• Metabolism (the sum of all the chemical processes that occur in the human body

there are 2 phases catabolism anabolism)

• Movement (includes motion of the whole body, individual organs, single cells, and

even tiny structures inside cells)

• Responsiveness (body's ability to detect and respond to changes)

• Reproduction (formation of new cells for tissue growth, repair or replacement or

the production of a new individual)

• Growth (increase in body size that results from an increase in size of existing

cells,)

• Differentiation (development of a cell from an unspecialized to a specialized state)

•Basic Life processes (certain processes that distinguish organisms (living things) from non-living things

Physiology: is the study of the functions of the human body of how

the body works, from cell to tissue, tissue to organ, organ to system,

and of how the organism as a whole accomplishes particular tasks

essential for life.

The study of physiology includes study not only of how each of

body systems carries out its functions, but also of the mechanisms

involved to regulate these activities in order to maintain homeostasis

under a variety of conditions

(Homeostasis Is the ability of the body to maintain a relatively stable internal

environment

What is Physiology?

Physiology: Start mainly by the questions How and

Why, and end by the explanation of the physical and

chemical factors that are responsible for the origin,

development, and progression of life Example:- How

do RBCs carry oxygen and Why do RBCs carry

oxygen?

The scope of physiology ranges from studying the

activities or functions of individual molecules and cells

to the interaction of our bodies with the external world

Levels of Organization

1. The Chemicals

2. The Cell

Levels of Organization of the Human BodyAtoms

Molecules

It is the smallest living unit of the human body (the most basic structural and functional unit of organisms) examples- Nerve cells - Blood cells - Muscle cells - Fat cells

The Tissue• Tissues are groups of cells, and the

surrounding environment, which work together to produce a specific function.

• There are only 4 types of tissues in the body:

• Epithelial tissue• Connective tissue• Muscle tissue• Nervous tissue

The Organ• Organs are structures that are

made of two or more different types of tissues.

• They have specific functions and a defined shape.

• The heart is an example of an organ.

• It is made of muscle, as well as connective and nervous tissue.

• The tissues work in concert to move blood through the body

Protection from environmental hazards; temperature controlSupport, protection of soft tissues; mineral storage; blood formation

Locomotion, support, heat production

Directing immediate responses to stimuli, usually by coordinating the activities of other organ systemsDirecting long-term changes in the activities of other organ systems

Internal transport of cells and dissolved materials, including nutrients, wastes, and gases

Defense against infection and disease

Delivery of air to sites where gas exchange can occur between the air and circulating blood

Processing of food and absorption of organic nutrients, minerals, vitamins, and water

Elimination of excess water, salts, and waste products; control of pH

Production of sex cells and hormones

Organ System Major Functions

Integumentary system

Skeletal system

Muscular system

Nervous system

Endocrine system

Cardiovascular system

Lymphatic system

Respiratory system

Digestive system

Urinary system

Reproductive system

HomeostasisAbility to keep the internal environment nearly constant

• For the body’s cells to survive and function properly, the composition and temperature of interstitial fluid must remain constant.

• Body’s cells are said to be in homeostasis when the internal environment contains:

The optimal concentration of gasesThe optimal concentration of nutrientsThe optimal concentration of ions and waterAt the optimal temperature

Homeostasis

• All body systems interact to maintain homeostasis through a combination of hormonal and nervous mechanisms.

• Alterations in homeostatic state = disease or dysfunction → death (Homeostasis is about staying alive).

• It is controlled by Negative Feedback Mechanism

Importance of homeostasis• The relatively stable internal environment needed to

maintain life and provides an optimal environment for cell function. How?

• Metabolic reactions are controlled by enzymes

• Enzymes work best in a narrow range of temperature & pH only

• So, it is important to keep the internal environment as steady as possible

1-12

Homeostatically regulated Variables

Body Temperature.

Blood Composition (ions, sugars, proteins).

Blood Gases (O2 , CO2).

Acid-Base Balance (pH).

Blood pressure, cardiac output, Heart rate.

Respiratory rate and depth.

Secretions of endocrine glands (hormones).

• Set point: The ideal normal value of a variable (e.g. body temperature 37oC, pH 7.4)

• Variables fluctuate around the set point to establish a normal range of values

• Blood pressure (100 - 140 mmHg)• Heart rate (60 - 100 beat/min)• Respiratory rate (12 - 16 cycle/min)• Plasma Ca++ (9 - 11 mg/dl)

Homeostatic control mechanisms Sensory receptors, Control centre, Effectors

• The 3 interdependent components of control mechanisms are:

• Receptor: detects any changes in the environments and sends input signals along afferent pathway to the control center.

• Control center: determines the set point at which the variable is maintained and sends output signals along efferent pathway to the effector.

• Effector: structures that respond to the stimulus and restore the variable to the optimal physiological range.

• E.g. Increase in blood sugar levels or body temperature

Stimulus:Produceschangein variable

1

2

3

Changedetectedby receptor

Input:Informationsent alongafferentpathway to

5 Response ofeffector feedsback to influencemagnitude of stimulus andreturnsvariable tohomeostasis

Variable (in homeostasis)

Imbalance

Imbalance

Receptor (sensor)

Controlcenter

4 Output:Information sentalong efferentpathway to

Effector

Homeostatic Control Mechanisms

E.g. Regulation of body temperature

E.g. Regulation of blood glucose

BODY FLUIDS COMPARTMENTS

ICF= Intra Cellular FluidECF= Extra Cellular FluidISF= Interstitial fluid