Introduction to Physiology Dr. Ranjay Choudhary College Of Applied Medical Sciences Majmaah University

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PHYSIOLOGY What is Physiology? Greek Origins: Physis: Nature; Logy: Study Physiology is the study of biological function—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.

Physiology and pathophysiology Physiology (physio = nature; logos = study): study of how the body works to maintain life Study of the functions of cells, tissues, organs, organ systems, and organisms - cell  tissue  organ  organ system  organism Pathophysiology: how physiological processes are altered in disease or injury

THE SCIENCE OF PHYSIOLOGY BEGIN BEFORE THE BIRTH OF CHRIST. HOWEVER, THE FATHER OF MODERN PHYSIOLOGY IS THE FRENCH PHYSIOLOGIST CLAUDE BERNARD ( ). PHYSIOLOGY

Physiology Science of body functions Teleological vs Mechanistic views – Teleological – the why, explains purpose of a physiological process – Mechanistic – the how, explained in terms of cause and effect of physiological process Example: shivering Teleological - shivering elevates a low body temperature Mechanistic - when body temperature drops below normal, a reflex pathway causes involuntary oscillating skeletal muscle contractions which produce heat

Definition: human body contain many body fluid like blood, urine, saliva, sputum, tears, semen, milk, or vaginal secretions The major component of the human body is water, which is for 50 to 80% according to the age and gender. Changes with age: : Changes with age: Newborns – 75-80% of body weight is water One year – 65 % of body weight is water Adult – males 60%, females 50% Body fluid in Human Definition: Physiology (physo = nature; logos = study): study of how the body works to maintain life - cell  tissue  organ  organ system  organism

Organismal Level Chemical level Atoms combine to form molecules. Cellular level Cells are made up of molecules. Tissue level Tissues consist of similar types of cells Organ level Organs are made up of different types of tissues. Organ system level Organ systems consist of different organs that work together closely. Organismal level The human organism is made up of many organ systems. Cardiovascular system Organelle Molecule Atoms Smooth muscle cell Smooth muscle tissue Connective tissue Blood vessel (organ) Heart Blood vessels Epithelial tissue Smooth muscle tissue

Chemical or Molecular Levels Atoms in combination Complex protein molecules Protein filaments Organ System Level The heart Cellular Level Heart muscle cell Tissue Level Cardiac muscle tissue Organ Level Cardiovascular Reproductive Urinary Digestive Respiratory Lymphoid Endocrine Nervous Muscular Skeletal Integumentary Organism Level

Levels of Structural Organization Chemical Level - atomic and molecular level Chemical Level - atomic and molecular level Cellular level - smallest living unit of the body Cellular level - smallest living unit of the body Tissue level Tissue level Group of cells and the materials surrounding them that work together on one task Group of cells and the materials surrounding them that work together on one task 4 basic tissue types: epithelium, muscle, connective tissue, and nerve 4 basic tissue types: epithelium, muscle, connective tissue, and nerve

Molecular composition of the human body Water 67% Proteins 20% Carbohydrates 3% Lipids 10% Elemental composition of the human body Hydrogen 62% Oxygen 26% Carbon 10% Nitrogen 1.5% Other Elements: Calcium Phosphorus Potassium Sodium Sulfur Chlorine Magnesium Iron Iodine Trace elements 0.2% 0.06% 0.05% 0.04% 0.03% % % (see caption) Chemical and Molecular Level

Tissue Level of Organization Tissue level – Cells of similar shape and specialized function Four major tissue types – Muscle Specialized for contracting and generating tension – Nervous Specialized in impulse production and transmission – Connective Specialized for connecting and supporting – Epithelial Specialized for surface lining and exchange

Levels of Organization: Tissue _____tissue _____tissue _____tissue_____tissue Cells with similar functions grouped into the 4 primary tissues

Organ system of the body Tissue: A group of cells with similar structure and function plus the extracellular substances located between them is a tissue. The many tissues that make up the body are classified into four primary tissue types: Epithelial, Connective, Muscle, and Nervous. Organ: Organs are composed of two or more tissue types that together perform one or more common functions. The skin Stomach Eye And heart are examples of organs. Organ System: An organ system is a group of organs classified as a unit because of a common function or set of functions. In this text the body is considered to have 11 major organ systems: Integumentary, skeletal, muscular, nervous, endocrine, cardiovascular, lymphatic, respiratory, digestive, urinary, and reproductive

Body Systems

The Organism Collection of body systems working together to maintain life. Strive to maintain an internal balance – Homeostasis oxygen-review.com

The process through which a nearly stable internal environment is maintained in the body so that cellular functions can proceed at maximum efficiency. – Does not mean that composition, temperature, and other characteristics are absolutely unchanging HOMEOSTASIS Homeostasis is essential for survival and function of all cells Each cell contributes to maintenance of a relatively stable internal environment

Sensing and responding to changes in surrounding environment Control exchange of materials between cell and its surrounding environment – Obtain nutrients and oxygen from surrounding environment – Eliminate carbon dioxide and other wastes to surrounding environment Perform chemical reactions that provide energy for the cell Synthesize needed cellular components BASIC CELL FUNTIONS

In average young adult male: % of body weightBody composition 18%Protein, & related substances 15%Fat 7%Mineral 60%Water BODY COMPOSITION

Body cells are in contained in watery internal environment through which life-sustaining exchanges are made Extracellular fluid (ECF) - Fluid environment in which the cells live (fluid outside the cells) – Two components: Plasma Interstitial fluid Intracellular fluid (ICF) - Fluid contained within all body cells BODY FLUIDS

Fluid Compartments  60% of body weight Extracellular fluid (  1/3)  33% of TBW   20% of body wt Intracellular fluid (  2/3)  67% of TBW   40% of body wt Interstitial fluid  75% of ECF   15% of body wt Plasma  25% of ECF   5% of body wt Transcellular fluid CSFIntraocularPleuralPeritonealPericardialSynovial Digestive secretions BODY FLUIDS Water content in body is divided into 2 compartments:

Q. Calculate TBW for a 70 kg man. TBW = 60% of body weight TBW = 60% X 70 = 42 L of water How to calculate total body water (TBW)?

