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Introduction. Instructor: Li Li. Department of Physiology. Jining medical college. Office: 0850 physiological sciences. Email: [email protected] Introduction. ⑴ Definition and Scope of Physiology. ⑵ Structure and Fundamental Characteristics of Living Organism.

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slide1

Introduction

Instructor: Li Li

Department of Physiology

Jining medical college

Office: 0850 physiological sciences

Email: [email protected]

slide2

Introduction

⑴ Definition and Scope of Physiology.

⑵ Structure and Fundamental Characteristics of Living Organism.

⑶ Internal Environment, Homeostasis and Biorhythm.

⑷ Regulation of Body Function.

slide9

Definition and Scope of Physiology

Definition

Physiology is the study of how living organisms work. It is a study of the normal functions of organs and organ systems of the body, the conditions under which these functions are carried out and the mechanisms by which they are achieved.

Scope

① whole organism (interplay of many separate organs).

② organs and organ systems.

③ Molecule and cell.

slide10

Salty food

Excretion of sodium in the urine

slide11

gone wrong - disease

Definition and Scope of Physiology

Status

① Many areas of function are still poorly understood.

② The integration of molecular biology with physiology will provide an ever-sharper view of how our bodies work.

③ Physiology is essential for the study and practice of medicine.

normal function - physiology

slide12

⑵ Structure and Fundamental Characteristics of Living Organism

Structure of Living Organism.

The definition and multiplication and differentiation and classification of cell.

Fundamental Characteristics of Living Organism.

Three characteristics.

slide14

Structure of living organism

Cell

The basic units of Living Organisms. The simplest structural units into which a complex multicellular organism can be divided and still retain the functions characteristic of life are called cells.

Multiplication

A single cell divides to create two cell.

Differentiation

①Definition: The process of transforming an unspecialized cell into a specialized cell.

②Effect:The formation of tissues and organs and organ systems.

slide15

Structure of living organism

Cell

Classification (according to the function they perform)

⑴ Muscle cells .

①generate the mechanical forces that produce movement.

②Be classified into skeletal, cardiac, smooth muscle cells.

③form muscle tissue.

⑵Nerve cells.

①initiate and conduct electrical signals.

②control the activities of other cells .

③form nerve tissue.

⑶ Epithelial cells.

⑷ Connective tissue cells.

slide16

Structure of Living Organism

Cell

Classification

⑶ Epithelial cells.

① For selective secretion and absorption of ions and organic molecules and for protection.

②form epithelial tissue .

⑷ Connective tissue cells.

① Connect, anchor, and support the structures of the body.

②form connective tissue .

slide17

Figure Classification of muscle cell.

① skeletal muscle; ② cardiac muscle; ③ smooth muscle.

slide22

multiplication

fertilized egg

two cells

four cells

Spherical mass

differentiation

differentiation

epithelial tissue

muscle tissue

nerve tissue

connective tissue

cell

tissue

organs and organ systems

Unspecialized cell

Specialized cell

organ and organ system

slide24

Fundamental Characteristics of Living Organism

⑴ Metabolism .

① All the chemical reactions in all the cells of the body.

② It include the energy and material metabolism.

⑵Excitability.

Definition: The property of living organisms that permits them to react to stimuli.

Manifestation: Action Potential.

Assessment: Intensity and time period of stimulus.

⑶ Reproduction.

Help to maintain static conditions and the automaticity and continuity of life.

slide25

⑶ Internal Environment, Homeostasis and Biorhythm.

Body Fluid Compartments and Internal Environment

① The composition of body fluid.

② The definition of internal environment.

Homeostasis

① The definition and characteristics of homeostasis.

Biorhythm

① The definition of biorhythm and circadian rhythm.

② The effect of biorhythm on homeostasis.

③ The characteristics of biorhythm.

slide26

Internal environment

Extracellular fluid

Intracellular fluid

plasma

Interstitial fluid

Figure Body fluid.

slide27

Intracellular fluid (2/3)

body fluid

plasma (20%)

extracellular fluid (1/3)

interstitial fluid (80%)

Body Fluid Compartments and Internal Environment

Composition

internal environment

Internal environment

The extracellular fluid are the ions and nutrients needed by the cells for maintenance of cellular life, and all cells live in the environment, so extracellular fluid is called internal environment.

slide29

Intracellular fluid

membrane

Extracellular fluid

Figure Significance of concentration difference.

slide30

Homeostasis

Definition

A state of reasonably stable balance between physiological variables (a stable state of internal environment).

① Homeostasis is a dynamic, not a static process.

② It can be quantified by Time-Averaged Means.

③ The maintenance of homeostasis rely on a wide variety of control system.

④Nonhomeostatic state can have life-threatening consequences.

slide32

Biological Rhythms

Definition

A characteristic of many body functions changesrhythmically.

Circadian rhythm

Circadian rhythm is the most common type, which cycles approximately once every 24 h.

① waking and sleeping.

② body temperature.

③ hormone concentrations in the blood.

④ the excretion of ions into urine and so on.

slide33

Biological Rhythms

Effect on homeostasis

They add an anticipatory component to homeostatic control system, in effect a feedforward system.

Characteristic

① They are internally driven, and they are free-running rhythms( the biological rhythms persisted in the complete absence of environmental cues).

② Environmental time cues can entrain a circadian rhythm to 24h, and they also function to phase-shift rhythms( rest the internal clock).

