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Types of control systemsTypes of control systems

I. Non-autocontrol system I. Non-autocontrol system

II.II. Feedback control system Feedback control system (autocontrol system) (autocontrol system)

III.III. Feed-forward control systemFeed-forward control system

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Composition of control systemComposition of control system

Control system

Controlled system

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I.I. Non-autocontrol systemNon-autocontrol system

Control system

Controlled system

Output variables

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II. Feedback control system II. Feedback control system (autocontrol system)(autocontrol system)

structure of autocontrol systemstructure of autocontrol system1) Control system and controlled system1) Control system and controlled system

2) A Closed loop 2) A Closed loop

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Autocontrol SystemAutocontrol System

comparator Control system

Controlled system

monitor

Controlling signals

Feedback

Output variables

Feedback:Feedback:The effect of the controlled part on The effect of the controlled part on the control part the control part

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Autocontrol SystemAutocontrol System

comparator Control system

Controlled system

monitor

Controlling signals

Feedback

Output variables

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Temperature↑

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+3

35-2

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1) negative feedback1) negative feedback

The feedback signals produce The feedback signals produce an effect an effect oopposite to that of pposite to that of the control system. the control system.

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EatingEating Blood glucose Blood glucose ↑↑

Insulin Insulin ↑↑

Cellular uptake of glucose Cellular uptake of glucose ↑↑

Pancreatic isletPancreatic islet

Blood glucose Blood glucose ↓↓

--

EatingEating Blood glucose Blood glucose ↑↑

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Blood glucose Blood glucose ↓↓

Insulin Insulin ↓↓

Cellular uptake of glucose Cellular uptake of glucose ↓↓

Pancreatic isletPancreatic islet

Blood glucoseBlood glucose↑↑

--

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Significance of negative Significance of negative feedbackfeedback

maintaining homeostasis:maintaining homeostasis:

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The feedback signal or output from the The feedback signal or output from the controlled system increases the action controlled system increases the action of the control systemof the control system

significancesignificance ：： accelerate the accelerate the completion of a physiological completion of a physiological process. process. For exampleFor example ：：Blood clotting, Micturition, defecation, Blood clotting, Micturition, defecation, parturitionparturition

2) Positive feedback2) Positive feedback

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Positive Feedback: Stimulatory.Stimulus trigger mechanisms that amplify the response and reinforces the stimulus.

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III. Feed-forward controlIII. Feed-forward control

The direct effect of interfere signal on The direct effect of interfere signal on the control system the control system

Interfere signal　

Control part

Controlled part

Output variables

monitor

Feed-forward control

Concept: a direct effect of stimulus on the control system before the action of feedback signal occurs.

Here the direct effect of the stimulus is termed disturb signal or interfere signal.

Example: Shivering before diving into the cold water

Thank you

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