HOMEOSTASIS

ECF Anions: Cl - (108) HCO 3 - (24) Cations: Na + (142 mmol/L ) K + (4.2) Mg 2+ (0.8) Nutrients: O 2, glucose, fatty acids, & amino acids. Wastes: CO 2, Urea, uric acid, excess water, & ions. ICF Anions: Cl - (4) HCO 3 - (10) Phosphate ions Cations: Na + (14) K + (140) Mg 2+ (20) Nutrients: High concentrations of proteins. Differences between ECF & ICF

Homeostasis involves dynamic mechanisms that detect and respond to deviations in physiological variables from their “set point” values by initiating effector responses that restore the variables to the optimal physiological range. Two systems that maintain homeostasis are: Nervous system & Endocrine system MAINTENANCE OF HOMEOSTASIS

Nervous system – Controls and coordinates bodily activities that require rapid responses – Detects and initiates reactions to changes in external environment Endocrine system – Secreting glands of endocrine regulate activities that require duration rather than speed – Controls concentration of nutrients and, by adjusting kidney function, controls internal environment’s volume and electrolyte composition MAINTENANCE OF HOMEOSTASIS

Factors homeostatically regulated include Concentration of nutrient molecules Concentration of water, salt, and other electrolytes Concentration of waste products Concentration of O 2 = 100mmHg and CO 2 = 40 mmHg pH = 7.35 Blood volume 4-6 L and pressure 120/80 Temperature = 37 o C Factors controlled through Homeostasis

Homeostasis is continually being disrupted by – External stimuli heat, cold, lack of oxygen, pathogens, toxins – Internal stimuli Body temperature Blood pressure Concentration of water, glucose, salts, oxygen, etc. Physical and psychological distresses Disruptions can be mild to severe If homeostasis is not maintained, death may result Control of Homeostasis

In order to maintain homeostasis, control system must be able to – Detect deviations from normal in the internal environment that need to be held within narrow limits – Integrate this information with other relevant information – Make appropriate adjustments in order to restore factor to its desired value HOMEOSTATIC CONTROL SYSTEMS

Control systems are grouped into two classes – Intrinsic controls Local controls that are inherent (natural) in an organ – Extrinsic controls Regulatory mechanisms initiated outside an organ Accomplished by nervous and endocrine systems HOMEOSTATIC CONTROL SYSTEMS

Feedforward - term used for responses made in anticipation of a change Feedback - refers to responses made after change has been detected – Types of feedback systems Negative Positive HOMEOSTATIC CONTROL SYSTEMS

Negative feedback loop – Original stimulus reversed – Most feedback systems in the body are negative – Used for conditions that need frequent adjustment Positive feedback loop – Original stimulus intensified (increased) – Seen during normal childbirth Feedback Loops: Types

Receptor structures that monitor a controlled condition and detect changes Control center sets the normal range, receives input from the receptor and sends output when changes are needed Effector – receives directions from the control center – produces a response that restores the controlled condition Feedback Loop: 3 Main Components Negative feed back loop consists of:

Negative feedback loops are very common in the human body. Negative feedback loops are excellent mechanisms of controlling parameters and allow for the “fine-tuning” of physiological processes, such as blood glucose, oxygenation level and blood pressure. A negative feedback loop tends to bring a system back to equilibrium… Negative Feedback Loops in the Body

Negative Feedback Loop

Blood glucose concentrations rise after a sugary meal (the stimulus), the hormone insulin is released and it speeds up the transport of glucose out of the blood and into selected tissues (the response), so blood glucose concentrations decrease (thus decreasing the original stimulus). Homeostasis - Negative Feedback Loop

Baroreceptors in walls of blood vessels detect an increase in BP Brain receives input and signals blood vessels and heart Blood vessels dilate, HR decreases BP decreases Homeostasis of Blood Pressure

Positive feedback loops are rare in the human body. A positive feedback loop tends to push a system away from equilibrium. Examples: Stomach’s digestion of protein, and Childbirth The classic example of a positive feedback loop in the body is the action of oxytocin during labor… Positive Feedback Loops in the Body

Stretch receptors in walls of uterus send signals to the brain Brain induces release of hormone (oxytocin) into bloodstream Uterine smooth muscle contracts more forcefully More stretch, more hormone, more contraction etc. Cycle ends with birth of the baby & decrease in stretch Positive Feedback during childbirth

Positive Feedback: Blood clotting

Unit 1 Introduction Homeostasis 1.Define Physiology? Who is the father of modern biology? 2.Define Homeostasis? 3.Give any two examples of homeostasis? 4.What is feedback system? Name the types of feedback system? 5.Write about the components of Homeostatic mechanism? 6.What is negative feedback mechanism? 7.How is blood pressure regulated taking into account the negative feedback mechanism? 8.How is body temperature controlled taking into account the negative feedback mechanism? 9.What is positive feedback mechanism? Give example of positive feedback mechanism? 10. What is the mechanism of cooling body in summer? 11.What is the mechanism of warming body in winter? 12.How does body controls high and low blood sugar?