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

What is Physiology? 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

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

Levels of Organization of the Human Body 1. The Chemicals 2. The Cell Atoms 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 Epithelial tissue Connective tissue Muscle 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

Organ System Major Functions Protection from environmental hazards; temperature control Integumentary system Support, protection of soft tissues; mineral storage; blood formation Skeletal system Muscular system Locomotion, support, heat production Directing immediate responses to stimuli, usually by coordinating the activities of other organ systems Nervous system Directing long-term changes in the activities of other organ systems Endocrine system Internal transport of cells and dissolved materials, including nutrients, wastes, and gases Cardiovascular system Lymphatic system Defense against infection and disease Respiratory system 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 Digestive system Elimination of excess water, salts, and waste products; control of pH Urinary system Reproductive system Production of sex cells and hormones

Ability to keep the internal environment nearly constant Homeostasis Ability 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 gases The optimal concentration of nutrients The optimal concentration of ions and water At 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

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).

Copyright The McGraw-Hill Companies, Inc Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display 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

Homeostatic Control Mechanisms 3 Input: Information sent along afferent pathway to 4 Output: Information sent along efferent pathway to Control center Effector Receptor (sensor) 2 Change detected by receptor 5 Response of effector feeds back to influence magnitude of stimulus and returns variable to homeostasis Stimulus: Produces change in variable 1 Imbalance Variable (in homeostasis) Imbalance

E.g. Regulation of body temperature

E.g. Regulation of blood glucose Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display E.g. Regulation of blood glucose

BODY FLUIDS COMPARTMENTS Total body weight TBW = 60% ICF = 40% ECF = 20% Plasma = 5 % ¼ ECF ISF = 15 % ¾ ECF Transcellular F BODY FLUIDS COMPARTMENTS ICF= Intra Cellular Fluid ECF= Extra Cellular Fluid ISF= Interstitial fluid