③ The suprachiasmatic nucleus in the hypothalamus functions as the principal pacemaker for circadian rhythms.

slide34

suprachiasmatic nucleus

optic chiasma

Figure The neural basis of body rhythms.

slide35

⑷ Regulation of Body Function.

General Characteristics of Homeostatic Control System.

Feedback System.

Resetting of Set Points.

Feedforward Regulation.

Components of Homeostatic Control System.

Processes Related to Homeostasis.

slide36

General Characteristics of Homeostatic Control System

① Homeostatic control systems include nerve system and hormonal system.

②The nerve system is composed of three major parts: the sensory input portion, the central nervous system and the motor output portion.

③The hormonal system include eight major endocrine glands that secret chemical substances called hormones.

④The regulation of internal environment include nervous regulation and hormonal regulation and auto-regulation.

⑤ Hormonal system and nerve systems complement each other to maintain homeostasis.

slide37

The sensory input portion

The motor output portion

The central nervous system

Figure The nerve control system.

slide38

Figure Endocrine system

1 Hypothalamus; 2 Pituitary gland; 3 Thyroid gland; 4 Pancreas; 5 Adrenal gland; 6 Testicle (male only); 7 Ovary (female only) ; 8 Parathyroid glands .

slide39

Feedback System

Classification

① Negative feedback system.

② Positive feedback system.

Negative feedback system

A change in the variable being regulated brings about responses that tend to push the variable in the direction opposite to the original change, Homeostatic control operates mainly on negative feedback.

Example: the thermoregulatory system; enzymatic processes and so on.

Positive feedback system

An initial disturbance in the system sets off a train of events that increase the disturbance even further, less frequently seen in biological systems.

Example: the process of parturition and micturition and the blood coagulation and so on.

slide40

Effector

Normal

Figure Negative feedback system.

slide41

Negative feedback

BP

BP

Enzymes

C6H12O6+O2

CO2+H2O+ATP

Figure Example of Negative feedback.

slide44

posterior pituitary gland

fetus

oxytocin

uterus

pelvis

Figure Process of parturition.

slide45

Resetting of Set Points

Set point

The values that the homeostatic control system are trying maintain.

Characteristics of Set point

① The set point for many regulated variables can bephysiologically altered or reset.

② The set point can be reset in response to external stimuli such as bacteria, and it also occur on a rhythmical basis every day.

③ It is often possible to keep one property relatively constant only by moving others away from their usual set point, so it is not possible for everything to be held relatively constant by homeostatic systems.

slide46

Homeostatic control system

Homeostatic control system

Set point

37℃

Set point

38℃

37℃

fever

Chills and shivering

Create heat

temperature

( Inhibits proliferation of pathogens)

pathogens

slide49

Feedforward Regulation

Definition

Feedforward regulation anticipates changes in a regulated variable, improves the speed of the body’s homeostatic responses, and minimizes fluctuations in the level of the variable being regulated.

Example

① when it becomes cold, you will wear more clothes.

② When you see the picture of delicious food, you salivate.

③Your heart beats faster before you start running.

slide50

Components of Homeostatic Control System

Reflexes

A reflex is a specific involuntary, unpremeditated, unlearned “built-in’’ response to a particular stimulus.

Many of homeostatic control system belong to the general category of stimulus-response sequences known as reflexes.

Reflex arc ( the pathway mediating a reflex)

① receptor

② afferent pathway

③ integrating center

④ efferent pathway

⑤ effector

slide51

Integrating center

Efferent pathway

Afferent pathway

Smooth muscle

Effector

Receptor

Skeletal muscle

Begin

Body temperature

Response

Heat loss

Stimulus

Heat production

Negative feedback

Specific neurons in the brain

Endocrine gland

Nerve endings

hormone

Figure General components of reflex arc.

The present usage of reflex was not restricted to the nervous system!

slide52

Components of Homeostatic Control System

Local Homeostatic Responses

Like a reflex, a local response is the result of a sequence of events proceeding from a stimulus.

Unlike a reflex, the entire sequence occurs only in the area of the stimulus.

The significance of local responses is that they provide individual areas of the body with mechanisms for local self-regulation.

Intercellular Chemical Messengers

① Hormones

② Neurotransmitters

③ Paracrine agents

④ Others.

slide57

Day 1

Heat chamber

Heat chamber

Temperature and the volume of sweat are measured.

30min

Day 2-9

Temperature and the volume of sweat are measured.

1-2h

Results: on day 10, he sweat earlier and much more profusely than he did on day 1, and his body temperature does not rise to nearly the same degree.

Conclusion: he become acclimatized to the heat.

slide58

Processes Related to Homeostasis

Adaptation and Acclimatization

Adaptation

A characteristic that favors survival in specific environments. Homeostatic control systems are inherited biological adaptations.

Acclimatization

An improved ability to respond to an environmental stress, it is a type of adaptation.

The representation of acclimatization is varied. Some are reversible, some are irreversible.

slide60

GI tract

Lungs

Food

Air

Pool

Metabolism

Excretion

Synthesis in the body

Storage depots

Reversible incorporation into other molecules

DISTRIBUTION

NET GAIN

NET LOSS

Figure Balance diagram for a chemical substance.

slide61

Processes Related to Homeostasis

Balance in the homeostasis of chemicals

① The balance of substances in the body is achieved by matching inputs and outputs.

② Total body balance of a substance may be negative, positive, or stable.

slide62

Summary

⑴ Definition and Scope of Physiology.

⑵ Structure and Fundamental Characteristics of Living Organism.

⑶ Internal Environment, Homeostasis and Biorhythm.

⑷ Regulation of Body Function.

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