Lecture 1 Functions of Human Body and Biophysics PDF

Foundations of Body Functions and Biophysics Functional Organization of the Human Body, Body Fluids and Homeostasis Prof Dr. Abdelaziz M. Hussein Prof and Chairman of Medical Physiology Department Contacts : Email: [email protected] Mob. #: +201002421140 Of...

Foundations of Body Functions and Biophysics Functional Organization of the Human Body, Body Fluids and Homeostasis Prof Dr. Abdelaziz M. Hussein Prof and Chairman of Medical Physiology Department Contacts : Email: [email protected] Mob. #: +201002421140 Office hours : 10.0 AM- 11.0 AM Tuesday, Thursday Lecture Objectives At the end of this lecture you will be able to: 1) Describe the functional organization of the human body 2) Recognize the components of body fluids 3) List the main differences between ICF and ECF 4) List the functions of the body water 5) Explain the mechanisms of regulation of body water 6) Define the concept of homeostasis and list its mechanisms and significance  01 Organization of the human body Contents 02 Body fluids and its distribution 03 Body Water and its functions and regulation 04 Concept of homeostasis and its regulatory mechanisms  Organization of Human Body 1 Outcome  The human body is made up of different systems e.g. digestive system, whose functions are coordinated together  Each system consists of many organs that are made up of many tissues with complementary functions  Each tissue consists of millions of cells.  The cell is the basic unit of structure and function in the body  The Cell: Basic Structure and Function  The cells are surrounded a cell or plasma membrane which allows selective communication between the intracellular and extracellular compartments.  These cells contain a mass of cytoplasm, cell nucleus and numerous other membrane-bound structures called cell organelles (little organs) e.g. mitochondria and ribosomes.  Each organelle performs specific function (ribosomes help in protein synthesis, and mitochondria help in production of energy) that contribute to the cell’s survival  Body Fluids Def 2  Body fluids are solutions of water containing; i) Organic molecules (carbon-containing molecules such as carbohydrates, lipids, proteins, and nucleic acids) ii) Inorganic molecules and iii) Ions (atoms with a net charge) Value:  About 65% of total body weight i.e. 40-42 L in an adult weighing 70 Kg Organization of Body Fluids 3 Intracellular Fluid (ICF) Extracellular Fluid (ECF) Fluid inside cells Fluid outside cells 2/3 of Total body fluids 1/3 of Total body fluids i.e. 28 Liters i.e. 14-15 Liters ECF ECF ICF 10  ECF is known as the internal environment that supplies the cells with nutrients and other substances  ECF is composed of; Plasma Interstitial fluid Transcellular fluid Fluid inside blood vessels Fluid inbetween cells and lymph Fluid in body vessels cavities e.g. CSF About 3- 3.5 L About 10- 12 L About 1 L 11  The ECF contains large amounts of Na+, Cl-, and HCO3 ions, while ICF contains large amounts of K+, Mg2+, and HPO4 ions  These differences are extremely important to the life of the cell. Concentration in mmol/L Ion ICF ECF Na+ 10 140 Cations K+ 160 4 Ca+2 10-4 2 Cl- 3 115 Anions HCO3- 10 28 Proteins 55 10 Body Water Percentage: 60% of the total body weight in adult men 50% of BW in adult women because their bodies contain much fat. More than 70% of BW in infants, so water loss leads to rapid dehydration. In old age the water content is decreased 15 1. Important for chemical reactions inside the body 2. Acts as powerful solvent that dissolve various substances 3. Acts as a vehicle that carries nutrients and gases 4. Important in regulation of body temperature 5. Moistens tissues such as mouth, eyes and nose, and lubricates joints. 6. Important for many functions such as formation of digestive secretions in GIT, absorption of fluids at capillaries and filtration in kidneys Regulation of Water Balance Def  Body water is kept constant by adjusting water input and water output Insensible water loss (about 700ml) Sweating (100 ml) Endogenous water 200 ml/day Feces (about 100ml) Exogenous water Urine (about 1500 2200 ml/day ml) Water Input Water output 2400 ml/day 2400 ml/day 18 ↓ blood volume Thirst Center Thirst sensation ↑ plasma osmolarity Increased water intake ↓ plasma osmolarity ↑ blood volume 19 ↓ blood volume Hypothalamus ↑ plasma osmolarity ↓ed Urine Volume ADH ↓ plasma osmolarity Posterior Pituitary ↑ blood volume 20 Concept of Homeostasis Def.,  They are the mechanisms that keep the internal environment constant. Importance:  This is very important as the cells lie in the internal environment  This keeps the normal cellular functions as body water, temperature, blood glucose, ions, pH and arterial blood pressure (ABP) 22 Def  Feedback mechanisms are the mechanisms that keep the functions of the system constant Negative Feedback Positive Feedback 23  Keep the environment constant as the response inhibits the stimulus The most common type of feedback Examples: a) ↑ CO2 (stimulus) → hyperventilation (response) → washout of excess CO2 → ↓ CO2 to normal. c)↑ arterial blood pressure (ABP) (stimulus) → reflex vasodilatation and ↓ heart rate (response) → ↓ arterial blood pressure back to normal. 24 25  Disturb the environment as the response stimulate the stimulus The less common type of feedback Examples: a) Death cycles→ fatal cycles leads to death In heart failure → decreased cardiac output (stimulus) → decreased arterial blood pressure → decreased coronary blood flow (response) → more heart failure 26 b) Some positive feedback cycles are useful e.g. during labour: During delivery of the baby, the dilatation of the cervix (stimulus) → increases the uterine contractions→ descent of baby → more cervical dilatation → more uterine contractions (response) → more descent of baby, till complete labor 27  The cell is basic unit of the human body  Body fluids constitutes 65% of TBW and divided into ICF and ECF  The composition of ICF and ECF is not the same Summary & Wrap up  Body water is kept constant by balance between water input and output  Homeostasis is to keep the internal environment constant  Negative feedback keep the homeostasis but positive disturb homeostasis  Questions 1-The intracellular fluids contain 2-As positive feedback mechanism is high concentrations of: important in regulation of; a) Na ions a) Regulation of arterial blood pressure b) Proteins b) Regulation of body temperature. c) Chloride ions c) Regulation of blood level of glucose d)Calcium ions d) Delivery of the baby during labour e) HCO3 ions e) Regulation of blood pH  References 1. Costanzo, Linda S. "BRS Physiology (Board Review Series)." (2018). 2. Ganong, William F. "Review of medical physiology." (2020). Discussion and Feedback THANK YOU